Leptospirosis is a dangerous, potentially fatal bacterial disease of dogs and many other wild animal species. While infection is possible in cats, clinical disease is extremely rare. The organism attacks the many of the body’s organ systems severely compromising the affected organs and making the patient extremely ill. Leptospirosis is characterized as a zoonotic disease, that is, it has potential to infect humans in contact with an infected canine patient. Zoonotic infection from dog or other animal to people is quite rare, but given the severity of this type of disease, anyone suspecting that a family pet has leptospirosis, should wash hands after handling the animal, and keep small children, the elderly, and immune suppressed people from having contact with the pet.
Leptospirosis tends to survive well in wet, freshwater environments, such as lake basins, marshes, or areas where puddles frequently form or persist. Chief carriers of leptospirosis are wild squirrel populations, with the organism shed through the urine of carrier squirrels. Thus, areas with high squirrel populations are also carry a heightened risk of exposure.
Infection begins by contact with mucus membranes of the nose or mouth or through cuts or abrasions of the skin. Once inside the host, leptospirosis bacteria multiply rapidly, after which they spread to the liver, kidneys, spleen and other organs. Even if the disease is successfully cleared through treatment, the patient may shed organisms for weeks or even months following recovery.
Dogs infected with leptospirosis typically present with a history of severe vomiting, dehydration, jaundice, severe weakness, convulsions, and very high fever. Diagnosis is based on presentation, significant white blood cell count elevations, kidney, and liver elevations in general blood work are also supportive of leptospirosis infection, with diagnosis specifically confirmed through directed antibody blood testing.
Treatment consists of aggressive fluid therapy, antibiotics, and supportive care. Prognosis is guarded at once clinical signs set in, with many leptospirosis patients dying despite the best treatment efforts. An effective yearly vaccine is available for dogs at risk for the disease.
Roger L. Welton, DVM
Founder and Chief Editor, Web-DVM.net
President, Maybeck Animal Hospital
Article updated 10/5/2018