Some types of stress include various physical stresses that are based on the physical makeup of the animal and its ability to respond to changes in diet, injury, etc. Psychological stresses are based on a horse’s personality and its perception of life. For example, some horses are more stressed than others by being in a stall for long periods of time.

How do Horses Cope with Stress?

Each horse deals with stress in a different way depending on their personality.

Demonstrative, Confident Horse

• Lets you know when it is stressed!

• Bucks, kicks, bites, is very curious, mouthy, a troublemaker, etc.

 

Demonstrative, Fearful Horse

• Worries about everything!

• Shies the first time it sees things and needs time to relax.

 

Passive, Confident Horse

• Usually wonders, “What’s everyone worried about?”

• Not normally stressed, internalizes stress, shows little change even when stressed.

• Usually is the last one in the field to take off running if something runs out of the woods.

 

Passive, Fearful Horse

• Wants to please!

• Seems willing to do anything, but will tighten muscles and lips when stressed.

• Won’t show fear until pushed over the limit.

To help horses decrease their critical temperature, one needs to precondition them for cold weather. Making sure horses carry enough weight to use as energy and insulation is a good way to go into winter. Provide free choice grass hay during the winter months, which will allow the horses to always produce enough internal heat through gastrointestinal fermentation. Providing shelter from wind, rain, and cold is important. If you have a horse that is not allowed in the shelter with other horses it is a good idea to provide a blanket, especially when there is freezing rain. Be sure blankets are waterproof. A wet blanket may cause a horse to lose more heat than it would if it were not blanketed.

• Physical factors

-unnatural sense of confinement

-withholding food and/or water

-noise and vibration of a moving vehicle

-balancing and bouncing during the ride

-poor ventilation

-presence of exhaust, dust, molds, manure, and urine

 

• Psychological factors

-separation from the herd

-exposure to strange animals and environment

 

• Climatic factors

-high internal temperature and humidity

 

• Health factors

-dehydration

-fatigue from constant balancing

Studies in the past decade have investigated numerous factors during transport to try and make a horse’s haul more comfortable. Some of these factors include orientation of the horse in the trailer during transport, design of the suspension and ventilation of the trailer, quality of the transport environment and air quality, and generally the amount of stress a horse is under during various lengths of hauls. Most studies have shown that levels of the stress hormone cortisol to increase during transportation, along with greater fluctuations in heart rate (known as heart rate variability). Some studies have reported as much as a 6% weight loss during a 24-hour haul. Half of this weight was replaced over a 24-hour recovery period. Muscle enzymes called creatine kinase and aspartate aminotransferase (CK & AST) leak out of the muscle after a 24-hour haul. This is a potential indicator for muscle damage.

Oxidative Stress

Antioxidants are the body’s way of combating the negative effects of the ROS. Some common antioxidants include: vitamin E, vitamin C, beta-carotene, glutathione, lipoic acid, selenium, cysteine, glutathione peroxidase, etc. 11. What is oxidative stress, and how does it affect my horse? Oxidative stress occurs when the body’s antioxidants are overwhelmed by production of ROS. Antioxidant supplementation may be needed during times of stress that have been associated with an increase in oxidative stress. These include: intense and endurance exercise, rapid growth, reproduction, transportation, illness, or other types of stressful situations described above. When supplementing antioxidants, mixtures usually work best. It is important to avoid over-supplementation due to the fact that some of the antioxidant vitamins and minerals can be toxic to the system in extremely high doses.

Stomach Ulcers

Are you giving your horse an ulcer? Did you know that 80–90% of all racehorses have ulcers? Also, 60% of all performance horses (including eventers, jumpers, and western performance events), and 30–40% of all dressage horses develop ulcers.

A horse’s stomach secretes acid even when they are not eating, unlike in humans. However, only ½ of their stomach is protected against damage from the acid. When a horse grazes all day the roughage helps absorb the acid and the saliva produced neutralizes acid. Ingestion of a grain meal increases ‘gastrin’, a hormone that stimulates acid secretion. Therefore, it is important to always feed forage along with a grain meal. The main causes of stomach ulcers are changes in eating behavior, changes in management, or an increase in training intensity. Horses that are accustomed to being outside can develop ulcers after only 1 week of being kept in a stall, while others could develop them within 24 hours.

Some signs that a horse is developing ulcers include a change in attitude, poor appetite, colic, decreased performance, decrease in body condition, weight loss, and a dull or sour attitude. To prevent ulcers, you need to prevent stress and minimize the use of non-steroidal anti-inflammatory agents (NSAID) such as, phenylbutazone (Bute).

Exertional Rhabdomyolysis (ER)

Other terms for ER are "tying-up", "azoturia", or "Monday morning sickness". This condition is muscle pain and cramping associated with exercise. Its main prevalence is in the middle gluteal or semitendinosus muscles of the hindquarters. There are sporadic or chronic forms of ER, which could be severe enough to decrease performance or end a career. There are different causes of tying-up for different breeds, however, recurrent ER (RER) primarily affects Thoroughbreds, Standardbreds, and Arabians. Nervous two-year-old fillies are most severely affected due to the stress associated with their training regime. With these horses the incidence may increase in severity as fitness increases.

One way to test for ER is to take a blood sample after exercise and have the sample analyzed for CK and AST (muscle enzymes described above). These enzymes will be drastically elevated during a bout of ER and may even be elevated at rest in a horse that chronically ties up. The clinical signs that your horse is tying-up include: stiffness of gait in the hind legs, unwillingness to move, and sensitivity of touch to the affected muscles. These muscles will feel very tight or tense. In severe cases the horse’s urine will be a brown or reddish color from the breakdown and excretion of the myoglobin in the muscle.

To treat a horse afflicted with ER, immediately move it to a box stall and call a veterinarian. Blanket the horse if weather is cool or hose the horse to remove sweat if weather is warm. Check for signs of dehydration using the skin pinch test and look at mucous membranes. Allow small frequent sips of water when the horse is hot, and free access to water when the horse is cool. Many other factors can contribute to tying-up. However, to help decrease the incidence of the disease attempts should be made to decrease training-induced stress. Dietary changes and vitamin E supplementation may also help in some cases.

Summary of How to Minimize Stress in Your Horse’s Life:

 •  Keep horses turned out as much as possible but if not possible, feed ad libitum hay.

 •  Stick to a routine but if you need to make changes, do so slowly.

 •  When traveling take items that are familiar (e.g. your own hay, water, grain, etc.).

 •  Avoid riding in extreme weather conditions.

 •  Feed a well balanced diet.

 •  Maintain a good health program.

 •  Provide a pleasant environment.

 •  Provide regular varied exercise.

 •  Allow for play time.

 •  Prevent boredom.

 •  Allow your horse social activity.

 •  Keep yourself happy, healthy, and stress free!!

References and Other Recommended Reading:

Anon. 2002. Equine Industry Welfare Guidelines Compendium for Horses, Ponies, and Donkeys. (A. Michael, ed.). www.adas.co.uk/equinewelfare/ compendium.pdf.

 

Andersen, K. 1996. Winter Care for Horses. Univ. of Nebraska Cooperative Extension Fact Sheet, #G1292.

 

Grandin, T. 1997. Assessment of Stress During Handling and Transport. J. Anim. Sci. 75: 249-257.

 

Malinowski, K. 1993. Stress Management for Equine Athletes. Rutgers Cooperative Research and Extension Fact Sheet, FS716.

 

 Ralston, S.L. 1994. Performance Horse Conditioning and Notes on Conditioning. Rutgers Cooperative Research and Extension Fact Sheet, FS752.

 

Valberg, S. 2005. Equine Exertional Rhabdomyolysis: Management of Sporadic and Recurrent Exertional Rhabdomyolysis. Mid-Atlantic Nutrition Conference Proc. p. 197-203.

 

Williams, C.A., D.S. Kronfeld, T.M. Hess, J.N. Waldron, K.M. Crandell, K.E. Saker, R.M. Hoffman, and P.A. Harris. 2004. Antioxidant Supplementation and Subsequent Oxidative Stress of Horses During an 80km Endurance Race. J. Anim. Sci. 82:(588-594).