Canine Influenza – What Is The Real Threat?

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In a Veterinary Information Network (VIN) posting, author Edie Lau took a hard look at just how prevalent canine influenza really is.

In 2011, canine influenza and the need for vaccination were heavily covered in the media.  Even ABC News carried an article, urging dog owners to vaccinate their pets.  Excerpts from the article (See the full article here) include:

“There are outbreaks of dog flu right now in the New York metropolitan area and near San Antonio, Texas, and other states have reported epidemics throughout the year. Since the virus, known as H3N8, was first identified in 2004, thousands of dogs in 38 states have become sick with the flu, and veterinarians say that number continues to climb.

“We’re seeing an increasing number of dogs being affected by this virus,” said Dr. Cynda Crawford, clinical assistant professor in shelter medicine at the University of Florida’s College of Veterinary Medicine.

Canine influenza is endemic in several states, including New York, New Jersey, Pennsylvania and Colorado. But like the virus that causes the flu in humans, the dog flu virus is very easily spread and highly contagious.

The American Veterinary Medical Association recommends that dogs that are in frequent contact with other dogs be vaccinated against canine influenza to help prevent the spread.

“This is a very mobile virus, and we live in a highly mobile society that contributes to the spread of influenza, which means it can go from one community to another simply by travel of infected dogs that are still contagious,” said Crawford.

“There’s increased risk for dogs that board, go to day care, are in shelters or that travel to areas of the country where canine influenza is circulating,” said Crawford.  She added that people who work with dogs, such as veterinary and animal shelter staff, may unknowingly transmit the virus to their own dogs.  “People are one of the biggest transmitters of canine influenza. They may handle an infected dog, and the virus is shed and it gets all over their hands and their clothing.”

“If you want to have a proactive strategy to protect against the unpredictability of canine influenza virus, the best preventive strategy is vaccination,” said Crawford.”

Who Profits From Canine Influenza?

The VIN report stated that many veterinarians advise vaccinating dogs before they’re boarded and dogs that frequent dog parks. However, other practitioners consider that unnecessary.

According to the VIN,

A-Animal Clinic in Fort Worth, Texas, began in mid-November to require that all dogs left at the facility — whether for boarding, day camp, grooming or medical procedures — be vaccinated against canine influenza virus. 

Practice Manager Newley Spikes said he and his wife, Dr. Karen Spikes, established the policy after receiving information from Merck about confirmed flu cases in their region. 

He said the vaccine vendors “pounded us with the information. We’re one of the largest boarding facilities (in the area); we hold 150 dogs. They’ve been after us for about 24 months or so that we need to get on board with CIV. They continue to bring it to our attention if there are cases anywhere.” 

Spikes, who co-owns the clinic with his wife, said the vaccine requirement makes good business sense. “In August 2007,” he recalled, “we had something go through our kennel, an upper-respiratory (infection) — drippy eyes, green stuff out of the nose and cough that was persistent. We treated hundreds of dogs. It cost us, net giveaway, the cost of drugs, something like $10,000. If they get sick here … if they get hurt here, we take care of it without charging.” 

Spikes said he doesn’t consider Merck’s vigorous marketing inappropriate. “Frankly, they aren’t pushing it hard enough, if you ask me,” he said. “… We are in business here, and our business is animal care. … If there’s a (method of) prevention that’s easy and safe and economical to the client that could keep an outbreak from taking place in a facility such as ours, we should be on it.” 

Spikes said the clinic charges $19.85 for the first shot and the same for the booster. “Our clientele has been nothing but receptive,” he reported. 

Although it takes a week following the booster for the vaccine to confer immunity, Spikes said his facility’s requirement is met as long as the dog receives one shot. That shot may be administered immediately before the dog is admitted. 

He acknowledged that requiring only one shot upon admittance doesn’t actually protect the dog, but said that to demand dogs be fully immunized before check-in is impractical. “In a business situation, perfection isn’t an option,” Spikes said. 

The goal, he said, is to get patients and boarders protected over time. Spikes estimated that more than 1,000 of the facility’s canine patients and visitors have completed the two-shot series. 

A Little Math

At two shots per dog, that’s nearly $40,000 in revenue in just over two months from the canine influenza vaccine.  The cost to the veterinarian is about $1 to $2 per vaccine, so that would be a tidy profit of $36,000 or more.  The dog owners seem happy enough to pay for this vaccine but in many cases, the dog is simply not protected because he is vaccinated at the time of boarding.  In this case, the pet owner is paying $19.85 for a vaccine that has virtually zero likelihood of protecting their dog – and given the immune-suppressing qualities of vaccines, will actually increase the susceptibility.  Dr. H.H. Fudenberg, world-renowned immunologist with hundreds of publications to his credit, states: “One vaccine decreases cell-mediated immunity by 50%, two vaccines by 70%.”

At the center of most of the media articles reporting the need to vaccinate for canine influenza is Dr. Cynda Crawford.

Who Is Dr Cynda Crawford?

Dr. Cynda Crawford is a veterinarian at the University of Florida (UF) who led the research team that first identified the canine influenza virus in 2004.  Crawford, along with colleagues at UF, Cornell University and the U.S. Centers for Disease Control and Prevention (CDC), share intellectual rights to the canine influenza virus; Merck has licensed the right to use the virus to make a vaccine. However, Crawford maintains that she and the others do not receive compensation from vaccine sales.

The VIN reports:

Some veterinarians suspect that vigorous marketing of canine influenza vaccine plays a part in confusing perceptions of disease prevalence.  “It seems to be getting harder to (determine) when a disease is real and when it is being ‘pushed’ by vaccine or drug manufacturers these days,” commented Dr. Margaret Mason, a practitioner in Carpenteria, Calif. 

A number of Mason’s colleagues have expressed similar sentiments on VIN. Several related anecdotes about and experiences with Merck Animal Health, maker of one of two canine influenza vaccines on the market, pressing boarding kennels and shelters to require or administer the vaccine routinely. 

Merck confirmed that it markets the vaccine through “education of boarding facility operators, kennels, pet owners and veterinarians about the disease state and about steps they can take to encourage prevention.”  Told that some practitioners are concerned about overzealous marketing, a company media-relations official had no comment. 

Dr.  Crawford said that regardless of Merck’s role in calling attention to the disease, documented infections are occurring. She said the company is making worthwhile contributions to scientific understanding of the disease. 

“It’s an accepted practice for different pharmaceutical companies to market their wares. I view their interest in canine influenza as a valuable asset to the veterinary community,” she said. “Merck Animal Health has taken an active role in tracking canine influenza in an effort to provide updates on where it is occurring. In addition, their tracking provides opportunities to acquire field isolates for analysis to determine whether the virus is mutating in a way to affect diagnostic test accuracy (and) vaccine efficacy.

What Of The Documented Infections?

Were the 2011 news reports justified?  From the VIN:

The relatively short history of canine influenza virus makes it all the more challenging for practitioners to sort out the facts, since researchers still are learning how the virus behaves. For example, unlike human flu, canine influenza does not follow a season. That’s another confounding factor in tracking its spread. 

Furthermore, no single agency or institution tracks the virus. In veterinary medicine, there is no equivalent of the CDC. 

Of the three laboratories believed to evaluate the majority of samples from suspected canine influenza cases, Idexx had the most varied information on positive results in 2011. 

Dr. David Lewis, director of consultation services at Antech Diagnostics and a consultant on VIN, said his lab has seen no unusual flu activity outside of the New York City area in the past six months. 

Dr. Edward Dubovi, director of the virology laboratory at the Cornell University Animal Health Diagnostic Center, reported seeing an uptick in positive results from greater New York City as well as cases from a single kennel in San Antonio, Texas. 

Leutenegger said Idexx noticed spikes in California; New York City and environs; and Texas, all occurring in August, September and October, as follows: 

• California, eight cases. Five in the Los Angeles area, three in the Sacramento area. 

• New York region, 10 cases. Three were in New York City, three on Long Island, and one each near Poughkeepsie, N.Y., Middletown, N.Y., Hartford, Conn., and Delaware. 

• Texas, 10 cases. Five were in San Antonio, five in Dallas/Fort Worth. 

Dr. Christian Leutenegger, head of molecular diagnostics for Idexx, said clusters of cases occurring in a relatively short period within a particular geographic region stand out because positive results on canine influenza tests typically pop up in more scattered fashion. For example, last July, Idexx detected five positive samples. Two were from Connecticut, one from Arizona, one from North Carolina and one from Texas. 

Because canine influenza virus prevalence is not very high overall, Leutenegger said, attention-getting peaks can form easily from a relatively small number of cases.

The Merck canine influenza virus vaccine, dubbed Nobivac Canine Flu H3N8 — developed by Intervet/Schering-Plough Animal Health, which is now owned by Merck — was available for the first time in 2009 under a conditional license from the U.S. Department of Agriculture. A full license was granted the following year. 

A second canine influenza virus vaccine made by Pfizer Animal Health, called Vanguard CIV, went on the market in February of 2012. Dr. Oliver Knesl, marketing manager for companion animal biologicals at Pfizer, told the VIN News Service that his company’s marketing efforts focus on educating practitioners about how the virus works in tandem with other pathogens that cause respiratory disease in dogs. 

Read the full VIN article

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