How can I recognise liver problems in my horse?

For liver disease in humans, doctors usually have a simple explanation ready: alcohol damages the organ, and extreme obesity leads to a fatty liver. In horses, toxins in particular play an important role in damaging the liver. To understand why the liver is so important and also so vulnerable, let’s first address the question: what do we actually need the liver for?

The most important functions of the liver

We give you a brief overview of the most important functions of the liver in your horse’s body:

• Involvement in fat and carbohydrate metabolism, as well as water and hormone balance 
• Building up and breaking down vital proteins 
• Formation of urea to dispose of excess, unusable proteins 
• Production of bile (necessary for fat digestion) 
• Storage of vitamins and trace elements, blood storage, glycogen storage 
• Detoxification: breakdown and excretion of metabolic products, medications and toxins
  

Culprits Toxins

Toxins are particularly challenging for the liver and therefore place a strain on it – above all, mould and its associated mycotoxins in hay, straw and oats, as well as toxins in plants such as ragwort or autumn crocus. 

You should therefore pay particular attention to ensuring that roughage and oats are free from mould and poisonous plants. Storage and feeding hygiene also play an important role. Roughage that becomes wet or damp during storage or in the hay rack can develop mould after just a few days. Chronic vitamin E deficiency also damages the liver. 

You can find more on the topic of poisonous plants in the specialist article “How can I protect my horse from poisonous plants?” featuring the 10 most important poisonous plants with descriptions, symptoms of poisoning, and ways to combat them.

Go to the specialist article “Poisonous plants” 

Drinking water, hygiene and worming 

There is also plenty you can do in the stable and on the pasture to support your horse’s liver health: 

Too much iron in the drinking water, for example, can cause liver problems and should therefore be monitored. In addition to feed buckets and troughs, water troughs must also be kept clean. Dirty tubs, basins, bird or rodent droppings near water sources, or generally contaminated drinking water can become a problem. 

Especially where horse pastures are located in wetland areas, worming against liver fluke should be carried out. The best worming strategy depends on the age of the animals, the composition of the herd (frequent changes), and also on management practices (removal of horse droppings). Worming based on a prior faecal examination can help prevent resistance as well as excessive strain on the liver.  

In general, veterinary treatments or medications can also affect liver values.

Elevated liver values

Elevated liver enzyme values (e.g. GLDH, GGT, AST) are often discovered “by chance” during a routine blood test. In many cases, the horses are otherwise fit, healthy and show no clinical abnormalities. The possible causes of elevated enzyme activity are varied. 

Alongside serious liver diseases, damage and specific problems, harmless factors may also be responsible: liver enzyme activity in healthy horses – at least for AST, GGT and GLDH – is subject to seasonal fluctuations (Gabe et al., 2018). This means that these liver parameters tend to be elevated in late summer and/or early autumn. 

Slightly elevated liver enzyme activity can also occur when the liver has performed increased metabolic work, for example after intensive training or a colic episode. If liver values are poor and the horse’s general condition is noticeably affected, these influencing factors must be checked and a gentle ration should be fed. 

If the liver is seriously damaged, its functions are impaired. In addition to adjusting nutrient intake, everything that places additional strain on the liver should then be avoided.