A Windsor veterinarian is warning dog owners about a rare and sometimes fatal bacteria that’s returned to the city.

A dog had to be euthanized this week after being diagnosed with leptospirosis.

Many have never even heard of it, but Michigan vets have been warning about it for some time.

Windsor vet James Sweetman says he had to put a dog down due to the disease because it wasn’t vaccinated.

“It’s emotional. It’s emotional. The bacteria goes into the blood stream to the liver, to the kidney and they get very sick. We treat them with antibiotics and an IV,” he says.

Now he has a warning for the public to get their dogs vaccinated.

For some dog owners the issue isn’t easy.

Jean Bosson says vaccinations are a tough subject. “It's a personal decision,” she says.

But others say the decision is clear.

"You don't want him to suffer and go through things,” says Tarah Toughty.

"If you are bringing them to dog parks you don't want the other dogs to get sick."

It can be expensive, too.

"It doesn't concern me because my dog is vaccinated. But it's an optional vaccine that I don't think a lot of people get because it's expensive. But I love my dogs. I'll do anything for him,” Toughty says.

Leptospirosis is often carried by rodents and raccoons and spread to dogs when they drink standing water. Infected dogs can spread it through their urine.

Dr. Sweetman says leptospirosis can be transmitted to humans so it’s necessary to wash your hands often with soap and water when around pets.