SAN DIEGO (KGTV) - Veterinarians in the downtown area are seeing a rise of the disease Giardia.

One vet told 10News they're seeing about one case every day.

It hit Ashley Tonelli's dog, Maverick, last week.

"He just hasn't been the same," she told 10News.

According to the VCA Hospitals website, Giardia is an infection caused by a parasite. It causes diarrhea in dogs, but is rarely fatal.

According to the VCA, "the stool may range from soft to watery, often has a greenish tinge to it, and occasionally contains blood. Infected dogs tend to have excess mucus in the feces. Vomiting may occur in some cases."

Other symptoms could include fever and a loss of energy. But in many cases, no symptoms show up at all.

It's passed through feces or drinking contaminated water. Tonelli believes both are to blame for the outbreak downtown.

"You can't take a few steps downtown without seeing it," she says of dog waste. Tonelli says she sees a lot of people who don't clean up after their pets.

"The city has bags on every corner," she says.

Communal water bowls are also an issue downtown. As businesses try to be more dog friendly, they may be doing more harm than good. Bowls of water left on patios and in doorways can spread the disease if an infected dog drinks out of it.

"It's such a nice gesture and it's horrible that something like this can ruin that for dogs," says Tonelli. "I'm definitely going to think twice before letting my dog drink from them again."

Vets can do a fecal test to determine if pets are carrying the disease. However, the parasite can be in a dog's stool and not result in any symptoms. Some vets recommend only treating it if your dog becomes ill. The most common drugs used to treat Giardia are fenbendazole and metronidazole.