Horses are large, beautiful animals that people often own either as work animals or for casual riding. People who own horses often do so with a great sense of pride in having such a majestic creature. A part of this pride of ownership should come from providing horses with the care that they need to remain healthy. To successfully do that, it is crucial that horse owners and keepers recognize that there are numerous threats that can make a horse ill and even cause its death. Illness and disease can strike a horse without warning, and some can be fatal within a relatively short period of time. In addition to knowing of these illnesses, people must also be able to spot the signs that something is wrong, know what to do to provide immediate help to the animal, and know when to contact a vet for assistance. While there are many diseases that affect horses, some of the more common concerns include colic, equine arthritis, laminitis, West Nile Virus, equine encephalomyelitis, Potomac horse fever, azoturia, and botulism.
In horses, colic is a series of conditions that cause varying degrees of abdominal pain. It is a digestive disorder that is very common in horses. The severity of colic varies from mild to severe to the point of euthanization. The most common types of colic include spasmodic and impact colic. Spasmodic colic is caused by excessive gas that causes pain when it stretches the gut. Impact colic occurs when the gut is stretched due to a buildup of feed due to dryness or coarseness of the feed or some form of obstruction. Pain occurs when the stretched gut wall contracts in an attempt to push out the obstruction. Horses suffering from colic pain may bite at their flank or belly or make kicking motions toward it. In some cases, an animal may attempt to lie down or roll on the ground. Other symptoms of colic include anxiety, lack of appetite or defecation, playing in water, an elevated pulse rate, and/or seeming to play in their water bucket yet not drinking from it.
Degenerative Joint Disease (DJD)
Degenerative joint disease is a chronic and progressive type of arthritis. It is often called osteoarthritis and results in deterioration of the cartilage in the joints. The degree of joint damage associated with degenerative joint disease often leads to lameness. There is no cure for DJD, or osteoarthritis; however, affected animals may benefit from physical therapy or treatments for stiffness and pain in the joints using corticosteroids or NSAIDs.
Equine arthritis is a term that is given to swelling, redness, and pain (inflammation) of the joints. The inflammation typically hinders the animal’s ability to move comfortably and freely. There are several different types of arthritis that can affect horses, including osteoarthritis. These conditions include traumatic arthritis, septic arthritis, subchondral cystic lesions, and osteochondritis dissecans. Anti-inflammatory drugs can be helpful in the treatment of arthritis in aging horses, as may certain types of physical therapy.
Laminitis is an inflammation of the laminae in horse’s hooves. The tissue is a type of connective tissue that attaches the coffin bone to the hoof wall. It is a very serious condition that can result in lameness in horses and may even lead to its eventual euthanasia. Typically, the condition affects the front hooves, but it can affect all four. The condition progresses through four stages, which include the developmental stage, acute, subacute, and chronic. Obesity, high fevers, and working on hard surfaces are considered to be risk factors.
Mosquitoes carry the viruses that cause equine encephalomyelitis, which is also called sleeping sickness, a disease that affects the central nervous system. There are several strains of the virus, such as the St. Louis strain, the Western strain, and the Eastern strain. Horse owners can prevent it by vaccinating their horses and controlling mosquitoes in the area. Signs that a horse has this condition include depression, nervousness, fever, lack of coordination, poor reflexes, a drooping lower lip, and grinding of the teeth. Other severe symptoms involve the animal lying on its side while bicycling its legs, an inability to swallow, paralysis, and even death.
West Nile Virus
The West Nile Virus is a disease that horses get from being bitten by an infected mosquito. The virus can lead to inflammation of the brain, which is called encephalitis. Animals affected by West Nile Virus may also develop meningitis. Symptoms of a horse that is infected by West Nile include fever, impaired vision, convulsions, head pressing, difficulty swallowing, and paralysis or weakness of the hind limbs. Ideally, horse owners will want to vaccinate their horses to prevent infection and reduce areas that can attract mosquitoes, such as standing water.
Potomac Horse Fever
Potomac horse fever is a bacterial infection caused by an organism called Neorickettsia risticii. This organism is found in aquatic insects and freshwater snails. Mayflies, damselflies, and dragonflies are an example of where the N. risticii organism can be found. It is a condition that affects the tissue and blood and occurs most frequently in the spring, summer, and fall months. Most cases occur in July, August, and September. A horse that has this condition displays signs such as diarrhea, fever, depression, and a decrease in gut sounds.
Azoturia is a condition that affects a horse’s muscles. It can cause problems such as cramping and stiffness. Often, this condition develops after a horse has been overexerted and is left to rest for a day without any changes to its diet. Azoturia has several names associated with it, including “Monday morning disease” and “tying up.” In addition to the cramps and stiffness, a horse may stagger, have an elevated temperature, sweat, and have an elevated heart rate. The pain may be so bad that standing may be difficult or impossible for some horses. To treat this condition, seek the assistance of a vet and allow the animal to rest. Typically, the vet will give anti-inflammatories and muscle relaxants and require the muscles to be massaged. Recovery may take as long as eight weeks. People can prevent azoturia from occurring by adjusting the feed on days of rest and properly warming and cooling down their horses.
There are three types of botulism that affects horses: botulism from spoiled hay that is either wet or dry, botulism from hay that is contaminated with the carcass of an animal, or botulism from a wound. Most often, horses that suffer from equine botulism get it from the hay that they eat. It is important for those caring for horses to recognize the signs of botulism, as an untreated horse is at high risk of dying or needing to be euthanized. The signs or symptoms associated with botulism include muscle weakness in the form of a weak tongue, weak eyelid tone, flaccid paralysis, and dysphagia. A horse that has come in contact with the toxin from contaminated feed may show edema of the face and muzzle, trembling of the muscles, and an inability to hold up its head. Treatment involves an antiserum.
- Colic: Public Enemy #1
- Overview of Colic in Horses
- Equine Colic: Causes, Symptoms, Treatment, and Prevention
- Equine Arthritis, Osteoarthritis, or Degenerative Joint Disease
- The Aging Horse
- Common Infectious Horse Diseases
- Equine Laminitis
- Equine Laminitis Fact Sheet
- Control of Infectious Diseases of Horses
- Control of Common Infectious Horse Diseases
- West Nile Guidelines for Horses
- What Horse Owners Should Know About West Nile Virus
- Tying Up in Horses
- A Perfect Killer (PDF)