Liver Disease and Liver Failure in Dogs
The early signs of liver disease are nonspecific. They include loss of appetite, weight loss, and chronic intermittent vomiting and diarrhea. Vomiting is more common than diarrhea. Drinking and urinating more often than normal may be the first signs, and the principal reason for seeking medical attention.
In the early stages of liver disease the liver swells and enlarges. As the disease progresses, the liver cells die and are replaced by scar tissue. The liver then becomes rubbery and firm. This condition is called cirrhosis. It is not reversible. Before the liver reaches this terminal stage, it can recover from damage and heal itself to the point where your dog has normal liver function. This is possible if proper treatment is instituted early on; the extent of recovery depends on the exact cause of the liver damage. Eighty percent of liver cells must die before the liver begins to fail. The signs of liver failure are jaundice, hepatic encephalopathy, ascites, spontaneous bleeding, and dependent edema-swollen lower limbs. Treatment of liver failure is directed toward treating the liver disease that is causing it.
With impaired liver function, bile accumulates in the blood and tissues, staining the tissues yellow. This can be seen in the yellow appearance of the white of the eyes and in the mucous membranes of the gums and tongue. The inside of the ears is another area where yellow pigment can be detected. Bile excreted in the urine turns the urine dark brown (the color of tea).
Jaundice may also result from the breakdown of large numbers of red blood cells, such as in acute hemolytic anemia. Post hepatic bile duct obstruction can also cause jaundice.
This is a type of brain dysfunction caused by high levels of ammonia and other toxins in the blood. Ammonia is a byproduct of protein metabolism, and is normally removed from the bloodstream by a healthy liver. When the liver is sick, ammonia accumulates to toxic levels and exerts a poisonous effect on the brain.
Dogs with hepatic encephalopathy develop incoordination, sporadic weakness, disorientation, head-pressing, behavioral changes, drooling, stupor, and mental dullness. Symptoms tend to wax and wane. They become more severe after a high-protein meal. Seizures and coma occur when hepatic encephalopathy is advanced.
Ascites is the accumulation of fluid in the abdomen. In a dog with liver disease, it is caused by low serum proteins and increased pressure in the veins that supply the liver. A dog with ascites has a swollen or bloated look. Thumping on the abdomen produces a dull, flat sound.