Breeding Chinchillas - Mating and Pregnancy
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In this second of three articles in the series on breeding chinchillas, we look at the mating process along with the actual pregnancy.
We're assuming here that you are working with a pair of chinchillas that has already been well socialized. When the male is ready to mate (which of course he pretty much always is once mature enough - just waiting for the signal from the female) he may make a cooing, chuckling noise and both sexes may rub their chins on the floor or nest box. Mating usually takes place at night, but often it also can be observed in the evening or the early morning hours. Following what often becomes an all night romp you will often find bunches of fur and perhaps the "mating plug". This is a waxy plug, larger then the "estrus plug", about 1 1/2 inches long.
After mating the male should be checked for the presence of a hair ring. Most males are very careful about cleaning the penis after each mating, but due to the often large amount of hair loss during mating it can be hard for him to remove all of the loose fur that can accumulate inside the penile sheath. This can create a ring of fur that will act as a constricting band around the penis resulting in pain, difficulty urinating, and eventually prolapse, swelling, and damage of the entrapped organ. This can lead to excessive grooming which leads to further damage. If hair rings are present the penis should be gently lubricated with petroleum jelly. The hair ring should then be carefully teased open and cut off (VERY CAREFULLY) with fine scissors.
Complications During Pregnancy
These are rare, but certainly a possibility. Spontaneous abortion can occur at any stage of gestation due to poor nutrition, a concurrent illness, stress (even loud noises), trauma such as a fall, and unskillful palpation. If an abortion does occur be sure to watch for signs of illness resulting from retention of tissue in the uterus.
A few days before the due date be sure to remove the dust bath. The night before delivery the female may become aggressive toward the male and any other cage mates. She may also refuse food or become more passive. Most births take place in the night or the early morning hours and are generally a quick process. If you have the privilege of witnessing the birth make yourself as invisible as possible! Preliminary contractions and the loss of amniotic fluid announce the onset of labor. The female may groan, writhe, stretch, and make sounds of pain and her genitals, mouth, and nose will appear wet. The strenuous phase is usually brief, about 1/2 hour and you are justified in being concerned if it lasts for more than an hour. Finally, the female will carefully pull out the kit. In multiple births the entire process can take several hours. Each kit has its own placenta and this afterbirth can be delivered after each kit or perhaps all of them at once. The female will eat it and this is actually good for her. While it may be messy, let nature run its course. She will be busy cleaning herself and the kits for quite awhile after this and would love to have a dust bath. DON'T give her one for at least a week. She will now warm and dry the kits, probably also nipping them to the point of squealing (her way of stimulating them and helping to clear fluid from the lungs) and then you'll be glad to know more about Development of the Young.
Complications at Birth
These also are rare but can include: dystocia (difficulty in delivering), metritis (inflammation of the uterus), pyometra (pus in the uterus), puerperal septicemia (bacteria from uterus get into bloodstream), agalactia (absence of milk production), damaged teats, mastitis (inflammation of mammary glands), caked mammary glands, cannibalism, tympanites (abdominal distention due to intestinal gas - associated with hypocalcemia), and constipation. In the case of dystocia if you have a female who appears to be having trouble delivering you should get her to a veterinarian within 3 - 4 hours of first observing trouble.
Weight Gain During Pregnancy
If the female becomes pregnant she will start gaining weight. Below is a diagram showing the weight of some pregnant chinchilla females.
Female chinchillas have a postpartum estrus. That means that they come into heat again right after delivery. If she hasn't just had her second consecutive litter it's okay for her to breed back. While most male chinchillas make wonderful dads it's best to separate the male if it's time for mom to get a break. Her postpartum heat will have passed within 7 - 10 days, at which time you can reintroduce dad. The best way to make this successful is to be sure to give the entire family plenty of supervised playtime during the day (when chinchillas aren't particularly interested in mating) to maintain the social structure. Otherwise mom may become very defensive of the babies and not let dad anywhere near them after a week or so. If this happens you will have to wait until the kits are weaned before reintroducing the parents.