Liver Disease in Dogs: Causes, Complications and Treatments
Another great article by yourdogadvisor.com.
Owning a dog with liver disease can be challenging. I know this for certain because my dog, Joey, a 13-year-old shih tzu, was diagnosed with a rare form of liver disease about three years ago. In his case, we found the problem quite by accident. During an exam for an unrelated issue, my vet found lesions on Joeys spleen, which subsequently had to be removed. During that operation, the vet noticed that Joey’s liver looked “odd.” He took a biopsy, which came back positive for copper storage disease.
My dog Joey, who, at 13, is still happy and doing well despite having liver disease.
That said, my and Joey’s situation was definitely atypical. Most cases of liver disease in dogs are diagnosed after symptoms appear. And since many of those symptoms are subtle, the dog may have advanced liver disease before a diagnosis is made. That’s why it’s so important for dog owners to know if their dog is at risk for liver problems and to be vigilant about spotting the signs.
Signs of Liver Disease in Dogs
The liver is a complex organ that performs many vital functions. So when it isn’t working properly, your dog may develop a variety of symptoms ranging from minor to very severe. Depending on the underlying cause (I’ll talk more about those later) they may come on suddenly or develop slowly over time.
Since there are many symptoms of liver disease, it can be helpful to look at them in the context of the functions the liver normally performs.
No. 1. Gastrointestinal Symptoms
The liver produces bile acids, which are necessary for the digestion of food, particularly fat. If this function is compromised by liver disease, your dog may have a variety of gastrointestinal symptoms. According to PetMD, these include:
- Poor appetite
- Weight loss
- Excessive thirst
A poor appetite, tiredness and vomiting and/or diarrhea may be the first sign that your dog has liver disease.
No. 2 Jaundice
The liver is also responsible for the excretion of bilirubin — a normal by-product of the breakdown of red blood cells. If the liver isn’t working properly, this yellow-tinged pigment accumulates in the body, which can give the whites of the eyes, the gums and other mucus membranes a yellow tinge. This is known as jaundice.
Excess bilirubin may also turn your dog’s urine very dark.
No. 3 Abnormal Bleeding
Another function of the liver is to produce proteins that help the blood to clot. If these proteins aren’t present in sufficient numbers, bleeding can occur. According to PetMD, signs of abnormal bleeding include:
- Very dark stools
- Red blood in the stool
- Blood in the urine
- Vomiting blood
- Bleeding gums
- Sudden bruising
No. 4. Ascites
Ascites is an abnormal accumulation of fluid in the abdominal cavity. In liver disease, ascites is typically caused by a combination of abnormalities, including increased blood pressure within the liver itself and low levels of certain proteins. Dogs with ascites usually have a large, firm, distended abdomen, which may even interfere with breathing if it’s severe.
No 5. Neurological Problems
The liver is responsible for detoxifying the blood and preventing a variety of harmful substances from reaching other organs of the body. When this function is compromised, a condition known as hepatic encephalopathy (HE) may occur. Although the underlying mechanism isn’t well understood, the syndrome is probably related at least in part to the accumulation of ammonia — a byproduct of protein metabolism — in the blood. The symptoms of hepatic encephalopathy can be mild or severe, and include:
- Mental dullness, failure to follow commands
- Lethargy, fatigue
- Abnormal gait
- Personality changes
- Aggressive behavior
A dog with hepatic encephalopathy may appear confused, wary or aggressive.
No. 6. Infections
The liver plays an important role in a dog’s immune system, so dogs with liver disease can get serious bacterial infections quite easily. Signs of infection may be difficult to detect in a dog who is already ill, but may include:
- Poor appetite
- Excess tiredness
Causes and Risk Factors
Any dog can develop liver disease. However, certain factors may put your dog at increased risk. These can be congenital (the dog is born with the problem) acquired (for example, an infection or exposure to a toxin) or related to another disease. Let’s take a look at each of these categories one by one.
Congenital and Hereditary Factors
Congenital liver problems are usually referred to as “inborn.” That is, the dog is born with a defect that causes problems to develop, either early on or later in their lives. Additionally, some hereditary factors predispose certain breeds of dog to liver disease.
Here’s a rundown on a few of the most common congenital and hereditary issues you may encounter in your dog.
Congenital Portosystemic Shunt
The most common liver issue in young dogs is a congenital defect known as a portosystemic shunt. According to the Merck Manual of Veterinary Medicine, a healthy dog’s liver filters blood coming from the intestines, which prevents toxins and other harmful substances from entering the bloodstream. But in dogs with a portosystemic shunt, blood bypasses the liver via one or more abnormal blood vessels, sending unfiltered blood throughout the body. This results in a variety of symptoms, such as stunted growth and neurologic problems, including disorientation and seizures. In advanced cases, the dog may also develop ascites.
Congenital portosystemic shunt is not hereditary. But it is more common in certain breeds of dog. These include:
- Cattle dogs
- Cairn terriers
- German shepherds
- Golden retrievers
- Irish wolfhounds
- Labrador retrievers
- Old English sheepdogs
German shepherd puppies may have a congenital liver defect known as a portosystemic shunt.
Copper-associated hepatopathy (Copper storage disease)
Generally an inherited condition, copper storage disease occurs when abnormal amounts of copper accumulate in the liver, causing chronic hepatitis (inflammation) and cirrhosis (scarring). My experience notwithstanding, it is seen most often in specific dog breeds, including Bedlington terriers, West Highland white terriers, Sky terriers, Dalmatians and Doberman pinschers.
Bedlington Terriers are genetically prone to copper storage disease, as are West Highland White Terriers and several other dog breeds.
Amyloid is a stiff, fibrous protein that can accumulate in various organs and tissues, a condition called amyloidosis. When amyloidosis affects the liver, enlargement of the liver, high liver enzymes, liver failure and/or liver rupture may occur. The disease is often familial and is seen most often in beagles, foxhounds and Chinese shar peis, says PetMD.
Infections and Toxins
Filtering the blood of toxins and other harmful substances is one of the liver’s most important jobs. To facilitate this, the organ has a rich blood supply. And while that is physiologically beneficial, it also means that anything and everything that enters a dog’s bloodstream goes through the liver, often in an unaltered state.
A number of medications have the potential to cause liver damage, even those prescribed by your veterinarian. Some of the most common culprits are drugs in the class known as nonsteroidal anti-inflammatory drugs or NSAIDS, which are often prescribed for joint pain. Although generally safe at prescribed doses, these drugs may be harmful to the liver, especially in dogs with pre-existing liver disease, explains the FDA. If you are giving your dog NSAIDs, watch her carefully for any of the signs and symptoms mentioned above. If any of them occur, stop giving the medication, and call your vet.
Acetaminophen (Tylenol) is another drug that can cause liver damage in your dog. This is typically a dose-dependent reaction, meaning the more of the drug the dog ingests, the more likely liver damage will occur. However, small or young dogs can develop acetaminophen toxicity from a single, relatively small dose, according to Dr. Colleen M. Almgren, DVM, PhD. To keep your dog safe, never give her Tylenol or any drug not prescribed by your vet, and keep all medicines in a safe, secure place.
Poisons and Toxins
There are many natural and man-made substances in the environment that can damage a dog’s liver. According to the Merck Veterinary Manual. some of the most commonly encountered environmental toxins that have the potential to cause liver damage include:
- Heavy metals, such as lead, mercury and cadmium
- Herbicides and fungicides
- Rat or mouse poison
- Amanita mushrooms (death cap mushrooms)
- Cycad plants (Sago palms)
- Blue-green algae
- Aflatoxin, a substance produced by mold
If you suspect your dog has ingested a toxin of any kind, call your veterinarian at once. If your vet can’t be reached immediately, call your local poison control center or the Pet Poison Helpline any time day or night at 800-213-6680.
Amanita phalloides, or death cap mushrooms, are highly toxic to dogs
Almost any type of organism can take up residence in the liver, including bacteria, viruses and fungi. The most common infections that may cause lasting and even life-threatening liver damage are listed below.
- Infectious canine hepatitis.
Caused by a virus known as adenovirus CAV-1, canine infectious hepatitis starts in the upper respiratory tract and makes its way to the liver via the blood, says PetMD. Once there, it replicates and begins to damage liver cells.
Most dogs who become infected with canine infectious hepatitis mount an immune response to the virus and improve in several weeks. However, some dogs will develop chronic inflammation and scarring of the liver, which can have more serious consequences. They may also experience damage to the kidneys and the eyes.
Fortunately, canine infectious hepatitis is preventable with a vaccine.
Leptospirosis is a bacterial infection caused by the organism Leptospira interrogans. Dogs often contract the infection by drinking water from contaminated sources, according to PetMD. The disease is treatable with antibiotics and supportive care. However, permanent liver and kidney damage may occur.
A vaccine is available to prevent leptospirosis, but it is not recommended for every dog. Speak with your veterinarian about whether your dog is at risk of contracting the illness and whether or not vaccination is advisable.
- Histoplasmosis and Coccidioidomycosis
Both histoplasmosis and coccidioidomycosis are fungal infections that can severely damage the livers of dogs. According to the Merck Veterinary Manual, symptoms include an enlarged liver and fluid buildup in the abdomen. The dog’s eyes and gums may be also be jaundiced (yellow-tinged.)
Treatment of both infections usually involves a course of antifungal drugs. However, the outlook for recovery from histoplasmosis is poor. Coccidioidomycosis may be treated successfully with very long-term administration of antifungal therapy, but relapse is common. Some dogs must take antifungal medication for life.
Although often associated with cats, toxoplasmosis can infect dogs as well, causing rapid destruction of liver cells. Caused by the parasite toxoplasma gondii, the infection usually affects young dogs or dogs whose immune system is not working well. According to the Merck Veterinary Manual, symptoms include fever, vomiting, diarrhea and low energy. Signs of acute liver failure, such as jaundice and ascites, can also occur.
Some endocrine disorders predispose dogs to developing liver disease. According to the Merck Veterinary Manual, the most common of these are Cushing disease, diabetes, and hyperthyroidism. If your vet has diagnosed your dog with any of these disorders, it’s important to be vigilant for any signs of liver disease.
Just like their human counterparts, dogs can develop cancer in many organs of the body, including the liver. Primary liver cancers (cancers originating in the liver) are usually hepatocellular carcinoma, a malignant tumor that originates in the tissue that lines the liver, explains PetMD. If the tumor is localized to one lobe of the liver, it can often be surgically removed. Sadly, however, the likelihood that the cancer has spread by the time surgery is performed is quite high, and many dogs succumb to the disease within several months.
Treating Liver Disease: What You Can Do
Obviously, liver disease in dogs is multifaceted problem, and medical treatment will depend on the underlying cause. In some cases, such as that of a young dog with a portosystemic shunt, surgery can correct the defect and your dog can go on to lead a long, healthy life. But for many dogs, inflammation and scarring from the underlying disease process leads to chronic, long term liver dysfunction. These dogs will need ongoing support from you and your vet in order to live their best lives.
Diet is of paramount importance for dogs with liver disease. Whether the illness is acute (short term) or chronic, your dog needs sufficient calories to maintain their weight while the liver tries to repair itself. (Yes, liver cells can regenerate!) This can be challenging, since your dog may have a poor appetite and vomit after he eats. He may also have diarrhea, which means he will have a harder time absorbing the nutrients in his food. Offer him small meals frequently throughout the day, and try hand-feeding him if his dietary intake is poor.
Your veterinarian may recommend a special diet, especially if your dog has hepatic encephalopathy. Most of these “veterinary diets” contain limited amounts of protein in order to minimize the amount of ammonia entering the blood. You should know, however, that limiting protein in the diets of dogs with liver dysfunction is controversial, and may not be appropriate for your dog. According to guidance from U.C. Davis Veterinary School, the need for dietary protein may actually be increased in many dogs with liver disease.
Eggs may be an option to add an appropriate amount of protein to the diet of a dog with hepatic encephalopathy.
Switching to a vegetarian diet with eggs and cheese as the primary protein source may be a good option for a dog with HE, since evidence shows that neurological symptoms tend to worsen after a meat-based meal. That said, always speak with your vet before changing your dog’s diet, and consult a pet nutritionist if you need additional guidance about meeting your dog’s nutritional needs.
Diets for Copper Storage Disease
If your dog has copper storage disease, limiting his copper intake can help prevent further liver damage and oxidative stress. This, too, can be challenging, since most commercially prepared dog foods add supplemental copper, and copper is also present in significant amounts in certain dog-food ingredients, such as salmon, lamb, whole grains and legumes. At the same time, currently available commercially prepared veterinary diets for dogs with liver disease contain very little protein, so they may not be the best choice for your dog. To solve this dilemma, I’ve chosen to feed Joey a homemade diet made with low-copper ingredients, limited fat and adequate amounts of protein. But make sure you speak with your vet before taking this route.
Many veterinarians recommend dietary supplements for dogs with liver disease. These include antioxidants such as vitamin E and vitamin C, S-adenosyl-methonine (SAMe) and silymarin (milk thistle.) On the advice of my vet, Joey takes Denamarin, which contains both SAMe and silymarin. He also takes a zinc supplement, which the vet believes may help to reduce the amount of copper in his liver by slowing down copper absorption from his gut. I also give him MCT oil (medium-chain triglycerides), because there is some evidence that it helps to protect the liver from further injury.
Silamarin, a supplement that may help dogs with liver disease, is made from the milk thistle plant.
Rest and Exercise
If your dog has active liver disease, she probably will not have the same amount of energy she had before she was ill. Liver disease in and of itself can cause your dog to be more tired, and poor nutrition due to gastrointestinal symptoms can sap her energy as well. Abdominal distention from ascites may make it harder for your dog to breathe, causing her exercise tolerance to drop. And, of course, if your dog has a fever, she will need more rest.
Pay attention to cues from your dog as to how much exercise she can tolerate at any given time. If she seems eager to go for a walk, by all means take her, but make it a shorter walk than the walks she took before she became ill. If she seems tired and listless, let her stay indoors except for potty breaks. Joey has good days and bad days, and I’m sure your dog will too.
As you can see from the above, liver disease in dogs is a complex problem with many underlying causes, some of which are easily treatable but many of which are not. Chronic liver problems are common following infections, the ingestion of toxins, or as a result of hereditary defects that doctors don’t fully understand. The important thing for you to remember, however, is that a dog with liver disease can lead a happy, fulfilling life with the right medical care, and lots of love and support from you.