The Most Common Horse Diseases

By Josie F. Turner, Journalist specialized in Animal Welfare. August 24, 2020
The Most Common Horse Diseases

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Without doubt, one of the most important animals to contribute to human development is the horse. Evidence of their importance can be found in the fact that veterinary medicine arose almost exclusively to treat their ailments. This is why we know much about equine diseases, even if you will have to see a specialist veterinarian to treat them.

In this AnimalWised article, we look at the most common horse diseases. We look at the equine illnesses which a horse is most likely to contract, as well as highlight those which can be fatal in acute circumstances.

You may also be interested in: The Most Common Diseases in Cats

The most common diseases in horses

Horses have strong constitutions, but they can suffer from disease as with any animal. Some of the most common are:

  1. Equine colic
  2. Horse tetanus
  3. Equine influenza (or horse flu)
  4. Equine babesiosis or piroplasmosis

We look into each of these most common horse diseases in more detail below. If you want to know more about how to recognize symptoms of disease in horses, take a look at our article on horse body language and communication.

1. Equine colic

Colic is not a disease limited to horses, but it is both one of the most common in equines and potentially fatal. However, it is also not technically correct to call colic a specific disease. Rather, it refers to a group of diseases which all result in spasmodic pain in the horse's abdomen. Since there are a range of diseases which lead to this symptom, its treatment will depend on the underlying cause.

Since the pain is chronic, the horse will often have great difficulty sleeping. A horse suffering from colic will also generally display the following symptoms:

  • Sweating
  • Nervousness
  • Uncontrolled movements (including self-injury)
  • Rolling over on itself
  • Dehydration
  • Constipation/diarrhea
  • Sitting (helps relieve pain due to accumulation of gases)

Causes of equine colic are too numerous to mention all here. They range from impaction of the large intestine, constipation, presence of foreign bodies, parasites and more. However, there are certain guidelines caretakers need to follow if their horse has equine colic. These include:

  • Feed the horse little by little over a period of 16 hours. It is the time these herbivores spend grazing in nature. A horse that remains in a box and is fed morning and night has a greater chance of suffering digestive disorders.
  • Use quality feed, avoiding excessive amounts of straw, and allow frequent access to water.
  • Allow the horse to perform light exercise several times daily to promote intestinal transit.
  • Install feeders in an elevated trough if horses are confined.
  • Offer distractions to prevent aerophagia (swallowing air) common in horses suffering from boredom. In this case we can also see animals which perform cribbing. Cribbing is when the horse bites on to their door, fence or other part of their environment and then sucks in air.

Treatment of colic in horses

If your horse os suffering from colic, the most important thing to do is to take them to the veterinarian. They will perform the correct diagnostic tests to determine the underlying cause and begin the correct course of treatment. However, treatment of colic as a symptom will likely involve:

  • Relieve pain with spasmolytics (buscopan) and NSAIDs (non-steroidal anti-inflammatory drugs such as flunixin meglumine).
  • Rehydrate and/or lubricate the gastrointestinal tract with paraffin. They may use a nasogastric tube to access the digestive system.
  • Sedate if the animal is in the self-harm phase.
  • Antibiotics may be required if the problem is due to a blockage and there is excess fermentation of the ingested material. In this case, microorganisms are released into the blood that can cause infections.
The Most Common Horse Diseases - 1. Equine colic

2. Horse tetanus

One of the most common diseases in horses, it is the result of the bacterium Clostridium tetani. This is an anaerobic bacterium as it can live without oxygen. It is found in soil, especially in soil rich in organic matter (such as manure). Horses suffer small wounds or abrasions through various types of trauma. For example, wounds caused by head-butting, stepping on sharp material, etc. Bacteria enters the body via such wounds and an infection occurs.

Although the incubation time is variable, after an average of about 8 days, we can see the typical symptoms of this disease. One of the most characteristic symptoms of equine tetanus is a series of involuntary and chronic muscle contractions. These are known as tetanic contractions due to the disease. Other symptoms include:

  • Mandibular lockjaw: tightly clenched jaws, which are unable to open.
  • Hyperextension of muscles: this usually occurs in the legs, causing them to become rigid and inflexible. Serious muscular damage can occur if theses muscles are moved.
  • Expression called Risus sardonicus: also known as the rictus grin, this is more common in dogs than horses. Those which do show it have wide eyes and a retraction of the corners of their lips.

How does the bacterium Clostridium tetani cause this ?

It produces two toxins that act of the central nervous system of the horse. The closer the entry point of the bacteria (wound) is to the central nervous system (brain), the more aggressive is the presentation of this disease and the less time it takes to develop.

Can you cure horse tetanus?

If it is reached before the toxins paralyze the respiratory muscles (diaphragm, intercostal muscles, etc.), tetanus antitoxin serum and penicillin can be administered. Support therapy will also be provided. This will take the form of fluid therapy, lowering their temperature, sedation (if necessary) and mechanical ventilation if there is respiratory paralysis.

However, it is important to know that the majority of horse tetanus cases are fatal. The sooner the tetanus is treated, the better the prognosis. However, we often don't see symptoms of equine tetanus until the disease has progressed.

Can we prevent horse tetanus?

Yes, through the relevant vaccination with the frequency indicated by the veterinarian. We must also always disinfect any wounds we see in the horse. We will have to use hydrogen peroxide in each injury we observe to inactivate the responsible bacteria. This is especially so in parts of the body which have contact with the ground.

The Most Common Horse Diseases - 2. Horse tetanus

3. Equine influenza (or horse flu)

Equine influenza is similar to that suffered by humans in that it is caused by a virus that affects the upper respiratory tract. If complications arise, it can affect the lower respiratory tract also, potentially resulting in death. It is transmitted through the air via sneezing and nasal secretions.

In specimens which contract horse flu, we can see a mild case with the symptoms of a runny nose, coughing and/or conjunctivitis. They should recover within a few days. This usually happens when the horse has suffered the disease before since they will retain some immunity. However, the virus can return, especially when the weather is cold. If the horse is otherwise sick, has been poorly fed, is very young or has an in-any-way compromised immune system, the consequences can be fatal.

The most common symptoms of equine flu are the following:

  • Thick nasal discharge
  • Conjunctivitis
  • Loss of appetite
  • Recurrent high fever

If it is not treated in time, equine influenza can lead to:

  • Pneumonia
  • Chronic obstructive pulmonary disease
  • Bronchitis
  • Death

Treatment of horse flu

If the animal is partially immunized, and the presentation is mild, the veterinarian can simply prescribe a mucolytic to thin the mucus. One common example is bromhexine. The horse will need to be quarantined away from other animals for a few days. A quality diet to support their immune system helps until the horse is able to repel the virus attack.

If the picture becomes complicated, it may be necessary to use specific antibiotics of the respiratory system, and supportive therapies in very debilitated animals.

Remember that mixing horses from different areas without knowing anything about their history can lead to the appearance of an outbreak of equine influenza. If we introduce a partially immunized animal among young horses, we can have an acute outbreak that is difficult to tackle. This will usually have a high morbidity rate.

Prevention of horse flu

To prevent this common disease in horses, annual vaccination is required, This is especially important during the cold season. We will also need to avoid mixing animals from different sources without knowing their health status. This can happen when wild horses are brought in to be broken with domestic horses. There is a horse vaccine that combines protection against equine tetanus and influenza.

The Most Common Horse Diseases - 3. Equine influenza (or horse flu)

4. Equine babesiosis or piroplasmosis

Another of the most frequent diseases in horses is also relatively common in dogs, cows and other domestic animals. It is caused by a protozoan known as Babesia equi. It is believed to be the second most common blood parasite in mammals.

Babesia is transmitted by ticks, one of the most common types of horse parasites. It is their multiplication inside the horse's red blood cells produce all the symptoms of the disease. Said symptoms of equine babesiosis include:

  • Anemia (pale mucous membranes as babesia break down red blood cells)
  • Fever
  • Cognac colored urine
  • Anorexia
  • Prostration and sudden death in very acute cases

Babesiosis (or prioplasmosis) transferred via ticks is a common reason why your horse isn't gaining any weight.

Can babesiosis in horse be treated?

If we detect the presence of ticks in the horse and/or environment, and we notice our horse behave abnormally, the veterinarian will likely administer an injection of imidocarb. This is an antiprotozoal agent and is usually given in a single intramuscular dose. Administration does sometimes need to be repeated after a few hours.

The ideal is to detect babesia in blood through a blood smear, but it is not always possible in the field. Imidocarb is often administered without a blood test since early application will improve prognosis.

Can babesiosis in horses be prevented?

The only way to prevent this pathology is to prevent the horse from being bitten by ticks. This is very complicated. We can apply permethrin products weekly on the horse to prevent ticks from being attracted to them. However, they do not last long.

The area where the horse lives (their box or stable) must also be disinfected weekly. If the animal is free to roam in the field, they should not have access to humid areas with thick foliage. Certain areas in various countries have greater risk of infection with this parasite. However, it is something with a worldwide distribution, so all horse caregivers need to be careful.

Some horses are more prone to certain diseases than others. This is due to genetic inheritance. For these diseases, we need to look at the different horse types and breeds individually. This is something you can do with our video on Arabian horses below:

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

If you want to read similar articles to The Most Common Horse Diseases, we recommend you visit our Prevention category.

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