Horse Liver Problems

Horse liver problems

The liver is one of the most important organs in the horse's body that performs numerous functions, including metabolizing carbohydrates, proteins, and fats. It also breaks down and excretes many potentially toxic compounds. Because of this, the liver is susceptible to injury and disease.

What is the liver's role?

Detoxification and removal of harmful substances
The ammonia produced from protein metabolism is converted to urea and secreted.
Bile production and secretion, which breaks down fats
Destination for the products of digestion
Defends against disease, especially infections
Carbohydrate metabolism: Glucose is converted to and stored as glycogen and glycogen is broken down to glucose to help maintain blood sugar levels
Fat metabolism: Fatty acids are converted to carbohydrates and stored, and fatty acids are exported to fat stores
Protein metabolism: Almost all of the blood proteins are synthesised in the liver including albumin, fibrinogen and clotting factors
Storage of fat soluble vitamins (A, D, E, K) and vitamin B12.
Photoactive chemical production: The liver produces chemicals that protect the body from sunlight
Iron storage

Causes of liver disease

There’s a number of causes of liver disease in horses and some are more common than others – in some cases, the actual cause is difficult to decipher. Some of the more common causes include:

Ragwort contains pyrrolizidine alkaloids which are toxic to the liver. Despite its bitter taste, hungry horses will eat ragwort if there is nothing else, and typically, ragwort thrives on overgrazed pastures. The effects of ragwort toxicity aren’t usally seen until months after the horse has ingested it.
Mycotoxins that are produced by certain moulds can contaminate feed and forage and cause liver disease in horses. Weather and reduced use of fungicides has seen an increase in mycotoxin contamination over the past few years.
Too much iron in the diet can be harmful for horses and even toxic in large doses causes liver damage. There have also been examples of iron overload from water contaminated with iron.

Horse liver disease symptoms

Horses may not show any clinical signs of liver disease until approximately 70% of the liver has been damaged. Signs include:

Jaundice (yellowing of the horse’s mouth, nostrils or eye areas)
Loss of condition
Abdominal pain
Reduced blood clotting
Diarrhoea
Discoloured urine
Yawning
Head pressing
Depression
Decrease appetite or anorexia
Photosensitivity (sensitivity to UV light)

How can liver disease affect the skin?

Horses with liver disease can show symptoms of photosensitisation on the skin which looks like sunburn, and usually affects white or pink skinned areas such as the muzzle or white socks. Liver disease can causes photosensitisation when there is an overload of specific toxins in the body which the liver struggles to remove. These then circulate to the skin where they react with sunlight inside the skin cells causing cell damage, resulting in inflammation and ulceration of the skin, which may also be very itchy.

Diagnosing liver disease

As well as taking the horse’s history and performing an exam, your vet will take blood samples to show the health and performance of the liver. If there are signs of liver disease, your vet may recommend an ultrasound scan and liver biopsy which will provide further information about the cause and type of liver disease and help formulate a treatment plan and prognosis. Sometimes the cause is not always found.

In order to take a liver sample, a special long biopsy needle is passed through the skin using ultrasound guidance under sedation, with local anaesthetic and pain relief. The liver samples are then sent to the laboratory to be analysed under the microscope.

It is common for multiple horses in the herd to be affected so your Vet may recommend testing to ensure no others are affected.

Treatment for liver disease in horses

The goals for treatment of horses with liver disease or failure are to treat the underlying disease and provide supportive care to allow time for the liver to heal. Treatment of horses with signs of liver disease may be started before the cause and extent of liver damage is known. However, specific therapies depend on the causes, the presence of liver failure, whether or not the disease is long term, and the degree of liver scarring.
Early intervention gives treatment the best chance of being successful.

Feeding horses with liver disease

Feeding horses with liver disease is a careful balancing act, ensuring they receive enough protein to meet their indivdual requirements and prevent weight loss, whilst ensuring the liver does not have to work too hard to metabolise the protein.

Horses with liver disease may lose their appetite, so small, frequent meals that are palatable should be offered. Higher carbohydrate diets will aid weight gain in horses suffering weight loss, and grazing can be an excellent way to encourage a horse to eat.