The liver has a vital role to play in almost every bodily function. It is the largest single organ in the body being approximately 1% of bodyweight.
The liver has many functions, including:
1. Digestion
2. Detoxification - poisons absorbed from the gut are removed from the blood before they can affect the rest of the body
3. Manufacturing proteins, clotting factors and vitamins.
4. Storage of vitamins, minerals and glucose Liver disease is probably more common then we think as signs of liver disease can be subtle and easily missed. Only when more more then 75% of the liver is damaged do we see obvious signs of liver failure and by this stage it can be to late for treatment to be effective. This means that any horse with unexplained subtle clinical signs (see below) or with very bad sunburn or non-responding mud fever should be investigated for liver disease.
Mild signs of liver disease:
1. Weight loss
2 Lethargy
3. Reduced appetite
4 Poor or reduced performance.
5 Poor coat quality
6 Photosensitisation (excessive sunburn arising from mild exposure to sun and restricted to white areas, this can mimic bad mud-fever on white limbs)
7 Behavioural changes
8 Repeated yawning
9 Diarrhoea (Cow pat like) or constipation)
10 Jaundice
11 Colic
Severe signs of liver failure:
1 Severe debility
2 Head pressing
3 Tendency to bleed without clotting
4 Fluid accumulation (Swelling of legs and head)
Central nervous signs including: depression, mania, seizures, bizarre behaviour, coma and death.
How do the vet diagnose liver disease? When the liver cells are damaged, liver enzymes are released into the bloodstream. A blood test will show increases in these liver enzymes and tell them that damage as occurred. Bile acids and bilirubin are produced and broken down by the liver. However, different types of liver disease will cause the same blood picture so further test are needed.
Ultrasound scanning and liver biopsy is a very safe and simple procedure. The hair on the skin over the liver is clipped, the liver is scanned and a biopsy is taken sterilely using ultrasound guidance with a biopsy needle. This is repeated and the very thin slithers of liver collected are sent to the lab.
Liver biopsy is the gold standard procedure and provides information about the cause of liver damage, what treatment will be effective and prognosis.
What causes liver disease?
Liver infections can be transient, but may be serious or even life threatening. Both viral and bacterial infection commonly develop. The most common cause of serious liver damage in the UK is ragwort poisoning. This is an insidious killer.
Each tiny amount of the poison absorbed from the gut causes corresponding additional amount of damage. There is no such thing as a safe amount of ragwort!
The damage is usually irreversible because the poison destroys the liver substance so the liver cannot regenerate or repair itself in the normal way.
How can we treat liver disease?
Liver biopsy gives the most information on how to treat a horse with liver disease.
The cell types present within the liver biopsy will tell you if there has been infection and whether antibiotics are needed or if there has been inflammation and corticosteroids therapy may be appropriate.
Liver biopsy will not always tell us what caused the damage, but it is invaluable in telling us how best to treat it and what the long term prognosis is.
Repeat blood test and sometimes repeat biopsies are used to assess response to treatment.
Horses with liver disease need special dietary management. The vet will help to formulate a diet for each case. They will supplement the diet of horses with liver disease with B vitamins as these produced and stored by the liver and also avoid high protein diets as they give the liver extra work.
It is recommend feeding a milk thistle supplement.
Milk thistle has been shown to help protect humans at risk of liver damage and is thought to be beneficial in horses with liver disease.
Scarsdale Equine health feature.