Determining the sex of a chinchilla is not difficult if you have a male and a female to compare. In females the gap between the anal and genital openings is much smaller than in males. Males are also said to be bigger than females but this is a totally unreliable way of sexing them.
Males normally reach puberty earlier than females. It is not advisable to let a female mate before 6 months of age. If you want to buy a young pair it is therefore best to buy a female that is 2 months older than the male. If she falls pregnant too soon she may miscarry or have stillborn kits. She might also not survive the pregnancy, although this is very rare.
It is possible to introduce older males and females to each other but it’s not always easy. Chinchillas that have been together for some time form a very strong bond and will not readily accept a new mate. We use a smaller cage that fits into the normal cage. The female is placed inside the smaller cage which is then placed in the male’s cage. We leave them like this for 3 days and then let the female out of the smaller cage which is then removed. So far it has always worked.
We have 2 pairs that will not accept another female but the ideal for us is to have a male with 2 females. Females only come into heat every 28 days. Mating is rarely observed as it normally occurs at night. The gestation period is 111 days but as with humans it is not always the same. There are seasons when more babies are born but again this is only a guideline. Most babies are born in spring and autumn although we get babies right through the year. Normally 2 babies are born but anything from 1 to 4 is not uncommon. They can have up to 6 babies but this is very rare.
A female chinchilla can fall pregnant again within 72 hours after giving birth but we remove the male after the female gave birth to prevent this. It is very hard on her body to suckle young while new fetuses are growing inside her. We put the male back 5 days after the babies were born. She will then fall pregnant when her body is stronger.
There are a few signs to look out for in determining if a female is pregnant. She will gain weight but it will not always be obvious. When she gets closer to term she will start eating a lot more, up until a few days before giving birth. Later in pregnancy she will become less active and spend more time in the nest box. She might also sleep in unusual positions, like on her side. Sometimes you can even see the babies move inside her when she is close to delivering them. Chinchillas almost always give birth early in the morning but this can happen at any time.
Problems when giving birth is rare but if you know she is close to delivery she must be checked every morning. A sure sign that she is in trouble is when her water broke but nothing is happening. Her nose will be wet and she will be plucking at her vaginal opening as if trying to pull out the babies, without success. Bleeding from the vaginal opening without the babies being delivered is also a sign of trouble. In these cases a veterinarian must be consulted as soon as possible. Luckily these problems are very rare and we have never so far encountered them. If you are lucky enough to witness the birth make sure she dries the kits properly. Cold is the biggest killer of newborn kits. You can assist her as she will not abandon the kits. The kits are born looking like miniature adults and will get going pretty quickly.
Caring for the young is the next step to consider. We give the biscuit supplement throughout the year so it is not necessary to give extra supplement during or after pregnancy. Even when 4 kits are born the mother is normally able to take care of them, although she might sometimes need some extra supplements. She has 3 pairs of teats so the biggest concern is to make sure that she produces enough milk. Signs to look for that will require your assistance is a baby that grows slower than the rest or babies with injured noses. This means some are not getting their fair share of milk and might be fighting each other to get to the milk. You can assist the mother by giving the babies extra milk. Corlet, who is a well known and reputable breeder weighs the mothers and babies to make sure all goes well. This is a very good habit to get into.
Babies can be bottle fed powdered milk like Royal Canin Baby Cat Milk or powdered Goat Milk. This can be done without removing the kit from its mother. If she abandons one of the kits you can remove it and feed it in the same manner as much as it will drink every 2 hours. Keep this up for the first 2 weeks and then reduce it to every 3 hours. You can also then stop giving milk after 10 at night. The babies will start nibbling on solid food within 2 weeks but will need milk until they are 6 weeks old. They are normally weaned at 6 to 8 weeks but we never remove the kits from the mother before 8 weeks. We normally sell them at 10 to 12 weeks.
One problem young kits face is being trampled. This can be overcome by placing structures like bamboo cut in half lengthwise (dry bamboo is safe to nibble on) in the cage. Even PVC pipe works. They will nibble on it but will not swallow it. We use PVC drainpipe in our cages for them to climb in.