Splenic tumours are very common in dogs, especially as they grow older. In dogs, the spleen plays a role in the immune system, aiding the body fight off infection and produce certain types of white blood cells. It also stores, produces new red blood cells and removes old, worn out blood cells.

What is a splenic tumour?  

The spleen can develop masses which can either be:

  • Benign tumour
  • Malignant cancers
  • Benign nodules.  

Benign tumours are most commonly splenic haematomas, whereas the malignant tumour is a haemangiosarcoma. The malignant haemangiosarcoma is a common tumour that is usually seen in older large breed dogs such as German Shepherds, Golden Retrievers and Labradors.  

The tumour is made up of cells that form blood vessels and as such the tumour is often filled with large pockets of blood. It can be very delicate and can easily rupture either through a bump/trauma or just through growth and stretching. If the tumour ruptures, it causes internal bleeding which can be very severe emergency. Up to 2/3 of dogs with splenic masses have a malignant tumour.  

What are the symptoms of a splenic tumour?

Signs can start as very subtle changes such as: 

  • Abdominal distention 
  • Weight loss 
  • Reduced appetite 
  • Weakness 

But they can progress (sometimes rapidly) if the tumour ruptures causing internal bleeding. Severe signs can include:  

  • Pale gums 
  • Increased heart and breathing rate 
  • Sudden slowing down 
  • Collapse 
  • Sudden death 


A suspicion of a splenic mass may arise during a routine booster appointment, as your vet will palpate/feel your dog’s tummy and might feel an enlarged spleen. If you are visiting the vet because you are concerned about your pet, the history you give, as well as a clinical examination, will alert your vet to the potential for a splenic tumour. Following a suspicion for the tumour, your vet will recommend an abdominal ultrasound to check for changes to the spleen as well as free fluid in the abdomen, which could suggest internal bleeding. They may also recommend a blood test, clotting test and may sample the fluid from the abdomen.  

Malignant tumours of the spleen can spread to the heart so echocardiography (ultrasound of the heart) may be performed to check for a tumour there, and x-rays may be taken to screen for spread to other parts of the body.  


Surgery is the primary method of treatment for dogs with splenic masses. The surgery involves removal of the spleen, after which a sample of the mass will be sent for histopathology to determine whether it is malignant (aggressive) or benign.  

Patients must be stabilised before surgery with intravenous fluids and medications, and will likely require intensive care after the surgery. If the spleen is actively bleeding, the surgery is a real emergency and prognosis depends on the severity of the bleed. Some dogs require a blood transfusion to replace the lost blood. Complications post-surgery can include: bleeding, irregular heart rhythm and pancreatitis. The surgery can be high risk.  

Surgery to remove benign masses can be curative, however if a mass is malignant, it is likely that it will already have spread. In these cases, surgery may slow progression but it is likely that the cancer will be terminal with a less than 10% chance of surviving one year. Mean survival times post-surgery when the tumour is malignant is 2-3 months or less. Chemotherapy may increase survival time to 6-8 months.  

If you think your pet is not looking right or just ‘getting a bit old’ then it may be worth getting them checked out for a splenic mass, especially if they are a larger breed. Contact the practice to make and appointment on 01626 835002 if you are concerned.