Causes and Treatment of Canine Liver Disease
I’ve got nothing but love and respect for the liver. This amazing, multitasking organ performs a vast array of functions essential for survival. Background information about these functions along with the symptoms and diagnostic testing associated with liver disease, are all found in the first portion of this article. Below is the rest of the story.
Causes of liver disease
More than two hands are needed to count the number of diseases that can affect the canine liver. Listed below are those that are most commonly diagnosed. As you read through them, it will help you to know that:
Hepa or hepato = liver
pathy = disease of
itis = inflammation (keep in mind that things other than infection can cause inflammation)
cholangio = bile vessel (vessels within the liver that are responsible for transporting bile to the gall bladder)
Liver shunt (portosystemic shunt)
As mentioned in the first portion of this article, blood from the abdominal organs flows into the liver via the portal vein before returning to the heart. Shunting is the term used when blood bypasses the liver and flows directly to the heart by way of other blood vessels (shunts). This is problematic for a few different reasons. None of the important products manufactured within the liver (protein, blood clotting factors, glucose, cholesterol, etc.) can be distributed into the bloodstream for transport throughout the body. Secondly, there isn’t an opportunity for substances such as vitamins and minerals to be delivered to the liver for storage. Lastly, the liver doesn’t have access to “detoxing” the blood. Substances normally removed by the liver accumulate in the bloodstream and cause the neurological symptoms commonly associated with liver shunts.
Most liver shunts arise during fetal development and are congenital abnormalities (birth defects). Such shunts most commonly occur in small breeds. Maltese, Schnauzers, Shih Tzus, Dachshunds, Poodles, and Yorkshire Terriers are at the top of the list in terms of frequency.
Shunts can also develop in response to liver disease severe enough to markedly increase pressure within the portal vein. Surgery is the treatment of choice for dogs with single congenital shunts, and is often curative. For dogs with multiple and more complex shunts, medical therapy is the treatment of choice and often provides significant benefit in the short term.
Given that the liver is the garbage disposal of the body, it’s no wonder that it’s often the first organ to take a hit when a dog eats or is exposed to something toxic. The classic example is the toxicity caused by ingestion of poisonous mushrooms, an all too common cause of life-ending liver failure. Many toxins affecting the liver are medically treatable and transient. If the damage isn’t devastating, the liver can repair and regenerate remarkably well.
Chronic active hepatitis
This is a frustrating disease in that the actual underlying cause is poorly understood. A liver biopsy reveals chronic smoldering inflammation without an identifiable infectious agent. Left unchecked, this inflammation can result in scar tissue (cirrhosis) within the liver. Treatment is aimed at reducing inflammation and protecting the health of the hepatocytes (liver cells).
Bacterial infection is the most common cause of infectious hepatitis. Infections can arise from gut bacteria (remember, all blood coming from the intestines passes through the liver before returning to the heart) or from a systemic bacterial infection such as leptospirosis. Adenovirus is a viral cause of infectious hepatitis, but is rarely diagnosed because protection against this disease is included in distemper/parvovirus vaccinations. Infectious hepatitis is treated with antibiotics and supportive care such as intravenous fluids and medications to support the health of liver cells.
This refers to inflammation within the liver as well as the biliary vessels that transport bile to the gall bladder. Cholangiohepatitis is usually a result of a bacterial infection, and the treatment consists of antibiotics, medications to hasten bile flow and supportive care.
Copper storage disease
Copper metabolism abnormalities result in excess accumulation of copper within the liver cells. Not only does this disrupt normal liver function, it can incite chronic inflammation that may ultimately result in liver failure. Copper storage disease has been identified as an inherited abnormality in Bedlington Terriers, Labrador Retrievers, Doberman Pinschers, Skye Terriers, and West Highland White Terriers. Treatment of this disease utilizes anti-inflammatory medications and chelation therapy. Chelation is the process by which copper is made more soluble in water. This enhances its elimination from the body via the kidneys.
This refers to the accumulation of globules (vacuoles) of water or fat within the liver cells. It is a default response of the liver to any sort of stress. In some cases, the cause of this hepatopathy cannot be identified. Vacuolar hepatopathy is a typical response to excess cortisone in the body, either by way of Cushing’s Disease or treatment with cortisone-containing medications. The treatment of choice is removal of the underlying cause.
Several types of cancerous growths originate within the liver, the most common of which include lymphoma, hemangiosarcoma, mast cell cancer, malignant histiocytosis, and adenocarcinoma. The liver can also develop metastases caused by spread of the cancer from another site in the body. Treatment varies depending on the type of cancer diagnosed.
A number of different medications can cause liver cell changes. The classic example is the vacuolar hepathopathy caused by cortisone (see above), whether given orally, via injection, or even topically (applied to the eyes, ears, or skin). In most cases, a drug-induced hepatopathy is reversible when the causative drug is discontinued. In addition to cortisone products such as prednisone or dexamethasone, medications that can induce liver disease include:
- Phenobarbital (antiseizure medication)
- Anti- fungal medications
- Some nonsteroidal anti-inflammatory medications
- Acetaminophen (Tyelenol)
- Diazepam (valium)
- Lomustine (chemotherapy drug)
This is a liver comprised of not much more than scar tissue. On ultrasound the liver looks like a small cluster of grapes rather than a normal sized, smooth surfaced organ. Cirrhosis is the end result of a chronic insult (inflammation, toxicity, infection) to the liver cells. These are the dogs who will be first in line if ever canine liver transplants become available.
Treatment of liver disease
Treatment plans for dogs with liver disease vary a great deal depending upon the type and severity of the disease diagnosed. Whenever possible, a liver biopsy should be collected in order to provide a clear-cut diagnosis. If a liver biopsy isn’t feasible, empirical therapy (“best guess” treatment) is provided. In some cases hospitalization is recommended for dogs with liver disease. Other can be successfully managed on an outpatient basis.
Treatment of liver disease often requires a good deal of finesse. For this reason, it is wise to consider enlisting help from a specialist in internal medicine (or surgeon if shunt surgery is required). Don’t hesitate to ask your family veterinarian for a referral.
Depending on the nature and severity of the disease process, recommended therapy for canine liver disease might include:
- Intravenous fluids or fluids administered under the skin to restore and maintain hydration, hasten delivery of medication, and promote elimination of toxins
- Plasma transfusion: rich in protein and blood clotting factors
- Anti-inflammatory medications: cortisone most commonly used
- Medications to reduce stomach acid production and promote appetite
- Medications to reduce nausea
- Diet change: type of diet recommended varies with disease diagnosis
- Ursodiol (Actigall): a medication that promotes bile flow
- Vitamin K: supports normal blood clotting
- Vitamin E: antioxidant that may support liver health
- Milk thistle (silymarin): an herbal supplement that supports and protects liver cells from damage
- S-adenosylmethionine (SAMe): a compound that promotes liver cell health
- Lactulose: binds and inactivates substances in the bloodstream that can cause neurological symptoms
- Surgery to correct a liver shunt or remove a cancerous growth
- Chemotherapy: treatment for some liver cancers
With so many different types of liver diseases in dogs, the prognosis truly runs the gamut. The prognosis for canine liver disease varies from good to poor, and is not always predictable. In fact, two dogs with the exact same disease and treatment can have completely different outcomes. Often, the best bet is to initiate therapy and see how the dog responds.
Questions for your veterinarian
- Do we know with certainty that my dog has liver disease?
- Do we have a confirmed diagnosis as to what type of liver disease?
- What are the treatment options?
- What is the prognosis?
Nancy Kay, DVM
Diplomate, American College of Veterinary Internal Medicine
Author of Speaking for Spot: Be the Advocate Your Dog Needs to Live a Happy, Healthy, Longer Life
Author of Your Dog’s Best Health: A Dozen Reasonable Things to Expect From Your Vet
Recipient, Leo K. Bustad Companion Animal Veterinarian of the Year Award
Recipient, American Animal Hospital Association Animal Welfare and Humane Ethics Award
Recipient, Dog Writers Association of America Award for Best Blog
Recipient, Eukanuba Canine Health Award
Recipient, AKC Club Publication Excellence Award
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Please visit http://www.speakingforspot.com to read excerpts from Speaking for Spot and Your Dog’s Best Health. There you will also find “Advocacy Aids”- helpful health forms you can download and use for your own dog, and a collection of published articles on advocating for your pet’s health. Speaking for Spot and Your Dog’s Best Health are available at http://www.speakingforspot.com