THE RABBIT OBJECTIVES Upon completion of this module the student will be able to: 1. State the genus and species names for the domestic rabbit. 2. Identify the different uses of rabbits. 3. Identify the ranges for the following: - Adult body weight (male) - Adult body weight (female) - Life span - Gestation period 4. Describe common behaviors that are unique to rabbits. 5. Explain the proper handling of rabbits. 6. Describe how to properly identify the sex of a rabbit. 7. Identify the breeding program(s) for rabbits and briefly explain them. 8. Describe appropriate husbandry for rabbits. 9. Describe the unique anatomical characteristics of the rabbit. 10. Identify the common diseases/health concerns of rabbits. 11. Describe the correct restraint and correct procedure for the following: - IP injection - SQ injection - IM injection - Marginal ear vein blood collection - Medial ear artery blood collection - Cystocentesis - Cardiac blood collection - Toe nail trim - IV catheter - Intubation INTRODUCTION The domestic rabbit, a lagomorph, originated in southwestern Europe where it is found in three forms domestic, feral, and wild. Only the domestic and feral forms exist in North America. It was domesticated in the late middle ages and is the only genus of rabbit in Europe. Hares (Lepus) and cottontails (Sylvilagus) are in different genera. Domestic rabbits released in the wild have established themselves in some areas of the United States. An example is the San Juan rabbit. In the wild, rabbits are gregarious, burrowing, herbivorous, and nocturnal or diurnal depending on the environmental conditions. TAXONOMY The domestic rabbit was originally thought to be a member of the order Rodentia. However upon discovery that the animal had six incisor teeth instead of the normal four of rodents they were reclassified to the order Lagomorpha. Class: Order: Family: Genus: Species: USES The rabbit is a popular pet used in a variety of ways in society. It is raised as a show animal, it is popular animal project for many suburban 4-H youth, and it finds it s way into entertainment, often being the center of attention for a magician and his audience. It is also often the animal of choice for some types of research. Reliable sources indicate that the current usage of rabbits for biomedical studies and classroom instruction is somewhere around 500,000 animals a year which amounts to around 23% of all animal usage. (Harkness and Wagner) Representative examples of studies in which include arteriosclerosis, hydrocephalus, hyperthermia, cancer, teratology, cosmetics, ophthalmology, reproductive physiology, antibody production, and aging. It s use in the classroom focuses on principles of mammalian physiology and surgery. STRAINS AND STOCKS All breeds of the domestic rabbit have descended from the European rabbit (Oryctolagus Cuniculus). Depending upon which source you use there are anywhere from 35 to 100 breeds of the domestic rabbit. The American Rabbit Breeders Association currently recognizes 45 breeds and 77 varieties. Breeds are distinguished by size at maturity, ear length, ear carriage, body shape, fur type, and fur markings. Rabbits come in a wide range of weights. The larger breeds such as the Flemish Giant or Giant Chinchilla may weigh over eighteen pounds whereas the smaller breeds of Mammalia Lagomorpha Leporidae Oryctolagus Cuniculus 2 which the Polish and Dutch are examples may only weight two and half pounds. In between are the medium size breeds, Californian and New Zealand White, which will range from two to five kilograms. There are approximately six inbred strains but they are difficult to raise due to decreased productivity, increased susceptibility to disease and infection, and greater mortality. Some of the more popular breeds are the New Zealand White, Californian, Chinchilla, Dutch Belt, Champagne D Argent, Flemish Giant, Checker Giant, Rex, Hotot, and Angora. ANATOMY Rabbits come in all shapes and sizes. There are several generally recognized body shapes. Among them are the commercial type (New Zealand White), mandolin type (Flemish Giant), full arched type (Checkered Giant), compact type (Netherland Dwarf), and the cylindrical type (Himalayan). The rabbit body is mostly covered with fur and characterized by guard hairs. The American Rabbit Breeders Association distinguishes the furs into the following categories normal, satin, rex, stand-up, and the wool. The head is closely set on the body having eyes with a nictitating membrane that are laterally directed. The large ears provide hearing for the animal and function in heat regulation. The marginal ear veins provide convenient sites for blood collection. The rear legs are well developed, aid in mobility, lack foot pads and have four digits. The front legs by comparison have five digits. The dental formula for rabbits is: I 2/1, C 0/0, P 3/2, and M 3/3. Rabbit teeth grow continuously. One unique characteristic of rabbits is the second pair of incisors located in the upper jaw. The second set of incisors are called peg teeth. The second set of incisors is the reason that rabbits are classified as lagomorphs. For nursing purposes the female has 4 5 pairs of nipples. Rabbits do have a short tail that has fur. Internally rabbits have a couple of features to note. The cecum is a large structure located at the juncture of the terminal end of the small intestine. Its function is to provide the area for fermentation and microbial digestion of food and to begin the process of formation of the soft feces. Also of interest are the female rabbit s reproductive organs. The uterus consists of two horns that are separated for their entire length and come together to form the vagina. RESTRAINT Good techniques are very important in working with rabbits. Since they panic easily and have a strong set of hind legs injury may result to both animal and handler. A struggling animal may both scratch the technician or worse yet break it s back and have to be euthanized. To pick up a rabbit one should alert the rabbit as to your presence and approach the animal with care and deliberateness. With one hand the scruff of the neck is grasped and the animal pulled toward the technician. With the other hand the rump is supported. Once the rabbit is secured all struggling normally ceases. Rabbits that are used to being handled will allow the handler to place one hand under the ventral side and to lift the animal into a cradled position in the crook of the arm. This method is used quite often to transfer animals from one cage to another. Restraint of rabbits may be 3 accomplished in several ways. There are numerous restraint devices that are available from equipment companies that are made of stainless steel or plastics or a combination thereof. Rabbits usually adapt to these rather quickly and minimize their injury during procedures such as blood collection. For some procedures the use of a towel to wrap the animal in is helpful to calm a struggling animal. Some rabbits will also lapse into a docile state by being placed on their back and being stroked on the stomach by the technician for several minutes. REPRODUCTION/BREEDING Distinguishing males from females is an anatomical exercise rather than looking for secondary sexual characteristics. To sex a rabbit place the animal on it s back and locate the anal region. In the case of a female the vulva will be recognized as a pointed slit whereas the male one will find hairless scrotal sacs and a penis. The penis may be protruded after two months of age by applying pressure posterior to the anal region. Most rabbits reach puberty at between the ages of four to nine months depending upon the breed size. Rabbits are induced ovulators. Most rabbit breeders use the polygamous system of breeding with an average of one buck to ten to fifteen does. It is important that the doe be brought to the buck s cage. If the reverse is attempted the doe demonstrates territorial aggressiveness or the buck becomes distracted in his new surroundings thus leading to a poor mating. Ten to fourteen days post breeding, nodules the size of marble can be palpated in the abdomen if the doe is pregnant. Palpation should be repeated at 26 to 28 days as resorption sometimes does occur at that point in the gestation. Gestation is normally 30 to 35 days long with an average of 32. Within one week of parturition the doe will normally build a nest using fur from her body and a next box provided by the breeder. The young (kits) are born hairless, blind, and helpless. After birth the doe will visit the box once daily to nurse her young. The kits will remain in the next box for approximately three weeks after which time the box may be removed from the cage. Post partum estrus does occur but breeding at this time is not recommended unless the doe has birthed a very small litter and she is on a high plane of nutrition. Weaning of kits is carried out at about four to fine weeks. HUSBANDRY Husbandry concerns for the rabbit involve housing and nutrition. Historically rabbits have been maintained in cages made of wood. Even today many rabbits especially pet rabbits and 4-H project rabbits are probably still kept that way. The cage consists of a wooden structure and enclosed with a wire mesh. Straw is the bedding of choice for these types of cages. Most commercial suppliers and research facilities house their animals in metal cages for sanitation purposes. Rabbit urine has a tendency to adhere to the surface of whatever material it comes in contact with. Because acids remove the deposit most readily husbandry personnel find that metals especially stainless steel clean the easiest. A new cage has been manufactured recently, which uses a plastic cage inserted in a stainless steel frame. In addition to facilitating cleanliness rabbits 4 seems to exhibit a more docile nature while housed in them. Rabbits housed in these cages do not require a bedding material. One however should consider using water in the pans. This practice confines the hair that the animal loses to the microenvironment and prevents it from entering the ventilation system and causing mechanical problems. Proper size for rabbit caging may be located in the Animal Welfare <a href="/keyword/regulations-promulgated/" >regulations promulgated</a> by the U.S.D.A. or the Guide for the Care and Use of Laboratory Animals. The macro environment for the rabbit is of crucial importance. Of all the factors (light, temperature, ventilation, humidity, and noise) involved in this area, ventilation is most important. Rabbits are very susceptible to respiratory diseases. A rabbit room should normally provide for approximately 15 20 changes of air per hour to control ammonia buildup but the room must be free of drafts and turbulence. The average lighting cycle for rabbits is between 12 and 14 hours per day with the females requiring slightly more than the males. The room should be maintained at approximately 50% humidity and the temperature in the upper 60 s Fahrenheit. Rabbits are known to tolerate temperature extremes but good husbandry should keep this situation from occurring frequently. One factor that the husbandry personnel have control over is preventing loud sudden noises from occurring. Routine husbandry duties and frequent cage changing should be carried out with a minimum of banging and clanging. Loud, sharp noises can cause reproductive problems as well as stampeding leading to potential broken backs. Rabbits are by design monogastric herbivores and have the unique practice of what is known as cacotrophy that will be discussed later. Diets of the past were hand made of grains and legumes but in most cases today commercial diets in a pelleted form are fed. They consist of hay, grains, and supplements and are useful for approximately 6 months after milling. Alfalfa hay may be supplemented but is normally not needed. There are no exact figures on nutritional needs of the domestic rabbit however the following are generally accepted for dry does, herd buck, and developing young: Crude Protein: Fat: Fiber: 12 15% 2 3.5% 20 27% Food consumption is of importance to the animal technician. Rabbits are picky eaters and any changes in diet must be carefully monitored. Rabbits so favor sweet tasting items and this may be used to advantage when working with diet changes. Molasses spread over the top of a diet may induce the animal to sample the contents of the feeder. Ambient temperature and water consumption are factors that must be watched as well as they affect the amount of food a rabbit will consume. A rise in room temperature or lack of water will decrease the intake of food. Feed is normally provided to the rabbit by means of a J feeder or a crock. The feed will need to be checked daily to insure cleanliness and freshness. In the case of J feeders the animal care person must be careful to check daily for fines. Fines occur when the 5 rabbit eats over the feeder and the dust from pellets settles on top of the hopper and the rabbit prevent the downward flow of the feed. In the past most rabbits were allowed to eat feed ad libitum. However recent data has shown that it is better to limit feed rabbits especially in the case of adults. Approximately 100 grams of feed a day seems to meet the nutritional needs of most mature rabbits. There may be some breed differences. Rabbits consume high amounts of water. A doe and litter may consume as much as a gallon of water daily. Water is normally provided to the animal via bottles, crocks, or an automatic watering system. If the automatic system is used it must be checked daily for proper functioning of the nipples. In the case of crocks they will need to be checked twice daily for freshness as well as availability. Rabbits have a tendency to play with crocks either by moving them around the cage or turning them upside down emptying the contents. Rabbits do practice what used to be called coprophagy but is now known as cecotrophy. The former is common among a number of domestic animals however with rabbits it is a necessary part of their health. Cecotrophy involves the rabbit eating a very specific part of the feces, which comes directly from the cecum. In most circles this is known as the night feces since the rabbit carries out this practice during the evening hours. Night feces appear as soft round pellets that are green colored, clustered (like grapes), and coated with a mucous like membrane. The rabbit utilizes them in Vitamin B-complex synthesis. HEALTH CONCERNS Good management practices eliminate a number of the health issues for the domestic rabbit. Good ventilation, aggressive cage sanitation, and periodic physicals will minimize respiratory diseases, parasites, malocclusion, and limb injuries. Some of the more common maladies for rabbits are: Diseases of the Respiratory System: Pasteurellosis (Snuffles) - Caused by Pasteurella multocida. It is characterized by exudate from the nasal passages and pneumonia. It rapidly spreads through the rabbitry. Diseases of the Gastrointestinal System: Tyzzer s Disease Caused by Bacillus piliformis, a bacteria. May see sudden deaths and/or diarrhea. Highly infectious. Coccidiosis Various species of coccidia can infect the small intestine (Eimeria magna, E. perforans, E. irresidua) or the liver (E. stiediae). May be sub-clinical or cause symptoms ranging from anorexia to severe, life-threatening diarrhea. 6 Trichobezoar (Hairball) Rabbits constantly shed hair and groom themselves. Occasionally this results in an accumulation of hair in the stomach. Symptoms are anorexia, lethargy, and death. Mucoid Enteropathy The precise cause is unclear, but appears to involve several agents and factors. Characterized by diarrhea containing a large amount of mucus in young rabbits (7 10 weeks old). Miscellaneous Diseases: Ear Mites (Otitis External) Caused by Psoroptes cuniculi. May see dry, crusty, exudate on inner surfaces of the ear with red, painful skin underneath exudate. Fur Mites Caused by Cheyletiella hominivorax. May see hair loss, especially over the shoulders. Can infect humans (zoonotic). Sore hocks (Ulcerative Pododermatitis) May see ulcers or scab-covered lesions on bottom of feet. Related to housing on wire bottom cages. One way to help alleviate sore hock is to place a solid resting surface in the cage. Broken Back Due to vertebral fracture of lumbar vertebrae (usually L7) often secondary to improper handling. Characterized by hind limb paralysis, urinary and fecal incontinence. Malocclusion Overgrowth of incisors. Animal is anorexic and may lose weight, and can have slobbers . 7