Hepatic Encephalopathy in Dogs
Hepatic encephalopathy arises as a metabolic disorder affecting the central nervous system due to underlying liver disease, known as hepatopathy. Encephalopathy denotes any brain disorder, with hepatic referring to the liver. The condition stems from an accumulation of ammonia in the body, a consequence of the liver’s inability to eliminate this substance.
The liver, the body’s largest gland, performs crucial functions such as bile production (essential for fat digestion), albumin production (a key blood plasma protein), and detoxification of drugs and chemicals, including ammonia.
Portosystemic shunt, or portosystemic vascular anomaly, is characterized by abnormal blood vessel connections permitting blood flow between the portal vein (responsible for carrying blood from the digestive organs to the liver) and the body’s circulatory system without liver filtration. This anomaly may be congenital (present at birth) or acquired later in life.
Congenital portosystemic shunt, or portosystemic vascular anomaly, is genetically predisposed in certain breeds and typically manifests at a young age. Acquired forms of the condition can present symptoms at any stage of life.
Symptoms and Types
- Circling, bumping into walls, and appearing confused after meals
- Difficulty in learning and training
- Lethargy, drowsiness, or excessive sleepiness
- Disorientation and aimless wandering
- Compulsive pacing and head pressing
- Brain-related blindness
- Occasional seizures and potential coma
- Sudden episodes of aggression
- Vocalizations and lack of appetite
- Changes in urination patterns, including increased frequency or difficulty in urination, especially in male dogs
- Frequent small-volume urination with orange-brown urine in male dogs
- Increased thirst and excessive salivation
- Vomiting and diarrhea
- Growth stunting
- Prolonged recovery from sedation or anesthesia
- Temporary improvement in symptoms with antibiotic or lactulose therapy
Causes
- Congenital factors (genetically inherited)
- Acquired portosystemic shunt associated with conditions that elevate blood pressure in the vein transporting blood from the digestive organs to the liver, such as progressive liver damage and scarring (cirrhosis)
- Sudden onset of liver failure triggered by drugs, toxins, or infections
- Alkalosis leading to elevated blood alkaline levels
- Low blood potassium levels
- Certain anesthetics and sedatives
- Methionine, tetracycline, and antihistamines
- Intestinal bleeding
- Predisposition following transfusion
- Infections
- Constipation
- Muscle wasting
Diagnosis
A comprehensive history of your dog’s health, symptom onset, and familial background is essential. Your veterinarian will conduct a thorough physical examination, including standard tests such as a blood chemical profile, complete blood count, electrolyte panel, and urinalysis to eliminate other potential causes of illness. Kidney function will be assessed through bloodwork.
X-ray and ultrasound imaging will enable visual examination of the liver, revealing changes indicative of certain diseases. If abnormalities are detected, your veterinarian may opt for liver sample collection through aspiration or biopsy to confirm the diagnosis conclusively.
Treatment
Most patients displaying symptoms of hepatic encephalopathy typically require hospitalization. Your veterinarian may prescribe medications to improve dietary protein tolerance, and your dog’s diet may be switched to one specifically formulated for liver or kidney disease. Restricting activity and providing a protective environment, possibly through cage rest, is crucial during the recovery and treatment period. Oxygen therapy and fluid therapy, along with electrolyte and vitamin supplementation, are necessary to stabilize your dog’s health. Maintaining warmth is important throughout the recovery process. If calorie intake is insufficient, your veterinarian may recommend a feeding tube. They will provide instructions for home care if this becomes necessary.
In cases where the liver disease stems from a congenital shunt, surgical correction may be an option. However, if the portosystemic shunt is acquired, abnormal blood vessels should not be ligated.
Zinc supplementation may be administered as required. Other prescribed treatments may include antibiotics, enemas, diuretics, and medications to control seizures.
Living and Management
Your veterinarian will arrange follow-up appointments based on the underlying disease condition. It’s important to promptly contact your veterinarian if your dog’s symptoms reappear or worsen, if there’s weight loss, or if your dog starts to seem unwell.