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[RC] EHV-1 A Must Read On Vaccinating Part 2 of 4 - Don HustonThe neurological form of the disease tends to occur in sporadic but deadly clusters. The first horses involved tend to be some population of horses subject to typical show or race stress. The typical stresses felt by this population include, but are not be limited to: intermittent travel, social isolation (stall confinement), exposure to a changing population of equine neighbors, exposure to other communicable diseases, performance in the face of low or moderate grade musculo-skeletal injuries, performance enhancing medications, a diet too rich in cereal grains but low in anti-oxidants, short or little breaks from the same training routine and little to no time spent outside, grazing green grass. There is often a history of a vaccination within the preceding 60 days, sometimes even for Rhinopneumonitis (EHV). Once started, infection can spread by direct contact, aerosolized particles or mechanical vectors. The virus is not especially long lived in the environment and is susceptible to almost all properly applied disinfectants. In 2004 there was an outbreak of the neurological form of EHV1 at Finley University in Ohio. That outbreak claimed the lives of over 20 horses. This was despite heroic 24 hour care provided by the two veterinarians on staff. What was note worthy about that outbreak was that both the morbidity (attack rate) and mortality (death rate) were higher in horses vaccinated for the disease than among those never vaccinated (Dr. Stephen Reed, Ohio State University, January, 2004, personal communication). I am aware of how discouraging that statement reads to Vets and the public alike. If vaccinated horses are at, the very least, not more immune to the neurological form of EHV1, then what options do we have? We do have options available to us. These include the proper use of vaccines and a larger view of health. The answer to this puzzle lies in the way vaccines achieve their effectiveness. Vaccines present to the body a modified form of the infectious agent that the body can recognize as foreign and wage a brief and successful battle. When exposed to the same infectious agent in the future (that is, exposed to the disease), the response will be quicker and more efficient. The body wins the battle without becoming sick at all or, perhaps, not as sick. Each and every vaccination causes a transient dip in the body's level of immunity as the body fights the battle and processes the information for the future use. The more vaccines that are grouped together in one vaccine, the more profound are the transient negative effect upon the bodies' immune status. Grouping vaccines together also negatively impacts the bodies' ability to respond to each individual vaccine. For the sake of convenience and economy, most of our equine vaccines are grouped together in batches. For example, the commonly used 4-way vaccine contains Eastern and Western encephalomyelitis, Influenza (flu) and tetanus. We often add other vaccines at the same time such as Rabies or Rhino. There is now on the market a 6-way vaccine which adds Venezuelan encephalomyelitis and Rhino to the already over-loaded vaccine. I would advise you to try to limit your use of these vaccines. Do not use the 6-way vaccine; the downside is greater than the potential benefit. Try at the very least to avoid vaccination with more than one vaccine at a time. Do not go to vaccine clinics where horses are vaccinated for many diseases at the same time. If your veterinarian performs your vaccinations, see if you can influence him to not group vaccines. Perhaps if you offer to van the horse to his place of business or allow him to send a technician over to perform the mechanical act of giving one vaccine at a time. More effort will lead to better results and fewer complications. The sense of urgency that we sometimes feel as regards vaccinations is generally due to external perceptions about the need to vaccinate. This is often due to the need to adhere to some new requirements such as travel to a foreign country, a different state or to a new barn that has more stringent vaccination requirements. The most dangerous sense of urgency comes as an urge to vaccinate because of a fear of recent exposure to disease. The desire to vaccinate in the face of a potential recent exposure is an understandable one. After all, we are helping him to resist the disease, right?
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