A disease potentially harmful to dogs, leptospirosis is caused by a bacterium called Leptospira interrogans. Omni-present in the environment because it’s borne by numerous animals, including rats and skunks, raccoons, feral cats and domestic livestock, the organism is carried in their kidneys and excreted through their urine. Dogs will often contract the disease by swimming in stagnant water or by drinking from contaminated puddles of water.

Known to exist as well in dampness and in mud, especially following heavy rainfalls, more cases of leptospirosis are diagnosed during the late summer and fall, while winter tends to lower the risk since the bacteria can’t tolerate freezing temperatures.

Although many infected dogs never exhibit any signs of illness, the disease is usually most severe in unvaccinated puppies younger than 6 months of age, and takes between four and twelve days following exposure for them to feel sick. While the symptoms may vary from dog to dog, they usually include lethargy, poor appetite, fever, vomiting, and increased thirst or urine production. Some dogs may also become jaundiced.

Veterinarians diagnose the disease by running blood tests (these will reveal changes in kidney values or both kidney and liver values) and urine tests that look specifically for leptospirosis. They then typically prescribe antibiotics to treat the active infection and assist in keeping an infected dog from becoming a carrier of the organism.

Unfortunately, leptospirosis is also a zoonotic disease, which means it’s contagious to humans. While the most common way for people to contract the disease is through exposure to infected dog or rat urine, any contaminated bodily fluid, including vomit and saliva, can be the culprit. If your own dog is ill with leptospirosis, it’s essential, then, to observe such hygiene protocols as wearing protective gloves when cleaning up after him and not allowing him to lick your face until he’s fully recovered.

Familiar with the old adage, “An ounce of prevention is worth a pound of cure”? Never was it more applicable than when dealing with leptospirosis. Prevent your own dogs from contracting the disease by eliminating their access to contaminated water, by keeping your property free of food, and by using durable garbage containers to reduce attracting rats, raccoons or feral cats to your area.

If you believe that your dog is at high risk of contracting the disease, you might consider having him vaccinated for leptospirosis. The American Animal Hospital Association, however, considers it a “non-core” vaccine, only recommending it if a dog is very likely to be exposed to leptospirosis. Not only does its effectiveness vary from short term to longer lasting, there have been reports of reactions to the vaccine that also vary -- from minor to severe.

While a vaccination doesn’t always prevent the disease, it does make the disease much milder should infection occur. There’s also the potential for vaccinated dogs infected with leptospirosis to become long-term carriers of the disease, with some experiencing a more frequent incidents of reproductive failures and stillbirths.

As with all matters concerning your cherished canine companion, discuss the vaccination with your vet. Your decision should be based on your lifestyle, whether your community is experiencing any cases of leptospirosis, as well as your vet’s own experiences – positive and negative -- with dogs and the vaccine.