How can I tell if my horse has a liver problem?

Since the liver has a very high regenerative capacity and functional reserve capacity, most liver diseases in horses initially progress without visible signs of disease and are only diagnosed at an advanced stage.

INHALT
Anatomy and function of the liver Cause Symptoms Diagnosis Treatment Forecast Prophylaxis
Anatomy and function of the liver

The liver is the largest gland in the horse. It is located in the abdominal cavity between the diaphragm, stomach, and large intestine and plays a central role in metabolism. It is responsible for bile production, the production of amino acids and blood proteins, the metabolism of food components, and the breakdown and excretion of toxins, metabolic waste products, and medications.

Diagram of the abdominal organs of a horse
1 Esophagus | 2 Liver | 3 Stomach | 4 Small intestine | 5 Appendix | 6 Large intestine
Cause

Liver dysfunction can have many different causes, which are not always easy to identify. Certain plant toxins (ragwort, autumn crocus) or chemical toxins (pesticides or insecticides) and molds that are ingested by animals through contaminated feed or water are among the most common causes of primary liver damage. Liver disease can also be caused by parasites, infections, tumors, medications, or disorders of the immune system. In many cases, however, liver damage is only a consequence or accompanying symptom of other underlying diseases such as infectious anemia, foal paralysis, or blood poisoning.

Symptoms

As already described, liver disease remains asymptomatic for a long time. Only when 70 to 80% of the liver tissue is damaged do clear signs of the disease appear. Given the diverse functions of the liver, the clinical symptoms can vary greatly depending on the type and extent of the damage.

A characteristic, but not always present, symptom of liver damage is jaundice, colloquially known as yellowing of the skin. The increased concentration of bilirubin, a breakdown product of the red blood pigment hemoglobin, in the blood causes yellowing of the skin, mucous membranes, and the conjunctiva and sclera (white of the eye). Functional disorders or impairments of the liver often initially manifest themselves as rather unspecific symptoms such as reduced performance, loss of appetite, fatigue, weight loss, diarrhea, constipation, or colic. Less common are generalized bleeding, increased photosensitivity (an abnormal reaction of the skin to ultraviolet light), or fluid accumulation such as ascites (fluid in the abdomen) and edema.

Hepatoencephalic syndrome or hepatic encephalopathy occurs when the liver is so severely damaged that it can no longer break down the toxins produced in the intestines during protein breakdown. The toxins accumulate in the blood and enter the central nervous system via the circulatory system, where ammonia in particular can cause various neurological symptoms (disorientation, lethargy, ataxia, head pressing, constant yawning, compulsive movements) and, in the worst case, a so-called hepatic coma.

If you notice one or more of the signs described above in your pet, or if you suspect that your pet may be suffering from liver disease, please take it to a veterinarian as soon as possible, even if the symptoms seem harmless.

Diagnosis

The veterinarian will thoroughly examine your sick horse and ask you for a detailed preliminary report, especially regarding the horse's husbandry and feeding. Information about pasture management, any fertilizers and poisonous plants, the composition and assessment of the feed, and any medication administered are particularly important for the veterinarian.

However, further examinations are essential in order to make an accurate diagnosis. A blood test is used to determine the liver enzymes and bile acids in the blood, the levels of which provide initial indications of liver disease but do not allow an exact diagnosis to be made. Conversely, a normal blood count is no guarantee of a healthy liver, as functional deficiencies can be compensated for by the liver tissue to a certain extent.

Even if only part of the liver tissue and bile ducts can be visualized, ultrasound examination of the liver is one of the most important diagnostic tools in horses, as most changes affect the entire liver tissue. Ultrasound can be used to assess both the size and structure of the liver tissue.

Ultrasound examination also serves as an aid in taking a tissue sample from the liver (liver biopsy). Using a long biopsy needle and under ultrasound guidance, altered tissue can be removed and then examined in the laboratory. The different cells provide information about the type and cause of the liver disease.

Treatment

The primary goal in treating liver disease is to eliminate the causative factors, if known. Due to the liver's high regenerative capacity, most therapeutic measures are limited to protecting and supporting the organ. This treatment, known as "liver protection therapy," may include anti-inflammatory and ammonia-reducing medications as well as vitamins and herbal products to support liver regeneration.

An important accompanying measure in the treatment of liver disease is feed management. Rations for horses with liver disease should be low in protein and high in carbohydrates. Concentrated feed can therefore be almost completely eliminated, while the patient should always have sufficient roughage available.

Forecast

Thanks to the liver's ability to regenerate, most liver diseases have a good prognosis if they are detected and treated in time. The extremely rare tumorous diseases of the liver have a poor prognosis.

Prophylaxis

To prevent liver disease, it is essential to ensure optimal feeding and husbandry management. It is particularly important that the ration is not too rich in protein and fat and, in particular, that the roughage is free of poisonous plants, mold, or other harmful substances. Regular veterinary checks and blood tests play a key role in ensuring that even minor changes are detected at an early stage, their causes identified, and, if necessary, remedied.