Liver disease affects many dogs but is hard to diagnose
February 21, 2014
Liver disease is a leading cause of death in dogs. Unfortunately, signs of liver disease in dogs are generally vague and indistinct, making it difficult to recognize early. The term liver disease describes a wide range of liver problems that includes infectious diseases, inflammatory problems, toxicities, genetic issues, and cancer.
The liver is a large organ found in the abdomen next to the diaphragm. It is predominantly composed of liver cells, bile ducts, and blood vessels. Bile ducts connect to the gall bladder. Incredibly, the liver has tremendous functional reserves: three-quarters of the liver can be removed and still maintain appropriate function while regenerating. This reserve plays an important role in maintaining liver function.
The liver is responsible for maintaining optimal health through an incredible range of metabolic activities including carbohydrate, protein and fat metabolism; detoxification; vitamin, trace mineral, and glycogen storage; and bile production. The liver is intimately associated with the digestive tract with blood from almost the entire digestive tract entering the liver for processing before moving to the rest of the body. This is important for removing toxic substances from the blood before they can harm the rest of the body. In addition, the liver is in a prime location for dealing with bacteria that have inappropriately passed through the intestinal wall. These bacteria are attacked by white blood cells that are specifically maintained in the liver for that purpose. This also means that good intestinal function is critical for a healthy liver. Like all other organs, the liver relies on a steady blood flow from the heart to deliver oxygen and important nutrients and to remove cellular waste products. Clearly good heart function and blood flow are important for proper liver activity.
With its central role in maintaining health through its vast metabolic activities, the liver can be affected by a range of problems. Some problems like bacterial infections, inflammatory conditions of the liver (hepatitis) and bile ducts, or abnormal liver cell function directly involve the liver. Other problems are caused by disease in other organs or glands such as intestinal wall dysfunction, excess production of steroid (cortisol) by the adrenal glands, inadequate blood flow to the liver, or pancreatitis.
Signs of liver disease are typically vague and can range from "just not doing right" to vomiting, diarrhea, increased thirst and urination, or even seizures. From a diagnostic perspective these signs do not clearly focus on the liver. Adding to the diagnostic complication is that some problems like ingestion of a poison can cause damage very quickly while others like a chronic hepatitis can occur slowly over time. Diagnosing liver disease involves a number of steps starting with blood tests for liver enzymes like ALT (alanine aminotransferase) and ALP (alkaline phosphatase) that are released into the blood. A healthy liver releases these enzymes at a relatively constant rate while an unhealthy liver or a liver being damaged by indirect causes will typically have an increased release of these enzymes.
Unfortunately, these enzymes do not evaluate function since they leak from liver cells (ALT) or can be induced by poor bile flow (ALP). In addition, these enzymes can be increased by drugs like phenobarbital, NSAID, and steroids; muscle damage; or congestive heart failure. Measurement of bile acids before and after a meal can provide information about liver function. Levels of albumin, coagulation proteins, and bilirubin also provide insight into liver function but generally change only late in the course of disease. X-rays, ultrasound, and liver biopsies may be required to obtain a final diagnosis.
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Treatment of liver disease depends on the cause and severity. Addressing the initial insult is essential if it can be determined, however, it is not always possible to identify. In most situations, regardless of the initial cause, it is important to provide supportive therapy for the liver itself. This can be done by diet changes and using products that support liver cell function including SAMe, herbs like milk thistle and schisandra, vitamins C and E, and bile acid products. Intravenous fluids and antibiotics may be required initially in some situations. Additional support of the intestinal tract with probiotics and glutamine may be beneficial as well as herbs that help move bile like dandelion.
Liver disease is a significant problem in dogs. It has a wide range of causes. Unfortunately, signs of liver disease are ambiguous and similar to many other problems. If you have concerns about your dog, contact your veterinarian and discuss blood testing for liver problems and supportive care if needed.
— Ron Carsten, DVM, PhD, CVA was one of the first veterinarians in Colorado to use the integrative approach and has been a pioneer in the therapeutic use of food concentrates to manage clinical problems. In addition to his Doctor of Veterinary Medicine, he holds a Ph.D. in Cell and Molecular Biology and is a Certified Veterinary Acupuncturist. He practices integrative veterinary medicine in Glenwood Springs.