Although congenital hepatic fibrosis is more commonly seen in other species of mammals including humans, it is occasionally seen in one breed of horses, and that is the Swiss Freiberger horse. In research tests, all of the reported cases of congenital hepatic fibrosis within the breed can be directly linked back to offspring and decedents of one stallion named Wigar, thereby confirming that the condition is hereditary. Since the condition does not occur in every foal born in the line, researches have determined that it is a recessive autosomal gene that causes the condition.
Congenital hepatic fibrosis is present at birth and results in a thickening and altering of the tissues of the liver. Typically in most affected horses the condition is progressive, fatal and non-treatable with the liver enlarging significantly and large cysts developing throughout the organ. Since the liver is responsible for filtering and detoxifying the blood, when a malfunction in the liver occurs the results are very serious and usually fatal.
In both horses and humans, the congenital hepatic fibrosis is often noted with cysts on the kidneys and pancreas that are just as problematic. Often the bile ducts are blocked or constricted, resulting in lower levels of bile produced in the body. Since bile production is an important part of digestion, lack of bile in the digestive tract can cause digestion problems as well as associated health problems.
Typically foals born with congenital hepatic fibrosis will not survive for more than one year, with the average age of death at 3-7 months. Since the condition is very rapidly progressive and results in death, the symptoms may be noticed only very shortly before death occurs. In most cases the early signs were fatigue and lack of growth, jaundice or yellow coloration to the gums, eyes and mucous membranes, swelling of the abdominal area and behavior typically noted with colic. These are usually described as kicking at the stomach with the hind legs, restlessness, constant, repetitive rolling and turning the head towards the abdomen.
Treatment for congenital hepatic fibrosis is not available, so all that can be done is to keep the foal comfortable and use pain management if needed. It is critical to rule out other conditions such as digestive problems, anemia and colic that may have the same type of symptoms. It is important to note that this is a very rare condition and is not common even in the Swiss Freiberger breed. Horses that have a foal with congenital hepatic fibrosis should never be bred again and their lineage should be checked to confirm they can be traced back to the stallion Wigar. The University of Berne is involved in ongoing research on this condition and all records and information on affected foals can be provided to the study to help research this rare condition.
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