Reptile & Amphibian Forums

How do you sex a very young "hopper" before the nads drop in males? I've heard the distance from the two orifices is longer in males or something.

It's all in their head structure...haha j/k
That's correct, the males' tiddler or whatever you want to call it is slightly further from its anus than a female's is. Also the male's tiddler is often a bit longer. Just compare several and grow them up a couple weeks and you'll know for sure. It's pretty easy once you know what to look for... Cheers, Lance

Krusty
I'll post a photo for you.
Mike
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Mike's Monitors!

Thanks. Much appreciated. The reason i ask is that when i reintroduce females back (after pinkies are gone or grown to self-eating), i am getting some killing issues. This leads me to buy more mice from a pet store/herp shop (which are usually very young). I'd like to get a 1:5 together as juvi's and see if there's less killing going on. There is always constant food and water, and i don't pack them into trays. So i'm a little confused w/ the territoriality. My rat pairs are baby-machines (none of this crap), but i need pink or fuzzy mice for my Kimberley monitor and ackies.

Oh yeah, i saw the wildest thing today at the pet shop. A huge female rat was kept alone in a 10 gallon fish tank. The pet store girl lifts up the rat and there are approx. 20 pinky MICE suckling off the rat. She said teh rat just keeps lactating if there are any pinks (mice,too) and it keeps the pinkies that come in from dying. That blew me away.

Yeah I have that problem sometimes too, not really sure what causes it. I have the best luck setting up my groups when they are just weaned. For some reason, they tend to not kill the males that way. If I have older female mice kill off their male, it's pretty much like volunteering to be argus food. Since I think it is easier to raise up a new group all together than it is to pair up older mice with new males... :/
Guess its the same way with monitors though eh!? Haha

O just an interesting fact that I found while researching highly reproductive mouse strains the other night: I read that a study was done recently on a 1.5 group of mice, the study results said that within a year and a half of the original group reaching maturity, 1 million offspring had been produced from that single line! ...Just thought that was pretty impressive so thought I'd share. Cheers, Lance

just as an observation when I bred mice. I found that a group of females that live together before any of them became pregnant got along well. But, when I threw a female in that was already pregnant viscous fights and death would occur.

I have been breeding fancy rats and mice for 16 years. I have found that what you are experiencing can be bred out of your colony. Example: If you have a female that eats babies, get rid of her and keep none of her offsping as breeders. If you have females that don't foster pups other than hers, get rid of her and keep none of her offspring as breeders. And so on. Try to keep a "family of breeders". Never remove the adults or put new ones in unless you HAVE to. Especially if you are hhaving fighting/cannabalism problems. I do keep a 40 gallon cage with 30 mice, 2 males rest females just to get them pregnant. Then I have a 10 gallon that I put the pregnant ones in to deliver and raise their babies. I don't have anything that needs to eat mice, I breed them because they are pretty. I breed rats for feeders. When I have pets that need to eat mice my breeding system is much different. I have found that personnalities and behaviors are genetic with breeder rats and mice. I work with several rodent vets and they do not know of any viruses that cause the problems Frank is referencing. Good luck
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Shannon in Reno
1 savannah monitor (Pombe-means "beer" in Swahili)
6 dogs
1 cat
32 rats
50 mice
54 chickens
2 beardies
1 black rat snake
~100 hissers
1 giant milipede

I am not sure what to tell you, but that is not normal. I am a small scale mouse breeder, produce around 5 to 6 thousand a week. I do not see that at all, unless I mess up something. We can switch and change, add and subtract. I even have bins of old animals that we throw in handfulls of pinkies and fuzzies and they normally take good care of them.

So all I can say is, something is wrong. Now let me add some heresay. Petshop mice are often exposed to virus carried by other rodents and in particular rats(told to me by many Huge mouse breeders(plus tens of thousands a week) These virus do not kill mice right off, but weakens them and causes them to be very finikie and prone to canibulism. And commonly dying after the first or second clutch. By the way, one friend spent 5 thousand dollars in lab fees to find this out.

For that reason, I do not allow any outside rodents into my colony. And so far so good.

Also years ago, I bred rats and I had one female that would nurse fuzzie squirrels(roundtail ground squirrels)(picture tiny prairie dogs) that was about as funny as it gets, the roundtails would stand on their hind legs(think prairie dogs) and whistle. The mother rat would just sit and stare at them.

Try to find some successful mouse breeder and get your mice from them. Cheers

hahahha...small scale is 5 to 6 thousand a week. Sweet Jebus that's a lot of friggen mice! I know it's all relative...you know some of the serious mice breedin folks...but still caught me off guard. I never realized I guess just how many mice your operation takes.

Ground squirrel story is classic. "The mother rat would just sit and stare at them." - that had me chuckling all day.

I used to have to trap a species of ground squirrel for a study my brother (one of dem der scientist folks) was doing on esterus production, etc (we be studying varmint poontang he used to say). I'd place a pvc tube with screen covering one end over their hole and pour a little water in there...THUMP. We always felt badly bothering them. In fact that led my brother away from live animal research for this reason.

Anyway...funny stuff.

Tom

Krusty
I don't get the whole reintroduce thing?
I keep 1.5 in rat sized lab cages and never pull pregnant females! The only time I pull them is when they are retired.
Mike
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Mike's Monitors!

Rats are so awesome.
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Shannon in Reno
1 savannah monitor (Pombe-means "beer" in Swahili)
6 dogs
1 cat
32 rats
50 mice
54 chickens
2 beardies
1 black rat snake
~100 hissers
1 giant milipede

I keep my mice together constantly, no seperating pregnant females etc.. I have had females take care of other females babies. I can pick them all up and clean cages without it bothering them (even if they have babies). I haven't had them eat each other or any of that other stuff some people are mentioning.

I can say the same for my rats as well. I got both my rats and mice from a breeder who produces thousands of them a week. They are all housed together so perhaps that is why my rats have never made my mice sick??

I would say get them from someone who is already producing them rather then a pet shop.

Yeah, i think next frozen order from the breeder will include a hundred or so live ones. I'm going to build one of those racks like you pictured, Jody. Fish tanks are a pain in the rear and take up too much space.

If you want just shoot me an email and I can send you off the instructions on how to build the racks I made.

Female left, male right, Sorry for the quaility of the photo.
Mike

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Mike's Monitors!

Don’t be sorry for the photo quality, theirs none!
But you deserve a 10 for trying tough, lol
Now we know the wife takes your monitor shots, thankfully!

Hope all is well
Rgds

!
Mike
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Mike's Monitors!

You don’t need them, theirs a contrast adjustment on your pc, lol

Man on my screen this photo was black as night.
How are the monitors doing?

Rgds

Could you please leave me my pic style.... Don't try, you can't do it my way
Hihihi! On this pic Steeve we can clearly see this monitor refuse food.
Take care!

Steeve
All of my Jobiensis are doing great!
Did you ever rebuild your collection after your situation?
Mike

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Mike's Monitors!

I have a much smaller collection, mostly tree monitors and agamas, to be honest a few weeks ago I was still to weak to handle any medium size monitor, there was to many risk involved for me to keep them.

However I just finished my blood treatment and this week I actually bench pressed 50lbs WOW, my health is improving and my passion for the big guys is stronger then ever.

I wanted to stop keeping monitors entirely, but I cant, it’s like an addiction.
Every time I look at some empty cages I visualise something to put in them.

To calm my impulse I simply look in my freezer, sometimes it works nowadays not much.
What can I say this drug has a hold of me!

Rgds

Steeve
50 lbs is good for a guy with one nut. lol...that was a good one!
Hang in there Brother!
Mike

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Mike's Monitors!

Its easy, apply a tiny bit of pressure to the stomach and out pop the nads, like popping snakes only much easier. On Sundays, I sex many hundred. hahahahahahaha true too. Cheers

Testicles are supossed to drop naturally. I know that it is painful to squeeze and pop them out. The pick Mike posted it a great guide. Just because an animal is to be a feeder doesn't mean that it should not be cared for as well as ones that are not
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Shannon in Reno
1 savannah monitor (Pombe-means "beer" in Swahili)
6 dogs
1 cat
32 rats
50 mice
54 chickens
2 beardies
1 black rat snake
~100 hissers
1 giant milipede

hheemmiinn
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Mike's Monitors!

hahahahahahahahahaha I am sorry, but if you knew how to do it, it is no more bother to them then moving them from on cage to another.

I understand you "want" to rationalize that your kindness somehow makes it better for you to raise mice and KILL them all off. (they all will die very soon) It doesn't.

Consider mice crawl thru very small holes which is far more pressure then it takes to pop them.

I am glad your so nice to your mice. Good day, I said GOOD DAY

What you are seeing when you push on the pups abdomon is fatty tissue not the testicles going into the scrotum. By forcing the testicles out of the abdomon can cause reproductive problems and hernia. Rodents testicles naturally descend much later than humans. Humans typically descend before they are born. Rats and mice 3-4 weeks of age. The gubernaculum is what controls all mammal testicle descent. By the time a mouse is squeezing through holes their testicles are dropped. Nothing should ever suffer and should be taken care of with the same quility as "pets" before they are to die. And to die in a human manner. Proper food, water, clean housing, and cervical dislocation or CO2.
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Shannon in Reno
1 savannah monitor (Pombe-means "beer" in Swahili)
6 dogs
1 cat
32 rats
50 mice
54 chickens
2 beardies
1 black rat snake
~100 hissers
1 giant milipede

Shannon
CO2 looks like a horrible death!
I use CO2 for mass killings only.
If I were a Mouse I would rather take the "hit", SAMACK it's over, no choking, no writhing just an immediate death!
Mike
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Mike's Monitors!

CO2 and cervical dislocation are 2 of the methods deamed as humane according to the AVA American Veterinary Association. Cervical dislocation is much better then wacking them. Cervical dislocation with adult rats is VERY tuff. They come after you and if you don't get them the first time, forget it. Thats the only time I wack them. Wack then dislocate. I only CO2 when I have 5 or more. I have found that a cloths pin is perfect for dislocating mice. Put the head in the pin and pull the tail. I put a towel over adult rats heads to get a good grip on the head. Rats are much more calm when you restrain them through a towel then with just your hand. Wack a rodent and then cut it open. The damage is incredable.
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Shannon in Reno
1 savannah monitor (Pombe-means "beer" in Swahili)
6 dogs
1 cat
32 rats
50 mice
54 chickens
2 beardies
1 black rat snake
~100 hissers
1 giant milipede

Shannon
I can imagin the damage from whacking rodents. I use the "plink" method, where I put my index finger behind my thumb and "plink" it's done. Of course this method only pisses off Rats.
Mike
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Mike's Monitors!

The AVA does not recommend cervical dislocation for rodents larger than small rats (approx. 60 grams). Also if you do it properly, cervical dislocation should never be 'tuff'.

No it's not tuff if you can get a hold of the rodents head. Thats what I mean by tuff. They usually don't just let you grab/restrain their heads.
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Shannon in Reno
1 savannah monitor (Pombe-means "beer" in Swahili)
6 dogs
1 cat
32 rats
50 mice
54 chickens
2 beardies
1 black rat snake
~100 hissers
1 giant milipede

Dear, Freedomdove(freedom, to be free of confines)(dove, the sign of peace) Yet you keep animals confined and captive, hmmmmmmmmmm another human paradox(at least three different meanings of paradox fit this situation)

Next, you seem to have a learning handicap. Your the one with problems with your mice eating eachother. As you STATED. I don't have that problem. (how you became offensive in the first place)

About popping them, that is how I sex questionable males and I have been doing it for years(I have cages over 40 years old, in use) and I do not have problems with hernias or infertility. You my dear, must be doing it wrong. Besides, no one is forcing you to do anything. You simply keep on doing what your doing and blaming the mice because they are cannibalistic. Maybe you need a non-cannibalistic tribe of mice. You know, a dovemouse

I think before you pick on me, you ought to get your own problems in order. If I pop them wrong I may cause a herina, and yours are eating eachother, hahahahahahahahaha my problems appear very minor compared to yours. Cheers

I very rarely have cannabalism in mice and never in rats and I know from experience that it is something that can be bred out of your colony. If you buy from a breeder that has an established breeding colony then you should not have cannalbilism. My mice came from a pet shop, since I breed fancy mice, so that is why I had problems.
I have been working professionally with rodents for 10 years and personnally for 16 years. I work with a total of 8 rodent vets/pathologists, some that have 30 years of rodent experience. I am sorry, but I think that they know more about rodents and what you should or should not be "popping" out.
I am not picking on you, like you with monitors, I am trying to educate the ones that are ignorant about rodents. And like you with monitors, I have learned what works from my experience.
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Shannon in Reno
1 savannah monitor (Pombe-means "beer" in Swahili)
6 dogs
1 cat
32 rats
50 mice
54 chickens
2 beardies
1 black rat snake
~100 hissers
1 giant milipede

No your not like me with monitors, and your wrong. Its that very simple.

Whats like I say with monitors is, THE RESULTs. Your results indicate something wrong. You said MICE, are worse then rats, YOUR wrong, YOUR MICE, are worse then YOUR rats. OR how you manage your mice makes them worse then rats.

I only added, my mice do not do that. And I added I do not believe its a trait of mice to eat their babies. Its a condition of mice caused by their keepers or their history. Which means, you can avoid that condition. ITS NOT THE MICE, ITS YOU.

About your link, its great, but, if you actually talk to the author, my bet is, they would tell you that is not ALL their is, but a good overview. My suggestion to you is the same as I say to monitor keepers, do not blame YOUR failures on the animals.

About popping them. I have not caused harm, it works and too bad for you. Again you limit yourself. Which is great, but don't you try and limit me, or others. Cheers

"Frank seems to have a strain of mice that take to fostering other moms pups without issue. Some strains do not foster others pups good at all and will kill all the babies." From arta.
This is what I am talking about Frank. Different strains of rodents are kind of like different breeds of dogs.
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Shannon in Reno
1 savannah monitor (Pombe-means "beer" in Swahili)
6 dogs
1 cat
32 rats
50 mice
54 chickens
2 beardies
1 black rat snake
~100 hissers
1 giant milipede

Seems my rats and mice must be from the same strain as they also will adopt other females babies.

Don't know if you're trying to be funny. But, there are strains of rats and strains of mice. Rats and mice can't come from the same strain because they are different species
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Shannon in Reno
1 savannah monitor (Pombe-means "beer" in Swahili)
6 dogs
1 cat
32 rats
50 mice
54 chickens
2 beardies
1 black rat snake
~100 hissers
1 giant milipede

Rats and mice are different species? Are you sure I mean they are the same color and look the same, perhaps rats are just giant mice??

haha come on now you were not serious were you??

Like I said, the virus thing is heresay, as I did not have it tested, my friends did. I went by their advice and I have not had a problem. To me, thats good advice. They led me to success. That is what good advice is suppose to do. Good advice is not, mice eat their babies. That is poor advice, as its YOUR mice that have that problem, not others.

You can blame anything you like, pet shop mice, strains, WHATEVER. But that does not change the fact that I do not have that problem. My task was to help Krusty breed mice. Not tell him what poor husbandry or poor choices results in.

If you choose to use poor mice, or sick mice, then thats your fault and your ignorance. To get rid of your ignorance, you should have researched what mice work better, and found out about this virus effect. Not live in your little world of mice are bad.

I know, I am wrong, just like I am about monitors. I know nothing, but dang I am lucky, as my animals do all this stuff others don't. And that stuff is good stuff.

By the way, I make my own racks, and they are designed to meet several important needs of mice. Needs other rack systems fail to meet. Like, my mice eat sitting down, not hanging upside down, Think heavily gravid females hanging upside down, try to eat super hard rodent chow. hahahahahahaha hard chow is DUMB. My mice have hiding places(THATS WHAT MICE DO) as in, they can get in shelters or in the open. These are important and help LOWER stress levels. But then, you failed to ask anything. You just accuse and defend your brillant experience.

Did you know, you can raise up fuzzies quickly and without problem, without mothers?? You can. Cheers

I know what strains work better for mass reproduction. I breed mice now because they are pretty. For the color of their fur not for how many babies they can have. I have bred out cannalbilism and bred in good foster moms. I have zero animals that need to eat mice so I do not need to breed for numbers. If I needed to I would obtain a different strain.
Since I have good reproduction and do not have mice dieing for no reason, I am ruling out a virus. I am not saying that it does not excist, I just don't think my colony has it.
I have had one rodent vet and one rodent pathologist inspect my rat and mouse colony. I HAVE TO HAVE a very healthy colony so I do not transmit diseases.
Frank, your racks sound great. Can you post some pics? I make all of my own feeders also. All of my rodent cages have cardboard boxes, tubes, and pvc pipes. I use cardboard boxes that open from the top so I can disturb the nest at a minumum.
I have asked questions. I asked questions to the people that I know know the facts. I would not be running my mouth about viruses and popping out testicles if I didn't have the facts. I asked rodent vets and pathologists that have the facts and I would rather give facts then opinions and hear say. If I worked with a bunch of reptile vets then I could help with monitor health questions
"My task was to help Krusty breed mice. Not tell him what poor husbandry or poor choices results in." I think that this is important. You do it with monitors. Kind of to scare people into doing whats proper. Isn't it best to give an animal the proper conditions from the beginning? Learn from others mistakes. If I would have known of you, Shay, Mike, Robyn, and JC before I bought my sav I could have saved him a lot of stress.
I know that you can raise fuzzies before they are to be weaned but I do not because it is not necassary. But the concerns of this is a whole other thing that I am not getting into.
I am not here to bicker with you people. I am here to help in the areas I can. And I hope that my posts come across as polite and give clear advice.
Relax...take a deep breath...and have a beer
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Shannon in Reno
1 savannah monitor (Pombe-means "beer" in Swahili)
6 dogs
1 cat
32 rats
50 mice
54 chickens
2 beardies
1 black rat snake
~100 hissers
1 giant milipede

>>Like I said, the virus thing is heresay, as I did not have it tested, my friends did. I went by their advice and I have not had a problem. To me, thats good advice. They led me to success. That is what good advice is suppose to do. Good advice is not, mice eat their babies. That is poor advice, as its YOUR mice that have that problem, not others.

Heresay or not I have experienced similar. I considered that the moms, having gotten sick then didn't have energy enough to raise the young and cannabalized them. I have seen mice that were sick just lose young and let them rot, but often they 'clean up' and eat them. Otherwise cannabalizm is stress (too much changes or handling) or poor diet. So, husbandry issues.
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Sonya

I'm not mean. You're just a sissy.
Happy Bunny

>>I very rarely have cannabalism in mice and never in rats and I know from experience that it is something that can be bred out of your colony. If you buy from a breeder that has an established breeding colony then you should not have cannalbilism. My mice came from a pet shop, since I breed fancy mice, so that is why I had problems.

Cannabalism is from stress and diet....husbandry issues. If all mice cannabalized it would be a rare species....HMMMMMM You are blaming the animals for something you have done.

>>I have been working professionally with rodents for 10 years and personnally for 16 years. I work with a total of 8 rodent vets/pathologists, some that have 30 years of rodent experience.

ALL that experience hasn't taught you how to sex them yet??? Golly that is what I call a waste of time.

I am sorry, but I think that they know more about rodents and what you should or should not be "popping" out.

You obviously do not understand the process or you wouldn't think about all this cruelty. It is a tiny pressure, it isn't damaging a darn thing and it works. It is shifting masses and if a mouse is female it doesn't have a scrotum to shift anything to. Simple.

>>I am not picking on you, like you with monitors, I am trying to educate the ones that are ignorant about rodents. And like you with monitors, I have learned what works from my experience.

Apparently not. You are still sounding pretty ignorant yourself. And I doubt very much you have had anything approaching Franks successes, with rodents or monitors.
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Sonya

I'm not mean. You're just a sissy.
Happy Bunny

"Nothing should ever suffer and should be taken care of with the same quility as "pets" before they are to die."

Unless you are a strict vegan, that statement would make you a hypocrite.

OK not choosin' sides here, but I DO think the things we feed our charges should be kept healthy. After all, it would be a benefit to those that eat them , yes? JMO

Quig
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Don't interupt me when I'm talkin' to myself

Define what healthy is??????

LOL, I don't mean fat and sassy Frank. Just in a decent condition, not ratty lookin'(pardon the pun ), no illness. That sorta thing.

Quig
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Don't interupt me when I'm talkin' to myself

Of course I think feeders should be kept healthy. But I'm not convinced that sexing young mice the way FR does has any effect on their health.

What I was getting at in my post is that unless you are a vegan, raise all your own meat dairy and eggs etc, or something unusual like that, then you are more or less supporting cruelty to animals. Cheers

Pleas don’t worry, my wife presses on my belly all the time and my testicles are fine, at least I am sure one is fine?
The other I lost playing musical chair in kindergarten, now that’s dangerous don’t let your rodents do this.
Rgds

Ouch, testicular torticollis!!! I heard it is excruciatingly painful as your nut dies.

Yea, my wife does that too, only she says your suppose to use a baseball bat. And I am normal, hahahahahahahah

Sir, thanks for the laugh. Cheers

Yes, the distance between the "pee hole and the poop hole" is longer on the males then the females
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Shannon in Reno
1 savannah monitor (Pombe-means "beer" in Swahili)
6 dogs
1 cat
32 rats
50 mice
54 chickens
2 beardies
1 black rat snake
~100 hissers
1 giant milipede

Domestically raised mice and rats are very popular pets in the United States. They are readily available, relatively inexpensive and easy to care for, and usually enjoy human handling.

These animals have been used extensively in research laboratories for many years. Consequently, their medical problems (many of which are inherited disorders resulting from intensive inbreeding) have been traditionally approached on a group basis rather than on an individual basis. As a result, very little practical and useful information exists on the medical care and treatment of individual pet mice and rats. Furthermore, even less information is available to the pet owner on responsible home care of murine rodents and recognition of their potential medical problems.

Mice
The mouse, bearing the scientific name Mus musculus (interesting in light of the fact that the Great Blue Whale's scientific name is Balenoptera musculus, is thought to have originated in Asia. Its tremendous adaptability, long-time association with people and our dwellings, and unbelievably prolific breeding potential (one reference cites one million descendants from one breeding pair in 1 1/2 years) has allowed mice to enjoy a worldwide distribution. Mice are timid, social and territorial animals that spend a disproportionate amount of time in the wild pursuing an omnivorous (animal and plant material)diet. Feeding is most often carried out at night to escape predation. Laboratory and pet mice are not strictly nocturnal (night-active) but tend to exhibit alternating periods of activity and rest throughout the day and night.
In the wild, mice may exhibit aggression among themselves, though establishment of a social "pecking order" tends to reduce this potentially injurious behavior. Individual males apparently dominate groups of mice using this social pecking order. Females with litters may fight to defend their nests.

Domestication and intensive breeding of mice have resulted in a tremendous genetic diversity of mouse populations. The Swiss Albino mouse has become one of the most popular strains for pets but many others are commonly used in this capacity.

Rats
The rat, bearing the scientific name Rattus norvegicus, apparently also originated in central Asia. Rats were domesticated in the 17th century and the process has continued to the present, resulting in many breeds that are docile and of excellent pet quality. Rats, like mice, have been used extensively in biomedical research. Most of the tremendous number of breeds and strains currently in existence have resulted from intensive inbreeding efforts by research laboratories over the years.
Wild rats are found in all kinds of habitats and early all land masses of the world, an enduring tribute to their adaptability and their long-time association with people. They tend to be omnivorous (feed on plant and animal material) but exhibit tremendous opportunism in their feeding habits when living in and around human dwellings. Wild rats tend to be nocturnal (night-active) animals but often use daylight hours to forage for food. Laboratory rats, like laboratory mice, on the other hand, are not strictly nocturnal.

Mice and rats are both relatively short-lived animals, which can be disconcerting to owners of these pets. Some, however, feel that having their children experience the relatively short period of companionship and subsequent death of pet mice and rats is a meaningful way to expose children to the "ups and downs" of life.

Handling and Restraint
As stated above, domestic mice and rats generally tolerate gentle handling, though both may bite if startled or handled roughly. Mice are more likely to bite than rats under these circumstances. In fact, mice housed alone are more likely to be aggressive with a handler than those housed in groups. Cage territoriality (possessiveness) may be exhibited by some pet rats. We have encountered a large number of pet rats, normally docile in nature, that attack the fingers hands of a handler opening and entering its enclosure. This aggressive behavior is not noted when attempts to pick up these rats are made outside of their enclosures.
It is customary to pick up a pet mouse by gently lifting it up by the tail and placing it into a cupped hand. If a more secure hold is necessary (giving medications or food orally), the handler may grasp or pinch as much skin as possible over the neck, just behind the head. The mouse can then be picked up and turned over on its back by rotating the wrist. The tail can be restrained by gently grasping it with the other hand, or between the fourth (ring) and fifth (pinkie) fingers of the same hand.

Rats can be lifted by their tails but great caution must be exercised in doing so. The skin of a rat's tail can easily tear, so it is best to grasp only the base of the tail. Furthermore, suspending the entire weight a rat by its tail is, no doubt, painful for the rat. Therefore, this practice should be only momentary. Tall-lifting a rat that is grasping a fabric (wire mesh, etc) may injure the tail and may also break or tear the toenails.

The best way to pick up a pet rat is to place one hand over the back, just behind the head, gently grasp it around the rib cage, and lift it upward. The rat can then be gently cradled against the handler's body, using minimal restraint.

Potentially aggressive or known vicious rats and mice can be captured and restrained using gloves and small towels to protect the hands of the handler. Cage-aggressive rodents should be allowed to come out of their enclosure before an attempt is made to pick them up.

Housing
Proper housing is a major factor in the maintenance of healthy mice and rats. The psychosocial well-being of the animals must be a primary consideration. Mice and rats can be housed within enclosures made of wire, stainless steel, durable plastic or glass. The last 3 materials are preferred because they resist corrosion. Wood and similar materials should not be used in construction of enclosures because they are difficult to clean and cannot withstand the destructive gnawing of rodents. The construction and design of the enclosure must ensure that the resident(s) cannot escape. Furthermore, the enclosure must be free of sharp edges and other potential hazards.
The enclosure must be roomy enough to allow the rodents to pursue normal movement and breeding activity, if the latter is desired. Visual security (a place into or under which the rodents can retreat for privacy) should be provided, as well as exercise wheels for optimum mental and physical health. Rats, in particular, tend to be burrowers and seem to enjoy hiding under things for extended periods.

Enclosures should be easy to clean, well lighted and adequately ventilated (see vital statistics for preferred temperature and relative humidity ranges). Bedding must be clean, nontoxic, absorbent, relatively dust-free and easy to replace. Shredded paper, hardwood (NO PINE-it is a soft wood) shavings and processed corn cobs are preferred bedding materials. Tissue paper or cotton are often supplied to breeding rats for nest-building material. Cedar shavings should be avoided as the aromatic oils in the cedar are toxic to animals.

Pet mice and rats seem most comfortable when they are spared exposure to excessive noise, needless excitement and confusion, and other similar or perceived stresses. Sudden environmental temperature changes should also be prevented because pet rodents do not tolerate them well.

Mice can be aggressive toward one another, so great care should be taken when housing more than one mouse within the same enclosure. Newly assembled male groups and new males entering established territories, in particular, are likely to fight, so it is wise to always house male mice separately. Domestic female mice seldom fight unless they are defending their nests.

Rats are more communal and, in contrast to mice, several males and females may be housed within the same enclosure, provided that it is roomy enough. In fact, young rats are raised by the group and nursing responsibilities are shared between females. These nursing females may fight among themselves. Males may occasionally bother the young, but aggression between rats is generally infrequent (in contrast to mice).

Every effort to prevent the escape of pet rodents should be made because they can be a tremendous nuisance when allowed the "run of the house." Escaped rats tend to eventually return to their enclosures, whereas escaped mice tend to fend for themselves within the home and do not return to their enclosures.

Hygiene
The frequency with which the enclosure should be cleaned depends on its design, the materials out of which it is made, and the number of rodents within. As a general rule of thumb, however, the enclosure and all cage "furniture" should be cleaned and disinfected once weekly. The food and water containers should be cleaned and disinfected once daily (Roccal: Winthrop). More than one set of containers should be maintained, and the soiled set should be washed in a dishwasher, if possible.
Vigorous scrubbing of the enclosure and "furniture" with hot water and soap and a thorough rinse should be followed by the use of a disinfectant. Vinegar is often required to remove the scale deposited by rodent urine.

Food and Water
Good-quality food and fresh, clean water must be readily available at all times. Laboratory rodent chows (milled pellets or blocks) are preferred. These foods are readily available from feed stores, pet shops, and suppliers or users of such commercial diets. Kibble-type kitten chows can be substituted. The rodent diets containing seeds and nuts are not recommended because they contain too many fats and oils, provide inadequate protein levels, and are not necessarily balanced. Obesity is a common problem with pet rodents (especially rats). Consequently, oil-rich and high-fat foods must be avoided. Healthy maintenance of small pet rodents depends upon their receiving foods with relatively high protein levels 16% or more). Seed/nut-based diets generally fail to meet this requirement.
Table scraps and alternative foods can be offered pet mice and rats, but these should be limited to healthful items (whole-wheat bread, non-fat yogurt, fresh fruits and vegetables, lean protein sources such as tuna, chicken, etc) and should not exceed 15% of what the pet consumes daily. If the above feeding recommendations are followed, malnutrition and related problems are very unlikely among pet rodents. Vitamin or vitamin/mineral preparations and salt blocks (licks) are generally unnecessary.

The food can be "dispensed" from a specially designed wire or mesh cage top that provides a generous depression into which the dry food is supplied and through which the food can be eaten by the rodent(s). This food-delivery system obviously depends upon the animals' ability to easily reach the food by standing on their hind legs. This type of arrangement is, therefore, not recommended when there are juvenile rodents within the enclosure preparing to wean. This food-delivery system is used most often in laboratory situations. It has 2 major advantages. One is that there is much less wasted and discarded food. The other is that there is little opportunity for fecal (stool) and urine contamination of food. Metal "hoppers" can be used for dispensing food or it can simply be placed in heavy ceramic crocks (preferred because they cannot be easily tipped over) or similar containers.

Water is most easily made available and kept free from contamination by providing it in water bottles equipped with "sipper" tubes. The tubes can become clogged with food debris, so they must be checked daily. The dispensing end of the tube must be accessible to the smallest rodent within the enclosure. Before juveniles are fully weaned, they begin drinking water and eating pelleted foods, so these essentials must be accessible to them at this time. Many deaths involving very young rodents of this age are due to starvation and dehydration.

Food consumption varies with the quality of the food(s) offered, the age, health and breeding status of the individual, the environmental temperature, and the time of day. Both mice and rats tend to feed at night, though daytime feeding among both is quite common. Mice are voracious feeders and consume proportionately more food per day than rats. This is because of their smaller body size and relatively high metabolic rate. Rats tend to be more reserved in their feeding habits. In fact, rats show great caution and selectivity while eating and tend to avoid unfamiliar foods.

Breeding Considerations
Sexing
Sexually mature mice and rats must be properly paired to breed successfully. A single male mouse may be included in an enclosure with one or more female mice without difficulty. Including more than one male mouse in this situation invites fighting between them. By contrast, more than one male and female rat may be housed together for breeding purposes, within the same enclosure without aggressive plays.
Sexually mature male mice and rats usually exhibit prominent scrotum. Sexually mature female mice and rats usually exhibit a prominent double row of nipples. Furthermore, the distance between the rectal opening and the penis of the male is greater than the distance between the rectal opening and the urinary opening of the female in both mice and rats.

Mice
Female mice should not be bred before 50 days of age. They are continuously "polyestrous," which means that they come into heat at fairly regular intervals (every 4-5 days) throughout the entire year until they are bred. The period during which the male is receptive to the male and allows breeding is out 12 hours and usually occurs at night Female mice can come back into heat within l4-28 hours after giving birth to a litter. This is called a "postpartum estrus," which means that they can be nursing a litter and pregnant at the same time!
Pregnancy lasts an average of 3 weeks but can be tended as much as 10 days longer if the pregnant male is suckling a previous litter. Litter sizes average 10-12 pups, though it is not unusual for a male's first litter to be smaller in number. Litter sizes decrease as breeding females age. Though mutilation and cannibalism of the young are rare, it is wise not to disturb mice for the first 2-3 days after giving birth. Pups are usually weaned at about 3 weeks of age. The female resumes her breeding cycle 2-5 days after her pups have been weaned (unless she was bred during her postpartum estrus).

Rats
Females rats should not be bred before 65 days of age. They are continuously "polyestrous," which means that they come into heat at fairly regular intervals (every 4-5 days) throughout the entire year unless they are bred. The period during which the male is receptive to the male and allows breeding is out 12 hours and usually occurs at night. Female rats can come back into heat 48 hours after giving birth to a litter. This is called a "postpartum estrus." This period of receptivity is not used when breeding rats because the breeding male is removed from the enclosure just before the female delivers her litter because of the high probability of injury to the new pups by the male.
After mating, a white, waxy substance, called a coupulatory plug, is visible within the female's vulva for 12-24 hours. It is not uncommon to find these plugs within the enclosure after they have been discharged.

Pregnancy lasts an average of 3 weeks. Litter sizes average 6-12 pups, though it is not unusual for a male's first litter to be smaller in number. Litter sizes decrease as breeding females age. Female rats should not be disturbed for the first few days after delivery because stressed females may destroy their pups. Excessive handling, loud noises, and even insufficient nesting material have all been implicated with this destructive behavior. Pups are usually weaned at about 3 weeks of age. The female resumes her breeding cycle 2-5 days after her pups have been weaned.

Disease Prevention
Strict quarantine or isolation of all newly acquired rodents for at least 4 weeks greatly helps prevent disease among pet mice and rats. This recommendation is especially important for pet rodents because of the severity of certain diseases that they may harbor without showing signs of illness.
Mice and rats should be purchased from reputable sources. The prospective pet owner should never purchase an obviously or even suspiciously ill rodent Furthermore, it is never wise to purchase an animal that has been in contact with one appearing ill, even though the intended purchase appears perfectly healthy. These risky purchases never have happy endings and sometimes unnecessarily expose healthy pet rodents to serious and even life-threatening disease.

Laboratories associated with universities, colleges and research institutions most often purchase mice and rats from pathogen-free (disease-free) colonies. This is the preferred source for pet mice and rats, but purchases from these sources are not always practical or possible.

Rats and mice are especially sensitive to the irritating effects of ammonia. This chemical builds up quickly in the bedding from the relatively large volume of urine excreted by pet mice and rats. Bedding must be changed 2-3 times each week, or more often if necessary. Furthermore, ventilation must be adequate to reduce or eliminate the irritating effects of ammonia on the respiratory lining of pet rodents.

Conditions Requiring Veterinary Attention
Obesity
The tendency to become overweight (often grossly overweight) is more often a problem of pet rats than mice. Overindulgent pet owners and the of diets rich in seeds and nuts are most often responsible for this condition. Owners of pet rats must resist the temptation to feed "junk food," such as french fries, doughnuts, cookies and candy. Commercial diets specifically designed for rats are always preferred and can be supplemented with whole-wheat bread, dry cereal, pasta, fruits, vegetables and non-fat yogurt
Overgrown Incisors
The incisor (front, gnawing) teeth of all rodents and rabbits grow continuously for the life of the individual. The continual wear between the uppers and lowers usually prevents overgrowth of the teeth. Hereditary abnormalities of the jaw bones and/or teeth, abscessation of the incisor teeth, or injury to he jaw may result in malocclusion (improper meeting of the upper and lower incisors). Malocclusion, in turn, results in overgrowth of one or more of the incisors, with subsequent injury to the mouth. Mice and rats with this problem must have their overgrown incisors trimmed periodically by an experienced veterinarian or veterinary technician.
Tumors
Both mice and rats are very susceptible to formation of tumors. Rats over 2 years of age are reported, have an 87% chance of developing one or more types of tumors!
Mice frequently develop tumors representing a wide variety of tissue types. The tumors may be external or internal. Leukemia (cancer involving the white blood cells) is quite common in mice as well.

Both male and female rats develop benign mammary breast) tumors, and females develop benign tumors of the uterine and vaginal linings. These are the most common tumors of pet rats. Because rats have mammary tissue in locations beneath the skin other than along the underside of the belly, it is not uncommon to find lumps and bumps representing mammary tumors over the shoulders, flanks and base of the tail. These tumors are relatively easy to surgically remove under general anesthesia.

Owners of pet mice and rats should seek veterinary attention at once after discovering a lump, bump r unusual mass protruding from a body opening, the mass can be surgically removed by the veterinarian and biopsied to determine its exact identity issue type, benign vs malignant, etc) which, in turn, helps to determine the long-term outlook for the patient. Tumors tend to grow continuously larger nd may ulcerate and become infected if they reach very large size. For this reason, it is always preferable to remove them when they are small.

Chronic Murine Pneumonia (Murine Mycoplasmosis)
Chronic murine pneumonia (CMP), or murine mycoplasmosis is the most significant and serious bacterial infection of mice and rats. It is caused by the rather unusual bacterium, Mycoplasma pulmonis. This organism is relatively difficult to isolate because it cannot be grown in the laboratory using ordinary culture methods. This makes diagnosis of CMP more difficult except for the fact that the disease is so very common and well recognized. For this reason, CMP is usually diagnosed by signs of illness, without attempts to isolate the causative bacterium.
Signs of CMP include sniffling, sneezing, squinting, red-brown tears, rough hair coat, and labored and audible respiration. If the inner ear becomes involved, a severe, often incapacitating, head tilt usually develops. In colony situations, this disease can seriously affect the reproductive capacity of female rodents, resulting in infertility and reduced litter sizes.

Because this disease tends to have a very chronic (long-lasting) course, afflicted individuals should receive antibiotic treatment as soon as the first signs are recognized. Antibiotics can be added to the drinking water for long periods. Individuals exhibiting serious, life-threatening signs must be treated aggressively with injectable antibiotics if there is any hope of helping them. Frequently, other harmful bacteria complicate CMP. This often necessitates use of multiple antibiotics.

Elimination of the Mycoplasma pulmonis organism from infected individuals is regarded by most experts as a practical impossibility. However, early treatment reduces the severity of the disease in affected rodents.

The outcome of treatment is always unpredictable because there are so many factors that can have an influence on it: individual susceptibility and resistance to the causative agent; age, physical condition and nutritional status of the individual; and the presence of complicating factors (other bacterial and/or viral infections, high levels of ammonia within the enclosure, etc).

The bacterium responsible for CMP, Mycoplasma pulmonis, is highly contagious. It may be transmitted between mother and offspring in the womb during embryonic life and by direct contact after birth. Transmission among infected and uninfected older rodents results from exchange of respiratory aerosols and sexual activity.

Rabbits, guinea pigs, and other rodents may carry the causative agent but do not manifest signs of disease. Caution must, therefore, be exercised when allowing contact between murine rodents and these potential "carriers." Mice and rats, too, may carry the Mycoplasma pulmonis organism without showing obvious signs of illness. This is especially true of newly acquired mice and rats. This fact underscores the importance of restricting contact between mice and rats of unknown health status and those whose health status has been proven by remaining disease-free for relatively long periods. Furthermore, all newly acquired rats and mice should be quarantined (strictly confined from other pet rodents) for at least 4-6 weeks before contact with them is permitted. Any mouse or rat exhibiting respiratory signs (no matter how mild) should never be housed with or near a healthy pet mouse or rat

The severity of CMP can be increased substantially by any agent that harms the respiratory linings. Other bacterial and/or viral infections and exposure to the irritating chemical effects of ammonia from urine within poorly maintained enclosures can complicate CMP, making the disease far more deadly.

Tyzzer's Disease
This disease most often infects gerbils and mice, though rats also are susceptible. It is caused by the bacterium, Clostridium piliforme, which is usually transmitted by eating contaminated food or water. The bacterium may survive in spore form for extremely long periods in soil, bedding and feed and is, therefore, highly resistant
Signs of infection are often inapparent but may include lethargy, rough haircoat, and sudden death. Another form of the disease results in chronic wasting and death. Diarrhea may or may not be noted.

The disease is difficult to diagnose in individuals before death. It is considerably easier to diagnose during an autopsy. Sacrificing 1-2 individuals of a large group and performing autopsies on them are recommended to successfully treat and perhaps spare he majority of the group.

Specific antibiotics must be used early in the course of the disease. Some evidence indicates that his disease can be transmitted to pregnant women. Therefore, all necessary precautions should be taken to prevent this possibility.

Miscellaneous Bacterial Infections
A wide variety of other bacteria can cause illness n pet mice and rats. Your veterinarian is best equipped to diagnose and prescribe medications for these diseases.
Wounds (from fighting and other forms of trauma) are commonly infected with bacteria that already exist within the living quarters. Abscesses commonly result from wounds when they have gone Unnoticed and untreated. Successful treatment of certain wounds (especially long and deep cuts) and abscesses requires veterinary intervention. Abscesses usually must be surgically opened because the relatively solid nature of rodent pus precludes lancing and draining them.

Viral Infections
Numerous viruses can infect mice and rats. Only few of the most important viral infections among them will be discussed.
Sendai Virus Infection: In many mouse colonies, Sendai virus infection is the most significant and how mild) should never be housed with or near a healthy pet mouse or rat
Nursing mice and those being weaned are the most commonly and seriously infected. Adult mice may become infected but rarely show signs. Signs of the infection include labored breathing, rough haircoat, weight loss and death. Bacterial infections complicate the picture and usually increase the death rate.
There is no specific treatment for this disease. A commercial vaccine is available but it is only of practical use with large colonies of susceptible mice.
Sialodacryoadenitis: Sialodacryoadenitis is a highly contagious viral disease of rats and recently weaned mice. Initial signs include squinting, blinking and rubbing of the eyes. Later, sneezing and swelling in the neck region are noted. As the disease progresses, swellings below or around one or both eyes, bulging of the eyes, red-brown tears, and self-trauma to the eyes are noted. Respiratory signs also may occur.
There is no specific treatment for this viral disease. This virus is very unlikely to infect pet rats and mice unless they were acquired from a colony with this infection already established within its members.
Mousepox (Ectromelia): Mousepox is a highly contagious viral disease of mice that was only recently recognized in the United States. The mouse is the only natural host of the virus.
The acute (sudden onset) form of the disease affects the entire body. Clinical signs include lethargy, hunched posture, rough haircoat, diarrhea, inflammation of the eye membranes, swelling of the face and legs, and death. Another form of the disease results in a body-wide skin rash. Soon, the skin becomes swollen and ulcerated. Because of the resulting pain and discomfort, afflicted mice begin to chew on themselves. This behavior often becomes obsessive, resulting in amputation of appendages.
There is no specific treatment for this viral disease. This virus is very unlikely to infect pet mice unless they were acquired from a colony with this infection already established within it members.
Parasitic Infections
External Parasite Problems: Pet mice and rats may be infested with a variety of external parasites. Mites, nearly microscopic, spider-like organisms, live on the skin surface and feed primarily on skin debris. They are transmitted by direct contact between infested and uninfested rodents. Signs of infestation range from mild scratching to severe scratching, with hair loss and ulceration of the skin.
A veterinarian should be consulted if mite infestation is suspected. Microscopic examination of a scraping of the skin is necessary to confirm the diagnosis. Treatment may include a new injectable drug (ivermectin) that has proven very effective in treating mange in a wide range of animals.
Lice may also parasitize the haircoats of pet mice and rats. They are flattened, wingless insects that suck tissue fluids and blood from the skin of the host. Ace are larger than mites and can usually be seen without a magnifying lens. Lice are most often transmitted by direct contact with infested bedding and between infested and uninfested individuals.
The lice of mice and rats are found most often on the neck and body. They suck blood and can, therefore, cause anemia (sometimes death) and transmit bloodborne diseases to rodents. Louse infestations may also cause scratching, hair loss and skin wounds. veterinarian should be consulted if louse infestation is suspected.
Intestinal Parasite Problems: Tapeworms and pinworms are the most common intestinal parasites of pet mice and rats. They often go undetected unless present in large numbers. Signs of infection may include weight loss, inactivity, inappetence, constipation, and excessive licking and chewing of the rectal area and base of the tail.
Stool examination should be conducted by a veterinarian to diagnose these parasitisms. Appropriate treatment will be recommended by the veterinarian. Pinworms are especially difficult (sometimes impossible) to eliminate from mice and rats.
Transmission of these parasites to people is possible but unlikely. Therefore, great care should be (en when handling and disposing of rodent feces. Furthermore, contact between pet mice and rats, their feces, and young children should be limited and always supervised by adults.
Miscellaneous Conditions
Red-Brown Tears of Rats: Rat owners, at some point, notice red-brown tears staining the eyelids, nose and sometimes the front paws of their pet rats. This substance is always mistaken for blood. It is actually a normal secretion from a large gland behind the eyes. red-brown tears are noted most often in response to stressful situations (restraint, fright, illness, etc).
Cannibalism: Female rats (mice much less often) disturbed shortly after giving birth to a litter may destroy the pups and eat them. Male rats also engage the same behavior. For these reasons, it is important not to disturb female rodents for 2-3 days after they have given birth. Male rats must be removed m enclosures just before females deliver their litters.
Skin Disease: There are many causes of skin disease in pet mice and rats. Numerous infectious agents, including bacteria, viruses, fungi and parasites may be involved. Cagemates may be responsible for hair loss and/or wounds to the skin. Allergies are also a suspected cause of skin disease of pet rodents. In these cases, it is wise to replace the bedding being used with plain white, unscented paper toweling.
A veterinarian should be consulted when pet mice and rats exhibit signs of skin disease. The doctor will need to conduct diagnostic tests. Appropriate treatment is then based on the results of these tests.
Human Allergies to Pet Mice and Rats
Human allergies to rodents are common. The signs can be serious, even life-threatening. This problem is most frequently reported among laboratory personnel, but individual pet mouse and rat owners are equally vulnerable.
The offending allergens may be rodent skin dander and hair, or the proteins in aerosolized rodent urine. Signs among allergic people may include runny eyes and nose, sneezing, congestion, coughing, shortness of breath, and anaphylactic shock. Some people develop a rash and/or hives, especially in areas contacted by the claws or hair of a rodent. Allergy to a pet mouse or rat must be considered if someone in a household develops any of these signs. The medical doctor consulted about the problem must be made aware of the existence of a pet rodent within the home.

Suggested Reading
Harkness and Wagner: The Biology and Medicine of Rabbits and Rodents. 3rd ed. Lea & Febiger, Philadelphhia, 1988.
For More Information
American Fancy Rat & Mouse Association
9230 64th St.
Riverside, CA 92509
Karen Hauser
Riverside, CA
(714) 685-2350

Roxanne Fitzgerald
Long Beach, CA
(213)439-2002

Leona Pasley
Costa Mesa, CA
(714) 662-2000

Vital Statistics
Mouse Rat
Scientific name Mus musculus Rattus norvegicus
Life Span 2-3 years 3-4 years
Potential Life Span 4 years 7 years
Desirable environmental temperature range 65-80 F (68-72 F optimum) 65-80 F (68-72 F optimum)
Desirable relative humidity range 30-70% 30-70%
Age at onset of puberty 28-40 days 50-60 days
Estrous (heat) cycle length 4-5 days 4-5 days
Estrus length (period during which female is receptive to male for copulation) 12 hours 12 hours
Gestation (pregnancy) period 19-21 days 21-23 days
Average litter size 10-12 (1st litter usually smaller) 6-12 (1st litter usually smaller)
Weaning age 21-28 days 21 days

Return to MNAALAS Animals in Science Page

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Shannon in Reno
1 savannah monitor (Pombe-means "beer" in Swahili)
6 dogs
1 cat
32 rats
50 mice
54 chickens
2 beardies
1 black rat snake
~100 hissers
1 giant milipede

Christ, that was a lot of crap to filter through people. So if i get 5 young female mice, one male and let 'em be in a 10 gallon tank (as in no separating the females w/ young at all), they should coexist ok. Any barbering or killing mice should be culled until i get a happy group and raise em up from themselves incestually? I can do that. I was pulling the female plus pinks (nestbox and all with a sheet of cardboard under it)to a different 10 gallon tank. I'll 86 that and see how it goes.

Thanks for the National Geographic quality pic of the mouse hind-end, hehehe - it is good enough to get the point across, so really, thanks.

The guy up in Weeki Watchee that i get my frozens from said he doesn't have any of this problem either unless they go w/o food or water - so it's either genetic bad-attitude or viral or whatever. I'm not interested in any of that except to produce a steady supply of pinks and fuzzies vs. paying 99 cents for the buggers at a petstore. Thanks all.

Krusty,

You are right, some of that was a lot to go through I tried to touch upon everything so here's my .02 cents. Never seperate your pair/harem matings. Leave the male in or your production will suffer. A lot of people think because the females are pregnant, that they need to set them up seperatly to litter down. What they miss is the post partum estrus. Female mice go into estrus right after they litter down. Thats why the girls have a new litter before they first is weaned. They will have the babies at about 19 days and the older mice are usually weaned at 21 days. As for sexing, mice have an open inguinal ring, meaning the males can and do pull their testicles into the body. Pushing on the bellies as Frank suggested does work and causes no harm because of the open inguinal ring. In humans, with our closed inguinal ring, that is where hernia issues could possibly happen. An easy way to sex the young in to look at the distance of the urogenital opening from the anus. If all else fails, give it a sniff...lol
As for killing issues, sometimes they actually just die. Mice don't live long, and the living cage mates take a nibble. Sometimes they eat quite a bit. Frank seems to have a strain of mice that take to fostering other moms pups without issue. Some strains do not foster others pups good at all and will kill all the babies. Frank is also correct about the virus'. There are things that rats carry that will kill mice flat out. The canibalisim that Frank talks about, I think is an "opportunistic feeding".
It is the AVMA that determines humane forms of euthanasia and cervical dislocation should only be used if justified and by a highly trained person. Most people try to do it and just break their backs. Co2 hurts and causes bleeding of the lungs but is acceptable by the AVMA. Rats over a certain weight should not be cervically dislocated. Its just to tough and they are too strong to do it right.
I would also not be worried about barbering, it's normal. You can tell who the dominant animal in the cage is. It has a full coat with no bald spots. Before anyone jumps on my comments, they are made from my experience working with animals in a research setting for many years as a technician and now facility managment. I have dealt with many breeding colonies of mice that run up to and over 10k a mouse, not .99, so I couldn't be wrong or it was my a$$. Sorry for the ramble, but mice are my day job...

You have mail
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Shannon in Reno
1 savannah monitor (Pombe-means "beer" in Swahili)
6 dogs
1 cat
32 rats
50 mice
54 chickens
2 beardies
1 black rat snake
~100 hissers
1 giant milipede

Shannon,

I don't know if I took your email wrong, but what was the purpose of the email? I didn't "say" anything in my post other than answer some of the things that came up in the thread, and briefly stated what I have done... As for "popping", you are really missing what Franks is saying. All he is doing is restraining the young mice with a little bit of pressure causing the scrotum to buldge a little bit, not popping them like a snake. I restrain mice often. I can do it with two mice at a time, one in each hand and not get bitten. The small amount of pressure applied can cause what Frank is calling popping. I do not practice "popping" mice to sex them as I can tell without, so it's not something that I care to discuss with out vets. If you work for who your email address says, what are you doing breeding rodents at home....? If you have anything further to say to me please respond here, as I would rather not reply via email.

As far as sexing rodents UNDER THE AGE OF 3 WEEKS the "popping" thing is not recommended. After the testicles drop, Franks method is fine and should cause no harm. Yes, male rodents can pull/hold their testicle up at will after they have dropped.
My company knows what I have and is ok with that. Shower in and out. If it becames a problem as far as transfering diseases they will do testing. And it has never been a problem in 10 years.
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Shannon in Reno
1 savannah monitor (Pombe-means "beer" in Swahili)
6 dogs
1 cat
32 rats
50 mice
54 chickens
2 beardies
1 black rat snake
~100 hissers
1 giant milipede

And as others stated above. Get them from an already established breeding colony, it will save you a lot of trouble. Good luck and keep us posted
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Shannon in Reno
1 savannah monitor (Pombe-means "beer" in Swahili)
6 dogs
1 cat
32 rats
50 mice
54 chickens
2 beardies
1 black rat snake
~100 hissers
1 giant milipede

OK and thanks all.

Oh yeah, one last question. What is the deal with one or two mice becoming "greasy" looking. They have discolored, oily hair as opposed to the nice, healthy white sheen they should have. I always seem to get a few like this in the mix. I usually cull these as feeders, but was wondering why they get this way. Is it like a teenager with acne? Some develop greasy hair and pimples while some don't have to go through that?

What are you feed them?
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Shannon in Reno
1 savannah monitor (Pombe-means "beer" in Swahili)
6 dogs
1 cat
32 rats
50 mice
54 chickens
2 beardies
1 black rat snake
~100 hissers
1 giant milipede

What are you feeding them? Sorry!
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Shannon in Reno
1 savannah monitor (Pombe-means "beer" in Swahili)
6 dogs
1 cat
32 rats
50 mice
54 chickens
2 beardies
1 black rat snake
~100 hissers
1 giant milipede

Mazuri Rodent 6F

That's what I feed. Good stuff. I would guess that they are mice that don't groom themselves as often as they should and they may be individuals that huddle underneath the other mice and get urinated on. I don't keep poor groomers for breeding and I don't know how they would be as breeders either. Some people feed their rodents dog food and that can make their coats greasy and discolored.
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Shannon in Reno
1 savannah monitor (Pombe-means "beer" in Swahili)
6 dogs
1 cat
32 rats
50 mice
54 chickens
2 beardies
1 black rat snake
~100 hissers
1 giant milipede

Isn't it funny that such a simple, naive question turns into an all-out battle? This forum is intense!