When we think about surgery in dogs and cats, the liver is probably not the first organ that comes to mind. The liver is a large organ tucked away in the front of the abdomen, so surgery in this area can understandably sound daunting to owners. Liver surgery is performed in both dogs and cats, and, in lots of cases, it is an important treatment option. One of the most commonly performed procedures is a liver lobectomy, where part or all of a liver lobe is surgically removed under general anaesthetic. 

This sort of surgery may be recommended when a mass is confined to a particular part of the liver and can be removed while leaving enough healthy liver behind. In some dogs and cats with a solitary liver tumour, surgery can provide good long-term control of the disease. Liver surgery is not suitable for every patient. The location and appearance of the liver lesion, the type of disease involved, whether it has spread elsewhere and the animal’s general health all need to be considered before surgery is recommended. 

Why would a dog or cat need liver surgery? 

There are several reasons why your vet may consider removing part of the liver. One of the indications is a liver mass or tumour. Primary liver tumours are relatively uncommon in dogs and cats, and liver lesions can also occur as a result of cancer that has spread from another part of the body. 

In dogs, hepatocellular carcinoma (HCC) is the most common primary liver tumour. These tumours can occur in different patterns. There can be one big tumour forming one large mass, usually affecting a single lobe or region of the liver although smaller masses may also be present elsewhere in the organ. Alternatively, nodular disease can occur, which involves multiple masses, while diffuse disease affects the liver more extensively. This distinction matters because massive HCCs are often amenable to surgical removal, whereas nodular and diffuse forms are generally much more difficult to treat surgically.  

Other focal conditions, including some benign masses and hepatic abscesses, can also occasionally be treated surgically. 

The presence of a liver abnormality on an ultrasound scan therefore does not automatically mean that surgery is required. The individual patient and the nature of the lesion need to be assessed. 

What is a liver lobectomy? 

A lobectomy means removing a lobe, or part of a lobe, of the liver. The liver is divided into several anatomical sections, each with its own network of blood vessels and bile ducts. This allows your vet to remove an affected section while preserving the remaining healthy liver tissue. 

Some masses are relatively straightforward to remove, particularly when they involve the left side of the liver. Others, especially those involving the central or right divisions, can be more challenging because of their relationship with major blood vessels and bile ducts. This is one reason why detailed imaging is so useful before surgery. Ultrasound can identify a mass and provide information about its location, while CT can give much more detailed information about its relationship with important blood vessels and surrounding structures. 

Can dogs and cats cope with having part of their liver removed? 

Fortunately, the liver has a considerable capacity to compensate following partial removal. Provided enough healthy liver is left, the remaining liver tissue can increase in size and restore liver function after surgery. This does not mean that an unlimited amount of liver can be removed safely though, the amount and health of the remaining liver are important considerations. 

A patient with otherwise healthy liver tissue may tolerate removal of a substantial portion of the organ, whereas an animal with significant underlying liver disease may have much less functional reserve. For this reason, your vet will consider both the mass itself and the condition of the remaining liver before deciding whether surgery is appropriate. 

What happens before surgery? 

Liver surgery requires careful planning. Blood tests are usually performed to assess your pet’s general health and look for abnormalities involving liver function, anaemia or blood coagulation. The liver has an important role in producing many of the proteins involved in normal clotting, so assessment of bleeding risk is particularly important. Abdominal ultrasound is often the first investigation used to identify a liver mass. CT scans may then be recommended to provide more detailed information for surgical planning and to assess the relationship between the mass and major blood vessels. Chest X-rays may also be recommended if cancer is suspected, to check whether there are any signs that the cancer has spread to the lungs or elsewhere in the chest. Finding evidence of spread may affect whether surgery is considered appropriate. 

A fine needle aspirate or biopsy may sometimes be performed before surgery, although these tests do not always provide a definitive diagnosis. In many cases, the final diagnosis is made after the mass has been removed and examined by a veterinary pathologist. 

What does liver surgery involve? 

A traditional liver lobectomy is performed through an abdominal incision under general anaesthesia. Once the abdomen has been opened, your vet will examine the liver and other abdominal organs. This allows them to assess the mass directly and look for evidence of disease elsewhere. The affected liver lobe is carefully isolated, and its blood vessels and bile duct are controlled before the lobe is removed. 

One of the major concerns during liver surgery is bleeding or haemorrhage. The liver has a substantial blood supply, and some masses can be closely associated with large vessels. Modern surgical equipment, including stapling and vessel-sealing devices, can help your vet control the blood supply and reduce operating time in appropriate cases. However, the technique used will depend on the location and size of the mass. More complicated right-sided or centrally located lesions can present greater surgical challenges for your vet team. 

Is liver surgery dangerous? 

There are significant risks, and liver lobectomy should not be regarded as a routine abdominal operation. As mentioned above, bleeding is one of the main concerns. Depending on the location of the mass, a blood transfusion may be required. Other potential complications include low blood pressure during anaesthesia, anaemia, postoperative bleeding, bile leakage and other complications associated with the patient’s underlying disease. This is why liver surgery is generally best undertaken by a veterinary surgical team with appropriate experience, equipment and access to blood products. 

What about cats? 

Cats can also undergo liver lobectomy, although there is less published research in cats than in dogs. Studies have shown that cats with certain malignant liver tumours can benefit from surgery, with some cats living for considerably longer following removal of the affected part of the liver. However, complications and tumour recurrence can occur as with dogs, so surgery cannot guarantee a successful outcome. 

What are the chances of success? 

The outlook depends heavily on the underlying disease and whether the affected part of the liver can be completely removed. 

For dogs with a hepatocellular carcinoma that may be surgically removed, the outlook can be encouraging. Studies have shown that dogs undergoing surgery for these tumours can have a good long-term outcome, with some living comfortably for several years following treatment. Liver lobectomy has also been associated with good short-term survival in dogs undergoing surgery for liver tumours. However, these results need to be considered alongside the individual patient. Tumour type, size and location, how aggressive the tumour is and whether it has already spread can all affect the outcome. 

A single tumour that can be completely removed is very different from cancer affecting several areas of the liver or disease that has already spread elsewhere in the body. Your vet will consider these factors carefully when discussing whether surgery is appropriate and what to expect afterwards. 

Does removing the tumour mean the cancer is cured? 

If a tumour is completely removed and there is no evidence of metastatic disease, surgery may provide long-term control and, in some cases, may be curative. Histopathology is important because it confirms the tumour type and assesses whether the margins around the tissue that has been removed appear free of tumour cells. This information helps determine the likelihood of recurrence and whether further treatment or monitoring is recommended. Follow-up examinations and imaging may therefore still be advised even when surgery has gone well. 

When might surgery not be possible? 

Finding a liver mass does not automatically mean that it can be surgically removed. If a tumour involves multiple liver lobes or is spread throughout the liver, there may not be enough healthy tissue remaining after surgery. Some masses are also positioned very close to major blood vessels or bile ducts, making complete removal very challenging. 

If the cancer has already spread to other parts of the body, your vet may decide that the risks of surgery are greater than the likely benefits. In these situations, the veterinary team may discuss other options, depending on the diagnosis. These could include chemotherapy, supportive treatment or palliative care. 

Final Thoughts 

Liver surgery, including liver lobectomy, is an established procedure in veterinary practice. For some dogs and cats, surgery can provide an opportunity for long-term disease control. It is a technically demanding procedure and there are genuine risks, particularly bleeding and postoperative complications. The location of the mass, the health of the remaining liver and the presence or absence of disease elsewhere all need to be considered. For owners, the prospect of liver surgery can understandably sound frightening. In the right patient, however, removing a diseased section of liver can be a worthwhile treatment and, in some cases, may improve your pet’s quality of life significantly.