Thoughts on the 2006 feline vaccine panel report

I read with great interest the new American Association of Feline Practitioners feline vaccine recommendations.¹ I agreed with some of the conclusions and recommendations and disagreed with others, as is probably true of the panel members themselves. One of the aspects with which I disagree is the recommendations regarding use of FIV vaccine. Please consider these facts:

• • FeLV and FIV transmission occurs as a result of bite wounds because both viruses are in the saliva of infected cats. Bite wounds probably account for most of the new infections of both viruses.

• • Cats with unsupervised outdoor exposure represent most new cases because they are the most likely to be bitten by infected cats.

• • Once an established infection develops with either virus, the cat is infected for life.

• • Some age immunity develops to the FeLV. This does not happen with FIV. Thus, adult cats are more likely to become infected with FIV than FeLV.

• • Both viruses can have adverse effects on the immune system. The resulting immunosuppression can lead to overwhelming, fatal infections with disease agents that may normally be only mildly to moderately pathogenic.

• • The 2006 panel is recommending FeLV vaccine for “cats permitted outdoors.”

• • The 2006 panel is recommending FIV vaccine for “outdoor cats that fight.”

I do not understand the double standard presented in the last two bullets. Fighting can be a proactive or a passive event. Many cats that become infected with the FeLV and FIV are not the aggressors; rather, they are the victims of fighting. Therefore, how can one predict whether an outdoor cat will be one that will sustain a fight wound? A single bite from an infected cat can be sufficient for transmission. Furthermore, waiting to determine whether the cat is an “outdoor cat that fights” means that exposure and infection could occur before the decision to vaccinate is made. This is like closing the barn door after the horse gets out.

My recommendation for FeLV and FIV vaccines continues to be the same for both antigens: 1) cats that go outdoors unsupervised and 2) cats living in a household with the respective virus.

Gary D. Norsworthy, DVM, DABVP

Alamo Feline Health Center

San Antonio, Tex

Dr. Richards responds:

Thank you for your interest in the American Association of Feline Practitioners Feline Vaccine Advisory Panel Report. The 12 panelists expressed diverse viewpoints during the report's development (understandably and desirably so, given that they were chosen because of their varied experiences and expertise), and the discussions were sometimes quite lively. Nonetheless, after extensive debate, the panelists created a consensus document and they unanimously supported the recommendations it contains.

Your comment that “bite wounds probably account for most of the new infections” and “cats with unsupervised outdoor exposure represent most new cases because they are the most likely to be bitten by infected cats” is true for FIV. However, although FeLV can be transmitted by this route, it is more likely to be transmitted via prolonged intimate contact, mutual grooming, sharing of food and water utensils, in utero exposure, and in some cases, through milk.¹ Thus, the population of cats at risk of FIV infection is not identical to that of FeLV, partly because the transmission routes of the two viruses are not identical.

As you've noted here, the report lists examples of cats that the panel believes should be considered for FeLV or FIV vaccination. Specifically, FeLV vaccines are noncore vaccines recommended for cats at risk of exposure; FIV vaccines should also be considered noncore “…with use restricted to cats at high risk of infection (eg, outdoor cats that fight) and cats not infected with FIV living with FIV-infected cats.” The panelists' differing comments (FeLV vaccination “recommended” for certain cats, with FIV vaccination “restricted” to certain cats) would be a double standard only if the epidemiology and routes of transmission were identical for both viruses and if the consequences of vaccination were also identical. But they are not. Since the early 1990s, a number of investigators have documented the performance of FeLV vaccines in both laboratory and field challenge studies.² While publications cited give reason for hope, there is still little known about how the available FIV vaccine will perform in real-world cats.

Another difference of considerable importance to the panelists is that FIV vaccination induces positive test results in vaccinates,³ whereas FeLV vaccination does not. After taking into consideration the relative paucity of information on FIV vaccine performance in the field, along with the loss of ability to identify infected cats, the panelists concluded that the population of cats that might benefit from FIV vaccination is likely much smaller than the population that would benefit from FeLV vaccination.

In conclusion, the epidemiology and likely transmission routes of these two viruses, and the vaccines themselves, are substantially different. In the report, general advice on vaccine usage for a particular disease was followed by examples of situations. However, these are for guidance only, and in any vaccination procedure, we would expect veterinarians to use their knowledge to assess the risks and benefits of a particular vaccine for an individual cat in relation to the likelihood of exposure and its specific circumstances.

James R. Richards, DVM

Chair, 2006 American Association of Feline Practitioners

Feline Vaccine Advisory Panel Director, Cornell Feline Health Center

College of Veterinary Medicine Cornell University Ithaca, NY

Comments on efforts to eradicate brucellosis

Brucellosis has recently emerged as a zoonosis in Korea. Given the geopolitical status of Korea and the United States, we believe that the high prevalence of this zoonosis, caused by a weaponizable agent, needs immediate attention from not only the government of Korea but the global scientific and political community as well. In Korea, the disease was first diagnosed in cattle¹ and in humans.² It had been predicted that this disease could turn into a major epidemic as food animal farming expands without any major regulatory change mandating an integrated approach to bovine brucellosis,³ as opposed to the current official policy of “test and slaughter.” We advocate that Korea take advantage of and emulate successful brucellosis eradication initiatives from Australia, New Zealand, and to a limited extent, the United States. These countries found that incorporating vaccination into the eradication program was essential to a long-term national brucellosis control policy. Regulatory agencies in Korea have been struggling with the reality that the “test and slaughter” policy per se has had no substantial impact on the prevalence of bovine brucellosis and human cases have escalated. More than 300 human cases have been reported between January 2005 and August 2006. In addition, during the same interval, more than 50,000 cattle have been slaughtered because they developed brucellosis.^a The socioeconomic impact of this disease is particularly felt among the farmers, many of whom have been bankrupted by the epidemic. The scientific community appears frustrated by the apparent lack of political will to adopt control methods that exploit the availability of Brucella abortus strain RB51 vaccine. This strain offers regulatory benefits as it does not confound serologic testing. Although vaccination of pregnant animals with a live vaccine should be conducted with caution, studies have suggested that RB51 vaccination is safe in pregnant cattle, particularly in cattle that received brucellosis vaccines as calves.^4–6 Although the pathogenicity of RB51 in humans remains uncharacterized, countries that have implemented widespread use of RB51 vaccination have not reported serious problems with human infections.

An international seminar covering the history and global impact of brucellosis, vaccination strategy with strain RB51, treatment of human brucellosis, and the current situation of brucellosis in Korea was held in Seoul during April 2006. The public and government officials now appear better informed about the disease, and the organizers decided to make the seminar a biannual event.

Ibulaimu Kakoma, DVM, PhD

University of Illinois, Urbana, Ill

Byeong K. Baek, DVM, PhD

Chonbuk National University, Chonju, Korea

Stephen M. Boyle, PhD

Nathan Srianganathan, DVM, PhD

Virginia Polytechnic Institute and State University, Blacksburg, Va

Steven Olsen, DVM, PhD

National Animal Disease Center, Ames, Iowa

Edward Young, MD

Baylor College of Medicine, Houston, Tex

Qualities of successful food animal veterinarians

I write in response to a letter to the editor by Dr. Louise Murray¹ and to the American Association of Bovine Practitioners coverage report² written by Susan Kahler in the November 15, 2006, JAVMA. Dr. Murray and the AABP addressed the issue of a shortage of food animal veterinarians. I wish to express my thanks to these authors as they are right on target.

I am a practitioner in a 15-veterinarian, all-bovine practice in California's Central Valley. The shortage of high-quality bovine practitioners is a very real issue.

Food animal practitioners serve their constituents, in our case, dairy farmers. Our job is to balance meeting the needs and desires of farmers with public health demands and our own self-interests while always regarding the humane interest of the cattle. The farmer ultimately drives this equation however.

Successful long-term food animal practitioners must understand the agriculture industry. Farms have been growing rapidly in size. The typical US dairy farm is doubling in size every 10 years. Larger units are over 5,000 milking cows, with some owners possessing multiple units. These farmers expect a large volume of repetitive tasks from their veterinarians, including rectal palpations, vaccinations, and surgeries. Veterinarians serving these farms must master these techniques and have tremendous endurance and strength.

Veterinarians can influence the attitudes and expectations of their clients. However, these practitioners must first earn credibility with those farmers. Having a DVM/VMD degree provides us with a title only. This essential credibility takes months or years to build and can be lost in one day. It requires hard physical and mental work and complete honesty and competence.

To meet the needs of food animal practice, veterinary schools must choose individuals who will meet the needs of current and future farms. These candidates must inherently want to work within the food animal industry, not just work on individual cows. They must be strong and perseverant. They must enjoy being outside and driven by feeling satisfied from a good day's work. They must understand that the industry may be on a financial roller coaster and accept that as a substantial limitation.

The accredited veterinary schools must select individuals with the unique characteristics required of today's food animal practitioners. Veterinary schools primarily assess applicants on grades and test scores. The typical prerequisite classes are inadequate for choosing candidates for food animal practice. Potential food animal practitioners should have an academic background in animal reproduction, animal production, genetics, agronomy, food safety, statistics, computer science, industrial manufacturing concepts, problem solving, speech, leadership development, agricultural economics, and basic business practices. Calculus, physics, organic chemistry, and the humanities are less vital.

These applicants should be equally valued for commitment to practice as evidenced by years of large animal experience. They must be passionate and driven. They must be problem solvers, inspiring, and visionary as well as risk takers. They must love being outside and be team players. I think it essential that veterinary schools recognize these unique attributes required by today's food animal practitioners and have alternate selection criteria.

Robert B. Cherenson, DVM

Lander Veterinary Clinic

Turlock, Calif