Oseltamivir: Is There a New Treatment for Parvo?

In the 1970s, something terrible happened.

A new virus appeared on the scene, and it swept across the world like wildfire, killing dogs everywhere it struck. Puppies were especially hard hit, often dying within hours of the appearance of their first symptoms.

Breeders would notice the puppies were a bit lethargic, and by the time they got to the vet, some of the puppies would already be dead. Entire kennels and breeding programs were wiped out overnight.

Veterinarians were nearly helpless at first, and even when they got a grip on what was happening, still had very little to offer stricken puppies and their desperate owners. Most infected puppies required extraordinary and expensive medical care to survive, and very young puppies rarely did, as the virus infected the rapidly dividing cells of the heart.

Since the new virus, called canine parvovirus, appeared to be a mutated version of the feline panleukopenia virus, a few veterinarians began to vaccinate dogs with that cat vaccine, with some success. Soon a canine parvovirus vaccine was developed, and it was hoped that would spell the end of the worst threat of the disease, as the FPV vaccine had for cats.

Unfortunately, it turned out that CPV maternal antibodies, which prevented successful vaccination, were particularly persistent, sometimes lasting as long as 16 weeks or even more. These puppies had too much maternal antibody to be immunized, but not enough to be protected from the disease.

New vaccines, called "high titer" vaccines, were developed, in order to overcome these persistent maternal antibodies. Still, shelters and rescue groups, and some breeders, continued to have huge losses of young dogs to the virus. Treatment requires hospitalization and is expensive, with no guarantees, and few shelters or rescue groups have the funds to pay for it.

Now... cut away to a different area of veterinary medicine, halfway around the world. Scientists were interested in a bacterial disease in Nigerian cattle known as "blackleg disease," caused by the bacteria Clostridium chauvoei.

Nomads who kept cattle in Nigeria fed them a certain plant that was found to inhibit an enzyme vital to the spread of clostridium, neuraminidase, thus preventing the disease.

Neuraminidase inhibitors were studied and developed to combat mucosal infections in humans, with varying degrees of success. One such drug is the drug Tamiflu (oseltamivir), used to treat early influenza infections in humans.

In the last year, vets in small animal practice, primarily in shelters, began to experiment with Tamiflu in the treatment of parvo in dogs and panluekopenia in cats, and reported surprising success.

While it is not believed that parvo itself relies on neuraminidase to reproduce, it may be that the bacteria that are responsible for the actual deadly symptoms of CPV do.

What do I mean by that? Canine parvovirus and its close cousin feline panleukopenia virus share more than a common ancestry.

In kittens raised in a laboratory to be bacteria-free, the panleukopenia virus doesn't make them sick. It appears that in both diseases, it's not so much the virus itself that kills, but the effect of the normal bacteria present in every animal.

There may be some kind of relationship between the virus and bacteria that creates the symptoms that neither alone can produce. It may simply be that the virally-damaged mucosal immune system cannot prevent bacteria from growing and reproducing to dangerous levels. It may be that neuraminidase interferes with some of the body's own natural infection-fighting actions. Or there may be some other mechanism(s) by which inhibiting this enzyme stops the effects of certain types of infection.

Whatever the reason, vets are discovering that, given when symptoms first appear, Tamiflu seems often to stop parvo in its tracks.

While vets in private practice are still giving conventional parvo treatment along with the Tamiflu (IV fluids, antibiotics, hospitalization, etc.) to patients whose owners can afford it, these treatments were never available to the pets of people without large amounts of money to spend, nor to shelter dogs. Many dogs are being treated with Tamiflu and recovering rapidly with home care only.

Cost of this treatment? About $40 per dog.

Now, the disclaimers:

None of this has been studied. All these reports are strictly anecdotal from shelter experience and some private veterinary practice.

As far as I have been able to discover, no study or trial has yet been announced, although there are ongoing efforts to organize one or more in the near future. Many things have appeared incredibly promising at this stage and gone on to be impractical or disappointing when subjected to more complete examination.

Tamiflu is available by prescription only.

The dosages that you get for humans are not the right dosage for dogs.

Tamiflu is not approved or formulated for small animals and needs to be compounded by a compounding pharmacist or put into suspension by a veterinarian.

Once put in suspension it has a VERY short shelf life so it cannot be done in advance.

It will not reverse the disease when it is advanced and the puppies are deathly ill. At that point, there is too much tissue damage and the puppy is not likely to be helped by this treatment.

If you want to have it on hand to treat puppies you will need to work it out with your vet BEFORE you need it, as it needs to be given at the earliest possible stage of the disease to have its greatest benefit.

Your vet may not know about this drug yet. You can refer him or her to the following article:

Tamiflu

If your vet is a member of the Veterinary Information Network, they should be able to find good information on the use of Tamiflu, including dosages, there (subscription service for veterinarians only).

UPDATE: Veterinarians can contact Dr. Jack Broadhurst, a veterinarian coordinating research into Tamiflu in the treatment of canine parvovirus, kennel cough, feline distemper, and the canine flu, for information on dosages and his research. His email address is DocCat@aol.com.

UPDATE 2: Peter Fernandes DVM, of Aardvark Animal Hospital in Hialeah, Florida, has a good article on the use of Tamiflu in treating kennel cough, parvo, and other veterinary diseases here. Dr. Fernandes is past president of the South Florida Veterinary Medical Association and the South Florida Veterinary Foundation, and is a member of the board of the Humane Society of Greater Miami and Pet Rescue.

This information is not intended to be used as veterinary advice, nor to replace consultation with a qualified veterinarian.