Health information for your dog or just slick marketing?

My veterinarian's exam room is gray and white, all functional, cleanable surfaces with framed diplomas on the walls. The only splash of color is the rack of bright pamphlets near the room's one chair. They're usually about flea prevention or microchipping, and at one time or another I've read them all. But on a recent visit, I saw one I'd never seen before.

The three-page booklet was about something called "Canine Enteritis Complex," and it was published by a drug company. I was puzzled, because even though I've been writing about animal health since 1991 and pride myself on keeping up on canine health issues, I had no clue what this dread new disease was.

"Many disease agents," the pamphlet informed me, "can cause Canine Enteritis Complex, a potentially deadly inflammation of the small intestine. Some common enteritis-causing pathogens in dogs are parvovirus, coronavirus, and giardia lamblia, a microscopic protozoan that can severely damage the lining of the small intestine."

The pamphlet went on: "These pathogens are highly contagious and can be spread between dogs." What's more, it continued, "A published study showed a dual infection with parvo and corona was fatal in 90 percent of cases." They also added that "Pre-existing Giardia infection can make disease from parvovirus more severe."

After the obligatory advice to ask your veterinarian "about a vaccination program that includes protection against enteritis-causing pathogens such as parvovirus, coronavirus, and Giardia," there were some footnotes.

I assumed that for this newly discovered trifecta of canine intestinal doom we'd have some pretty cutting-edge science backing up their claims. Well, actually no. Those footnotes cited one 19-year-old study, and another that is 25 years old. In fact, it turns out the diseases are old, the citations are old, even the vaccines being promoted are old. The only thing new is the marketing campaign, which aims to convince you to protect your dog "from Canine Enteritis Complex by vaccinating routinely against parvo, corona, and Giardia."

The problem is that this marketing campaign is misleading. Canine parvo is indeed deadly, and can cause fatal diarrhea in dogs, mostly puppies. But the vaccine that protects dogs against parvo is one of the great success stories of vaccine development, and dogs who are immunized as puppies nearly always remain immune to the virus for years, probably their lifetime.

Certainly co-infections with any other disease agents will make parvo even more dangerous, including coronavirus and giardia. But if you've already protected your dog from parvo, how dangerous are the other diseases by themselves?

If you've never heard of canine coronavirus, there's a reason for that. Except in very young puppies -- too young to be vaccinated -- coronavirus does not cause clinical disease in dogs. Researchers cannot even induce disease with it in the laboratory. Many, perhaps most, dogs have coronavirus in their intestine all their lives. Texas A&M University's "Vaccine Protocols and Schedule" tells us, "(T)here are no studies that show that use of the vaccine reduces morbidity or mortality," which may be why this one is so often called a "vaccine in search of a disease."

If you live in California or spend any time hiking in the wilderness, you're probably already aware of giardia, a pesky protozoan parasite. It lives in our waterways and causes cramping diarrhea in humans as well as dogs. It can be cultured out of the stool of many healthy dogs in the state - in some areas, the majority of dogs - and is normally held to very low numbers by the dog's immune system and causes no symptoms.

When a dog is sick, stressed, or immune-compromised, however, the organisms can have a population explosion and cause diarrhea, which is treated with the drugs fenbendazole or metronidazole. Even though giardiasis is treatable, it makes sense we'd want a vaccine to prevent it. However, although this may seem counterintuitive, not all vaccines prevent infection, and this is one of them.

The giardia vaccine is not labeled to prevent giardia infection, and doesn't claim to do so. The 2006 American Animal Hospital Association Vaccination Guidelines lists the giardia vaccine in the "not recommended" category, and one study showed "there was no significant difference between the (vaccinated and unvaccinated) groups."

You might wonder what the vaccine is for, then. It's intended to be used as part of a total treatment plan for dogs who have giardiasis. The dog can still get sick, and you still have to treat it with the same drugs as in an unvaccinated dog. The vaccine does cause fewer cysts to be shed in the stool of sick dogs, so it's sometimes recommended for use in crowded facilities like kennels and shelters to reduce the infectivity of the disease to other dogs.

So, let me recap: Canine parvovirus is a common and deadly disease that is easily prevented with standard puppy immunizations, after which time the dog is immune for many years, most likely a lifetime. Canine coronavirus doesn't cause disease except in puppies too young to be vaccinated at all, and possibly in dogs who also have the preventable parvovirus. Giardiasis is a relatively mild, treatable disease that could be triggered if a dog is sick with canine parvovirus, but the vaccine doesn't claim to prevent the infection, just help treat it.

In short, this recommendation relies on the deadliness of canine parvovirus to justify recommending dogs receive these three vaccines annually. But if your dog is already immune to parvo, is there any benefit to re-vaccinating him every year for that disease, with or without the other vaccines? Research suggests there is not, and certainly not annually.

If canine coronavirus is a vaccine in search of a disease, "Canine Enteritis Complex" is a marketing campaign in search of a market. Because given the facts, you have to ask yourself: Was this regimen designed to treat and prevent canine disease, or treat and prevent a diminished bottom line for the vaccine manufacturer?

I don't need to ask my veterinarian to know the answer to that.

Christie Keith is a contributing editor for Universal Press Syndicate's Pet Connection and past director of the Pet Care Forum on America Online. She lives in San Francisco.