Brain Disorder Due to Liver Disease in Dogs

Just like our bodies, our dog’s body produces ammonia when it metabolizes (breaks down) the food we eat. Your dog’s liver is supposed to detoxify the ammonia and other waste in the body and send it to the kidneys to be excreted from the body. Other essential functions the liver is responsible for are producing albumin (a protein in the blood) and creating bile to digest fats. If your dog has liver disease or liver failure, the ammonia cannot be filtered and excreted so it builds up in the body. When the ammonia reaches the brain it is able to cross the blood-brain barrier and causes degeneration of the brain and mental functions (hepatic encephalopathy). If you notice that your dog is acting strangely or confused, walking in circles, acting as if he cannot see, and acting intoxicated, you need to call your veterinarian immediately. These symptoms are usually more prevalent right after eating or during times of stress.

Brain disorder due to liver disease (hepatic encephalopathy) is a metabolic disorder caused by liver disease that affects the brain. This disorder has three types: Type A, Type B, and Type C, but they are all related to a buildup of ammonia from other waste materials in the dog’s body and they all have the same symptoms. There are four stages of hepatic encephalopathy as well, graded on the severity of the brain damage. The liver is supposed to break down the ammonia to make it less toxic, but in hepatic encephalopathy, the liver is compromised and cannot perform this task. This causes the ammonia and other toxins to build up in the brain, which causes confusion and mental deterioration.

The symptoms of hepatic encephalopathy are the same for all types, but they are different depending on the stage of the disorder:

Stage I

• Confusion and walking aimlessly after eating
• Appetite loss
• Barking excessively
• Dull behavior
• Unable to train
• Whining
• Diarrhea
• Vomiting
• Frequent urination
• Dark urine (could be dark orange or brown)
• Males may be unable to urinate
• Walking like intoxicated

 Stage II

• Stunted growth rate
• Behavioral changes
• Excessive sleepiness or dizziness
• Disoriented
• Exhaustion
• Shaking
• Lethargic
• Pressing their head against the wall or other objects
• Inability to see

 Stage III

• Pacing back and forth
• Increased thirst
• Confusion
• Acting out of it
• Drooling
• Incoordination
• Laziness
• Occasionally aggressive
• “Daydreaming” or staring at nothing
• Hiding under tables or beds

 Stage IV

• Unable to rouse
• Seizures
• Coma
• Collapse

 Types

Type A occurs with acute liver failure that is abrupt and unexpected from a rapidly moving liver disease, infection, or injury.

Type B is a gradual disorder related to a portal bypass of the liver with no underlying disease or infection.

Type C occurs gradually with chronic liver failure (cirrhosis) and is rare in dogs. It causes the toxic waste to bypass the liver into your dog’s bloodstream.

Finding out the cause of the hepatic encephalopathy is essential to determine the best treatment for the health of your dog. There are some precipitating factors for hepatic encephalopathy, which are too much protein in the diet, overmedicating, infections, kidney failure, and dehydration. However, each type of HE has its own causes. Some of these causes are:

Type A

• Toxicity from ingested poisons
• Encephalitis
• Brain abscess
• Infections
• Interruption of blood flow
• Some metabolic diseases
• Uremia (kidney failure)
• Hypoxia (low blood oxygen)
• Hypoglycemia (low blood sugar)
• Ketoacidosis (high blood sugar)
• Thyroid dysfunctions

Type B

• Portosystemic shunts (vascular abnormality that causes blood to bypass the liver)
• Portal vein hypoplasia w/o hypertension
• Urea cycle disorder (genetic enzyme deficiency)

Type C

• Cirrhosis
• Fistula
• Chronic hepatitis
• Portal vein hypoplasia with hypertension

While the veterinarian is doing a complete physical examination of your dog he will need to know your dog’s complete medical history (e.g. recent illnesses), what symptoms you have noticed, when the symptoms started, how fast the symptoms have progressed, changes in eating habits, personality, or activity. Some tests that will need to be done are:

• Complete blood count (CBC)
• Blood chemistry panel
• Blood clot profile
• Blood ammonia level
• Urinalysis
• Bile acid test
• Digital radiographs (x-rays) of the abdomen
• Ultrasound of the abdomen
• Portal scintigraphy
• Biopsy of the liver

Treatment depends on the cause and stage of the hepatic encephalopathy but the first thing your veterinarian will do is to stop the cause of the hepatic encephalopathy. The veterinarian will most likely hospitalize your dog and administer IV fluids, oxygen therapy, enema, electrolytes, and antibiotics. Food will be withheld until your dog’s condition is improving. Anti-epileptic medications will be given if your dog is having seizures.

Once your dog is stable, the veterinarian will concentrate on preventing it from getting any worse. Although most times it is a progressive disease and cannot be stopped, it can be slowed if the right measures are taken. A diet low in protein is essential to your dog’s health because protein induces ammonia in the body, which causes the hepatic encephalopathy. Lactulose is a medication that is actually just sugar that changes the pH in your dog’s intestines to decrease the absorption of ammonia. Vitamins will also be added to your dog’s diet.

If your dog has a portosystemic shunt, your veterinarian will probably suggest surgery to fix the condition. Surgery is the most favorable choice for a successful recovery and the success rate is more than 95%. Most dogs are completely cured following surgery.

Since hepatic encephalopathy is not usually found until the damage to the liver is significant, the chances of a cure are not good. However, depending on the cause, if the veterinarian can treat the underlying illness or remove the cause before your dog reaches stage III of hepatic encephalopathy, the chances of recovery are good. It is important to give any prescriptions as directed, maintain a high quality and low protein diet for your dog, and keep all follow-up appointments with the veterinarian.