Published by Communications and Public Affairs (519) 824-4120, Ext. 56982 or 53338
March 21, 2005
Profs Studying Re-emerging Canine Bacterium
University of Guelph researchers are following the re-emergence of a canine bacterium that can have dire health consequences for dogs and their owners.
The bacterium, Leptospira, can cause the infectious – and potentially deadly – disease leptospirosis. Leptospira lives in its host’s kidneys, and once infected, dogs may show a variety of symptoms that can range from lethargy to vomiting, kidney failure or even death.
The disease emerged widely in dogs across North America in the 1970s before being controlled by vaccination. But new cases of leptospirosis have been increasing in the past several years. Guelph pathobiology professor John Prescott has been working with colleagues Beverley McEwen in the Animal Health Laboratory and Guelph small-animal clinicians, including Prof. Paul Woods, to follow the re-emergence of this disease.
This resurgence isn’t quite the same as past outbreaks, said Prescott. This time, the infection is caused by different strains and it’s being transported in new ways. He believes climate change and the raccoon population are among the accomplices.
“In the 1970s, the type of leptospirosis seen was transmitted from dogs to other dogs so it was easily controlled with vaccinations. But these new strains are being passed from raccoons to dogs. Vaccinating the entire raccoon population is impossible.”
Raccoons are natural carriers of Leptospira – the bacterium is well-adapted to living in their kidneys – and dogs can be infected by exposure to raccoon urine. This could explain why the disease is found mostly in urban areas, where there are high numbers of raccoons, he said.
Climate may also have played a role in the sudden increase. Leptospira bacteria thrive in wet, warm conditions such as those seen in the fall, and average fall temperatures have increased since 1990, Prescott said. “For example, the year 2000 had the greatest resurgence of canine leptospirosis, and it was by far the warmest fall, and the third wettest, in the last decade in Ontario.”
Leptospirosis is sometimes hard to diagnose in dogs because they may only show a few, if any, symptoms. It also poses a threat to humans and can be transmitted from animals through their saliva. It’s known as an occupational disease, meaning that people who are commonly in contact with animals — farmers, veterinarians — are more likely to be infected.
But because it’s usually spread through urine, and raccoons often urinate in streams, creeks or rivers, people can be exposed through canoeing, swimming and fishing, Prescott said. Humans afflicted with leptospirosis can suffer a variety of symptoms similar to those of the flu. As in dogs, severe cases can cause kidney failure and other serious illness in humans. The disease can be easily treated with antibiotics if caught early.
Prescott and his team are speaking to veterinarians about protecting dogs from the new Leptospira strains with new vaccines designed to control the problem.
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