Question: My horse was diagnosed with liver disease. It was a shock to me. I had heard liver disease was rare in horses and I’ve never come across it in 20-plus years . We fought hard to save him for a whole year before he succumbed to it. I work at a small animal hospital and deal with liver failure/disease frequently. But I’ve learned it is not the same for horses.
In researching my horse’s problem, I found that sudden, frequent hoof abscesses can be an early sign of liver failure. My horse had just that. My horse’s veterinarian had not heard that though so didn’t connect the dots. Oddly enough, one of my veterinary coworkers had a horse die from liver failure due to an abundance of clover. I’d like to know more. Is it really that rare and do the hoof abscesses point to liver disease?
Understanding liver disease
Answer: Those are all great questions. Liver disease in general is probably under-appreciated in horses. Part of the reason is because we have historically had a pretty short list of possible causes of liver disease and ways to treat it. In mature horses, the most common causes are presumed to be toxic plants, bacterial infection, fatty liver and idiopathic (meaning we don’t know the cause). More recently, we have discovered two liver viruses that affect horses. In contrast to small animals, we don’t see many drug toxicities and congenital defects. Likewise, horses are much less prone to fatty liver than cats, for example.
Additionally, while liver disease or injury is quite common, liver failure is rare. I expect that, with the new virus discoveries, there will be a period of increased recognition of liver disease, and that will hopefully bring along some advances in diagnostics and treatments.
Causes of liver failure
While liver failure might be associated with increased risk of hoof abscesses or other infections, it isn’t a common explanation for those type infections. This is why it wasn’t the first thing your veterinarian considered. The liver contains many immune cells, produces key proteins for immune functions and prevents gut bacteria from reaching the general bloodstream.
In other species, there is clear evidence that liver failure causes immunocompromise, increased risk of bacteremia (bacteria in the blood) and increased risk of bacterial infections in multiple organs. However, liver disease isn’t the only cause of immune compromise in horses and conditions like PPID (pituitary pars intermedia dysfunction or Cushing’s disease) are more common.
When to investigate
In any horse with increased unexplained infections, it is a good idea to have a full health exam done. This should include general bloodwork and endocrine testing. More common signs of liver disease are weight loss, poor appetite, yellowing of the sclera, nose or gums, sunburn on white markings and even unusual behavior (playing in the water bucket, yawning a lot, unsteady gait, dullness, pressing the head into the wall, circling or walking compulsively).
Joy Tomlinson, DVM DACVIM PhD
Baker Institute for Animal Health
Cornell University College of Veterinary Medicine
Ithaca, New York
Joy Tomlinson, DVM, DACVIM (LAIM), PhD, is a Senior Research Associate studying the immunopathogenesis and epidemiology of equine hepatitis viruses at the Baker Institute for Animal Health at Cornell University College of Veterinary Medicine. Tomlinson also has a dual appointment as a Visiting Lecturer in the Cornell University Equine Nemo Farm Animal Hospital.