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Horses and Other Equines

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Horses belong to the equine family, which includes the domesticated African wild ass, also known as the donkey or burro. Historians believe that domestication of the horse began circa 6000 BC and the donkey at least as early as 2600 BC. The mule, bred for work, is a cross between a male donkey (jack or jackass) and a female horse (mare). A mule is unable to reproduce. When a male horse (stallion) is bred with a female donkey (jennet), the offspring, also sterile, is called a hinny. Horses and donkeys have also been crossed with another equine, the zebra, and the offspring are collectively called zebroids. Zebroids are also sterile and of little economic importance (Caras 1996).


Of the 10 million horses in the United States, about 75% are used for personal pleasure riding. Other uses include racing, ranching, breeding and commercial riding. The horse has become a performer in racing, jumping, rodeo and many more events.

The three main horse enterprises are breeding, training and boarding stables. Horse breeding farms breed mares and sell the offspring. Some farms specialize in training horses for show or racing. Boarding stables feed and care for horses for customers who have no facilities to house their horses. All three of these enterprises are labour intensive.

Horse breeding is an increasingly scientific process. Pasture breeding was typical, but now it is generally controlled within a breeding barn or corral. Although artificial insemination is used, it is more common that mares are brought to the stallion for breeding. The mare is checked by a veterinarian and, during breeding, trained workers handle the stallion and the mare.

After giving birth, the mare nurses the foal until it is from 4 to 7 months of age; after weaning, the foal is separated from the mare. Some colts not meant for breeding may be castrated (gelded) as early as 10 months of age.

When a racehorse becomes a two-year-old, professional trainers and riders start breaking it to ride. This involves a gradual process of getting the horse used to human touch, being saddled and bridled, and finally mounted. Horses that race with carts and heavy draught horses are broke to drive at about two years of age, and ranch horses are broke at closer to three years old, sometimes using the rougher method of bucking a horse out.

In horse racing, the groom leads the horse to the saddling paddock, a trainer and a valet saddle it, and a jockey mounts it. The horse is led by a pony horse and rider, warmed up and loaded into the starting gate. Racehorses can become excited, and the noise of a race can further excite and frighten the horse. The groom takes a winning horse to a drug test barn for blood and urine samples. The groom must then cool the horse down with a bath, walking and sipping water.

A groom cares for the performance horse and is responsible for brushing and bathing it, saddling it for the exercise rider, applying any protective bandages or boots to its legs, cleaning the stall and bedding down straw, shavings, peat moss, peanut skins, shredded newspaper or even rice hulls. The groom or a “hot” walker walks the horse; sometimes a mechanical walker is used. The groom feeds the horse hay, grain and water, rakes and sweeps, washes the horse’s laundry and carts manure away in a wheelbarrow. The groom holds the horse for others such as the veterinarian or farrier (farrier work is traditionally done by a blacksmith). All horses require parasite control, hoof care and teeth-filing.

Performance horses are typically stabled and given daily exercise. However, young stock and pleasure riding horses are generally stabled at night and released during the day, while others are kept outdoors in paddocks or pastures with sheds for shelter. Race horses in training are fed three or four times a day, while show horses, other performance horses, and breeding stock are fed twice a day. Range or ranch stock are fed once a day, depending on the forage present.

Horses travel for many reasons: shows, races, for breeding or to riding trails. Most are shipped by truck or trailer; however, some travel by rail or plane to major events.

Hazards and Precautions

Several hazards are associated with working around horses. A groom has a physically demanding job with a lot of forking of manure, moving 25 to 50 kg hay and straw bales and handling active horses. Startled or threatened horses may kick; thus, workers should avoid walking behind a horse. A frightened horse may jump and step on a worker’s foot; this can also occur accidentally. Various restraints are available to handle fractious horses, such as a chain over the nose or a lip chain. Stress on horses due to shipping may cause balking and injuries to the horses and handlers.

The groom is potentially exposed to hay and grain dust, dust from bedding, moulds, horse dander and ammonia from the urine. Wearing a respirator can provide protection. Grooms do a lot of leg work on the horses, sometimes using liniments containing hazardous chemicals. Gloves are recommended. Some leather-tack care products can contain hazardous solvents, requiring ventilation and skin protection. Cuts can lead to serious infections such as tetanus or septicaemia. Tetanus shots should be maintained current, especially because of exposure to manure.

A farrier is exposed to injury when shoeing a horse. The groom’s job is to hold the horse to keep it from kicking the farrier or pulling its foot in a way that could strain the farrier’s back or cut the farrier with the horseshoe and nails.

In the drug test barn, the test person is enclosed in a stall with a loose, excited and unfamiliar horse. He or she holds a stick (with a cup for urine) that may frighten the horse.

When riding horses, it is important to wear a good pair of boots and a helmet. Any mounted person needs a protective vest for racing, jumping, rodeo broncs, and ponying or exercising racehorses. There is always a danger of being bucked off or of a horse stumbling and falling.

Studs can be unpredictable, very strong and can bite or kick viciously. Brood mares are very defensive of their foals and can fight if threatened. Studs are kept individually in high-fenced paddocks, while other breeding stock are kept in groups with their own pecking order. Horses trying to move away from a boss horse or a group of yearlings at play can run over anyone who gets in the way. Foals, weanlings, yearlings and two-year-olds will bite and nip.

Some drugs (e.g., hormones) used in breeding are given orally and can be harmful to humans. Wearing gloves is recommended. Needle-stick injuries are another hazard. Good restraints, including stocks, can be used to control the animal during administration of medication. Topical sprays and automatic stable spray systems to control flies can easily be overused in horse rearing. These insecticides should be used in moderation, and warning labels should be read and recommendations followed.

There are a variety of zoonoses that can be passed from horses to humans, especially skin infections from contact with infected secretions. Horse bites can be a cause of some bacterial infections. See table 1 for a list of zoonoses associated with horses.


Table 1. Zoonoses associated with horses


Viral diseases

Rabies (very low occurrence)
Eastern, western and some subtypes of Venezuelan equine encephalomyelitis
Vesicular stomatitis
Equine influenza
Equine morbillvirus disease (first documented in Australia in 1994)

Fungus infections

Ringworm (dermatomycoses)

Parasitic zoonoses

Trichinosis (large outbreaks in France and Italy in the 1970s and 1980s)
Hydatid disease (echinoccosis) (very rare)

Bacterial diseases

Glanders (now very rare, restricted to Middle East and Asia)
Brucellosis (rare)
Leptospirosis (relatively rare, direct human contamination not definitively proven)
Melioidosis (outbreaks in France in the 1970s and 1980s; direct transmission not reported)
Tuberculosis (very rare)
Actinobacillus lignieresii, A., A. suis (suspected in Lyme disease transmission, Belgium)




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