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Anyone that has found a lump on their dog knows that immediate feeling of dread. Straight away you think the worst, that it must be cancer. However, that is not always the case. There are various types of non-cancerous lump typically found in dogs, with two of the most common types being lipomas and polyps.
One of the most common types of lump found on a dog, lipomas are fat deposits. Soft, rounded and non-painful to your pet, they will move around under the skin when touched.
Usually found just under the skin, they can also arise from the connective tissues found between the muscles.
Largely benign, they may need to be tested with a biopsy. Generally, they grow to a certain size and do not need to be removed, however they can sometimes grow into large deposits which can cause discomfort to your dog. In this case, they should be removed.
Lipomas can develop into an invasive form known as ‘infiltrative lipoma’, which is red and grows rapidly. These should be removed. Very rarely, lipomas can be malignant and spread through your dog’s body.
Usually found around your dog’s anus and rectum, polyps are flap-like growths. Most recto-anal polyps in dogs are non-cancerous, as they are extensions of the tissue lining of their intestinal walls.
Although rare, some dogs may suffer from multiple polyps.
Dogs with polyps will strain and show signs of pain when they are passing stools. Their stools may be blood stained and covered in mucus.
Your vet will examine your dog and perform a blood test and urine test. X-rays and ultrasound scans are not needed in the diagnosis of polyps. Abscesses, intestinal infections, prolapsed rectum and tumours display similar symptoms to polyps, so these need to be ruled out.
Once a polyp is diagnosed, your vet may perform a colonoscopy to check if any other polyps are present. Surgery is then performed to remove the polyps. This is usually through the anus, or it may be performed endoscopically.
The exact causes of polyps are unclear, although older dogs are more likely to suffer from them. Dogs with single polyps usually do not relapse, whilst those with multiple polyps are at a much higher risk of relapse.
If a lump is not a lipoma or polyp, it may be a sebaceous cyst, which is caused by blocked oil glands in the skin, or a skin cyst, caused by a buildup of dead skin cells and sweat. Cysts tend to rupture then heal of their own accord, however some can become infected. If this is the case, they should be removed.
Some breeds are particularly susceptible to sebaceous cysts, such as the Cocker Spaniel.
Rarely, sebaceous cysts can develop into tumours known as sebaceous adenomas.
Cysts, warts, infected hair follicles and blood blisters can all appear on your dog and whilst some may cause discomfort, these can be easily treated and, as such, are not a cause for concern.
Whilst many lumps are benign, some are cancerous and should be investigated and treated as a matter of urgency. Cancerous lumps, or tumours, take two forms – malignant and benign.
Malignant lumps spread rapidly and can metastasise to other areas of the body than that on which they are located. Benign lumps do not metastasise, however they can grow to a vast size and become inoperable.
Tumours which warrant swift attention include:
Mast cell tumours – the most common malignant skin tumour found in dogs. Most common in certain breeds
Mammary gland tumours – the most common type of tumour in unspayed female dogs. Spaying can largely reduce the risk of this type of tumour developing
Malignant melanoma – the most common form of oral malignancy in dogs, these growths are caused by cells called melanocytes
Fibrosarcoma – slow growing tumours, typically found in the connective tissue of the skin and beneath the skin, often on the limbs. Most common in male, older dogs and larger breeds
Cutaneous lymphosarcoma - the third most common cancer in dogs. Found in both male and female dogs, usually aged between 6 – 9 years. Found in the liver, spleen, lymph nodes, intestinal tract and bone marrow.
If your dog is diagnosed with any of these tumours by your vet, you should notify your pet insurance company straight away, as the terms of your insurance policy and in turn, the cover provided, could be affected.