A guide to common lumps and bumps on your dog
Does your dog have a lump or bump on or under their skin? While lumps and bumps are more common in older dogs, younger dogs can get them too. Most lumps and bumps are benign (non-cancerous), but some of them can be malignant (cancerous). The older your dog is, the higher their chance of getting malignant lumps. The good news is that early detection and treatment of cancerous lumps can increase the chances of a cure, so it is always worth getting any new lumps checked at the veterinary clinic. This is especially so if there is fast growth, redness, swelling, pus, an opening, or if the dog is in pain.
Identifying the type of lump
Your vet will conduct one or more of the following tests to determine the type of lump or bump your dog has and the treatment required:
- Fine needle aspiration (FNA) – This can often be done in the consultation without the need for a sedative. A small needle is inserted into the lump to suck out cells which are then deposited onto a slide and then examined under the microscope. About 95% of lumps and bumps can be diagnosed via FNA.
- Impression smear – If the lump discharges fluid, your vet may rub a glass microscope slide onto the lump, and examine the fluid as with an FNA.
- Biopsy – If the FNA is not diagnostic, your vet might take a biopsy of the lump. Generally, your dog will receive a sedative or anaesthetic and a small part of the lump or the entire lump will be removed. Then the lump is then sent to a lab, where thin sections of it are examined under a microscope.
- Lab test – If the lump contains fluid, the fluid could be sent to a lab to culture and check for infectious agents like fungi or bacteria.
Types of lumps and bumps – benign vs malignant
- Benign (non-cancerous)
Benign lumps and bumps do not invade other tissues and spread to sites beyond where they first grow. Most cause little concern, however, those that continue to grow can cause problems, like restricting movement or breathing because of the lump’s size, or your dog keeps scratching them because they are irritating. If benign lumps are causing problems, removal should be considered.
Lipomas (fatty lumps)
Lipomas are the most common benign lump dogs can get; they are often found under the skin of older dogs and are more common in larger breed, obese dogs. They tend to be round, soft tumours of fat cells that grow very slowly and rarely spread, and can be easily diagnosed with FNA. They might need removal if they are very large or affect movement.
Abscesses
An abscess is essentially a pocket of pus under the skin. They are caused by bacteria getting trapped and multiplying, for example after a cat bite or grass seed working in. They will generally need to be drained under sedation and flushed thoroughly with antibacterial solution. In some cases, your vet will prescribe antibiotics if they deem it necessary.
Hives (urticaria)
Hives on dogs are similar to those on humans – an allergic rash of round, red welts on the skin that itch and swell after, for example, a bee sting or contact allergy. They will often resolve on their own, however sometimes they need steroids or antihistamines to provide relief.
Sebaceous cysts
A sebaceous cyst is a plugged oil gland in the skin- essentially a very large pimple that is harmless to your pet and may feel like a raised bump. If left alone, it might go away without treatment, but may recur. If it bursts, a white, paste-like or cottage-cheese-like material is seen. Most sebaceous cysts do not cause trouble, although they can become red and sore.
Histiocytomas
Histiocytomas are an ulcerated nodule (or red button-like lump) often found on the legs of young dogs. They normally go away quite quickly but you should still have them checked by your vet as they can look similar to some very nasty cancerous tumours.
Sebaceous adenomas
Sebaceous adenomas are tumours of sebaceous glands that appear as multiple wart-like growths, most commonly seen in older woolly-haired dogs like Poodles, Maltese, Bichons, and their crossbreeds. Most of them do not cause problems, but should be removed if they are ulcerated or causing the dog irritation.
Perianal adenomas
Perianal adenomas are tumours of the oil glands around the anus, mostly in older entire male dogs. Any lump or bump around the anal region requires proper assessment and investigation as malignant tumours in this area are common.
Warts
Warts are more common in puppies, older dogs and dogs that are immunocompromised, and look like small skin tags or lumps. They are caused by a papillomavirus and are usually found on the head, face, genital area, lower legs, feet, on the footpads and between the toes. Dog warts typically have a cauliflower appearance similar to the warts people get and grow alone or in clusters. Dogs that go to a doggy daycare or dog parks can get warts due to close social contact with other dogs. No treatment is necessary, as they will usually go away by themselves after a few months.
Granulomas
Granulomas can be raised red lumps that may have a surface crust, or they can be found under the skin and have a firm consistency. They are not usually adhered to muscle. They can look similar to a highly aggressive tumour so vets will usually recommend a FNA or biopsy/ surgical removal. Surgical excision is often required for treatment.
- Malignant (cancerous) lumps and bumps
Malignant lumps and bumps grow and can spread through the body and affect other organs. They can spread by local growth (destroy nearby tissues) or by metastasis (tumour cells enter the bloodstream or lymphatic system to spread to other body sites). It is important that malignant lumps and bumps on your dog are surgically removed as soon as they are diagnosed to keep them from spreading.
Mast cell tumours
Mast cell tumours (MCTs) are the most common skin cancer in dogs. Mast cells are a type of immune system cell found in skin and other organs and normally play a role in inflammation and allergies. MCTs are most often found in dogs older than 8 years of age and in specific breeds, including Boxers, Boston terriers, Labrador retrievers, Beagles and Schnauzers. These tumours can look like many other lumps and bumps, which is why it is important to have your veterinarian check them out. The appearance of MCTs varies tremendously with some occurring as small, freely movable tumors of the skin, while others may be large, ulcerated and hairless.
Fibrosarcomas (soft tissue sarcomas)
Fibrosarcomas are locally invasive tumours of the skin’s connective tissue that grow fast. They are common in large breeds. They feel a lot like lipomas, so it is important to diagnose them with a FNA or biopsy. They often invade surrounding tissues and can be difficult to remove, however they do not tend to metastasise.
Melanomas
Melanomas in dogs are not caused by sunlight and are a lot less aggressive than human melanomas. Canine melanomas are tumours involving cells that give pigment to the skin. They can be benign or malignant and appear as dark lumps on the skin that grow slowly. Melanomas should be be removed, but they can recur.
Squamous cell carcinomas
Squamous cell carcinomas are skin cell tumours caused by sun exposure, so they are found on unpigmented or hairless areas such as the eyelids, vulva, lips and nose. They appear as raised, crusty sores and are locally invasive as they grow. Because of their location, removal can be difficult, however if left they can cause deformities and pain, and spread to lymph nodes and other organs.
Mammary carcinomas (breast cancer)
Mammary carcinomas are cancerous growths of the mammary glands. They are more common in unneutered female dogs and can be both benign or malignant. They can also occur in male dogs and are almost always malignant in these cases. They spread by metastasis to the lymph nodes, other mammary glands and organs. In most cases, surgical removal is recommended.
Osteosarcomas (bone cancer)
Osteosarcomas are the most common bone tumour, especially in large male dogs. They are caused by abnormal bone cell growth, unusual hormone stimulation, a previous fracture in the area, or genetic factors. They present as a lump or deformity in the bone, most usually of the leg and often spread to the lungs. Whilst radiography can give a presumptive diagnosis and assess lung metastasis, further tests may be needed for definitive diagnosis. They need surgical removal, which may include amputation of the affected leg.
- Other lumps and bumps on dogs
Ticks
Ticks are a member of the spider family that can attach to your dog when walking through parks, forests and heathland. They suck blood and in doing so can transfer some infectious diseases (such as Lyme disease) to your pet.
The best way to avoid your dog getting ticks is to use tick preventatives year-round. Check your dog daily for ticks by running your hands over their body, paying particular attention to their neck, ears, under their collar and legs.
There are many types and of lumps and bumps that can occur in dogs of all ages. If you find a mysterious lump, you should make an appointment with your veterinarian to have it evaluated. While it might be nothing to worry about, it could also be a more serious problem. The good news is that early detection can lead to successful treatment.