New evidence suggests long-held assumptions about risk, vaccination, and exposure may be leaving dogs unprotected, explains Jane Sykes, BVSc, DACVIM (SAIM), PhD, MPH, MBA, FNAP, in this interview with dvm360.
Cases of leptospirosis are emerging in dogs that some veterinarians would not have considered high risk, including puppies and otherwise healthy pets in urban settings. In this interview with dvm360, Jane Sykes, BVSc, DACVIM (SAIM), PhD, MPH, MBA, FNAP, a researcher and professor of medicine and epidemiology at the University of California, Davis, School of Veterinary Medicine, explains what researchers are learning about the drivers behind these cases, from rodent exposure and overcrowded facilities to gaps in vaccination, and what the findings mean for clinical practice.
Below is a partial transcript, lightly edited for clarity.
dvm360: Cases of leptospirosis are appearing in otherwise healthy dogs, including puppies. What factors are contributing to these cases in the US?
Sykes: That’s a really great question and something that we're actively involved in researching. It does seem like it's multifactorial. Probably in urban regions, in big cities, it's associated with population growth and rodent proliferation. So we do think that in the United States now, rodents might be an important source of infection for dogs, and that's based on pretty new evidence, and it's probably going to vary a little bit from place to place.
We also know that the outbreak that recently occurred in West Los Angeles that we were involved in studying actually was driven in part by overcrowding of boarding facilities, and we don't know for sure whether it was dog-to-dog transmission that occurred in those doggy daycare-type environments. But we do know that the boarding itself was a risk factor, and it might have been rodent problems in those facilities, or it might have just been really overcrowded facilities with lots of dogs in close contact with one another.
We're also seeing lepto in regions where we're studying an outbreak right now associated with homelessness and dogs of the homeless. So we know that dogs that are in homeless encampments also are at risk of lepto. But very importantly, not being vaccinated for lepto is the biggest risk factor. And so the dogs that were affected in West Los Angeles were either completely unvaccinated for lepto because they didn't think it was a problem in the region—and many vets didn't even carry leptospirosis vaccines—or they had just had one vaccine and not a follow-up booster three to four weeks later. Or some of them were actually getting vaccinated when they started developing leptospirosis, so they started getting sick. Owners in the region had heard about the outbreak, came running into their vets for vaccines, but it was too late. Or the second vaccine in the series was too late; the dog acquired illness or infection before they were able to get protection from a second vaccine.
And so disease in puppies, again, is related to the fact that it's difficult to vaccinate a dog by the time it's three months of age. You know, you start—you can start around, you know, eight to nine weeks of age, depending on the vaccine label, of course—and then you still need a second one three to four weeks later, and then you still need a week after that before there's adequate immunity. So it's difficult to get puppies vaccinated in time, and that's probably explaining some of the cases in puppies and in geriatric dogs.
Again, it's because people don't believe an older dog is at risk and needs a vaccine; same with small-breed dogs. But there's good new evidence that the current lepto vaccines are really safe...