Reptile & Amphibian Forums

I have a friend (another breeder) who has hatched several clutches of eggs this year (various colubrid species) and has several more cooking. In one clutch of California King Snake eggs, 8 of the 12 eggs failed to pip. 4 hatched perfectly. This snake produced a large clutch last year, from the same male, with a 100% hatch rate. After the eggs were several days overdue hatching, he opened them and examined them. In each egg, was a partially formed embryo, with umbilicus, spinal column, skull, ribs and skin beginning to form, but the development had stopped there and all 8 of these embryo had died at approximately the same point in development.

I'm at a loss as to what would cause this to happen. I've seen one egg out of a clutch do that, or maybe 2 out of a large clutch, but I've never seen 75% just stop developing and die like that, while the other 25% develop into perfect neonates and pip perfectly.

Things that are NOT a factor:

Temperature control. Temperature is well within acceptable range, both in the parent cages and in the incubators.

Reproductive failure in the parent snakes. All eggs were fertile.

The eggs were not disturbed or turned during incubation.

Fungi, none was ever present on any of the eggs in any of his clutches.

Humidity. Humidity is well controlled and all other clutches incubated in the same fashion have either pipped or are doing well.

Things I've thought of but have not ascertained yet:

Was any medication given to the female during the gravid period?

Did she feed during the gravid period, and if so, was she fed live prey (possibly damaging the developing embryos during constriction).

Has she been checked for bacterial infections and internal parasites (long shot)?

Was she exposed to any form of anti-mite or anti tick preparation, such as Vapona strips, Provent-a-mite, etc.

Was she exposed to any cleaning agents, such as Roccal-D, Nolvasan, etc.

Any other ideas as to what other possible causes are? This breeder is very experienced and normally has a very high success rate.

Any idea what exact stage of development they were at when they perished? As in, at that stage of development would they normally be 1 week from being laid, or perhaps 20 days into gestation before being laid, etc etc. Could help if there was an approximate on when eggs are in that exact developmental stage. Once this is known, if the events in the week or weeks surrounding this guestimated period are examined, it could be that some possibility could be determined. I'm not familiar enough with the exact development of snake embryos from the moment of conception to the moment they pip.
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~Sasheena

Yeah, my guesstimate is between 21 and 30 days.

Hey O.H.

What was the posistion of the dead eggs in relation to the ones that hatched out ? Where they clumped or all on their own ? No possibility for a small or short temp spike ? I know my thermometer will tell me the highest temp of the day etc... Also one unrelated question.... What is your name ?

Regards,

Keith

Hey Kieth,

I'd say zero chance for temp spikes. All eggs were incubating in the same environment, this is the only clutch with problems. Colubrid eggs are generally pretty tolerant of temperature variations. These definitely were always within the tolerance range. The eggs, I think, were all separate. That's another question I'll add to my list of things to find out for sure, though.

Oh yeah, my name is Gerald.

My first thought when you said that the development seemed to be arrested at the same point for all the dead eggs was that it was a fatal gene. Are these proven breeders. Just a thought. I don't really have any idea.
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International Snakes Meetup

Yes..they are proven. This same pair last year produced a clutch of I think it was 10 eggs with a 100% hatch rate.

OH,
My opinion only. To have 75% of these embryos stop development at approximately the same stag of development a key genetic factor/code was missing or destroyed which caused the embryos to stop at that point.

The possible missing/destroyed genetic factor could be male or female related. It could be pesticide/chemical exposure, which may have occurred during gestation or a prior contamination. Question the breeder of the cleaning/insecticides used prenatal. Mother nature can sure play her games.

Dann,

Yeah, that's kind of the direction I'm leaning to, also. Out of the possibilities that I'm still considering viable, those that are high on my list are exposure of the female to pesticides, drugs or other chemicals during the gravid period. There are some drugs, such as Flagyl, that work by altering cellular DNA production. Many other chemicals could have similar properties. Other things that may be possibilities are things like if the female was moved to a new cage during that period...was it a homebuilt cage with a fresh finish? What kind of finish? Was she in a room where she could have been exposed to some insecticide? Did the exterminator come during the gravid period, or shortly before?

There are some other possibilities that I may never be able to pin down, such as did the breeder or someone else use some sort of pesticide or herbicide outside, then come in and handle her forgetting to wash his hands? Many pesticides work by attacking the reproductive systems of the targeted pest animals, preventing reproduction. I know he wouldn't spray a pesticide in his snake room without moving the animals out and allowing it to completely dissipate, but accidental exposures can occur.

OH,
I think your tracking in the right direction. The method of ingestion could be hard to determine. And the suspect chemical may be equally as hard to determine.

As you stated it could be as simple as something on some ones hands, a new enclosure finish, a flea and tick collar on the family pet that is touched and then contact made with the snake without washing hands?

Ask him if he changed his rodent supplier during any of this? That has been a fear of mine with the Dry’s, if a pesticide was introduced to the caging area and transfer to the pry item. I wash all pry items thoroughly, quail, mice, chicken, and fish.

All of the above questions have been answered, all negative. I have no idea what caused this. Unfortunately, he didn't save one of them for me.

OH,

We may never know what causes things like this to happen. You gave it a good try. Testing would have been expensive and may have been inconclusive. But who Knows.

I like a good mystery. I enjoy the answers at the end better.

Yeah, I HATE problems I can't solve. It drives me crazy. I really wish he would have saved one of them...

Another possibility is a vitamin deficiency in the mother. Were the parents on a diet solely of mice?

I'd be real interested to hear what happens next year if the owner feeds the female one baby chick a month from now til egg laying time next year in addition to the regular ration of mice.

Paul Hollander

That's a possibility. One that I hadn't thought of. I hadn't carried the diet/nutrition thought process past mating, egg production and egg laying. Certain things are necessary for full embryo development, though. If there was a deficiency of some necessary nutrient, then it would be possible some of them would not to get everything they need. I will run that past him and see what we can do.

Another possible course of action would be to try feeding a diet of frozen thawed mice, but to fortify them with supplemental vitamins and minerals by injecting them before feeding. Of course, the absorbtion rate is different for manufactured vitamins and minerals than for those obtained from natural food, so that has to be taken into account also.

Good thinking, Paul.

OH,
Paul just may have something there. My vet here keeps Dry’s, he keeps reminding me to feed whole pry items and to include foul and fish. He feels calcium and vitamins from whole pry items is essential for structure, growth, and development of the adult and there eggs.

Good thinking Paul H.

Yeah, Dann, he just might. Like I said, I hadn't carried the nutrition thought past the point of egg laying. I'm going to try to get him to explore that area. This would be an interesting point of study. If we could poll breeders as to species and diet (from feeding records), and % of fertile eggs that fail to develop fully (and dead in egg embryos), we may be able to begin to establish a clearly defined link. Then we may be able to better understand the exact nutritional requirements for consistent high hatch rates.

One thing I seem to see setting up...it seems like overall first and second clutches for young breeding females have a higher rate of infertile eggs and generally somewhat smaller clutches, but older females (fourth breeding year and beyond) while generally having larger clutches and a higher ratio of fertile eggs seem to be more likely to have embryos that die in development. Not always, of course, but when there are problems it seems to line up like that. Maybe it's just me....more digging would be needed to firm that up. Could it be something that the female is being depleted of by breeding over the years and not replenished with a captive diet?

OldHerper,
I am still interested in the thought that environment contaminates absorbed buy dermal and air intake contact may be having an effect on fertility rates. I have been searching/reading and have made contact with a study group that is testing mortality rates in reptile adults and embryos. Some tests have shown deformities, dead in egg, and missing genetic codes causing under developed organs. In all tests performed elements of pesticides and other chemicals have been discovered. This group is studying the effects of these different chemicals separately.
I am still interested in your question about nutrition and development. I think parts of the two my be linked as pesticides used have residual composites that are considered safe (not at toxic levels for human consumption and considered safe) but have been found in grain and other products used to feed the pry animals we feed to our Reptiles. The pry animals also tested positive for chemicals found in air, ground, and water.
Once I have more information if you like, I will send reports I get to you via e-mail. Dann.