By Josie L. Traub-Dargatz DVM, MS
When you ask most horse owners about controlling infection in their horses they say “Oh you mean do I vaccinate and worm my horses?” Certainly immunization of horses with vaccines to prevent or reduce the severity of infectious diseases is a very important part of any infection control plan. However, it is important for horse owners to realize that vaccination is only one part of a complete infection control plan for their horses. First, very few vaccines will protect 100 percent of the horses that receive them from the disease caused by the infectious agent(s) and second there are diseases of the horse for which there are no licensed vaccines. Certainly the dewormers we have today appear to be very effective, but there are opportunities to reduce parasitism even further by considering additional means of control. So what else can horse owners do to help protect their horses from infectious diseases?
This article will provide an overview of the major concepts in infection control for horse owners. The details of such a control program must be tailored to the individual horse based on factors like age, use, housing, health status of other animals nearby, and risk aversion of its owner.
There are two main components of an infection control plan. One part strives to optimize the horse’s resistance to disease if exposed to the infectious agent. The second part should be targeted at prevention or reduction of exposure of the horse to infectious agents.
Many horses, like people today, live a fast paced life. Horses are on the road to shows, breeding farms, race tracks and trail rides. It is critical to manage each horse to avoid an illness that could compromise performance in the short run or even result in permanent impairment of their ability to perform or result in loss of life. An even larger impact would be felt by the horse owner if an infectious disease outbreak occurs on their farm. If many horses become ill, this can result in substantial financial cost of treatment, lost use and potentially loss of business if horses are unable to move on or off of the facility for a time. A farm that has had an infectious disease outbreak in their horses can become stigmatized, which in turn can affect their business for a long period of time, even after the outbreak is resolved.
The first part of an infection control plan would include working with a veterinarian to develop a comprehensive vaccination program. A vaccination program needs to be tailored to the individual horse and the horses at a given facility. There is no one plan that will fit all situations. A veterinarian will be in the best position to consider all the necessary information about your horse’s risk for exposure to disease agents and the most effective vaccination strategy to enhance their resistance to disease if exposed. The ultimate goal of vaccination is to maximize the horse’s resistance to specific disease causing agents if exposed.
Another part of resistance to disease is so-called innate immunity or natural resistance. Since stress and nutritional deficiencies, especially trace mineral deficiencies, can result in degradation of innate immunity, it is important to address these areas in the overall infection control plan. Assuring that the horse is as comfortable as possible during transportation and when housed can help to minimize the adverse effects of stress. The horse owner should consider working with a professional to evaluate the horse’s diet to be certain not only meet his need for protein and energy, but also meet his need for vitamins and minerals. These micronutrients can play a key role in his resistance to disease.
The second major part of an infection control plan should be focused on reducing or preventing exposure of the horse to infection causing agents. There is no question this is the part that will require more work on the horse owner’s part and will be more difficult to do. So you might say “do I really need to do it?” I believe the answer is yes.
Here are just a few examples of ways to reduce exposure of a horse to infection causing agents. It is important to recognize there are a vast number of ways to reduce exposure beyond the examples given here. One way to begin to develop the strategies to reduce exposure is to think of how the horse is most likely exposed and the disease agents of most concern.
A few examples of ways to reduce or prevent exposure of your horse to infection causing agents:
1. Collect and discard manure at least once a week. Do this in both the paddock and pasture areas. This simple, albeit time consuming, practice will reduce the horse’s exposure to internal parasites, bacteria that cause diarrhea and help to reduce flies and other insects in the horse’s environment. (Figure 1)
2. Consider segregating horses based on the risk they may pose for infectious diseases. Horses that have traveled to sites where horses congregate, have been at a veterinary hospital or those that are new to your farm may be more likely to shed infectious disease agents. Keep horses that are new to the facility and those returning from outside events such as shows separate (quarantined) from the resident or home-based horse population. It is critical to work with a veterinarian to determine how far away and for how long horses should be kept apart to avoid spread of disease agents. Generally keeping horses at least 35 feet apart is recommended to avoid spread of respiratory pathogens. (Figure 2) Be sure you do not spread disease agents by sharing equipment such as feed tubs, water buckets, tack and grooming equipment between horses being kept separate. Also, take precautions to clean hands, boots or clothing between contact events with groups of horses you want kept separated.
3. Design the facility to have a place to keep certain groups of horses separated away from other horses on the farm. Be sure to have high traffic areas for visiting horses such as palpation stocks away from where the resident horse herd is kept.
4. Be sure to secure horse feed to keep out rodents and other wildlife that may spread disease agents such as those that cause diarrhea and Equine Protozoal Myelitis (EPM).
5. Design the horse facility to make it as easy to clean as possible. Porous surfaces and dirt floors will be impossible to clean adequately if they become contaminated with certain bacteria that can cause disease in horses.
6. Plan to reduce exposure to mosquitoes that can carry the West Nile Virus. Eliminate mosquito breeding areas by eliminating standing water where possible, cleaning water troughs at least once a week, controlling weeds, using fans on horses stabled in stalls, and applying insect repellent to horses.