Clinical diagnosis
In order to treat liver damage,the cause of the hepatitis must first be found. Often diagnosis is complicated and may require blood analysis to check liver enzymes and metabolite levels.
A specific blood test for liver damage is called the ‘BSP clearance test’ and is a more reliable indicator of liver disease than the liver enzyme test, which can give misleading information about the true severity of the hepatitis.
Once liver disease is diagnosed, a needle biopsy of the liver is often vital to establish the likely cause.
This involves a long biopsy needle being introduced through the right side of the chest and is undertaken with some caution, especially if the horse already has coagulation (clotting) problems or might have abscesses, which could be accidentally burst by the needle.
Ultrasound pictures will help guide the needle. A liver biopsy is the best diagnostic tool available and owners should not be resistant if a vet suggests one. It is not very invasive and not too painful.
Treating liver failure
Standard treatment of liver failure symptoms are well worth attempting in many cases because the liver usually has a remarkable ability to regenerate and replace damaged tissue.
Glucose may be given by drip to provide energy, and mineral oil by mouth to reduce the uptake of toxins from the gut. Oral doses of antibiotics, such as neomycin or lactulose, can also be used to reducegut toxin and ammonia production.
Horses which are behaviourally disturbed as a result of liver damage can be sedated if necessary. The best course of action for photosensitive horses is to apply sun block to affected areas and keep them out of bright sunlight.
Overall, liver failure cases that develop rapidly are more likely to respond to treatment and cases that have a slow onset usually indicate a more serious hepatitis. When symptoms are severe, there is real danger that treatment will be unsuccessful.
Taking precautions
It can be difficult to prevent many causes of hepatitis, but the following steps are vital:
- Protect your horse from ragwort poisoning, which often occurs when the weed is dried in the preparation of hay. Fresh ragwort is not as readily eaten because it tastes foul, but dried ragwort is quite palatable, so check hay carefully.
It is useful to remember that signs of ragwort poisoning may develop very slowly, perhaps not showing until a year after the consumption of the dried plant.
Make every effort to pull up all ragwort plants in grazed paddocks and especially those used for hay. This also applies tolupins, which occasionally occur in fields.
- Check your food storage. Toxins are found in grain stored in warm, wet conditions. The grain develops fungal growths which produce “aflatoxins” that damage the liver.
- Pregnant mares should be vaccinated for tetanus and must not given be equine serum containing tetanus antitoxin since this carries a small risk of producing serum hepatitis – rare in the UK, but more common in the US.
- Overweight ponies, especially pregnant mares, should not be starved or stressed suddenly, as this can induce hyperlipaemia, which in turn may induce liver failure.
There are no vaccines available for bacterial hepatitis, but equine herpes virus can be vaccinated against. This vaccine is useful in pregnant mares, not only to prevent abortions but also to reduce the risk of herpes infected foals developing liver failure.
It also protects against respiratory disease caused by the equine herpes virus.
Read more about ragwort poisoning:
