What are Hepatitis?
Hepatitis is the swelling of the liver. This can be caused by a number of things, including diet, toxins, and bacterial infections.Three viruses that may have an adverse effect on the equine liver have been discovered and identified in the last decade, and one of them is the same virus that causes Hepatitis C in the human population. Symptoms of hepatitis should be evaluated by a veterinary professional as soon as possible to prevent any further damage and in order to create a treatment plan.
When the liver of an animal is swollen, this is referred to as hepatitis. Hepatitis can have many causes, including the ingestion of toxic plants and viral infection.
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Symptoms of Hepatitis in Horses
The outward symptoms of liver disease are often vague until the disease has already damaged 60-80% of the liver. Symptoms that indicate trouble with the liver include:
- Abdominal pain
- Abnormal blood clotting
- Aimless wandering
- Altered gait
- General malaise
- Jaundice (a yellow tinge of the eyes and mucous membranes)
- Loss of appetite
- Poor performance
- Swollen abdomen and liver
- Swollen limbs
- Weight loss
Three types of viruses that may have a link to hepatitis in horses have recently been discovered:
- Theiler's Disease-Associated Virus (TDAV) - As indicated by its name, this pegivirus is the cause of Theiler’s disease, a disease that attacks the health of the liver after vaccinations using equine-origin anti-serum
- Non-primate Hepacivirus (NPHV) - This is the the same virus as the virus that causes Hepatitis C in the human population, but has only recently been discovered in dogs and horses
- Equine Pegivirus (EPgV) - This virus was the most recently discovered of the three, and although it is not known to cause clinical signs in horses, there was a correspondence between this virus and elevated enzyme levels
Causes of Hepatitis in Horses
This is the obstruction and inflammation of the biliary system, and in large animals is usually resulting from a parasitic infection. Normal clotting factors and ammonia levels are usually maintained with this condition.
Several types of plants can be toxic to the liver and cause it to swell. These can include plants that contain pyrrolizidine alkaloids like ragwort, or plants like the alsike clover, that can cause inflammation of the liver to the point that the liver may reach up to 5% of a horse’s weight. Considering that horses generally weigh between 800 pounds and 2,200 pounds, 5% can be a considerable amount. Mycotoxins and aflatoxins, poisonous molds, can induce and inflamed liver.
Three viruses linked to liver inflammation have been located since 2010, Theiler’s Disease-Associated Virus (TDAV), Non-primate Hepacivirus (NPHV), and Equine Pegivirus.
Diagnosis of Hepatitis in Horses
Because clinical signs of hepatitis can be variable depending on the amount of time since the damage started and the amount of damage that has occurred, other than jaundice, they may not be as helpful in diagnosis as the standard blood tests are. Although the swelling of the liver is occasionally palpable during the physical examination, the type and extent of the damage will require more specialized imaging technology. Abdominal ultrasonography can generally provide a clear picture of the physical state of the liver.
In order to get the clearest ultrasound image possible it is crucial that the transducer has as little air trapped between it and the animal’s skin as possible, and that the patient stands as still as possible. A patch of hair is usually shaved off to maximize the connection between the transducers and the skin, and chemical or physical restraint may be required to protect the safety of the horse's handlers, the equipment, and the horse itself. Standard blood tests should help to confirm the decreased function as well due to increased enzymes such as alkaline phosphates (ALP), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), and bilirubin.
Treatment of Hepatitis in Horses
Treatment of hepatitis is somewhat dependent on the cause of the disease. For instance, in the case of bacterial cholangiohepatitis, antibacterial medications will need to be prescribed, and if blood tests reveal a toxin, the source of the poison will need to be found and eliminated from the horse's environment. Corticosteroids may be useful in some circumstances and vitamin supplementation, including folic acid, will most likely be added to the diet. In most cases, supportive treatment will begin as soon as possible to help the horse’s body overcome the underlying disorder.
Your veterinarian may recommend keeping the patient calm and restricted to a well-ventilated stable during the healing process. Depending on the results of the previous liver tests or biopsies, serum ammonia levels may need to be reduced, and a specialized diet will be recommended. The diet during treatment may vary depending on the type of disorder, the severity of the damage, and the willingness of the horse to eat. Usually, four to six smaller meals per day are recommended during recovery.
Recovery of Hepatitis in Horses
Horses who recover from hepatitis should have their daily diet re-evaluated. Reducing the amount of ammonia in the system is the primary aim of the new diet. Lowering the protein levels in the diet will lessen the amount of ammonia produced in the intestines and mature horses in light work should only require about 8% of their food be made up of protein. Dividing up the meals into several small meals is also beneficial as this will reduce the load of ammonia that the liver is responsible for detoxifying. It is also advantageous to decrease the amount of fat in the diet in order to prevent fat deposits in the liver.