Hepatic Encephalopathy in Dogs
The liver is one of the powerhouse organs of the body. It has many functions including making proteins and bile (which digests fats), metabolizing (breaking down) nutrients and wastes such as ammonia or medications, and storing energy (primarily glycogen) for future use. When the liver is compromised, these functions are impaired. Fortunately, the liver is resilient and can even regenerate but when there is significant damage or dysfunction, neurological symptoms can manifest as hepatic encephalopathy. The term hepatic refers to the liver and encephalopathy relates to brain disease or dysfunction. Keep reading to learn how hepatic encephalopathy affects your dog.
What is hepatic encephalopathy in dogs?
Hepatic encephalopathy occurs when ammonia is not excreted from the body and affects the brain. When the liver is working properly, it breaks down proteins for energy, causing the by-product ammonia. The liver then turns the ammonia into less toxic chemicals like urea for excretion. When there is a shunt that causes blood to bypass the liver or liver dysfunction, the ammonia builds up in the bloodstream causing illness and neurological signs. Hepatic encephalopathy is often fatal but in some cases may be managed or reversed if diagnosed early enough.
Symptoms of Hepatic Encephalopathy in Dogs
The symptoms of hepatic encephalopathy are often worse after meals. The symptoms include general liver disease symptoms plus:
- Wobbly or clumsy walking (ataxia), disorientation, or circling
- Head pressing into a surface such as a wall
- Aimless wandering or pacing
- Behavior changes
- Lethargy - excessively tired or drowsy
Typical signs of liver (hepatic) disease in general:
- Nausea- vomiting, drooling, licking lips
- Lack of appetite
- Increased water consumption and urination
- Yellowing of the skin, gums, or eyes
- Distended belly
- Muscle wasting
- Weight loss
- Bruising or bleeding
What causes hepatic encephalopathy in dogs?
The most common causes of hepatic encephalopathy in dogs and cats are portosystemic shunts. Shunts are often genetically inherited at birth (congenital) but can be acquired. They occur when blood vessels bypass the liver. As a result, the liver is unable to filter the blood for nutrients and toxins like ammonia.
Liver failure caused by drugs, toxins, and severe infections can also cause hepatic encephalopathy in dogs and cats. Anesthetics, sedatives, and non-steroidal anti-inflammatories are among the more common medications that can induce damage. Xylitol is an artificial sweeter that is particularly harmful to the liver in cats and dogs. Blue-green algae, Sago Palms, and rodenticides are other common toxins. Any severe infection or inflammation can lead to hepatic failure including severe or chronic pancreatitis, cholangiohepatitis, or leptospirosis.
Hepatic lipidosis is the most common cause of hepatic encephalopathy in cats. Hepatic lipidosis is an abnormal deposit of fats in the liver typically caused by prolonged anorexia. It is diagnosed with blood work and imaging. Treatment involves supportive medication and placement of a feeding tube.
Diagnosis and Treatment of Hepatic Encephalopathy in Dogs
Blood work is essential in diagnosing hepatic encephalopathy. Liver enzymes are typically elevated and proteins and glucose tend to be low. Additionally, testing bile acids and ammonia levels should be performed. X-rays and ultrasound help evaluate the liver and may help identify a shunt.
Treatment of hepatic encephalopathy includes fluid therapy, enemas, lactulose (helps remove ammonia from the body), low protein diets, and medications like Denamarin, probiotics, and antibiotics for general liver support. Some portosystemic shunts can be corrected with surgery.
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