A small liver in dogs is also called microhepatica. When a dog is diagnosed with a small liver, it means they may have a condition affecting liver function or its access to blood flow or nutrients. This causes the liver to become small, or atrophied, decreasing its ability to perform important functions, like processing toxins, producing bile acids, and making proteins.
Causes of small liver in dogs
The portal vein is the large vein that moves blood into the liver. When it reaches the liver, the vein branches into many smaller vessels, moving blood throughout the organ. Any condition causing abnormalities of this vein, the blood vessels of the liver, or the blood flow to the liver could result in developing a small liver.
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If your veterinarian has diagnosed your dog with a small liver, they likely have also diagnosed your dog with another condition of the liver.
Chronic active hepatitis
Chronic active hepatitis is a progressive inflammation of the dog's liver and leads to normal liver tissue eventually being replaced by scar tissue. This process is also known as cirrhosis and can lead to a small liver.
The cause of chronic active hepatitis is not known in many cases but may be induced by canine hepatitis virus, leptospirosis, bacterial infections (Bartonella, Mycobacterium, and Helicobacter), fungal infections (Histoplasma), and certain parasites (Leishmaniasis). Long-term administration of certain drugs, exposure to toxins, genetics, and bioaccumulation of copper can also play a role in the development of chronic active hepatitis.
Chronic active hepatitis can occur in any breed of dog but is most often seen in breeds including beagles, Dalmatians, English cocker spaniels, English springer spaniels, German shepherds, German shorthaired pointers, German wirehaired pointers, golden retrievers, Great Danes, Jack Russell terriers, Labrador retrievers, Scottish terriers, standard poodles, Bedlington terriers, West Highland white terriers, Doberman pinschers, and Skye terriers.
Congenital or acquired secondary to another disease, a portosystemic shunt means that blood carrying toxins, proteins, and nutrients bypasses the liver. This can happen internally in the liver (intrahepatic) or outside the liver (extrahepatic). When this happens, the liver can't do its job, and in addition to other conditions, the liver becomes small.
The most common breeds to be born with this condition include miniature schnauzers, Yorkshire terriers, Irish wolfhounds, cairn terriers, Maltese, Australian cattle dogs, golden retrievers, old English sheepdogs, and Labrador retrievers.
Hepatic microvascular dysplasia and portal vein hypoplasia
When the portal vein or its small vessels through the liver are too small, underdeveloped, or missing, the condition is called primary hypoplasia of the portal vein, a congenital condition. Being born with this condition means that your dog's liver tissue won't have access to as much blood as it should. This could result in a small liver.
Symptoms of small liver in dogs
Clinical signs of a small liver are similar to those of other diseases that cause liver damage:
- Dark stool
- Weight loss
- Excessive urinating
- Excessive thirst
- Fluid in the abdominal cavity
- Jaundice (yellowing of the eyes, gums, and lips)
- Increased tendency to bleed
- Loss of coordination
- Loss of vision
- Pale gums
- Abdominal pain
Signs of liver disease can also present as neurological symptoms, like walking in circles, a wobbly gait, confusion or disorientation, pressing of the head against surfaces, loss of vision, and trembling or seizures. If you notice any changes in your dog's behavior or health, they should be seen by their veterinarian.
Diagnosis of small liver in dogs
Your DVM will employ several diagnostic tools to determine your pet's condition. These may include a complete blood test, including a blood count, biochemical profile, urinalysis, testing ammonia levels in the blood, blood clotting profile, abdominal X-rays, liver function test labs, and abdominal ultrasound. Additionally, a liver biopsy may be performed. It is during abdominal X-rays that your veterinarian is likely to note an enlarged liver, hepatomegaly, or a small liver.
Treatment of small liver in dogs
If your dog is diagnosed with a small liver, they may require hospitalization or long-term management of the underlying condition. Your dog will be given fluid and electrolytes to correct imbalances and dehydration caused by vomiting, diarrhea, and loss of appetite. The veterinarian will prescribe the appropriate treatment or management of the underlying condition for the small liver. Treatment may include antibiotics, steroids, or drugs to stimulate the liver.
Prognosis of small liver in dogs
The prognosis for small liver will vary depending on the underlying cause. Some conditions of the liver, including portosystemic shunts, may be corrected with surgery. Other conditions, including primary hypoplasia of the portal vein and chronic hepatitis, may require lifelong management with medications. For most conditions of the liver, your pet will be on a special diet and medications for the duration of their life.
If the underlying cause of your dog's condition can be determined and treated, such as a particular drug that is causing their illness, the prognosis is considered fair. However, if your dog is diagnosed with late-stage liver disease or liver failure, including cirrhosis, then recovery is not likely. Dogs generally survive from several months to three years after diagnosis.
The bottom line
When a dog is diagnosed with a small liver, their liver's ability to perform important functions is limited, and they may require hospitalization or long-term management of the underlying condition. Conditions that cause a small liver include chronic active hepatitis, portosystemic shunt, hepatic microvascular dysplasia, portal atresia, and other conditions. Treatment may include antibiotics, steroids, or drugs to stimulate the liver. Some conditions of the liver may be corrected with surgery, while recovery from other conditions is not likely.