Canine Leptospirosis

What is Leptospirosis?

Leptospirosis, often referred to as “lepto”, is a disease caused by infection with numerous different serovars of bacteria in the genus Leptospira. (Serovars are closely related microorganisms distinguished by a characteristic set of antigens.) It is a zoonotic disease affecting humans and animals that is spread through urine-contaminated water such as stagnant puddles and ponds frequented by infected wildlife. Outbreaks of leptospirosis have been reported after natural disasters such as floods and hurricanes where large amounts of standing water serve as a source of contamination. Even the thaw of snow or heavy rains can wash contaminated animal urine into streams and other bodies of water. In humans, leptospirosis can cause many symptoms such as fever, headache, vomiting, jaundice (yellow skin and eyes), abdominal pain, diarrhea, and rash. Infected dogs can also show a variety of signs, but the most common clinical presentation involves signs secondary to liver and kidney failure such as lethargy, anorexia, vomiting, abdominal pain, and excessive thirst and urination. If caught early, the disease is treatable with antibiotics. However, the prognosis is worse for animals already presenting to the veterinarian with severe organ dysfunction.

Examining the data led to some interesting results:

• More than 25% of lepto cases were fatal.
• Young dogs were more likely to be infected than older dogs and cases did occur in dogs six months of age or younger.
• Small dogs (less than 14 lb) were more likely to be affected than larger dogs (33-60 lb).
• Dogs not vaccinated for lepto were more than 20 times more likely to be affected than dogs that had completed an appropriate lepto vaccination protocol.

The high prevalence of leptospirosis in young dogs and small dogs in this study represents a change from the standard paradigm of lepto being a disease of large-breed dogs living in a rural environment. It indicates a need for further study, increased awareness of this disease among dog owners and veterinarians, and additional prevention efforts.