We can easily recognize signs of stress in ourselves. Headaches, fatigue, muscle soreness, and stomach pain are signs of strain. But horses can’t talk and they are stoic animals making it difficult to know they are feeling stressed.

Left unchecked, stress can affect a horse’s immune system.

Michigan State University helps horse owners understand the effects those stresses can have on their animals.

According to Carey Williams, Extension equine specialist at Rutgers University, stress may be defined as “…the body’s response to anything it considers threatening. For a horse, this could be a number of factors, including trailering and traveling, showing, poor nutrition, feeding at irregular times, changes in other routines, environmental toxins, interactions within their social environment, variations in climate and illness.” 

Each of these potential stressors can cause unique issues in the horse. Long-term stress may result in a depressed immune system and subsequently, a greater risk of illness in the animal.

The immune system of the horse is a fascinating and complex, yet typically effective physiological means of fighting off disease-causing agents such as bacteria, viruses, and other pathogens. The three main factors that influence immune system function in the horse include stress, nutrition, and age. If a horse is young or very old, when they are not receiving an appropriate level of nutrition, or when they are otherwise stressed, their immune system may fail to protect them effectively, therefore increasing the risk of disease. At this time of year, cold stress combined with age, low body condition, or some combination of the three may create a situation where horses are more susceptible to illness.

When considering the many factors of stress-causing agents, maintaining proper immune system function is a primary concern. When horses are transported to events where large numbers of unfamiliar horses congregate, such as a horse show, rodeo, or organized trail ride, there is the potential for them to be exposed to pathogens. It is imperative to realize that their immune system may be compromised by the stress of travel or a change in routine.

Michigan State University Extension recommends the following practices to reduce the risk of disease to horses:

  • Maintain a body condition score of 5
  • Keep horses on a regular vaccination, deworming, and dental schedule
  • Maintain a similar feeding routine when at home or on the road
  • Make sure horses are physically prepared for the work they are asked to do
  • Implement good biosecurity procedures when traveling and returning home

While there are no guarantees that horses will always stay healthy, practicing these methods will assist in the prevention of illness and disease.

By Michigan State University Extension