Monique Keiran: Pet disease spreading to sea mammals

A neighbour’s cat adopted me last year. When she’s bored and I’m home, she visits. She gets a lap to nap on. I get a cat without kitty litter, cat food or hair on everything.

It also keeps her safe, during each brief visit, from becoming roadkill, eating or drinking noxious substances, and from stalking birds, squirrels, garter snakes and other garden wildlife.

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I’ve never seen her hunt, but why would she differ from other cats?

Because Felix (or Felicia) the cat is deadly. When scientists from the Smithsonian Institute and the U.S. Fish and Wildlife Service scaled data from local surveys and studies to the national level last year, they estimated that domestic cats in the U.S. kill 2.4 billion birds and 12.3 billion mammals. Every year.

Backyard wildlife are only the obvious victims. Researchers in B.C. and the U.S. have uncovered more insidious damage to wildlife not normally considered vulnerable to pet depredations. The wildlife in question: marine mammals.

Micro-organisms go hand in hand with cats and the other animals we keep. The microbes include Toxoplasma gondii, which makes pregnant women nervous when confronted with kitty litter. These bugs can infect any warm-blooded animal. However, they each have a favoured primary host in whose gut they reproduce most enthusiastically. For instance, only when cat gets rodent does toxoplasma propagate and take over the world.

Yes, the world.

Veterinary pathologist Stephen Raverty of Abbotsford’s B.C. Agriculture Animal Health Centre and his U.S. colleagues reported recently that pathogens associated with land-lubbing animals — pathogens like toxoplasma — are moving into marine environments.

The microbes comprise a Who’s Who of disease. In addition to toxoplasma, the researchers fingered leptospira, which can cause meningitis and liver damage; Bartonella henselae, of cat-scratch disease fame; Coxiella burnetii, one of seven microbial agents the U.S. government advanced as biological weapons back in the 1950s and ’60s; and Cryptococcus gattii, which has killed several people on Vancouver Island.

The microbes are spread by rodents, raccoons, wild and domestic dogs and cats, deer, skunks, farm animals, and, yes, humans, too.

The bugs can jump from species to species. They’re also moving from dry land to sea water.

Infected land mammals like Rover, Felix, Molly Moo and Remy Rat release a crop of microbes every time they poop. Rain and snow wash the waste into rivers. Currents carry it out to sea, where it mixes into the marine stew. The pathogens move up the food chain, and mammals such as seals, sea lions, porpoises, sea otters and even orca, ingest and become infected with them.

Sea-dwelling animals have few defences against landlubber diseases. The microbes make the animals sick, rot their livers, damage their brains, cause lesions and tumours. Then the animals die.

Those that wash ashore and are found are sent to pathologists like Raverty.

We can do little about pathogen-carrying raccoons, cougars, wolves and deer. Squirrels, chipmunks, deer mice and voles are citizens of healthy, natural wilderness communities. We can’t control them.

We can control our pets. We can keep Felix indoors and prevent him from using the world as his personal litter box. We can keep Rover indoors, too. And when we do take these beloved four-legged family members out with us for walks or to play, we can pick up their droppings — not ignore them or flick them into nearby bushes.

Then we can dispose of the droppings as the bio-hazardous material they really are.

Rover and Felix are our pets. We are responsible for them. And for the micro-organisms they carry.

Even if it means I lose my sometime feline friend, my part-time pet.

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