How a Dog Virus Could Wipe Out Tigers


You might not see so much of a similarity between your dog and a majestic tiger (and if you do, you’re probably just kidding yourself) but the two animals do share one important threat: distemper virus. Canine distemper virus (CDV) is incurable and causes high fever, watery eyes, lethargy, vomiting and diarrhea, progressing to seizures, paralysis and death. For a long time, CDV was limited to canines, but in recent years it has jumped from dogs to other pets and even wildlife.

Today, CDV can infect ferrets, foxes, raccoons and even tigers. Some think that the virus contributed to the decline and extinction of the thylacine (also known as the Tasmanian wolf). In the 1990s, 30 percent of the lions who died in the Serengeti had succumbed to CDV. And in the past few years, it seems like the disease has jumped to tigers.

Reports of tigers behaving strangely was the first tip off, but a diagnosis of CDV requires brain tissue for analysis. In 2011, a confused and tired Amur tiger wandered into a town in Russia and had to be put down. She was the fourth radio-collared Siberian tiger in less than a year to be found confused, wandering into towns and villages, displaying strange behavior. An analysis of her brain tissue confirmed everyone’s fears: CDV had left her too weak to hunt, disoriented and willing to risk a human village to look for food.

“Since 2000, in the Russian Far East, there have been a few cats reported as behaving strangely and coming into villages, apparently not showing much fear towards people,” John Lewis, the director of Wildlife Vets International, told the BBC. “In the past few years, tissue from at least a couple of those cats have now been confirmed as showing the presence of CDV infection.”

These tigers are probably getting CDV directly from dogs, as tigers often will prey on the canines that stray too far from villages. And Lewis says it’s not just death from CDV that they’re worried about. Tigers infected with CDV show strange behaviors, like losing their fear of people. This puts them at greater risk of hunting from poachers and being hit by cars on roadways. And there’s not a ton people can do to stop it, says John Platt of Scientific American:

Now that canine distemper has been identified, the next step, according to WCS Chief Pathologist Denise McAloose, is to identify the source of the infection, which could be coming from domesticated dogs or other local carnivores such as wolves, badgers, red foxes or raccoon dogs. “From a vaccination perspective, vaccinating dogs would be a good first step,” she says. “If this were to be a recommended strategy, decisions about the safest vaccine for dogs and tigers that might eat the dogs would need to be made.” Distemper vaccinations are required for most pet dogs in the U.S., but not in Russia.

But even before that, Lewis says, researchers need to understand how to figure out the scale of the problem. He’s bringing together vets from all over the world who deal with tigers to try and nail down a strategy for understanding just how bad CDV is, what tests need to be done, and how. “We need to work out where we can send these samples for laboratory testing. We need to work out how we are going to store and move these samples. Once we have got that nailed down then we start work and try to design some sort of mitigation strategy, and that won’t be easy.”

The question is whether or not the scientists can keep up with the virus before it’s too late.

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