Leptospira species are an important zoonotic bacterium harbored by some species of wildlife, including rodents. The bacteria are shed in urine from infected animals. Infection of cats with the spirochete bacteria Leptospira occurs but cats have always been thought to be resistant to development of clinical signs following infection. This report describes three confirmed cases of leptospirosis in cats with disease. All three cases were indoor/outdoor cats that were known to hunt.
All three cases presented with kidney disease, but no involvement of the liver as is sometimes seen in dogs. Symptoms included lethargy, anorexia, frequent urination, and excessive drinking. One cat had blood in the urine, and also inflammatory involvement of the right eye. Two of the cats responded well to treatment, but one continued to deteriorate and had to be euthanized.
Interestingly, these cats developed disease several months after the known exposure to rodents, implying a longer incubation period than is seen in dogs, which is usually a few days. The authors conclude that while disease due to Leptospira infection in cats is rare, it must be considered in cases of kidney disease. Further work is needed to determine the ability of cats to carry and shed the bacteria asymptomatically. [MK]