Dog Owner's Home Veterinary Handbook.pdf - Mr. Walnuts

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
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.
Bleeding
Spontaneous bleeding occurs in dogs with advanced liver disease. Common
sites of bleeding are the stomach, intestines, and urinary tract. Blood may be
noted in the vomitus, stools, or urine. Punctate (pinhead-size) hemorrhages
may be seen on the gums. Bruises can appear under the lips and skin. Major
blood loss from spontaneous bleeding is relatively uncommon, but uncontrollable
bleeding can be a serious problem if the dog is injured or requires surgery.
Dependent Edema
Swelling of the abdominal wall and lower legs is related to malnutrition and
low serum protein levels. It is not as common in dogs with liver disease as it is
in those with congestive heart failure.
CAUSES OF LIVER DISEASE
THE DIGESTIVE SYSTEM • 295
A number of diseases, chemicals, drugs, and toxins can damage the liver. The
liver is directly affected by infectious canine hepatitis and leptospirosis. It is
frequently involved in heartworm infection, Cushing’s syndrome, and diabetes
mellitus. Primary and metastatic tumors are a major cause of liver failure
in dogs.
Chemicals known to produce liver toxicity include carbon tetrachloride,
insecticides, and toxic amounts of lead, phosphorus, selenium, arsenic, and
iron. Drugs capable of damaging the liver include anesthetic gases, antibiotics,
antifungals, dewormers, diuretics, analgesics (including NSAIDs), anticonvulsants,
testosterone preparations (Cheque drops), and corticosteroids. Most
drug reactions are associated with excessive dosage and/or prolonged use.