Lumps & Bumps in your Dog

Skin lumps and bumps are one of the most common problems I am faced with as a veterinarian every day.  It’s extremely important to regularly examine your dog to check for any lumps that may appear – this is especially true in long coated breeds as often lumps can go unobserved for a long period of time. 

As your dog gets older the chance of malignant lumps or ‘cancer’ become higher.  However, many lumps are benign (non-cancerous) and additionally, treatment of cancerous lump early can increase the chance of curing the disease.  So as soon as you find a lump, please take your dog to the vet for your peace of mind and for you dogs health.

Important questions your vet will need to know are:

1. How old is your dog? – The chance of cancer increases with age, but some growths are common in young dogs.
2. How long has the lump been present? – lumps present for a long time without any growth are more likely to be benign.
3. How quickly is the lump growing? – faster growing lumps are more of a concern.
4. Is the lump firmly attached to the underlying tissues? – this can indicate a possible cancerous growth.
5. Is the lump ulcerated/discharging fluid or worrying your dog?
6. Where the lump is – often certain tumours will grow in certain sites
7. Is there more than one growth?
8. Does your dog seem unwell, off his/her food or losing weight – this may be a concern if related to the growth as may be an indication of cancer.

Diagnosis

After examination your vet may have an idea about the type of lump present, however, many growths will require further testing to be 100% sure about the diagnosis.

1. Fine needle aspirate (FNA) – this is a simple test which can be performed in the consultation without sedation.  A small needle is inserted into the lump and cells are sucked out and placed onto a slide.  The slide is then stained to examine the cell type by either your veterinarian, or sent off to a laboratory to a specialist (cytologist).  Around 95% of lumps can be diagnosed this way.
2. Impression smear – if the lump is discharging fluid a slide may be rubbed onto the lump and stained and examined as with the fine needle aspirate.
3. Biopsy – if the FNA is not diagnostic or just contains blood/fluid then your vet may need a take a biopsy of the lump.  Your dog will generally need to be sedated or anaesthetised and a small portion of the lump or the whole lump (excisional biopsy) removed.  This is placed in formalin and sent to the lab to examine by taking very thin sections of the lump and looking under the microscope.
4. If the lump contains fluid then this may be sent to the lab to culture and check for infectious agents such as bacteria or fungi.

Types of lump

There are many different causes of lumps, many of which are completely benign.  These include:

1. Abscesses – caused by an infectious agent and require draining and antibiotics
2. Hives (uticaria) – a reaction of the skin to allergens eg bee sting, contact allergy.  These can often self-cure or require steroids or anti-histamines.
3. Sebaceous cysts – a blocked oily gland of the skin.  These can be left unless they become infected or irritate your dog.
4. Histiocytomas – an ulcerated nodule found in young dogs especially on the limbs, these can also self-cure.
5. Sebaceous adenoma – wart like growths (often multiples) commonly found on woolly haired dogs as they get older eg Bichon Frise/Poodles.  They are completely benign but may need removal in some cases as dogs can start to chew/irritate at them.
6. Lipomas – very common round soft benign tumours found in older dogs, easily diagnosed with a FNA.  These can be left unless they become very large or impede movement – eg growing behind a leg.
7. Perianal adenomas – benign tumours that grow around the anus generally in non-castrated older dogs.  These need removal and your dog is often castrated at the same time to prevent further tumours growing.

There are also many different types of cancerous lumps.  These tumours can spread either by local growth (destroying nearby tissues) or spread by metastasis (tumour cells invade into the blood stream or lymphatic’s to spread to distant sites) and these include:

1. Mast cell tumour – a cancer of a type of skin cell involved in the immune system.  These tumours can either spread by local invasion or spread by metastasis. 
2. Fibrosarcoma – a tumour of the connective tissue of the skin.  These generally spread by local invasion and can be hard to remove surgically.
3. Melanomas – these tumours involve the cells that give pigment to our skin.  They can be benign or malignant (cancerous) and are often pigmented.  More aggressive tumours are found on the legs and mouth.
4. Squamous cell carcinoma – this is a tumour of the skin cells found on un-pigmented or hairless areas.   It is often caused by excessive exposure to the sun.  This type of tumour usually grows by local invasion.
5. Mammary carcinomas – cancerous growth of the mammary glands, more commonly found in non-spayed bitches.  These tumours spread by metastasis to other mammary glands and to the lymph nodes.  

Treatment

This will depend of the type of lump present.  Many benign growths can be left and monitored only -  unless causing distress to your dog eg affecting mobility or your dog keeps scratching at the growth.  Many cancerous growths can be cured by surgically removing them early on in the disease, before they have had a chance to spread.  Other options for treatment that are gradually becoming more available, include chemotherapy and radiotherapy, with or with-out surgery.