UNIT 9

Lab Animal – Rodent, Rabbit Health Management

Part I – Background Information on Rabbits and Rodents

Background information on rodents

Mouse

  • The most popular animal used in research. Approximately 10 million are used annually in the U.S. for such research as drug testing, aging, virology, congenital defects, neoplasia, genetics, and autoimmune disease to name a few.
  • Mice live two to three years and are classified either ecologically or genetically. The ecology group is subdivided into axenics, gnotobiotes, specific pathogen free, and conventional. Genetically mice are classified as random-bred, inbred, or F1 hybrids.
  • There are over 100 strains of mice in existence today. The long established Swiss-Albino mouse is probably the source of most mouse strains. Some examples of popular inbred strains are the C3H mouse and the C57BL/6. The Swiss-Webster and the ICR are good examples of outbred mice.
  • Mice become sexually mature at approximately two months. They breed for approximately 7 to 18 months and produce 6 – 8 litters consisting of 10 – 12 pups per litter. The pups are weaned between 21 – 28 days.
  • Mice are fed ad libitum. They adapt well to either water bottles or automatic watering systems. A good maintenance diet contains 4 to 5 % fat and 14 % protein. These percentages should be raised 1 –2 points for animals that are in the growth and reproduction mode. An adult mouse will eat approximately 15 grams and drink 15 ml of water per 100 grams of body weight per day.
  • Mice have a highly developed sense of hearing. High-pitched sounds, for instance from a computer, may cause audiogenic seizures in some strains and possible destruction of litters.

Rat

  • Rats are well-defined animals that make excellent research animals ( 4 million used annually) as well as pets. They are classified in the same manner as mice – ecologically and genetically.
  • The laboratory rat, Rattus Norvegicus, is a rodent of the family Muridae. Wild rats are colonial nature and active burrowers. Laboratory rats do maintain some of the burrowing behaviors.
  • There are different strains of rats. Some examples are Sprague-Dawley, Wistar, Fischer, Brattleboro, and the Long-Evans. Rats are like mice in that there are inbred and outbreds. Some of the more popular inbred strains are the Fischer 344, Wistar, and the SHR (Spontaneously Hypertensive Rat). Outbreds include the Sprague-Dawley and the Long-Evans.
  • Rats are known to live beyond three years. The breeding age for rats varies from 65 to 110 days. The gestation period is 21 days and they normally deliver anywhere from 6 to 12 pups.
  • Rats are neophobic (cautious eaters) and nocturnal (feed at night). They are fed ad libitum and will consume 5 grams of feed and 10 ml of water per 100 grams of body weight. Commercial diets for rats should contain 17 % protein and 4.5 % fat. As in the case of mice this should be increased during periods of growth and reproduction.
  • Rats like horse lack a gallbladder and are unable to regurgitate.

Guinea Pig

  • The Guinea Pig, Cavia porcellus, is a popular pet that has its roots in the Andes Mountains of South America. This animal is known for its messiness, need for supplemental vitamin C, tendency to stampede, and fastidious eating habits.
  • The Guinea Pig can live up to 8 years, however, in most home environments they live not more than 5. Guinea Pigs are classified as hystricomorphs or hedge-hog like animals.
  • There are three major strains of the Guinea Pig. The English, widely used in research, the Abyssinian, and the Peruvian. The latter are quite popular for show as well as 4 – H projects.
  • Guinea Pigs are weaned at approximately 18 – 24 days and reach sexual maturity at around 12 weeks of age. Their breeding life lasts anywhere from 18 months to 4 years. They have one of the longer gestation periods, approximately 65 days, and give birth to 2 – 4 piglets.
  • Guinea Pigs are herbivores and like horses and rabbits are cecal fermenters. Due to a lack of an enzyme they are share a common bond with non-human primates as well as humans in that they need supplementary Vitamin C in their diet. Guinea pigs consume 6 grams of feed and 10 – 40 mls of water per 100 grams of body weight daily. The diet should contain 18 – 20 % protein and 10 – 16 % fiber.

Hamster

Hamsters, popular in research and as a pet, are known for their hardiness, periodic pugnaciousness, ease of taming, and ability to escape their confinement.

There are approximately 370,000 hamsters used in research annually within the U.S. Hamsters are characterized by short life spans living in most cases only 18 – 24 months.

There are three strains of hamsters that one should be familiar with – Golden Syrian, the Siberian, and the Chinese hamster. The Golden Syrian is the most frequently used strain in research, but the Chinese hamster provides a good model for Type 1 juvenile-onset diabetes.

Hamsters have the shortest gestation period of the rodent family at 15 – 18 days. They normally mature sexually at 32 – 42 days and have a breeding life span of one year. Litters usually average 5 – 10 young.

Hamsters are granivorous (i.e. they will eat insects). They are normally fed a commercial pelleted diet that contains approximately 16 % protein and 4 – 5 % fat. Hamsters are coprophagous and routinely carry out this practice 20 times daily. Hamsters eat 8 – 12 grams of feed and 10 mls of water per 100 grams of body weight.

An interesting fact about hamsters is that they are known to conduct what is called a pseudohibernation. If environmental conditions are present, shortened day length and lowered room temperatures, they will gather food and go into a sleep pattern for extended periods of time.

Gerbil

  • The common gerbil, Mongolian, is an active, nearly odorless, and normally non-aggressive animal of the rodent family. The Gerbil originated in the desert regions of northern China. They average three years for a life span.
  • The Mongolian gerbil is by far the most widely used gerbil in research in the U.S. Depending upon taxonomist 11 to 15 other species of gerbils are in existance and several of these are more popular for use in research in other countries.
  • Gerbils reach sexual maturity at about 10 – 12 weeks and average 15 – 20 months for breeding life. The gestation period is 24 – 25 days and usually 4 –5 animals are born each time. Gerbils are characterized as among those animals which mate for life.
  • Gerbils are classified as both herbivorous and gravnivorous. They are fed ad libitum and owners should be warned to be cautious with the use of treats. A pelleted chow containing 16 – 22 % protein is adequate. They normally consume 5 – 8 grams of feed daily and their water intake is rather low at 4 mls daily. This is not surprising since they are a desert animal.
  • An interesting behavior of gerbils is that they occasionally exhibit epileptic seizures lasting usually less than a minute.

Rabbit

  • The domestic rabbit, Oryctolagus cuniculus, is a lagomorph of the family Leporidae. There are over 20 breeds of rabbits as classified by the American Rabbit Breeders Association. Classification is based on size ranging from the large breeds (Flemish Giant), to the medium size breeds (Californian), and the smaller breeds of which the Dutch belted is a good example.
  • Rabbits reach sexual maturity at approximately 6 – 9 months. Their breeding life extends out to three years and they are capable of producing anywhere from 7 to 25 litters of 7 – 8 kits per litter.
  • Rabbits are monogastric, hindgut fermenters that practice cecotrophy. Adults consume approximately 130 grams of feed a day and drink 150 mls of water although consumption can increase to 900 mls for a lactating doe. The diet should contain 12 – 19 % protein, 2 % fat, and 16 – 25 %. A high fiber diet should be given to prevent obesity, hair chewing, and enteritis.

Part II - Rodent and Rabbit Management Practices

Public Health Concerns

Mouse: Salmonellosis and lymphocytic choriomeningitis are two zoonotic diseases that occur in mice, however, their occurrence is rare. Allergies to fur dander is a growing problem today among animal care technicians and pet owners.

Rat: Some of the zoonotic diseases carried by the rat are leptospirosis, streptococcal infections, salmonellosis, cestodiasis, hemorrahgic fever with renal failure, and rat bite fever. These diseases are common in wild rats but would be rare in domestic laboratory rats.

Guinea pig: Diseases of public health concern would be rare in the guinea pig. They may carry bacteria such as Bordetella, Salmonella, Yersinia, and Streptococcus but cases of transmitting this to human beings is extremely rare.

Hamster: An outbreak of Lymphocytic choriomeningitis (LCM) was recorded in humans in 1974 –75. But severe cases of this disease associated with guinea pigs is rare. Salmonellosis is a potential zoonotic disease but the risk of exposure is small. Rabies is also highly unlikely.

Gerbil: Gerbils in domestic and research settings have very few disease problems. They have potential to carry Salmonella and Hymenolepsis but the potential to pass this on to humans is extremely small.

Rabbit: Diseases of the domestic rabbit that have public concern are salmonellosis, tularemia, rabies, ringworm, tuberculosis, and toxoplasmosis. Risk to the public is as in the case of rodents small.

 

LAB ANIMAL - KENNEL MANAGEMENT CONCERNS

Part I - Background information on Canines

Dogs have been used for experimental physiology, pharmacology, and surgical studies since the 17th century. The family consists of 17 genera and about 35 species.

Canine behaviors vary. For instance they are by nature pack animals and therefore do well in a kennel environment. Socially they exhibit differing actions based on whether they are friendly or aggressive. In the case of feeding some dogs will only eat in the presence of the handler whereas other dogs will only eat when the handler leaves the room. Males are territorial and utilize raised leg urinating to mark their boundaries. The average life expectancy is around 12 years with the larger breeds living shorter lives than the smaller breeds.

The critical stage in socializing puppies to humans occurs at 6 - 8 weeks. Contact must be maintained through at 4 months of age, as the animals are capable of reverting to a wild nature.

Dogs reach puberty at 8 - 14 months of age with the males maturing earlier than the females. The average gestation lasts 63 - 65 days with the female delivering an average of 6 pups.

Canine Classification: Following are some terms used to classify dogs: Mongrel: A mixed breed of more than two pedigrees which are unknown. Random Source: A dog obtained for biomedical research from either a pound, animal shelter, or any one of many other sources (except purpose breeders) which results in a dog with unknown origin and pedigree. Pound Dog: A dog obtained from a municipal pound or animal shelter with unknown history (or background) and genetic background.

Unconditioned Dog: A random source dog that has only been held for 5 days in quarantine and therefore has not been afforded the opportunity to be vaccinated, wormed, or medically cleaned up.

Conditioned Dog: A random source or pound dog purchased for research or teaching that prior to being utilized has been vaccinated, treated for parasites, and has been held for a period of time (usually 2 weeks) to be considered medically cleaned up.

Purpose Bred Dog: A pure or mixed breed dog raised for a specific purpose, i.e. biomedical research.

Part II - Kennel Management

Design Drivers for Housing

Designing and building a kennel must take into consideration certain forces that drive the effectiveness of the finished product. Some of those design drivers are:

Usage: How will the animals housed in the kennel be used? Will they be for teaching, testing, or research? Will the research involve infectious diseases? Will the usage allow for group housing or will the protocols require singly housed animals?

Regulations: The Animal Welfare Regulations (AWR) discuss housing requirements for both indoor and outdoor housing. Security: With the increased threat from animal rights groups and individuals the ability to protect the animals and human beings must be carefully considered.

Physical plant: The specifications of the HVAC system will affect both the amount of space required as well as the location of the various units designed to control the macro and microenvironment.

Personnel health: There is an increasing problem today with human allergies to animals. The building must be designed so as to minimize exposure and maximize the work efforts of the staff associated with the kennel. Of particular importance is noise and odor control. A room of 12 barking dogs raises the decibel level to near risk conditions for human beings. The HVAC system must not only eliminate the odors from the animal rooms but must also dissipate it in such a manner that it does not raise an issue with the public living and working in and around the kennel.

Environmental Control

Ventilation

There are several areas to take under consideration in regard to kennel ventilation. First is distribution. Cage designs are variable. Some are open with galvanized fencing and others are fairly enclosed and made of stainless steel. Depending on the type of caging air distribution will be either enhanced or hindered. Secondly one must access the thermal load. The larger the breed of dog the greater the number of therms that a kennel room will need managed. A third consideration is the effectiveness of the system in eliminating hair and dander. The exhaust must be filtered so as to prevent these items from entering the duct system and eventually clogging it. The standard ventilation rate for most kennels is 10 - 15 changes of air per hour.

Lighting

Lighting is not an issue for dogs as much as it is for rodents since the dog has periods of activity day and night. However, Animal Welfare Regulations do made a number of recommendations. Among them are that lighting must be sufficient to allow observation of the animal, enhance husbandry operations, and provide for good housekeeping to be carried out. Of particular note is the fact that the lighting must be "uniformly diffused" throughout the kennel to facilitate the practices mentioned above and must protect the animals from "excessive light". The lighting system should provide for a 12 hour light cycle.

Temperature/humidity Control

Dogs have ability to adjust to a wide range of temperatures. Most kennels housing research dogs are maintained at 65 - 72 0 F. AWR require that ambient temperatures within the kennel not fall below 45 0 F and not rise above 85 0 F for four consecutive hours. Humidity recommendations for kennels are to maintain it at between 30 - 70 % relative humidity.

Caging

Caging must provide for the following factors: Comfort, safety, security, sanitation, functionality, accessibility, visibility, and regulatory compliance. Most of the caging recommendations are engineer based. (i.e. space is based upon dog's weight) As an example the AWR provide a formula for determining proper cage size; measure the length of the dog from the tip of the nose to the base of the tail and add 6 inches, square this number, and divide it by 144. This number is then the required square inches to house the dog. In contrast many professional animal care technicians feel that the better way is to base the recommended cage space using performance standards. This approach takes into account the dog's size, physiological needs, and behavioral patterns. Another factor that effects caging is environmental enrichment. Cage furniture may or may not decrease the usable space as dictated by Animal Welfare Regulations depending upon how it is employed.

Health management

Depending upon the source of dogs managing the health arena can be a major consumer of time. Dogs whose background, health, and genetics are known in most cases will pose little problem. Dogs who are obtained from random sources can present a myriad of problems. Conditioning of dogs in the kennel should involve at the least the following: Housing in an area designed especially for determining the health status. This area is known as quarantine and it should be located in such a manner as to lower the potential for cross contamination of the existing colony. Animals should be allowed to acclimate to the new surroundings for at least 24 - 48 hours before any handling or manipulations by the kennel staff.

Animals during the conditioning period should receive a physical in accordance with guidance from the attending veterinarian, vaccinations, have ears cleaned, toenails clipped as needed, be checked for internal/external parasites, heartworms, and be given a bath. Treatments for parasites will be in accordance with the results of the fecals as performed by a veterinary technician. The conditioning period routinely lasts anywhere from one week to four weeks depending upon the quality of the animal received from the vendor. A successful conditioning period is determined by the veterinarian and not necessarily by policy.

Sanitation

Sanitation of the kennel is very important. Good sanitation maintains the health of the animals, repair of the equipment, and reduces the likelihood of pest infestation. Animal Welfare Regulations require that all surfaces in contact with the animals be sanitized at least every two weeks. In addition all equipment (i.e. food bowls, water bowls) must be removed from the animal's run and sanitized as well. Having the proper equipment is essential to good sanitation. As a minimum the kennel should have hoses, buckets, brushes, and personal protective equipment to carry out cleaning operations. The use of a high-pressure power washer or a foam applicator machine can enhance cleaning operations. In most cases sanitation is rendered by exposing all surfaces to water at 180 0 F for a period of at least 3 minutes. The use of a quaternary ammonium product will ensure that all surfaces are cleaned and sanitized. Some kennels apply bleach following cleaning to ensure that the surfaces are indeed sanitized. A 10 % solution of bleach will suffice. The use of powdered bleach will be more effective than using household bleach off the shelf of the local grocery store.

Resources:

9 Code of Federal Regulations, Subchapter A (Animal Welfare), Parts 1, 2, 3
The Guide for the Care and Use of Laboratory Animals, ILAR, National Academy Press, 1996 The UFAW Handbook on the Care and Management of Laboratory Animals. 6th Edition. Universities Federation for Animal Welfare. New York: Churchill Livingstone. 1987. (7th Edition due out in 1999)

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