Stress Factors for Horses

Icon of a book About Stress for Horses

Stress is defined as the symptom resulting from exposure to a situation or environment that is not normal for an animal. Stress can often be seen when animals are handled and/or transported. 

Stress affects animals in two ways: 

  • Psychologically: fear resulting from restraint, handling, neglect or unfamiliar objects or environments 
  • Physically: hunger, thirst, fatigue, injury or thermal extremes 

A number of specific factors produce stress. These factors include: 

  • Temperature:
    • Effective ambient temperature: the combination of humidity, precipitation and heat radiation 
    • Comfort zone: range in which an animal does not have to increase normal metabolic rate 
    • Lower critical temperature:  animal shows symptoms of cold stress (i.e., increases feed intake, shivering) 
    • Upper critical temperature: animal show symptoms of heat stress (i.e., decrease feed intake, sweating) 
  • Poor ventilation: the movement of air through the environment 
  • Overcrowding: overpopulation of animals in one area of an environment
  • Transportation: trailer, truck or cage 
  • Changed housing or facility: unfamiliar living space 
  • Working equipment: unfamiliar facilities and equipment 
  • Pests: flies, mosquitoes, lice and ticks that irritate physically and psychologically
  • Human exposure: extent of familiarity or socialization with people. 

Symptoms of Stress

Animals often show common behaviours when they are experiencing stress. These behaviours include: 

  • Making noise
  • Attempting to run away
  • Lethargy
  • Decrease in, or lack of, appetite
  • Isolation
  • An elevated or increased respiratory rate
  • Dehydration
  • An elevated heart rate. 

Horses show specific behaviours when they experience stressed or fearful. Symptoms to watch for include: 

  • tail swishing/wringing, in the absence of flies 
  • the whites of the eyes are more visible 
  • sweating with minimal physical exertion 
  • flared nostrils or wrinkling at the mouth or nose • both ears laid flat back 
  • pawing or striking • running away from or charging at the handler 
  • vocalizations (e.g. snorting, squealing, calling) 
  • head held very high 
  • kicking or turning the hindquarters towards the handler.

Source: NFACC Code of Practice (2018)

Factors That Help Prevent Stress

Heat: Provide shade, airflow (i.e. fans) and readily accessible water. Avoid exercise during hot, humid weather.

Cold: Provide adequate shelter from cold or wet conditions, good quality feed, and provide blankets if necessary.

Ventilation: Ensure there is adequate ventilation and provide an outside area for animals when possible during the day.

Overcrowding: Make sure there is room for each horse to move easily, walk forward, turn around with ease, and lie down in a normal resting posture. There must also be sufficient space for horses to escape inter-aggression, and access water and feed. Time should be given to move animals from one place to the other to prevent crowding in pens and chutes. Never move animals in inclement weather conditions, as it can elicit further stress.

Transportation: Ensure a clean and safe mode of transportation that has adequate space allowance and ventilation for all horses. Provide potable water and food every 3 to 6 hours during transport and monitor behaviour. Prepare horses for transport by practising low-stress loading and unloading beforehand.

Housing or Facilities: Provide an environment that ensures comfort and safety, and minimizes exposure to disease, illness or injury.

Working Equipment: Chutes, pens and other equipment should promote ease of handling and horse safety. Any objects or equipment that could startle horses should be removed.

Pests: Provide pest control in the environment to prevent irritation by pests, and exposure to disease or illness. Ensure that living spaces are kept clean and well maintained through biosecurity protocols

Human Exposure: Approach horses slowly and pay attention to signs of stress or fear. Allow horses to habituate to new environments and apply the principles of learning theory when handling horses.

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