IACUC Learning Module - Rabbits

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GENERAL INFORMATION

The life span is normally 6-7 years, although rabbits may live to be 15 years of age. The body temperature normally fluctuates between 102-103 degrees F. Emotional stress causes a fall in body temperature which is unlike most other endotherms. (Fright or stress causes the autonomic nervous system to be stimulated-renal ischemia may develop as blood is shunted to the head and heart). The urine is a cloudy to thick, creamy color. This color is due to the high calcium salts, pH of 8, and may precipitate on floors as a white granular salt.

The rabbit has a large cecum and bacterial fermentation is an important component of digestion. Pelleted chow is the optimum feed, since rabbits prefer pellets rather than ground diets. Many laboratory facilities will limit the feed given to adult rabbits since obesity is a common problem. It is normal for rabbits to eat the feces passed at night (cecotrophy). Night feces are softer than other feces, composed of cecal secretions and are a rich source of the B-vitamins.

The rabbit was once thought to belong to the order, Rodentia. However, the rabbit has been reclassified as a Lagomorph, based on a unique dental structure. Lagomorphs have two pairs of permanent upper incisors, the additional set being smaller and placed directly behind the "normal" set of upper incisors. This is of some importance to investigators since Federal Law requires survival surgery on all non-rodent species (including the rabbit) to be performed in a dedicated surgical area and under strict aseptic conditions (mask, gown, gloves, sterile drapes and instruments, full surgical clip and preparation).

Males are called "bucks" and females are called "does"; when rabbits give birth, they are said to have "kindled". The bucks are sexually active at 6-8 months of age and are highly territorial. Bucks housed together may fight, even castrating one another! The doe is always taken to the buck's cage for mating since bucks do not breed well outside of their defined territory. The doe is sexually active at 4-6 months of age and may be active breeders from 1-3 years. Rabbits have a continuous estrus cycle and ovulation occurs following mating (induced). Females housed together may ovulate and go into pseudo-pregnancies. The doe will often accept the buck during pseudo-pregnancy and may become pregnant. Gestation is 28-35 days. Late in gestation, the doe will pluck hair from the dewlap and ventrum to make a nest. Nest boxes should always be provided to pregnant does. The doe is easily distracted from her young and should never be disturbed when nursing young. The doe will nurse the baby rabbits, called bunnies or kitlings for only 5-10 minutes per day. Litter size ranges from 6-8 and cannibalism is quite common, especially if the nursing doe is disturbed. Hair growth is noticeable at 5 days, the eyes open at 9-10 days and the bunnies begin to venture out of the nest box around 3 weeks of age. Weaning occurs at 6 weeks of age when the bunnies weigh around 4 lbs.

Rabbits are very susceptible to infections with various bacterial pathogens. Pasteurella multocida, the cause of "Snuffles" is a gram negative of particular importance. Clinical forms range from inapparent carrier states to snuffles, pneumonia, otitis media, conjunctivitis, pyometra, orchitis, abscesses and generalized septicemia. Since many rabbits asymptomatically carry this pathogen in the nasal cavity, it is very difficult to rid a colony of this agent. Specific Pathogen Free (SPF) rabbits are available, however the cost of such animals is quite high. Staphylococcus aureus and Bordetella bronchiseptica are also common isolates from the nasal sinuses of both healthy rabbits and those with snuffles. Although Bordetella usually does not by itself cause clinical disease in rabbits, it is a deadly pathogen for guinea pig colonies. Therefore, great care must be taken to ensure that staff do not move from rabbit rooms (even though the rabbits appear healthy) to guinea pigs rooms, without following proper disinfection guidelines.

All animals in University facilities are observed on a regular basis by one of the clinical veterinarians. Please assist us in maintaining colony health by immediately reporting any suspected health problems. Concerns regarding health care and husbandry should be reported to the Animal Care Supervisor for the area. Common signs of illness in rabbits include : nasal or ocular discharge, inflamed conjunctiva, head tilt, scabs in ears, inappetence, diarrhea and lethargy.

Rabbits may be identified by ear tattoos, ear tags, felt pens or hair dyes. Please consult with the Animal Care staff when determining the best method for a study, since all have advantages and disadvantages.

It is important that research staff consult with the Department of Animal Care concerning selection of breed or strain, unique housing or feed requirements, and proper agents for analgesia, anesthesia and tranquilization. The Institutional Animal Care and Use Committee follows the euthanasia guidelines established by the American Veterinary Medical Association, although scientific considerations may necessitate an exception.

All rabbits used in research or teaching must be ordered through University Animal Care (626-4511). The U.S. Department of Agriculture regulates those persons selling rabbits to research institutions and the University must obtain rabbits from licensed dealers. Although most rabbits ordered are not SPF animals, the sources which are on the University Animal Care's "approved vendor list" maintain stock which are generally in good health (all incoming rabbits are periodically monitored as to health status). The prevention of entry of viral or bacterial pathogens is one of the most important methods of disease control for laboratory facilities. NO ANIMALS MAY ENTER UNIVERSITY FACILITIES UNLESS ORDERED THROUGH THE DEPARTMENT OF ANIMAL CARE.

Never be hesitant to ask the Animal Care staff for assistance, particularly when dealing with a fractious animal. Rabbit "guards" which are heavy plastic sleeves which cover from the wrist to elbow are available through the Department. Although not common, rabbits may become aggressive and be quite dangerous. (Proper handling and habituation of new research animals will decrease the incidence of such "killer rabbits").

Animal Care staff are available to assist research staff in obtaining practical experience in the techniques demonstrated in the videotape. Please call Biotechnology Support Service (626-6702) to arrange a suitable time and location. Should a new member join your research staff, please do not allow them to handle the animals until they have received proper instruction from either an experienced member of your staff or an Animal Care staff member.

Important Link: IACUC Approved Analgesics, Anesthetics & Sedatives

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Last updated: 01/02/2008 gea