MSD Manual

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Routine Health Care of Horses


John A. Bukowski

, DVM, MPH, PhD;

Susan Aiello


Last full review/revision Jul 2011
Topic Resources

In addition to properly feeding and exercising your horse, other aspects of general care are needed to keep your horse healthy throughout his or her life. These include routine veterinary care for vaccinations, parasite control, and dental care; grooming and hoof care; and protection from the elements.

Importance of Veterinary Care

Adult horses should have a complete veterinary examination at least once a year. Geriatric horses (older than 20 years old) should see their veterinarian twice a year or more frequently because illness is more common in older animals and it can be identified sooner. Your veterinarian may recommend a wellness program for your horse, including routine blood tests.

Signs of Illness

You should monitor your horse regularly for signs of illness, such as during daily feeding and grooming times. General signs of illness include a lack of appetite, diarrhea, coughing and sneezing, or a discharge from the eyes or nose. Illness can also show up as a loss of hair or itchy areas on the skin. Problems with the musculoskeletal system are often seen as lameness (such as not putting weight on a particular leg), reluctance to move, or head bobbing. If your horse shows any of these signs for more than a day or two, a visit with your veterinarian is a good idea.

Giving Medication

Generally, administering medication to a horse is not difficult if you use common sense and follow good handling principles for keeping both you and your horse safe. Maintain physical contact with the horse by keeping your shoulder pressed against the horse’s shoulder or flank (depending on where and what you are treating) and make sure to use a sturdy halter and lead rope (hooked to the left halter ring). Never let a loop of any rope that is attached to your horse get wrapped around any part of your body.

If you need to apply medication to the horse’s feet or lower front legs, lift the hoof to be treated and cradle it between your knees. If you need to treat the rear legs, in addition to lifting the hoof, you will also need to bend the hock. If your horse “dances” around, have another person lift the other leg on the same side as the leg that you need to treat.

Oral medication is usually in the form of “horse pills” (called boluses), pastes, or drenches. When administering oral medication, identify the toothless gap directly behind your horse’s incisors and in front of the molars. Insert your thumb into this gap while holding the horse’s head down with your hand. Firmly pull the horse’s tongue out through the gap and, and gently hold it outside the mouth. You can now administer a bolus by placing it behind the “top” of the tongue with a balling gun. Always lubricate the bolus with something like petroleum jelly or vegetable oil to keep it from getting caught in your horse’s throat. Drenching guns and paste syringes can be placed far back in the mouth for administration of the fluid or paste. Hold your horse’s head level or tilting slightly upward until he or she swallows the medicine.

Correct administration of a bolus or “horse pill”

Correct administration of a bolus or “horse pill”

Some medications can be administered only by injection, which is usually given in the neck area or thigh. Ask your veterinarian for a demonstration and guidance to make sure you know how to give the injection properly.

Regardless of type of medication or how it is to be given, it is important to read and follow all label instructions regarding use and storage.


Vaccination is a key component of preventive medicine in horses. Vaccinations are given to stimulate the immune system against infection before exposure to disease. Several vaccines are routinely given to horses as the core defense against serious infectious illness. Several others are important in certain regions and situations. Your veterinarian can advise which vaccines are necessary in your local area and circumstances (see Table: Vaccines Required or Recommended for Horses).

Foals born to a vaccinated mare are usually protected against most infectious diseases for up to 6 months, so long as the foal consumed the antibody-rich mother’s milk known as colostrum within 6 hours of birth. In this case, vaccinations should be delayed until maternal immunity has waned. Otherwise, the vaccination will be ineffective.

Vaccinations should be administered by your veterinarian or other properly trained individual. If you administer vaccines yourself, learn how to do it properly. Use only vaccines from a reliable source who can verify that they have been kept clean and refrigerated. Poor-quality vaccines increase the risk of adverse reactions, which can range from inflammation at the site of the injection, fever, and malaise, to serious allergic reactions that affect the entire body (for example, anaphylaxis).


Vaccines Required or Recommended for Horses



Vaccination Frequency

Core vaccines


A bacterial infection that attacks the nervous system and causes the muscles to tighten (lockjaw)

First vaccine at 6 months of age, followed by 2 additional vaccinations at 3‑to 6‑week intervals; yearly boosters

Encephalomyelitis (sleeping sickness, Eastern equine encephalomyelitis, Western equine encephalomyelitis)

A family of viral infections carried by mosquitoes that result in inflammation of the nervous system, including the brain

Similar schedule as tetanus (usually given as combination vaccine)

Equine viral rhinopneumonitis

A highly infectious herpesvirus that can cause respiratory disease

Similar schedule as tetanus (usually given as combination vaccine) but semiannual boosters


A highly infectious viral respiratory infection; vaccine usually sprayed into the nose

Initial vaccination at 6 to 9 months, followed by revaccination at 11 months; earlier and more frequent vaccination for foals of unvaccinated mares; periodic boosters (for example, every 6 to 12 months)

Other vaccines

Potomac horse fever

A bacterial disease that affects many systems, causing fever, lethargy, diarrhea, and occasionally colic or laminitis (founder); vaccination recommended in areas where disease is common

Initial vaccination at 5 to 6 months followed by revaccination in 4 weeks; booster vaccinations at 1 year and annually after that


A viral disease of the nervous system that is both fatal and transmissible to people

Initial vaccination at 6 months of age; boosters at 7 months, 1 year, and yearly after that


A viral diarrheal disease; vaccination usually restricted to farms with a recurring problem

Pregnant mares are given a 3-dose series of vaccinations before foaling; foals protected through colostrum


A bacterial infection of the throat; vaccination usually restricted to farms with a recurring problem

Initial vaccine at 4 to 6 months, followed by 2 revaccinations at 4-week intervals; boosters at 12 months and annually after that

West Nile virus

A viral infection carried by mosquitoes that results in inflammation of the nervous system, including the brain; vaccination currently recommended for horses in continental United States

Initial vaccine at 3 to 4 months, followed by revaccination 1 month later; boosters every 4 to 6 months depending on risk

Parasite Control

Animals that graze on grasses, including horses, ingest parasite eggs that are found throughout the environment. The actual parasite burden for any individual horse depends on its age, the number of horses on the same pasture, and the pasture’s size and quality. Internal parasites of horses can cause many intestinal problems, including gastrointestinal upset, diarrhea, and potentially colic.


Signs Caused by Common Parasites of Horses*




Anemia, dry coat, diarrhea, general loss of condition


Loss of condition, bowel problems, or colic when present in large numbers; migrating roundworm larvae can also injure the lungs in young horses


Horse rubs its tail; itching and irritation around anus; discharge and worms visible around anus


Loss of condition and colic from large numbers in the gut; occasional diarrhea or constipation


Mild diarrhea, colic, failure to grow or put on weight as expected

The primary intestinal parasites of horses include roundworms (both large and small strongyles), tapeworms, pinworms, and stomach bots (see Table: Signs Caused by Common Parasites of Horses*). These worms can cause damage to the digestive tract and blood loss, and interfere with absorption of essential nutrients. The greatest damage is caused by strongyles (also called redworms or bloodworms), and most parasite control programs are designed around strongyle control. Young horses typically are infested with more parasites and have more signs than older horses.

Most intestinal parasites are ingested while horses are grazing, from eggs and larvae deposited on the grass and upper layers of the soil. The tapeworm lifecycle involves small mites (specifically, orbatid mites) that feed on tapeworm eggs and thus contain tapeworm larvae. These mites live on grasses and are ingested while grazing. Stomach bots are larvae of flies. The adult fly deposits eggs on the muzzle, legs, and chest of horses during the spring. When the eggs are licked by the horse, they hatch and are ingested by the horse. The larvae attach to the wall of the stomach and remain for a period of time (usually until the following spring). The bot pupae then pass into the feces, where they hatch as adult flies.

All horses should be on a deworming program that consists of either a periodic deworming treatment (usually by administering a paste) every 4 to 8 weeks or a daily dewormer in the feed. Pasture management and good grooming practices are also very important aspects of parasite control. You may want to periodically submit samples of your horse’s feces to your veterinarian to check for the type and number of intestinal parasites.

Suggested Practices for Controlling Intestinal Parasites in Horses

  • Mow and harrow pastures frequently. This breaks up manure piles and exposes parasite eggs to the damaging effects of air and sun.

  • Periodically rotate pastures to other livestock (such as cattle or sheep) if possible.

  • In multiple-horse settings, group horses by age to maximize the efficiency of your deworming program and to reduce exposure to certain parasites.

  • Keep the number of horses per acre to a minimum.

  • Place hay and grain off the ground by using a feeder.

  • Remove yellowish bot eggs from horses’ coats quickly. A daily wipe-down with a warm, wet towel will stimulate the eggs to hatch, and the emerging larvae will dry out and die. Good grooming practices are necessary to remove the bot eggs, because they are firmly glued onto the hair.

  • Rotate among different classes of deworming drugs (not just different brand names) to decrease resistance.

  • Consult your veterinarian about an effective deworming program.

External Parasites

As outdoor animals, horses are also bothered by flies and ticks. These can cause sores and subsequent infection on the head, neck, ears, face, abdomen, and legs. Irritation from external parasites can also cause general upset, failure to grow and thrive, and decreased appetite (for example, fly “worry”). Horses should be checked regularly for ticks or signs of fly damage. Fly control includes proper manure management and stall cleanliness. Many different insecticidal salves, lotions, sprays, and rubs are available that can be used to remove ticks and decrease insect irritation and annoyance. Consult your veterinarian or extension service about an appropriate control program for your area and circumstances.

Dental Care

Equine teeth grow and wear down continuously throughout life. Unfortunately, they often wear unevenly, leading to sharp points, edges, and even hooks that need to be trimmed down, or “floated.”

Signs of Dental Problems in Horses

  • Reluctance to eat or chew

  • Dropping food during eating (also called “quidding”)

  • Hesitating to take a bit or other signs of a sore mouth

  • Bad breath from tooth decay or gum disease

Horses require a dental checkup with their veterinarian at least once per year (older horses need more frequent checkups). Your veterinarian will check inside the mouth for teeth with sharp points or edges, trimming them down with a file or nippers. As with hoof trimming, this procedure is best left to an experienced professional.


Grooming is an important part of daily maintenance for horses. Daily brushing and currying helps remove dirt and debris that can allow bacteria a place to multiply. During grooming, you can also check the overall condition of your horse’s skin and find sores, infections, bumps, or welts when they first arise. Vigorous currying is required to remove dirt, and horses generally enjoy it. Hair that is bound up (tail bags and mane braids) should be taken down every 10 to 14 days for brushing and cleaning. Horses can be bathed with equine shampoo, but baths should be kept to a minimum to avoid drying out the skin and coat. Horses should not be bathed when winter temperatures are below freezing, because horses need to be dry to resist the cold.

Hoof Care

Hoof care is an important part of the daily grooming routine. The hooves should be “picked” daily to remove manure, dirt, and stones, and checked for signs of bruising, odor, discoloration, or discharge. The shoes should also be checked for wear and tightness of the nails (see Routine Health Care of Horses : Shoes). Hoof dressings may be needed, but care should be taken to apply them appropriately. For example, water-repellent dressings can be important to keep hooves dry and healthy during wet weather. However, excessive use of emollient dressings can soften the hooves and lead to problems. Antifungal solutions should be applied every 1 to 2 weeks during winter and wet weather to prevent thrush. Your veterinarian and farrier can provide information on when and how frequently to treat your horse’s feet.

Horses’ hooves grow constantly and require trimming about every 6 weeks. Horses need to be trained to stand properly so that their hooves can be trimmed correctly and damage to the foot can be avoided. Foot trimming is best left to your farrier or veterinarian if you do not have experience with this procedure.


Horse shoes provide traction on some surfaces and help prevent wear and tear of the hooves. The need for horse shoes depends on several factors, including foot conformation and health as well as the types of surfaces the horse will travel on. Horses with tender or bruised feet require shoes for protection, as do horses working on hard or rough surfaces. Various kinds of corrective shoes are available for particular hoof or lameness problems. For example, horses with cracked hooves or splayed feet may need a barred shoe for support, while horses with other specific lameness problems may need a shoe that slows down or stabilizes the gait. Veterinarians, farriers, and trainers can provide more information on the shoes needed for any particular problem.

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