Leptospirosis, also known as Weil’s disease, is a dangerous infectious disease that affects not only dogs but also cattle, sheep, rats, wild animals, and humans. Rats are the primary carriers of this disease. The causative agent is a spirochete bacterium from the genus Leptospira, which reproduces actively in stagnant water and bottom sediments. The bacterium is sensitive to sunlight and dry climates but resistant to frost. Infected animals can release the bacteria into the environment through their excretions, such as urine. Leptospira can enter an animal’s body in various ways, including through skin wounds, the digestive tract, eyes, and mucous membranes.

There are typically two forms of leptospirosis in dogs: hemorrhagic and icteric.

The hemorrhagic form is more common in older dogs, characterized by a high fever (40.5-42°C), depression, and sometimes eye inflammation (conjunctivitis). Following these symptoms, the fever drops, and the dog experiences heavy and rapid breathing, vomiting, constant thirst, and loss of appetite. The oral cavity is also affected: the mouth’s mucous membrane becomes dry, the corners of the mouth turn red and bleed, and an unpleasant odor emanates from the animal’s mouth. In advanced cases, seizures, vomiting with blood, and body temperature dropping below normal (36°C) may occur. The dog’s urine may contain bile and protein, with reduced excretion volume. The mortality rate for this form ranges from 65-90%, with the disease lasting 2-4 days, although it can extend from 5 to 11 days.

The icteric form is more common in puppies and often develops gradually. It can be challenging to notice until pronounced jaundice appears. Symptoms include vomiting, dark yellow urine with high protein content, vomiting with blood, yellowing of the mouth’s mucous membrane, eye inflammation (conjunctivitis), and itching. The disease’s duration is approximately 2-10 days, with a mortality rate of 40-60%.

In both cases, monitor your pet closely and contact your veterinarian immediately at the first sign of illness to determine the form and initiate treatment. Diagnosis requires clinical trials and tests (urine and blood tests) to detect the presence or absence of leptospira in the body.

If tests confirm leptospira in the dog’s body, the veterinarian will prescribe treatment, which typically includes various combinations of antibiotics and hyperimmune sera. Symptomatic treatment may also be provided, targeting diarrhea, vomiting, regulating food intake, and increasing fluid volume. Renal failure may develop in some affected animals. Additionally, recovered animals can become carriers of the bacterium and excrete the infection in their urine during and after the following year.

To prevent leptospirosis, vaccinate your dog. Since the infection can also affect humans, it is crucial to handle sick animals with care, avoiding contact with infected secretions.