Hepatic Encephalopathy in Dogs


also see West Nile Virus

Hepatic Encephalopathy

Q:Where can I find out more about hepatic encephalopathy? I am interested in what you find regarding Trixie's (my poodle) holding her neck and head extended.

Have you seen this symptom in any patient? She can't control her head moments very well to drink or eat properly.

Thanks again.


A: Ann-

Hepatic encephalopathy is central nervous system illness caused by severe liver disease. To the best of my knowledge, liver failure is the only cause of increased ammonia levels in the bloodstream other than ingestion of ammonia containing products. The ammonia and other toxins not being processed by the liver cause the central nervous system problems. Many neurologic signs are possible, including seizures, tremors, head pressing, blindness, behavioral changes and coma. Lactulose helps because it causes ammonia to be converted to ammonium ions which are not reaborbed into the body like ammonia is. Neomycin kills ammonia producing bacteria, lessening the amount of ammonia exposure. Holding the head and neck extended occurs with meningitis and encephalitis but I could not find it listed as a sign for hepatic encephalopathy (HE). Since this is a CNS disorder I would assume it could occur with HE, though. It may also occur in some cases of intervertebral disc disorders affecting the cervical spine. Also, there are a lot of strange postures associated with peripheral vestibular syndrome and so that would have to be considered, too. Especially since it does interfere with drinking and eating in many dogs.

If the ammonia levels in the blood stream are high enough to suspect hepatic encephalopathy I would tend to think that the neurologic signs relate to that until I could rule it in or out by further lab tests. It just seems like the most likely candidate in that circumstance. Talk to your vet and find out what he or she thinks is going on and then work out a plan together to finalize the diagnosis and treatment.

Mike Richards, DVM

Hepatic Encephalopathy follow-up

Q: Trixie has been taking neomycin for almost 2 weeks. What other lab tests might she have? Also why did you question prednisone? Her symptoms haven't changed Her coordination is still poor with her ability to direct her head. Do you think anything can be done?

A: I couldn't find the original messages, so I'll have to work from memory on them, which is a pretty unreliable way to go.

Prednisone is occasionally advocated for cases of peripheral vestibular syndrome but the syndrome almost always clears up on its own, so the use of prednisone seems unnecessary. Prednisone is also used for some cases of hepatic encephalopathy, particularly cases of liver disease in which an immune mediated disorder is suspected. It is important to be sure that the liver disease is not due to infection prior to using prednisone, though. The best way to differentiate between the types of liver disease is through the use of liver biopsy. Finally there is the use of prednisone for central nervous system disorders. Most of the time it is not possible for a general veterinary practitioner to definitely diagnose a central nervous system disorder. Some CNS disorders seem to respond better to corticosteroids than to anything else so prednisone is often used even though the specific disorder is unknown and may or may not respond. I have done this many times.

If I remember correctly I am guessing that your vet is treating for hepatic encephalopathy based on the treatment but I don't think that I know that for sure. If there is another reason for this course of treatment then much of this information isn't useful.

If your vet does suspect liver disease leading to hepatic encephalopathy a liver biopsy may make it easier to produce a long-term management plan. If there is some question about whether there is a primary CNS problem in addition to a liver problem, then something like an MRI may be useful if it can be arranged. I usually suggest that my clients consider allowing us to refer them to a neurologist or internal medicine specialist when I am uncertain about a diagnosis or feel that a disease or disorder is not responding to treatment the way I think it should.

The range of diagnostic options and therapeutic options keeps increasing for pets with central nervous system disorders. MRIs were unheard of for pets until the last few years but often provide very useful information. L-deprenyl (Anipryl Rx) was recently approved for canine senility problems and there is progress in other areas, as well. I do think there is more that can be done than ever before for dogs with CNS problems. It may still take a trip to specialist but I wouldn't give up searching for an answer easily.

Mike Richards, DVM


Michael Richards, D.V.M. co-owns a small animal general veterinary practice in rural tidewater Virginia. Dr. Richards graduated from Iowa State University's College of Veterinary Medicine in 1979, and has been in private practice ever since. Dr. Richards has been the director of the PetCare Forum...