A shelter puppy that died from canine parvovirus has probably saved lives. At the very least, the death seemed to spark a record-breaking turnout at a low-cost vaccination clinic.

The deadly and highly contagious virus is present and active in Pittsburgh and surrounding suburbs, according to the Western Pennsylvania Humane Society and the Animal Rescue League of Western Pennsylvania. Several dogs and puppies died at those shelters.

A parvo outbreak is cause for concern, but vaccinations can protect most dogs. The two local shelters announced the outbreak to educate the public.

"To show you how deadly this virus is, we had a puppy turned in to the shelter on May 27," said Gretchen Fieser, Humane Society director of public relations.

Like all incoming canines, it was tested for parvovirus and the results were negative. The puppy, a Rottweiler-mix, was vaccinated and adopted on June 4. On June 6, the new owner brought the puppy back to the shelter because it was sick. Another parvo test showed a positive result, and shelter veterinarians treated it. But the puppy died, and the staff and new owner were heartbroken.

Canine parvovirus attacks the gastrointestinal tract. The main symptoms are vomiting and severe, often bloody diarrhea. Victims rapidly dehydrate. Most deaths occur 48 to 72 hours after symptoms appear, so it's important to quickly get the dog to a veterinarian.

Hoping to make lemonade from lemons, the Humane Society issued a press release and scheduled a low-cost vaccination clinic for June 13.

"More than 400 people showed up. That's the most we've ever had at a clinic," Ms. Fieser said. "It's a way for something positive to come out of the death of that puppy."

Several dogs at the clinic also tested positive for heartworm, which can be treated when caught early.

Canine parvovirus is usually fatal to dogs and puppies that have not had shots. Puppies under 4 months old have a risk of getting parvo even if they've been vaccinated. Treatment is expensive, often topping more than $1,000, and some victims die despite the best veterinary care.

Parvovirus is spread in a number of ways, including direct dog-to-dog contact, as well as by direct and indirect contact with dog feces. Dogs can carry parvovirus on their hair or paws and on their collars, leashes, food bowls and toys.

The virus was not identified until 1978. In the early days people thought dogs could be protected by keeping them away from dog parks, shows, competitions and any place where dogs congregated.

But people can pick up the virus on their shoes, clothes and hands and carry it home to their dogs, according to the American Veterinary Medical Society website. The virus can survive in the environment for long periods of time.

So consult your own veterinarian to make sure your dog's shots are up to date.

Shelter staffs are "performing aggressive sanitation tactics to make sure parvovirus does not spread throughout the canine populations housed at both open-door shelters," according to a joint release from the local Humane Society and Animal Rescue League.

Open-door shelters take in all dogs, including strays. Some are sick or injured when they arrive.

Sick dogs are isolated from the general population kennels, and away from rooms where training classes and other activities are held. Staff step in foot baths with bleach and other strong disinfectants after coming in contact with sick animals.

None of the dogs owned by shelter staff or volunteers has gotten sick, said Ms. Fieser, who continues to bring her own dogs to work with her at the North Shore shelter.

It takes a lot of donations and special events to keep shelters functioning. The 2010 Panera Bread Pup Walk on Sunday at the Waterfront shopping center in Homestead will benefit the Western Pennsylvania Humane Society.

The one-mile riverfront walk starts at 9 a.m. Show up a bit before that to register for $15. Gift bags will be given to the first 200 people. Prizes will be given to top fundraisers.

Vendors will be selling pet products, pet photos will be taken, and baby pools will be set up to give hot dogs a chance to cool off.