Leptospirosis is a bacterial disease caused by spiral-shaped bacteria from the genus Leptospira. While more commonly recognized in dogs, this infection can affect various mammals, including cats. Although infection in cats is relatively uncommon, Leptospira antibodies are found in feline populations globally, with reported seroprevalence ranging from 4% to 33.3% depending on geographical location.
How Cats Contract Leptospirosis
Cats primarily contract leptospirosis through contact with urine from infected animals or environments contaminated by that urine. The bacteria can persist in moist soil or stagnant water sources like puddles, ponds, or marshy areas for weeks to months. Infection occurs when Leptospira bacteria penetrate mucous membranes, such as those in the eyes, nose, or mouth, or through abraded or broken skin.
Wild animals, including rodents, raccoons, skunks, and foxes, are common carriers of the bacteria and shed them in their urine. Cats that hunt and consume infected prey, particularly rodents, are at an increased risk of exposure. Cats living near wooded areas or farms, or those exposed to urine from cohabiting animals like dogs or livestock, can also become infected.
Symptoms of Infection
The clinical signs of leptospirosis in cats can vary widely, with many infected felines remaining asymptomatic or exhibiting only mild, non-specific indications. Some cats may show subtle signs such as a sudden fever, lethargy, or shivering. A decreased appetite, vomiting, or diarrhea, which may or may not contain blood, can also occur.
As the disease progresses, more noticeable signs might develop, including increased thirst and urination, which can lead to rapid dehydration. In severe cases, the infection can affect major organs, potentially causing acute kidney injury or liver disease. Liver involvement may manifest as jaundice, characterized by a yellowing of the skin, gums, or the whites of the eyes.
Veterinary Diagnosis and Treatment
When leptospirosis is suspected, a veterinarian will conduct a thorough physical examination and recommend diagnostic tests. Blood work, including a complete blood count and biochemistry panel, can assess kidney and liver function, which may show abnormalities in infected cats. A urinalysis is also performed to check for signs of kidney involvement or the presence of bacteria.
Specific tests are available to confirm a Leptospira infection. The microscopic agglutination test (MAT) is a common antibody test used to detect the cat’s immune response to the bacteria. PCR tests can directly identify Leptospira DNA in blood, urine, or tissue samples, confirming an active infection.
Treatment for leptospirosis in cats involves a course of antibiotics to eliminate the bacteria. Doxycycline is prescribed, administered orally twice daily for approximately three weeks, to clear the infection and reduce bacterial shedding. Supportive care is also provided based on the cat’s clinical signs, which may include intravenous fluids to address dehydration and organ damage, or anti-vomiting medications.
Prevention and Human Risk
Preventing leptospirosis in cats involves minimizing their exposure to contaminated environments and infected animals. Limiting access to standing water sources like puddles, ditches, or ponds can reduce the risk of environmental exposure. Discouraging hunting behavior, particularly of rodents, is also important, as infected prey are a common source of feline infection.
Implementing rodent control measures around the home helps reduce the presence of potential carriers. While transmission from cats to humans is rare, Leptospira is a zoonotic bacterium, meaning it can spread from animals to people. The risk to humans primarily arises from direct contact with an infected cat’s urine.
To minimize risk, hygiene practices are recommended, such as wearing gloves when cleaning a litter box, especially for outdoor cats that may hunt rodents. Thorough hand washing after any contact with a cat suspected of having leptospirosis or its waste is also recommended.