Though rats have long been considered the harbinger of dread diseases, including the epic Black Plague, a well-cared-for pet rat poses little risk of illness to its human companion. There are, however, viruses associated specifically with the rat species -- some of which may be transmitted unknowingly by you through contact -- so call your veterinarian if you notice possible signs of illness.
If your pet rat is unusually lethargic, spends her day hunched in a corner, is sneezing excessively or seems to be having trouble breathing, she may have contracted the highly contagious Sendai virus, which preys exclusively on mice, rats and hamsters. Other symptoms may include a gooey discharge from her eyes or nose, lack of appetite and reproductive difficulties, including delayed birth or stillbirth of a litter. There is no treatment for SV, which may lead to pneumonia or death. Because SV is transmittable by airborne droplets up to six feet away, it's very important to quarantine your sick pet from other, healthy rodents for three to four weeks. If you suspect your rat may have contracted SV, call your vet immediately. Diagnostic tests for SV are readily available, and your pet may need to be treated for secondary bacterial infections associated with respiratory viral illness. With managed care and TLC, your pet can recover from SV in roughly three weeks.
There are three types of parvoviruses in rats, and each group contains a number of strains, but only one is associated with apparent disease -- the Kilham virus, also known as rat parvovirus. Usually asymptomatic in adult rats, RV is of most concern in breeding colonies, where the virus is associated with smaller litters, stillborn litters, runting, infertility and litter reabsorption. Occasionally, a rat infected with RV may exhibit symptoms that include a failure to thrive, muscle weakness, balance or movement problems or jaundice (yellowing) of the eyes. There is no cure for RV, and diagnostic tests will continue to show a positive result long after the active infection has resolved. Because RV can remain on surfaces and bedding for months after infection and is resistant to disinfectant measures, quarantine of an infected rat is recommended for 60 to 90 days for younger rats and up to six months for affected adults.
Common symptoms of sialodacryoadenitis virus (also known as rat corona virus) include bulging eyes, swelling of the neck or cervical nodes, bleeding, oozing or staining of the tissue around your rat's eyes. If your rat has contracted a secondary infection associated with SDA, he may also exhibit respiratory symptoms including sneezing, difficulty breathing or extreme weight loss and lethargy. There is no cure for the highly contagious SDA, but the virus will usually clear within 7 to 10 days, though affected rats may need antibiotics to treat any secondary bacterial infections. Quarantine new rats for at least two weeks before introducing them to your rat colony to help prevent possible contamination.
Care for Virus-Infected Rats
Remove and quarantine any rat from a colony if he appears to have symptoms of illness, and call your veterinarian immediately. Though rat viruses may not be curable, secondary bacterial infections commonly associated with viruses may need to be treated with antibiotics to avoid further complications. Provide extra water to a sick rat to prevent dehydration. Regulate temperatures in his environment through the use of heating elements, such as a heating pad beneath the cage or a pet-safe microwavable isothermic product, to help keep his body temperature stable. Provide plenty of nutrient-rich food sources, and keep the lighting in the area of the cage low to help your sick rat get the rest he needs. Always wash your hands before and after handling your rat to avoid further contamination or the possible introduction of other harmful viruses or bacterium.