Lumps and bumps on dogs: what every pet parent should know

Finding a lump on your dog can stop you in your tracks. Whether you discover it during a cuddle on the couch or while giving them a good scratch behind the ears, the instinct is often to worry, and then hope it’s nothing. The truth is there’s no reliable way to tell what a lump is without a vet’s help.

The good news is that early detection and assessment can make a real difference. The sooner a lump is assessed, the more treatment options are likely to be available.

This guide covers the most common types of lumps and bumps in dogs, how vets may investigate them, and what you can do at home to stay on top of your dog’s skin health.

Table of contents

• How vets may investigate lumps
• Benign lumps and bumps
• Malignant lumps and bumps
• Ticks
• Checking your dog at home
• How pet insurance can support you and your pup

How vets may investigate lumps

When you bring your dog in for a lump assessment, your vet will start by asking a few questions: when did you first notice it, has it grown, and is your dog showing any other signs of being unwell? From there, a physical examination helps determine what kind of testing is needed.

Depending on what your vet finds, they may recommend a fine needle aspirate, or FNA. A small needle is used to draw cells from the lump, which are then spread onto a slide and examined under a microscope. In some cases, your vet will read the slide in-clinic, and in others, it may need to go to a specialist vet pathologist.

Sometimes, a tissue biopsy may be needed to get a diagnosis. Tissue biopsy samples are sent to a lab for detailed analysis.

Alternatively, if a lump is discharging fluid, your vet may use an impression smear, pressing a slide directly against the lump and examining the result. Suspected infections may be cultured in a lab to identify the specific bacteria or fungi involved, to help guide treatment.

Benign lumps and bumps

Benign lumps don’t spread to other parts of the body and rarely invade the local area. The vast majority cause no major problems, though those that grow large enough to restrict movement or cause irritation may need to be removed.

Lipomas

Lipomas are the most common benign lump in dogs. They’re soft, round fatty masses that sit just under the skin and grow slowly. They’re most common in older dogs and in dogs carrying excess weight. Most lipomas are left alone unless they grow in a location that interferes with movement, such as in the armpit or behind a leg.

Histiocytomas

Histiocytomas appear as red, raised, button-like lumps, often on the head, face, ears and limbs of young dogs. They typically disappear on their own, but a vet check is always worthwhile because they can look very similar to more aggressive tumours.

Sebaceous adenomas

These are clusters of wart-like growths arising from sebaceous glands (the oil-producing glands of the skin). They’re more common in older dogs. Most cause no problems, but those that ulcerate, get infected, or bother your dog (some may be itchy or in a location that causes irritation or interferes with grooming) may be assessed for removal.

Perianal adenomas

These benign tumours are hormone-dependent and grow around the anus, developing in older male dogs who haven’t been desexed. Any lump in this area warrants proper vet assessment, as malignant tumours are relatively common at this site.

Haemangiomas

Haemangiomas are tumours that arise from blood vessels in the skin, and appear as raised, red or purple blood-filled lumps or ‘blood blisters’. Sun exposure is one contributing factor, though they can develop without it. Because these tumours look the same as malignant tumours, and can change over time and become malignant, vet assessment is always recommended.

Other types of non-cancerous lumps and bumps

Abscesses

An abscess forms when bacteria enter the body through a wound (often a bite or scratch) and cause painful, pus-filled swelling under the skin. Treatment typically involves draining the abscess under sedation, flushing it with sterile saline, and sometimes a course of antibiotics. If your dog seems to be in pain, is lethargic, or is running a temperature alongside a new lump, see your vet as soon as possible.

Hives

Hives in dogs appear as raised, red, itchy welts, usually triggered by an allergic reaction to an insect sting or something they’ve come into contact with in the environment. Your dog may be very itchy or irritated. Allergies may require antihistamines, or a short course of steroids to provide short-term relief. Longer-term solutions are sometimes needed if your dog has ongoing allergies.

Contact your vet immediately if your dog seems to be having an allergic reaction, as anaphylaxis (a severe allergic reaction) can be life-threatening.

Sebaceous cysts

These form when a sebaceous gland (the gland that produces the skin’s natural oils) becomes blocked, creating a firm lump with a creamy internal content. They’re particularly common in older dogs. Most are left alone unless they become infected or cause irritation. There may be discharge if the cyst leaks or bursts.

Warts

Canine warts are caused by a contagious papillomavirus and mostly affect puppies, elderly dogs, and those with compromised immune systems. They have a distinctive cauliflower-like appearance and usually clear up without treatment within a few months. Dogs who attend doggy daycare or mix frequently with other dogs in parks are at higher risk due to close contact.

Granulomas

Granulomas can appear as firm, raised lumps under the skin, sometimes with a crusted or ulcerated surface. They form in response to local inflammation, which may occur due to infectious, allergic, or immune system triggers. There are many types of granulomas with different management and treatment options, so it’s important to see your vet for assessment.

Malignant lumps and bumps

Malignant tumours grow and can spread through the body, reaching organs like the liver, lungs, brain, and bones. Some spread by growing directly into surrounding tissue, while others shed cells into the bloodstream or lymphatic system. Options for treating malignant tumours may include surgery, radiation, chemotherapy and, for some tumours, local injections into the tumour itself. Depending on the type of tumour, and whether it has spread, your dog may need ongoing care. Once you have a diagnosis, your vet can support you and help determine the best course of action for you and your pup.

Mast cell tumours

Mast cell tumours are among the most common canine skin cancers. They’re more common in older dogs and can look like almost any other type of lump, which is why accurate diagnosis matters so much. Once confirmed, your vet may recommend assessing whether the tumour has spread to other organs.

Fibrosarcomas

Fibrosarcomas are fast-growing tumours of the skin’s connective tissue and are more common in older dogs and large breeds. They can look and feel similar to other types of benign lumps and can easily be mistaken for them if proper testing isn’t done. These tumours are locally aggressive and invade surrounding tissues.

Melanomas

Canine skin melanomas aren’t linked to sun exposure in the way human melanomas are, and they’re generally less aggressive. They appear as dark, slow-growing lumps on the skin. Canine melanomas can also arise elsewhere, commonly on the mouth and toes (often the nail bed, which can look like an infected nail). These types tend to behave more aggressively and can spread rapidly throughout the body.

Squamous cell carcinomas

These appear as raised, firm, ulcerated lesions on areas with little or no pigmentation, such as the eyelids, nose, lips, and vulva. Sun exposure is a contributing factor. This type of tumour can also grow inside the mouth, and looks like a pink, often bleeding, mass. Left untreated, they grow by local invasion. Oral squamous cell carcinomas are more aggressive and often spread throughout the body.

Mammary carcinomas

Mammary carcinomas are cancerous growths of the mammary glands. They’re common in female dogs who haven’t been desexed, with risk increasing with age and varying by breed. While mammary tumours can occur in male dogs, it’s rare. Desexing your female dog before puberty significantly reduces the risk of mammary carcinoma.

Osteosarcomas and chondrosarcomas

Osteosarcomas are an aggressive bone cancer, commonly affecting larger breed dogs. Appearing as a lump on the bone, or swelling (usually in the limbs) this cancer causes significant pain and can spread rapidly to the lungs. Chondrosarcomas are a tumour of the cartilage and tend to arise on flat bones such as the ribs, skull, or pelvis. These tumours are generally less aggressive and slower to spread than bone tumours.

Staging

When a malignant tumour is confirmed, your vet may recommend diagnostic imaging, such as x-rays or ultrasounds, to assess whether the cancer has spread. In some cases, a CT scan may be recommended. This process is called staging, and it guides decisions about surgery, chemotherapy, and radiation.

Ticks and skin lumps

Ticks are worth mentioning separately, because they can appear as lumps and because the risks they carry go well beyond a skin reaction.

When a tick detaches after feeding, it leaves a small, crater-like mark on the skin that can be felt as a raised bump. Most ticks favour the head, neck, ears, and the area under the collar, but they can attach anywhere on the body. If you find a tick crater, check your dog’s entire coat carefully. A tick that’s still attached to your dog will feel like a raised bump.

Paralysis ticks are a serious concern in many parts of Australia. The toxin they inject causes progressive weakness that starts in the hind legs and moves forward, along with changes to your dog’s bark, coughing, vomiting, and eventually, breathing difficulties.

If you notice any of these signs and you’re in a high-risk area, seek vet care immediately. If you find a tick still on your dog, make sure you remove all parts of the tick safely and call your vet to assist you.

Year-round tick prevention products, prescribed by your vet, are the most reliable protection. Check your dog’s coat and skin daily by running your hands through it, paying close attention to the neck, ears, and between the toes.

Checking your dog at home

One of the simplest things you can do for your dog’s health is get into the habit of checking their skin regularly. Doing this during grooming or a cuddle means you’ll notice any new lumps quickly and be able to tell your vet when they appeared, whether they’ve grown, and how fast. That information is genuinely useful and helps direct the right tests.

If you notice a new lump, book a vet appointment rather than waiting to see if it changes. The sooner a lump is assessed, the better the outcome may be.

How pet insurance can support you and your pup

Even with the best care at home, unexpected health issues can still arise. Diagnosing and treating lumps, particularly malignant ones, can involve FNA tests, biopsies, lab fees, surgery, chemotherapy, and follow-up visits, and those costs can add up quickly.

Pet insurance can help manage the costs that come with unexpected vet care, giving you the confidence to act promptly when something doesn’t seem right.

With RSPCA Pet Insurance, your policy also contributes to the RSPCA’s animal welfare work across Australia. To learn more about how RSPCA Pet Insurance could support you and your pet, click here. Or, if you’re ready to take the next step, you can fetch a commitment-free pet insurance quote online.

Disclaimer

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