Hepatomegaly in Dogs
The term hepatomegaly is used to describe an abnormally enlarged liver. Often occurring due to certain diseases and conditions that can either directly or indirectly affect the functioning of the liver, the liver organ may increase in size, taking on a diseased condition of its own.
Symptoms and Types
Puppies normally have larger livers in respect to their body mass as compared to adult dogs. However, hepatomegaly is most commonly diagnosed in older dogs. Depending on the underlying cause, the enlargement may involve the whole liver or only part of it. For example, infections and/or inflammation may lead to generalized symmetrical enlargement of the liver, whereas tumors, hemorrhages, cysts, or rotation of liver lobe may lead to asymmetrical or focal enlargement. That is, only a part of the liver may be enlarged.
Symptoms can vary depending on the cause. Enlargement of the abdomen is the most commonly observed symptom. On examination your veterinarian will find an enlarged liver or a palpable mass in the abdominal area. The mass is usually observed behind the rib cage and may even be visible with naked eye. However, in obese dogs it is difficult to detect an enlarged liver on physical examination.
- Extra blood pooling near the liver
- Hepatitis (liver infection)
- Chronic liver disease (cirrhosis)
- Obstruction in blood flow passing through the liver
- Heart disease and failure
- Liver neoplasia
- Heartworm disease
- Rotation of the liver lobe around its axis
- Diaphragmatic hernia (hernia resulting from the protrusion of part of the stomach through the diaphragm)
- Abnormal deposition of metabolic products within the liver tissue
- Accumulation of fat in the liver tissue
- Tumor involving the pancreas
- Liver abscess
- Liver cyst
- Drug toxicity
You will need to give a detailed history of your dog's health, onset and nature of symptoms, and possible incidents that might have led to this condition. Your veterinarian will perform a thorough physical exam to evaluate all body systems, and a complete blood profile will be conducted, including a chemical blood profile, a complete blood count, and a urinalysis. The results of the routine laboratory tests are highly variable depending on the underlying cause of the liver enlargement. The complete blood count may reveal anemia, abnormal spherical red blood cells (spherocytes), disrupted red blood cells (schistocytes), red blood cells with spots due to hemoglobin accumulation (Heinz bodies), presence of parasites with red blood cells, immature white blood cells (blast cells) in the blood, red blood cells with nucleus, and abnormally low or high number of platelets (tiny cells used in blood clotting). The biochemistry profile may show abnormally high levels of liver enzymes, and a high cholesterol level. Further testing may include blood clotting profile as blood clotting abnormalities are common in patients with liver involvement. Your dog may also be tested for presence of heartworm disease.
The abdominal X-rays may show an enlarged liver with rounded margins, or a displaced stomach and kidneys. The chest X-rays may help in determining any metastasis of a tumor to the chest cavity, and will also show diseases involving the heart and lungs. Abdominal ultrasonography can be used to view further details in the abdominal cavity, revealing changes in liver size and surface contour, as well as the presence of concurrent disease. Abdominal ultrasound will also help in discriminating diffuse or localized types of liver enlargement. More advanced diagnostic tests, like electrocardiography and echocardiography, can be used to evaluate the structure and functions of heart.
If tumors are seen or suspected, your veterinarian will want to take a sample of liver tissue in order to confirm either its benign or malignant nature, but even without a tumor present, a tissue sample can be helpful for determining the cause, severity and stage of the liver disease. The samples will be sent to laboratory for microbial cultures, and in case of infection, the culturing of the sample will help in determining the type of microorganism that is involved so that suitable drugs can be prescribed.