Veterinarians' reported use of the antiviral drug Tamiflu to prevent canine influenza in dogs has recently caused concerns. Distributed by Hoffmann-La Roche Inc., the U.S. pharmaceuticals branch of the Switzerland-based Roche Group, Tamiflu is marketed as a flu medicine for humans.
"(Tamiflu) is just very controversial to use in dogs because we just don't know that much about it and if it even works in dogs," said Dr. Cynda Crawford, a veterinary immunologist at the University of Florida College of Veterinary Medicine. Dr. Crawford was among the group of researchers who identified the canine influenza virus (see JAVMA, Nov. 1, 2005, page 1377).
"If you read the human medical literature on Tamiflu, it will tell you that its best efficacy is achieved when treating people within the first 48 hours of infection," Dr. Crawford said. She reported there is no accurate test available, however, to identify canine influenza in dogs within 48 hours.
Dr. Crawford previously announced that she would launch studies to find how Tamiflu benefits dogs infected with canine influenza virus. She has postponed the project because of the growing demand to stockpile Tamiflu for humans in case of an H5N1 avian influenza pandemic.
In addition to treating dogs for canine influenza, Dr. Crawford said, veterinarians have been known to use Tamiflu as an ancillary treatment for puppies with parvovirus infection and distemper, and for cats with calicivirus infections.
The AVMA recommends that veterinarians who use approved drugs in a manner that is not in accord with approved label directions, such as use of an antiviral drug approved only for use in humans, follow the federal extralabel drug use regulations of the Animal Medicinal Drug Use Clarification Act. For more information on the act, log on to the Food and Drug Administration's Web site, www.fda.gov/cvm/amducatoc.htm.
Treatment of canine influenza in dogs is largely supportive. According to the AVMA Canine Influenza Backgrounder, good husbandry and nutrition may assist dogs in achieving an effective immune response. In the mild form of the disease, a thick, green nasal discharge most likely represents a secondary bacterial infection that usually resolves quickly after treatment with a broad-spectrum antimicrobial. Pneumonia in more severely affected dogs responds best to a combination of broad-spectrum bactericidal antimicrobials (to combat secondary bacterial infections) and maintenance of hydration from intravenous administration of fluids.
For more on canine influenza, visit the AVMA Web site at www.avma.org/public_health/influenza/canine_guidelines.asp.