Leptospirosis is Becoming a Threat to Canine, Human Health


The incidence of leptospirosis is on the rise, with reports of the disease coming from several states. While leptospirosis most commonly affects dogs, humans are also at risk.

More and more cases of leptospirosis, a dangerous bacterial disease that can be spread from pets to humans, are popping up around the country this year.

Leptospirosis is caused by infection with Leptospira, a spirochete bacterium that can be found worldwide in soil and water, and is spread through animals’ urine. While leptospirosis is more common in areas with warm climates and high rainfall, it can occur anywhere—and it is. The disease most commonly affects dogs.

Infection in Dogs

At least 3 dogs were killed and 2 others were sickened by leptospirosis in northern New Jersey earlier this year. “Once it gets into the bloodstream it starts to cause inflammation inside of blood vessels in various organs,” said Benjamin Davidson, BVSc, MANZCVSc, DACVECC, a critical care specialist at Blue Pearl Veterinary Hospital, where the infected dogs were treated. “ One of the more common things to occur is kidney failure and sometimes it can affect the lungs, it can affect the liver,” he said. “If left untreated, a lot of cases do become fatal.”

Infection in dogs results most commonly when dogs come into contact with urine from wild animals in stagnant waters or by swimming in or drinking contaminated water. Leptospires enter the body through the dog’s eyes, nose or mouth, or through a break in the skin caused by a cut or scratch.

Signs of leptospirosis vary in dogs—some may not show any signs at all, some have a mild illness and recover, and some develop severe illness and even death. Signs may include fever, shivering, muscle tenderness, reluctance to move, increased thirst, changes in the frequency or amount of urination, dehydration, vomiting, diarrhea, loss of appetite, lethargy, jaundice, or painful inflammation within the eyes.

"It's appearing in areas that previously haven't had it,” Richard Goldstein, DVM, DACVIM, DECVIM-CE, a leptospirosis expert and chief medical officer at the Animal Medical Center, said. "The data that we have now suggest inner-city, urban dogs are just as likely to get leptospirosis as dogs in rural communities, and small dogs are just as likely to get it as large dogs."

A leptospirosis outbreak was also reported in Phoenix, Arizona recently, with more than 50 dogs being diagnosed with the disease since February 2016. Massachusetts, Rhode Island, Connecticut, Indiana, and other states have all reported a threat of the disease among dogs as well.

Infection in People

Leptospirosis is a zoonotic disease. If the canine infection reaches the kidneys and bladder, the dog may become a carrier of the disease, potentially spreading it through urination. The rise in the number of dogs that have contracted the disease means humans also need to be on the alert for symptoms.

A Bronx, New York man died from leptospirosis in February after contracting the disease; 2 others were also infected but recovered. According to the New Jersey Department of Health, there are no reported human cases of leptospirosis in the state.

Leptospirosis can cause flu-like symptoms in people but can also cause liver or kidney disease. Most cases of human leptospirosis are reported following recreational activities that involve water, with infection from pets much less common.

The disease is treated with antibiotics, such as doxycycline or penicillin, which should be given early for better results.

Prevention and Treatment

Prevention in the form of annual vaccination is the best way to protect dogs from leptospirosis. "You want your dog to be a dog; you want your dog to be able to have fun," Dr. Goldstein said. "It's not practical to say that dogs won't to be exposed it. The better solution is vaccination."

Along with the vaccine, veterinarians should remind pet owners about other potential sources of infection:

  • Pet owners should not let their dog drink from or swim in rivers, lakes, ponds, marshy areas, or slow-moving or stagnant water.
  • Pet owners should minimize contact with wildlife, farm animals, rodents, and animal carcasses.

Luckily, leptospirosis can be treated with antibiotics and supportive care if caught early enough. Dogs may also require fluid therapy and nutritional support depending on the severity, or in extreme cases oxygen therapy, mechanical ventilation, kidney dialysis, or other intensive care measures.

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