A Northwest Washington dog owner discovered his 5-month-old Doberman pinscher vomiting blood Tuesday afternoon. He took the dog to an animal hospital Wednesday where it died.

Another local couple found their 5-year-old Yorkshire terrier vomiting bile and suffering diarrhea a week ago Thursday. They took the pet to a veterinarian the following day. By Saturday the dog was dead.

Both animals had parvo virus, a quick-acting frequently fatal dog disease that veterinarians say is spreading throughout the metropolitan area.

Dr. Kenneth L. Crawford, director of the veterinary medicine division of the Maryland health department, said the parvo virus outbreak is not an epidemic.

"What we have seen is pockets of infection where one dog will be attending a dog show and infect a kennel or two," Crawford explained.

He said he could not estimate how many area dogs had contracted the virus.

The disease, particularly lethal in puppies, causes internal bleeding and sometimes heart infections. Dogs and humans can carry the disease through contact with dog feces, but the disease does not affect people according to Dr. Crawford.

According to Crawford, the disease was first noticed in Maryland about a year ago and began to spread in recent weeks. Because the parvo virus is a new strain of a previously known cat virus, dogs are virtually defenseless when they contract the disease. The outbreak has been compounded by an extreme shortage of the one available parvo vaccine for dogs, veterinarians say.

"This is the worst disease I've ever seen in dogs," said Steve Melman, a veterinarian at Washington's Berliner Animal Hospital. "It hits so fast, often within 24 hours, that owners can't believe it was really the disease that killed their pet."

Dr. Jerrold Goldfarb of the Fairfax Animal Hospital said parvo virus "appeared to be on the upswing in recent weeks" in Northern Virginia. He also said that state health authorities told him the Richmond and Tidewater areas have parvo outbreaks.

"It seems that we are surrounded and that we're next in line for an outbreak. Rather than wait for it to hit us, we'd like to practice preventive medicine and vaccinate beforehand," Goldfarb said.

Crawford recommended that dog owners have their pets vaccinated against the parvo virus as soon as possible. He emphasized that because of the virulence of the disease a vaccination often cannot save a dog that has already contracted the virus.

"If someone brings in their puppy immediately after it has begun to vomit and we can treat it right away, then the animal may have a 40 percent chance of living," Crawford said. The survival rate would be higher among older dogs, he added.

Veterinarians said vaccination efforts will be hindered by the severe scarcity of the parvo vaccine.

Only one company in the country -- Dellen Laboratories in Omaha -- has been licensed by the Department of Agriculture to manufacture a vaccine for parvo virus in dogs. A Dellen spokesman said yesterday the company plans to make 1.6 million doses of the vaccine this month, but already has backlog orders for 4 million additional doses.

Crawford recently recommended that all police dogs in Maryland be vaccinated with the serum usually administered for parvo virus in cats. While the cat serum has not been licensed for use in dogs, Crawford said field studies have shown it is effective.

Melman said he plans to inoculate dogs with a vaccine that is used to combat a strain of parvo that occurs in minks. He said researchers at Cornell University assured him that the mink vaccine was similar enough to the dog vaccine to make it effective also.

The dog strain of parvo virus was first identified in Dallas in early 1978.

A severe outbreak of the disease earlier this year throughout Texas is estimated to have killed several thousand dogs. Parvo virus outbreaks have since been reported across the south, along the eastern seaboard, and in northern Europe.