2024-02-01 23:05:31
Why are liver diseases so fatal?
Liver diseases are quite common in horses. All liver damage is an accident in the body’s own chemical laboratory. This is responsible for many processes in digestion and detoxification.
How do liver problems arise in horses?
The liver is the main organ in nutrient regulation. Among other things, it converts protein compounds into urea, which is excreted in the urine. If disruptions occur, the ammonia level in the blood rises, causing damage to nerve tissue. In addition, the liver converts bilirubin I released when red blood cells break down into bilirubin II. This is released into the bile, broken down into further products in the intestine and 90 percent excreted in the feces. “An excretion of bilirubin II in the urine is pathological in horses and indicates that severe hemolysis (destruction of red blood cells) or cholestasis (bile stasis) has occurred,” says equine veterinarian Dr. Inca Kreling-Boysen.
When photosensitization occurs, the breakdown of photodynamic substances no longer works. These are chemicals that are contained in plants such as St. John’s wort. If they are not broken down, the blood washes them into other organs. In the skin they are activated by UV light, which leads to the formation of free radicals that are highly damaging to cells. This triggers inflammatory reactions. Result: itching, pain, blistering, ulceration, necrosis and peeling of entire areas of skin.
Disturbances in the breakdown of photodynamic substances and in ammonia or bilirubin metabolism occur when liver cells are inflamed. This can have a variety of reasons, for example infections with liver flukes, strongyle larvae or roundworms or even bacterial infections with salmonella or the strangles pathogen.
In Tyzzer’s disease, liver cells die. The trigger is bacteria (Clostridium piliforme). The disease occurs in suckling foals between the ages of 7 and 42 days that become infected by drinking contaminated mother’s milk or eating contaminated soil. Liver problems can also be caused by a leptospira infection, in which horses become infected through the urine of rodents.
Theiler’s disease occurs in association with recent administration of biological substances originally derived from horses (e.g. tetanus serum or plasma from another horse). The exact mechanism of formation is still unclear. There is probably an overreaction to certain parts of the plasma. More common than liver inflammation are degenerative diseases that gradually destroy the liver tissue. Such hepatoses usually arise from poisons that the horse ingests, for example from plants. Ragwort contains alkaloids that cause fatal seneziosis (Schweinsberger disease). Mold contains metabolic toxins. The body’s own metabolic toxins, such as those produced in the intestines during colic, can also damage the liver.
Little wheel
Poisonous plants in horse pastures can put a lot of strain on the liver.
Cholangiohepatitis (inflammatory change in the bile ducts) results in an infection of the bile ducts caused by ascending bacteria from the intestinal lumen. In the case of ulcers in the small intestinal mucosa, small intestinal contents can flow back into the bile ducts, which also leads to inflammation of the bile ducts. Most horses have fever, yellowish mucous membranes and signs of colic.
Hyperlipidemia (secondary metabolic disorder) threatens if horses or ponies that are too fat eat little or nothing for days. Then her body mobilizes fat reserves, flooding the liver and other organs until the cells are destroyed. About 60 to 85 percent of these patients die. Liver disease as a secondary disease: Herpes infections in foals, strangles, foal paralysis, leptospirosis, parasite infestation or blood poisoning can precede liver disease and hide behind its symptoms. For example, obstruction of the bile ducts due to gallstones, pancreatic disease, colon displacement, mold disease caused by aflatoxins or a liver tumor can sporadically lead to liver failure.
Symptoms of liver disease:
- Mostly mucous membranes yellowish in color (jaundice)
- Poor performance
- Losing weight, unwillingness to eat
- Indigestion
- Fever (body temperature over 38.1 degrees Celsius)
- Reluctance to move or compulsive urge to move
- Depression
- Neurological symptoms, such as walking in circles
- Change in behavior, such as apathy or aggressiveness
- Muscle twitches and cramps
- Chronic liver failure: bloody urine or dark-colored diarrhea (rare)
- Photosensitivity (e.g. in cases of poisoning): Extreme sensitivity to ultraviolet light
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When the liver is disturbed
- Things to know about liver diseases
- causes
- Symptoms
- Diagnose
- Treatment
- Proper prevention
- With expert knowledge from Dr. Inka Kreling-Boysen, horse veterinarian and Dr. Kathrin König, specialist veterinarian in internal medicine for horses
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