But, your concerns are a valid one.
1) If you have children I really feel that you should invest in a REAL cage. I don't know what you have right now. But, buying a neodesha, boaphile, or vision cage is really what is needed in the future. Both cages a strong and lockable. This way the cage can be locked and you alone keep the keys. Stay away from aquarium type cages. They work for a while..........But, are useless IMHO when a boa has some size to it. This is a must in my book!!! And, you must also say to yourself......"If this boa gets out....I need to give it to someone". It sounds harsh I know. But, that really is my mentality. I have 10 boas right now and two kids. If one boa gets out. I personally have failed my children in keeping them safe. I am not willing to take the risk with my kids life. I really think that is the type of mentality people should have when owning a large boid when they have children.
2) Some type of seperation is a good thing as well. By this I mean don't keep the snake in an open area. Your first line of defense is locking the cage. Your second is having the snake behind a locked door. (ie your room, etc.)
3) If you are going to make this boa be a family "pet" it is up to you to teach your children about them. I am VERY anal about this. So, please excuse me.
I just really feel it is serious in nature so it needs to be stressed. These animals, no matter how tame, will bite. That has to be understood. If your child is going to hold the snake get him/her into the practice of washing his/her hands before and after handling. This is mainly to remove smells that could trigger a strike and to keep your child healthy due to the animal crawling thru it's own urated, food, etc.
Always keep the snakes face away from yours or your childs. Again, boas are tame. But, that does not mean they can be trusted.
Teach you child to learn to "read" boas by their body language. If you are not able to do this yet....This really is important. Once you are able to "read" the snake teach your child about it. This really transfers into a lot of good in life. Reading people and animals is a talent that can be developed by anyone willing to take the time. This "reading" will keep you from being bitten more times then not. Look for basic signs. (Rapid breathing, S-Curved next, acting "head-shy", hissing, hunger movements, etc.)
4) This may upset some buy I am going to share it anyway. A boa's size can be controlled somewhat. And, there is a fine line between maintaining a desired size and starving you boa. So, if you want to have a "smaller" female you could feed it a diet of one large rat weekly. (When it is able to eat that sized prey) A feeding schedule like that should keep your female around the 6-8 foot range. When you start feeding multiple rats is when their true size/girth is attained. When you feed weekly you boa will hit a topping out point. This way you can keep your boa in that size range for some time. I don't recommend doing this it's whole life. But, I have seen some 15 year old boas that are maintained at that size that look wonderful and healthy. A weekly feeding is necessary to maintain proper caloric intake and keep essential minerals present for the boas development.
Most normal boas will hit the 6-7 foot range natually at 3years of age. At that point, is really when they start to thicken up.
This is only a suggestion. I prefer to keep my boas big. It means a lot more responsibility on my part. But, I like big animals.
5) Proper handling techniques are a must as well. It is pretty easy when they are babies. But, when they are adults it becomes really important that you have conditioned the animal already.
I hope this helps. Here are some links for you to look at as well.
John
http://www.boaphileplastics.com/cages.html
http://www.neodeshacages.com/products.php
http://www.pythons.net/handling.html
http://www.mccarthyboas.com/BigSnake.html
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"To be the best..........You must lose your mind."