The liver: what vet techs need to know
NEW OREANS, LA – The liver is one of the most important organs in the body and, when affected, can cause whole-body illness, explained Amy N. Breton, CVT, VTS (ECC), presenting at the ACVIM Forum. The symptoms of liver disease can vary simply because of the vast number of roles the liver plays in the body. Weight loss, anorexia, jaundice, vomiting, diarrhea, polyuria/polydipsia, abdominal effusion, and abdominal pain are typical signs of liver disease or injury.
Most common liver diseases
Infectious canine hepatitis is a viral disease of canines that is transmitted by the oro-nasal route. Signs include fever, anorexia, hepatomegaly, disseminated intravascular coagulation (DIC), jaundice, and abdominal pain with or without effusion. Specific tests include IgM, IgG, and ELISA, and a serum chemistry profile will usually reveal elevated ALT, AST, ALP, and GGT. Canine hepatitis can also cause hypoglycemia, hypoalbunemia, and bilirubinuria. Ms. Breton differentiated between infectious and chronic canine hepatitis saying that chronic hepatitis indicates an inflamed liver, which can be caused from a variety of diseases, not just infectious canine hepatitis.
Leptospirosis, a bacterial disease caused by one or more of several known serovars, is a primary cause of liver failure. Dogs are the primary hosts and typically pass the disease from urine into mucous membranes or an open wound. As leptospirosis is a zoonotic disease, gloves should be used when handling animals suspected to have the infection. Symptoms usually are seen within 4-12 days after infection and include vomiting, fever, jaundice, anorexia, polydipsia, polyuria, melana, and hematuria. Initial bloodwork usually reveals anemia, thrombocytopenia, high liver enzymes, and azotemia.
Histoplasmosis, a fungal infection that causes secondary liver dysfunction, is acquired through inhalation or ingestion. Dogs and cats under four years of age are most often affected. Signs include dyspnea, abnormal lung sounds in about 50% of cats (< 50% of dogs), fever, lethargy, and severe diarrhea. A complete blood count (CBC) typically reveals non-regenerative anemia and thrombocytopenia, and a chemistry profile may show increased total bilirubin, AST, ALT, and ALKP.
Coccidiomycosis is another systemic fungal infection that originates in the lungs. It is not contagious and is usually transmitted by inhalation of the fungus. More than half of cats have cutaneous lesions on the liver, which may also include abscesses. Signs include dyspnea, abnormal lung sounds, fever, weight loss, bone lesions, and central nervous system signs. A CBC most commonly reveals a nonregenerative anemia. A serum chemistry profile may show an increase in total bilirubin, AST, ALT and ALKP.
Babesiosis is caused by Babesia, an intracellular protozoa, which is more common in the southern United States, Africa and Asia. With more dogs being imported from the south to other areas of the country, it is important to obtain a complete history on the animal. Typical signs include lethargy, pale mucous membranes, fever, and weight loss. Due to the severe anemia that is common with babesia, liver enzymes typically become elevated. Thrombocytopenia can occur along with the life-threatening anemia.Toxins/trauma
It is important to think about liver involvement when a traumatic injury has occurred, advised Ms. Breton. Typically patients present in shock or with a high amount of adrenaline in their blood stream. Blunt trauma to the liver typically reveals an increase in ALT, which generally resolves 4-10 days post-injury. It is important to monitor the animal for several days to ensure that the liver enzymes continue to decrease.
There are hundreds of toxins that can cause acute and chronic liver failure, including fungi and plants, and many pharmaceuticals. The larger the dose and the longer the exposure to any medication, the more risk to the liver.
Malignant hyperthermia, also known as heat stroke, can affect almost every system in the body, including the liver. Typical signs of liver damage include elevations in AST, ALT, and total bilirubin.
Metabolic diseases
Hepatic lipidosis is the intracellular accumulation of lipid (fat) within the liver. Anorexia is usually the predisposing factor. In dogs hepatic lipidosis is usually an incidental finding, while in cats it is the most common liver disease. Typically owners will describe anorexia, jaundice, and lethargy. Blood work will commonly reveal increases in ALT, ALP, AST, and bilirubin, and ultrasound can be helpful in diagnosis.
Liver shunt, also known as a portosystemic shunt (PSS), is an abnormal blood vessel that bridges the portal and systemic circulation allowing blood to bypass the liver. Animals with PSS usually have stunted growth, intermittent vomiting and diarrhea, and may also have polyuria and polydipsia. Animals may also have head pressing, stupor, or dementia, and cats may become aggressive. Approximately 25-50% of animals with PSS may experience seizures. Bloodwork may show mild elevations in ALT, ALP, and ASP, and ammonia levels are commonly elevated. A bile acid test is the most effective test. While ultrasonography and radiography can be useful, a portogram is the most accurate test.
Primary hepatic neoplasia is not very common in dogs and cats. Owners typically report that their pets are lethargic, anorexic, or are experiencing vomiting and/or diarrhea. When a dog has primary hepatic neoplasia, anemia is one of the most common findings on a CBC.
Copper storage disease is associated with canines and involves an accumulation of copper in the liver due to a metabolic defect, causing hepatocellular damage. Signs include vomiting, diarrhea, lethargy, anorexia, jaundice, ascites, and anemia. Bloodwork usually supports chronic liver failure and biopsies will help to diagnosis a copper storage disease.
Pancreatitis is a disease that can be chronic or acute; typically the acute form causes liver failure. Animals with pancreatitis can exhibit anorexia, vomiting, and signs indicating severe abdominal pain, such as walking with a hunched over appearance, or hiding in cats. In severe cases the animal may present in hypovolemic shock. A CBC usually reveals a leukocytosis and neutrophilia with a left shift. A serum chemistry panel may show azotemia and an increase in liver enzymes and total bilirubin. Ultrasound is usually the diagnostic instrument of choice.
Treatment
When caring for a patient with liver disease, the technician should frequently monitor all vital systems and alert the veterinarian to early signs of complications. For example, the colour of a jaundiced patient can change hourly, so it is important to notify the veterinarian if a change occurs.
Aggressive fluid therapy is one of the most important treatment options and can help to improve hepatic circulation and prevent complications such as disseminated intravascular coagulation, shock, or renal failure. Electrolyte levels should be monitored, and fluid adjustments should be made accordingly.
Proper nutrition is essential; a feeding tube may be necessary if a patient appears nauseous, is vomiting, or is unwilling to eat. Technicians can encourage unwilling patients to eat by offering a variety of foods or by hand feeding. Since patients with certain liver diseases require special diets, the veterinarian should be consulted before feedings are initiated.
Hepatosupportive agents, including antioxidant nutraceuticals, may be used in conjunction with other treatments to help control chronic liver problems in some pets.
Follow-up
In some cases, it may take months for a patient’s liver to fully recover; therefore, rechecking bloodwork and/or performing ultrasonography can help monitor response to treatment. Technicians should educate owners about signs that a pet’s condition has worsened; owners can be taught to look for signs of jaundice and they should also be asked to immediately report lethargy, inappetance, vomiting, diarrhea, or worsening jaundice to the veterinary clinic.
Prognosis
Depending on the underlying cause of liver disease, some patients recover quickly. However, some patients experience severe complications, potentially resulting in a wide variety of sequelae. Patients with acute liver failure generally have a good prognosis if the disease is diagnosed early and treatment is started immediately. However, patients with chronic liver disease have a variable prognosis. The prognosis is guarded in most patients with hepatic neoplasia.
Conclusion
Ms. Breton concluded by saying that technicians need to know how various liver diseases are diagnosed and should be able to recognize complications in affected patients. This way, the technician can quickly notify the veterinarian about important changes in a patient’s condition. CVT
