Connecticut lawmakers will consider today legislation that grants veterinarians the authority to adjust vaccine dosages and forego rabies boosters when it's in the best interest of their patients.

House Bill 5659 is slated for discussion in the General Assembly's Public Health Committee, the first hearing on the measure since it was introduced in January by state representatives Fred Camillo and Pam Staneski.

"I'm ready to have the debate," Camillo recently told the VIN News Service.

Connecticut, like most states, mandates that owned dogs and cats must be vaccinated against rabies and reimmunized on scheduled intervals. The state's immunization schedule calls for a rabies booster one year after initial inoculation and repeated thereafter every three years or less. Exemptions are granted if a veterinarian determines that inoculation presents a health risk to a patient and state officials agree. Connecticut law specifies that animals are considered legally inoculated for rabies only if the vaccine is administered as labeled by the manufacturer.

The law does not permit veterinarians to give partial doses of the vaccine based on an animal's size or health, and the Connecticut State Board of Veterinary Medicine is disciplining practitioners who break it. Dr. John Robb of Stamford received veterinary licensure probation on Feb. 1, following a four-year battle with regulators. Under the order, the 59-year-old practitioner is not permitted to vaccinate another animal for rabies for 25 years. For the next 18 months, Robb must practice under the direct supervision of a colleague who's approved by the regulatory agency to monitor him.

If passed, H.B. 5659 could shield other veterinarians who inoculate at their discretion by making Connecticut the nation's first state to permit titer testing for rabies antibodies in lieu of revaccination.

The bill's language permits Connecticut veterinarians to do two things: "(1) vary from established protocols when in the best interest and health of an animal, and (2) administer a rabies antibody titer [a blood test used to estimate antibody levels] to determine the need for a rabies booster vaccine."

Reaction to the bill has highlighted the controversy surrounding vaccine protocols and who has the authority to change them. At the core of the debate is whether veterinarians or public health policymakers should dictate vaccine administration guidelines. Critics of the potential change point out that the bill does not address how atypically vaccinated dogs should be treated if they contract rabies or bite an individual, nor does it define the potential exposure risks, which are necessary for determining medical interventions.

Dr. Arnold Goldman, co-chair of the Connecticut Veterinary Medical Association's Government Affairs Committee, explained that the bill's provisions create a "hugely gray area."

"As practicing veterinarians, not immunologists or vaccine researchers, we are in no position to question efficacy or manufacturers' directions for a FDA-approved vaccine product on a size-dependent, case-by-case basis or on any other basis. It would be the height of hubris to suggest we can," he said.

(The U.S. Food and Drug Administration's regulatory scope covers most prescription drugs and biologics; however, rabies vaccines are approved by the U.S. Department of Agriculture.)

Equally controversial is the idea that revaccination decisions should depend on antibody titer levels, which reflect the concentration of antibodies in a pet's blood. Opinions in the profession are mixed about whether the results of titer tests can accurately indicate continued immunity and protection. The American Veterinary Medical Association puts it this way: "For most common vaccine antigens, the correlation between serological response to vaccination, long-term serostatus, and protection in the host animal has not been adequately established. The lack of these data often precludes practitioners' ability to make well-informed vaccination decisions based on serostatus alone."

Technological advances in determining titer levels, however, are pushing the science mainstream. So are sporadic reports of adverse reactions associated with vaccinating.

As a founding member of the Connecticut Legislature's animal welfare caucus, Camillo said he's privy to anecdotes of dogs dying or reacting adversely to vaccines. Some of the reports come from Robb, the veterinarian who ran afoul of the licensing board. While Robb declined to speak with the VIN News Service, he was a guest on Camillo's local radio show, which debuted on Saturday.

Robb said he gave smaller dogs a smaller dose of rabies vaccine because he believes a full dose is "dangerous" and "potentially lethal."

That makes sense to Camillo, who expressed to the VIN News Service that he'd ultimately "like to allow doctors to go with their own intuition so that you're not giving a two-pound dog the same vaccination amount you'd give an 88-pound dog."

Veterinary immunologists, however, note that while most veterinary drugs are weight dependent, vaccines are not. Dr. Ronald Schultz, a longtime researcher of canine vaccines at the University of Wisconsin-Madison School of Veterinary Medicine, addressed the topic in a Journal of Small Animal Practice article that posed whether Great Danes should be injected with the same volume of vaccine as Chihuahuas.

"Yes," Schultz wrote. "Unlike pharmaceuticals that are dose-dependent, vaccines are not based on volume per body mass (size), but rather on the minimum immunizing dose."

The practice of splitting rabies vaccines has many in the veterinary profession wary.

"It's just dangerous," said Dr. Lisa Boyer of Loomis, California. "Immunologists say vaccines are not dose-dependent, that you need enough antigens to stimulate the immune system. It's not a weight-versus-dose question. My 7-year-old [child] and I get the same vaccine."

Boyer said she became a vocal advocate for the state's vaccination laws after an online campaign to support Robb spread misinformation that, in turn, was disseminated by media.

"The news was presented in a way that made it seem obvious [that] smaller dogs should get smaller vaccines," she said. "I don't think government should dictate medical care, but when talking about rabies — a fatal disease — there should be some governance and guidelines based on scientific evidence."

Evolving thoughts on titers

During today's hearing on H.B. 5659, Goldman said the CVMA will submit expert testimony asserting, among other things, that a high antibody titer against rabies does not necessarily correlate with actual immunity.

Rabies researchers at Kansas State University aim to take the uncertainty behind vaccine titers out of the equation by developing standards that specify what antibody titers are protective against rabies.

Working on it are scientists Rolan Davis, MS, and Dr. Susan Moore, a clinical assistant professor and managing director of KSU's Rabies Laboratory, one of the highest volume rabies serology centers in the world. The research team has been testing rabies titers of dogs and cats for several years. "We know they do respond very well to vaccination and may not need that routine booster to maintain immunity ...," Moore stated.

"Potentially, we'll be able to draw a line in the sand that says at what level you're OK skipping the vaccination," Davis added.

Even so, there are hurdles to taking the use of titer tests mainstream. First, there's the cost. "The reason we don't check titers regularly is because it's expensive," Boyer said. "This is where the law could be dangerous. If I wanted to check a rabies titer, it is going to cost $150 when the rabies vaccine costs $15."

It's also a matter of public health, not just the health of animals being vaccinated.

"As a veterinarian, I wouldn't want to treat a half-dosed dog," she said. "If I were bitten, how would I know if I need prophylactic treatment? There is no way to know the vaccine status of that dog."

Goldman plans to share with lawmakers the CVMA's perspective, which he says might be controversial: "We don't vaccinate cats and dogs primarily to protect them from rabies. We vaccinate them to protect people from rabies. They are more likely than we are to have contact with rabies vector species. They are our final barrier between that terrible disease and people."

Such sentiments suggest that it will take time to get H.B. 5659 passed, Camillo said. Without the veterinary profession's support, "I just don't think the legislature will have the appetite to be the first in the nation on this issue," he said.

While Camillo admits that he's no expert on animal health or vaccines, he reflects the voice of his constituents. "This comes down to when someone calls me and says their dog died or got violently ill after vaccination and they are small, it makes you wonder why that's happening," he said.

"Where there is smoke, there's fire. I think the law needs to change," he added.