Merck Veterinary Manual - Chinchillas - Reproduction

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alpayton

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Copied from http://www.merckvetmanual.com/mvm/in.../bc/171509.htm

Pet owners should be encouraged to maintain chinchillas in single-sex groups to provide companionship but avoid producing large numbers of offspring. Male chinchillas must be grouped before weaning or castrated to prevent fighting. When breeding, potential mates should be introduced before the female enters estrus to reduce fighting and increase compatibility. Males need a refuge box to escape potentially aggressive nonestrous females. Specially fitted muzzles or collars can be applied to the female to prevent her from biting or chasing the male. Repeated female-to-male aggression can lead to a conditioned avoidance response in the male, making him an unsatisfactory breeder. Polygamous and harem mating systems are commonly employed by breeders. As chinchillas approach parturition, they may become less active, anorectic, and aggressive toward previously compatible cagemates. Chinchilla dams do not typically build nests at parturition, although a nesting box may help decrease neonatal mortality caused by drafts or cold stress. Hypothermic kits should be warmed and revived quickly to prevent mortality.

Infertility:
Decreased reproductive performance may be due to several causes, including malnutrition, abnormal sperm, hormonal imbalance, infectious disease, lack of experience, lethal genes from inappropriate crosses, or poor conditioning. Infectious and dietary factors are often implicated. Obese females produce smaller litters. Matings between or among chinchillas homozygous for White and Velvet coat color genes should be avoided. Breeders should have access to a fresh commercial pelleted diet and adequate roughage, and colonies should be screened carefully for any heritable physical defects.

Abortion:
Pregnancy termination may be caused by improper handling, trauma, inadequate nutrition, septicemia, fever, or interruption of the uterine blood supply. At term, suddenly startled females may spontaneously abort. Frequently the female will immediately ingest the aborted kits. Abortion may take place unnoticed, but should be suspected if a female chinchilla suddenly loses weight. Often, a bloody vaginal discharge and perineal staining are observed. Treatment for post-abortion females includes flushing the reproductive tract gently with an antiseptic solution and administration of appropriate parenteral antibiotics.

Retained or Mummified Fetus:
A fetus that dies late in gestation may be delivered normally along with the live young, remain within the uterus, or become mummified. If a dead fetus is retained, the parturient female may neglect her live kits and become increasingly depressed as toxicity develops. A fetus that dies early in gestation is normally resorbed without complication, but loss of fetal fluids may lead to mummification. A mummified fetus can remain within the uterus for extended periods of time and prevent further pregnancies. Causes are thought to be similar to those for infertility (see above), with poor conditioning or infectious diseases being the most likely. All female chinchillas should be examined as soon as possible following parturition to determine if there are retained fetuses. Abdominal palpation may not be conclusive and radiography should be used to provide a definitive diagnosis. A female not able to pass a retained fetus may require cesarean section.

Dystocia:
Dystocia is very rare in chinchillas, but may be observed with an abnormally large or misplaced fetus or in young females bred too early. Poorly conditioned females may also develop primary uterine inertia or lack sufficient strength to deliver the kits. If labor continues >4 hr, oxytocin (1 U) or 0.5 ml of 20% calcium solution should be administered IM. If dystocia continues, a cesarean section should be performed.

Metritis:
A retained placenta or fetus may lead to bacterial contamination and inflammation of the uterus. Chinchillas with metritis may have anorexia, agalactia, abnormal gait, high fever, swollen discolored vulva, and a malodorous, mucopurulent vaginal discharge. Kits are at risk of infection through contact with infected discharge. Early detection and treatment are essential because affected females can develop a severe, fatal septicemia with sudden deterioration and death. Oxytocin induces uterine contractions and expulsion of mucopurulent debris. The reproductive tract can be irrigated with an antiseptic solution, followed by sulfathiazole in mineral oil, using a small rubber catheter to deliver the solution into the uterus. Appropriate systemic antibiotics should be administered and general support provided.

Pyometra:
Following an episode of metritis or retained placenta, and occasionally observed in unbred females, bacterial infection may lead to pyometra with accumulation of mucopurulent debris within the uterus. Clinically, chinchillas lose weight and have a rough hair coat and a mucopurulent vaginal discharge staining the perivulvar areas. Often, affected females are no longer capable of successful breeding and should be culled. Medical treatment of pyometra is ineffective and ovariohysterectomy is recommended.

Agalactia:
Inadequate milk production in postpartum chinchillas depends on a variety of age, genetic, infectious, and nutritional factors. Kits from agalactic females are vocal, restless, lose weight, and may die. Following parturition, the female’s mammary glands should be examined for milk production. If females have not begun to produce adequate milk within 72 hr, oxytocin should be administered to stimulate milk letdown. Cross-fostering with compatible females or guinea pigs may be necessary in unresponsive cases or large litters.

Mastitis:
Mammary glands of lactating females should be observed frequently for injuries caused by the sharp teeth of nursing kits. Superficial lesions can be treated with topical antibiotics and warm compresses. More extensive tissue trauma can lead to inflammation and infection. With clinical mastitis, mammary glands are warm, firm, enlarged, and painful. Milk may be thick or bloody and clotted. Appropriate systemic antibiotics are indicated and kits may need to be cross-fostered or hand-raised.

Hair Rings:
In male chinchillas, a ring of hair may surround the penis within the prepuce and cause a secondary paraphimosis, urethral constriction, and urinary retention. Affected males may be observed excessively grooming, straining to urinate, and frequently cleaning their penis. Hair rings often develop following copulation. Treatment includes lubricating the penis or mild sedation to facilitate gentle removal of the fur ring.
 
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