Institutional Animal Care & Use Committee

A Brief Overview of Laboratory Rat Diseases

 Rats are a hardly species and capable of withstanding many environmental insults. Even so, they are susceptible to certain diseases. As I noted earlier, low relative humidity can produce ringtail. This is particular true during the winter months when the heating system is in operation. The primary symptom of ringtail is an annular constriction of the tail. Parasites, particularly lice are also a problem. Like us, if infested with lice, the rats will spend their time scratching. Ectocide powder is effective. Rid Ex, available over the counter in most department stores is also effective. Middle ear disease is a troublesome problem sometimes seen in rats. Symptoms of this disease are a tilted head and an inability to run in a straight line. Unfortunately, there is no cure, so affected animals should be removed from the colony and euthanized. One problem that crops up from time to time in colonies is chronic respiratory disease. Symptoms of this disease include a nasal discharge and watery eyes, weight loss, and wheezing. Chronic respiratory disease is progressive. While it may be preventable with the use of antibiotics, it is usually a good idea to remove infected animals immediately and euthanize them.



Health Concerns for Individuals Who Work With Rats

Allergic Reactions to Rodents. It is a fact of life--some people are allergic to rats. this should not seem too surprising since they are furry animals, just like cats and dogs. Many do have some symptoms that reflect an allergy to rats. Luckily, the symptoms are not serious. Among the allergic responses that have been reported, are rashes after contact with the rat's toenails or tail and brochial asthma. Severe conjunctivitis after contact with rat urine has been reported. In extreme cases, allergies have led to anaphylactic shock. Allergic reactions to laboratory animals have caused technicians to change professions and researchers to choose a new research direction. My former major professor developed such an acute allergy to rat dander that he ceased all research with rodents. If you are allergic, don't dispair. Face masks, allergy treatments, and antihistamines are sometimes quite helpful.

Rat Bites. If you work long enough with rats, you will receive a bite. Laboratory rats are not vicious but will bite if handled improperly and sometimes when they are food deprived. Certain lesions also increase aggression. One thing you must remember. Bite wounds, regardless of species (including humans) must be cleaned thoroughly and an antibiotic ointment applied to the area of the wound. You should also receive a tentanus booster shot before working with rats. If your tentanus shot is not current, get one now! Other Concerns...  For a good discussion of disease concerns, consult Percy and Barthold (1993) or the many resources available on the "PBA IACUC Animal-Related Links of Interest page."

 Rat Bite Fever. Rat bite fever is the most commonly reported zoonosis from laborary rats. Luckily, it is rare but should be considered. Most cases of rat bite fever are caused by the bacteria Spirillum minus and Streptobacillus moniliformis, with most cases resulting from the latter bacterium. Death has been reported but antibiotics work quite well. If symptoms develop after a rat bite, seek immediate medical attention. Symptoms you need to watch out for are fever, chills, a rash, a sore throat, and arthritis-like symptoms. Complications can include endocarditis and pericarditis. However, when you consider how many laboratory researchers and technicians are bitten each year, the incidence of rat bite fever is extremely low!

Salmonella. Salmonella can be a problem in laboratory rats and, thus, a potential hazard to laboratory workers. As far as I know, no cases of rat to human transmission from laboratory rats has been reported.

Rabies. Rabies is fairly rare in rodents. It is extremely unlikely that a human can develop rabies as the result of a bite from a laboratory animal.


  • Bennett, B. T., Brown, M. J., & Schofield, J. C. (1990). Essentials for animal research: A primer. Available: The American College of Laboratory Animal Medicine.
  • Melby, Jr., E. C., & Altman, N. H. (Eds.). (1974). Handbook of laboratory animal science. New York: Academic Press.
  • National Academy Press (1996). Guide for the care and use of laboratory animals. Washington, DC: Author.
  • Public Law 99-198 (1986).  Code of Federal Regulations, Title 9, Subchapter A, Animal Welfare.
  • Universities Federation of Animal Welfare (1987). The Universities Federation for Animal Welfare Handbook on the care and management of laboratory animals (6th ed.). New York: Churchhill Livingstone.