It is always stressful to find a lump on your dog, but there are many possible causes. A lump that is painful, bleeding, or is producing discharge may need urgent treatment.

Lumps can happen due to infection, inflammation, an abnormal growth, fluid build-up, or an anatomical problem like a hernia. You can check a list of some common causes and read a brief explanation below.

What to do

What to do if you find a lump on your dog

If your dog has a bleeding lump, apply gentle pressure to the area for 60 seconds. If the bleeding continues or is severe, continue applying pressure but contact a vet straight away for further advice. Even if the bleeding stops, it is likely to happen again, and a vet assessment is recommended.

Contact a vet for further advice immediately if the lump is painful or your dog is otherwise unwell, for example, lethargic or refusing to eat.

If your dog is completely normal apart from the lump, monitor them closely and contact your vet when possible. It can be very useful to measure the lump and take a couple of photos of the area where you see or feel it.

Causes

Common causes of lumps on dogs

Infections and abscesses are common cause of lumps. These are most common on the paws, face, neck, tail and anal sacs. A wound is not always visible. Abscesses can sometimes burst and drain pus.

Allergic reactions can cause multiple red, raised wheals all over the dog’s body, especially their back and sides.

Allergies can also lead to nodules forming between the toes, usually called interdigital cysts or granulomas.

Lumps can be due to a tumour or growth. Many of these are benign, such as warts, but cancerous lumps are still common. A vet assessment is recommended. This is more urgent if the lump is red, sore, or growing rapidly.

Lymphoma can cause swelling of one or more lymph nodes, and this can be noticed as one or more lumps under the skin. This should be assessed by a vet as soon as possible.

Fatty lumps, or lipomas, are common in older and overweight dogs and are almost always benign. These are often very soft to the touch and move freely under the skin. They can still cause trouble if growing rapidly, especially if they are near areas of movement such as the groin or axilla.

Cysts related to the sebaceous glands and hair follicles are common. These are not dangerous but can cause irritation and get infected. If this happens, surgical removal is recommended.

Umbilical and inguinal hernias can cause belly or groin lumps in puppies. This is when the space for the umbilical cord or inguinal canal does not close properly. Some abdominal material squeezes through the muscle and can be felt under the skin. Small umbilical hernias should close on their own but larger ones may need surgery. Inguinal (groin) hernias are often more serious and should be checked by a vet.

Hernias can also happen after a traumatic injury, like a road traffic accident, and these require urgent treatment.

When to worry

When should I worry? What do cancerous lumps look like?

If a lump is painful or your dog is otherwise unwell, a vet assessment should be done as soon as possible. Joii can help you decide if an emergency vet visit is necessary.

No one can tell if a lump is cancerous just from the way it looks or feels. Testing is recommended, especially if the lump is growing rapidly or surrounded by redness and inflammation.

Prevention

Can I prevent lumps on my dog?

Fatty lumps have been associated with being overweight. Maintaining a healthy weight may prevent their development.

Good management of skin allergies, with appropriate diet and medications, if necessary, will help prevent interdigital granulomas.

Diagnosis

What should I look out for if I find a lump on my dog?

Lumps that are painful, inflamed or bothering your dog should be checked as soon as possible.

A lump that has been present for a while but suddenly changes should be checked promptly. Some benign growths can turn malignant.

Changes in appetite or weight loss could mean things are more serious as well.

Home treatment

How can I help my dog with their lump?

If a lump ruptures and is draining fluid, clean the area thoroughly with saline (roughly 1 tsp salt/500ml cooled boiled water) and seek advice from a vet.

Bandages can cause damage to the lump or skin if applied incorrectly. It is usually better to use a recovery collar or a medical vest to prevent injury.

Vet treatment

What is the vet treatment for lumps on dogs?

Painful lumps will be treated with pain medication in addition to further investigations.

Abscesses will need to be drained and flushed to remove the infectious material. Antibiotics may also be necessary.

Allergic reactions may require steroid medications. Further investigations may be advised to determine the trigger for the allergic reaction.

For suspected growths or tumours, one of the two tests below can be performed before deciding if surgical removal is needed.

• A fine needle aspiration involves scraping a few cells from within the lump with a needle. This is usually a simple test to perform and can provide a lot of information, but the results may be inconclusive.
• For a definitive diagnosis, a biopsy may be required. This involves removing a portion or the whole of the lump under anaesthesia.

Risk

Is my dog at higher risk of developing lumps?

Dogs that eat bones or play with sticks are at higher risk of injuries to the inside of their mouth or throat. This can lead to an abscess or lump under the skin.

Older dogs are more likely to get tumours.

Some breeds of dogs are more likely to get specific tumours, but the general risk of cancer is similar across all breeds.

Other causes of lumps in dogs

Sometimes fluid or blood can build up after surgery or an injury and form a lump under the skin. This is likely to resolve by itself but should be checked by a vet to be safe.

Violent head shaking or scratching can lead to a lump forming on the ear of dogs, this is due to bleeding under the skin and is called an Aural Haematoma. This can be very painful and require immediate treatment, always check with your vet.

Bulldogs are prone to develop inflammatory reactions on or between their toes, especially if they allergic skin disease. These are called interdigital cysts.