Expert guide to canine lumps and bumps

Oh no! Have you noticed a sudden lump on or underneath your pet’s skin? While it’s natural to feel concerned about such a thing, we’d recommend being alert but not alarmed about any bumps and lumps.

Canine lumps and bumps are generally classified as benign (non-cancerous) or malignant (cancerous, with the potential to spread around the body). Benign masses may require treatment if they are bothering your pet, but in many cases, they can simply be monitored for any changes. However, even if your furry friend's lump is diagnosed as a malignant type, rest assured that many can still be treated effectively if caught early on!

The safest course of action is to have any new lump promptly checked by your veterinarian. And who knows? Your furry friend's lump could be found to be something completely insignificant such as a nipple on a male dog (which happens more than you’d think, and usually results in a relieved chuckle from both vet and owner!)

Types of lumps and bumps on dogs

When assessing any lump on your pup, your vet will take close note of the lump itself and assess your dog’s overall health. This is important as some types of masses can have effects on your dog’s wellness.

Your vet will likely ask you questions about the lump, such as when it first appeared and whether it has grown since it was first noticed. They will then examine the lump itself, assessing its location (e.g. on the skin vs underneath the skin), its size, and other characteristics (such as whether it is painful to touch, hard vs soft, mobile vs fixed).

It's important to note that many skin bumps on our furry mates cannot be diagnosed on appearance alone and will require further testing to confirm their exact cause. However, based on the information gained during your pet’s initial assessment, your vet will start to prioritise the more likely diagnoses and will then be able to discuss any recommended next steps with you.

Benign (non-cancerous)

Benign lumps and bumps do not invade other tissues or spread to other areas of the body, so luckily most are relatively harmless. However, some benign lumps may still require treatment, such as those that grow large enough to cause movement or breathing restrictions, or those associated with irritation or infection.

Common types of benign lumps include:

Lipomas (fatty lumps)

Lipomas are the most common benign tumour in dogs and are more common in obese pets. They tend to be round, soft masses of fat cells located underneath the skin. Because they grow very slowly and rarely spread, it can take up to six months before you see any change. Lipomas can be easily diagnosed with something called an FNA (fine needle aspiration, where lump cells are collected with a needle to inspect under a microscope). If they become very big or hinder movement (e.g. by growing in an armpit), your vet might recommend removal.

Abscesses

Abscesses are pockets of pus and inflammation underneath the skin caused by infection. They will generally need to be drained and flushed out under sedation or anaesthesia. In some cases, your vet will also prescribe antibiotics to clear the remaining infection.

Hives (urticaria)

Hives are rashes of itchy, red wheals on the skin. Like in pet parents, they occur due to an allergic reaction to irritants such as insect stings or certain plants. They will often resolve on their own, however it’s usually recommended for pets to be prescribed steroids or antihistamines for quicker relief.

Sebaceous cysts

These cysts form when sebaceous glands within the skin become blocked, and occur most commonly on the backs of older pooches. They appear as swellings with creamy matter inside them and may become red and sore. Sebaceous cysts can also be diagnosed with FNA. Most of them don’t cause problems, so they’re usually left alone unless they’re infected or irritating your furry friend.

Histiocytomas

Histiocytomas are red, button-like lumps often found in young pups but in many cases, they resolve on their own after several months. This being said, it’s still recommended that you have the diagnosis confirmed by your vet, as some cancerous tumours can have a similar appearance.

Sebaceous adenomas

Sebaceous adenomas appear as wart-like growths on the skin. They’re more common in woolly-haired older dogs like Poodles, Maltese, Bichons, and their crossbreeds. A biopsy is required for a definite diagnosis, but vets can often identify these lumps by just looking at them, due to their classic appearance. Most sebaceous adenomas don’t cause problems, but those that are ulcerated or causing irritation are best to be surgically removed.

Perianal adenomas

Perianal adenomas are tumours that grow around the anus, occurring most commonly in non-desexed older dogs. Any lump or bump around the anal region requires proper investigation due to the frequency of malignant tumours in this area.

Warts

Warts are caused by canine papillomavirus and are therefore more common in puppies or pooches with reduced immune capacity. They usually appear as clusters of small, cauliflower-like or tufted lumps on the head or in the mouth. A biopsy is required for a definite diagnosis, but vets are often able to make an educated guess due to their classic appearance. They will usually go away by themselves after a few months. However, if they are irritating your furry mate or aren’t resolving, removal should be considered.

Granulomas

Granulomas may appear as raised red lumps with a surface crust or may be located under the skin. They can appear similar to more aggressive tumours, so vets will usually recommend a biopsy to confirm the diagnosis.

Haemangiomas

Haemangiomas are tumours of blood vessels. UV exposure can increase a dog’s risk of developing them. Diagnosis through a biopsy (which can be combined with surgical removal) is always recommended, as these tumours can change over time to become malignant. Plus, surgical removal is curative if the tumour is benign.

Malignant (cancerous)

Unfortunately, malignant lumps and bumps are cancerous, so they tend to spread through the body and cause harm. Depending on the type of tumour, they may spread locally (destroying nearby tissues) or distantly (through the bloodstream or lymphatic system) to affect organs like the liver, lungs, brain or bones.

Malignant tumours should be removed as soon as possible to improve your furry friend’s chances of successful treatment. In some cases, further diagnostic testing is required to check for potential tumour spread (such as x-rays, ultrasound or CT scan imaging), and additional treatment such as chemotherapy or radiation therapy may be required to target any remaining tumour cells floating around the body.

Common types of malignant tumours include:

Mast cell tumours

Mast cell tumours are a tumour comprised of mast cells (a type of white blood cell). They comprise up to 25% of all tumours and are most common in dogs eight years of age and older. Mast cell tumours can look similar to many other tumours and can range in behaviour from relatively benign to malignant, so it’s vital to have them diagnosed accurately by a vet. This will often initially involve an FNA, but a surgical biopsy is required to properly assess the aggressiveness of a particular mast cell tumour.

Soft tissue sarcomas

These are locally invasive tumours of the skin, muscle or nerve tissues. An FNA or biopsy is required for diagnosis, as they can feel similar to lipomas (also known as fatty lumps). These tumours can spread deeply through tissues and therefore become very difficult to remove surgically, so early treatment is always best!

Melanomas

Canine melanomas are tumours of melanocytes (pigment cells) of the skin or oral tissues that can be benign or malignant. Their cause in dogs is unknown, but they are most common in older pooches. These tumours require an FNA or biopsy for diagnosis. More benign types can usually be cured with surgery, while more aggressive forms may require additional treatment such as radiation therapy.

Squamous cell carcinomas

Squamous cell carcinomas are skin cell tumours that usually develop on pink or hairless skin that gets a lot of sun exposure. They can present as red, ulcerated or crusty sores, and tend to spread locally (ouch!). Early treatment is required to prevent the deep spread of the tumour cells that can make successful surgical removal difficult.

Mammary carcinomas

Mammary carcinomas are cancerous growths within the mammary glands (breast tissue) and are more common in non-desexed female dogs. These tumours can spread through the body to nearby lymph nodes, other mammary glands and organs such as the lungs. Surgical biopsy is required to differentiate these tumours from benign mammary lumps. Mammary carcinomas are best surgically removed whilst they are still small for the best chance of successful treatment.

Osteosarcomas

Did you know that Osteosarcomas are the most common type of bone tumour, especially in large breed dogs? They most commonly occur in the limbs, and usually create swelling, pain and eventual bone weakness in that area. These malignant tumours often spread to the lungs, so vets will often recommend chest imaging as part of their investigation of these tumours, as well as bone X-rays and biopsies. Surgery, which often unfortunately involves amputation of the affected limb, will be discussed as a treatment option to provide relief from pain, as well as other treatments such as chemotherapy or radiation therapy.

Chondrosarcomas

Chondrosarcomas are malignant tumours of cartilage. They can develop in limbs or more central body parts where cartilage is present, such as the nose or ribs. Chondrosarcomas most commonly occur in larger breed pooches. A biopsy is required for diagnosis, and treatment involves surgical removal where possible.

What to look for

It’s always a good idea to check your furry friend over once a month for any new lumps and bumps that may have popped up. This should ideally involve opening their mouth to have a look inside, and feeling all over their body from 'nose to toes to tail' and don’t forget to check underneath their tail and belly too! Lumps may be visible on top of the skin, or may be sitting deeper within the tissues, requiring a finger-pad massage technique to detect them (trust us, they’ll love the massage!)

If you notice your fur-friend being particularly sensitive to touch in one spot, it’s a good idea to part the fur in that area for a better look at the skin (checking for any hair thinning, redness, or raised or ulcerated skin patches), as well as examining gently for any swelling beneath the skin.

Treatment options

The best treatment options for your pooch will depend on the type of lump they have, whether it has spread to other regions of their body (in the case of malignant lumps), your pet’s general health, and your own preferences.

Based on your pet’s diagnosis, your vet will discuss with you the pros and cons of any viable treatment options, and allow you to decide on your pet’s course of treatment from there. Common treatment options include:

Non-surgical treatment

Some lumps luckily will not require surgical removal for resolution. Common examples of this include:

• Abscesses: Which will often resolve with drainage of the infectious fluid, flushing with sterile saline, and sometimes a course of antibiotics.
• Granulomas: Which often resolve with a course of steroids and the management of any infectious or allergic triggers.

Surgical removal

For some tumours, surgical removal under anaesthesia may be required and can involve:

• Lumpectomy: This is the surgical removal of the lump. Sometimes a large incision is required to ensure that all potential tumour cells are hopefully removed from around locally invasive masses – this is also known as 'taking wide margins'.
• Partial removal/'debulking': This involves surgically reducing the size of lumps that can’t be completely removed in one go (e.g. very large lumps or those located in awkward areas). Your pup may require further treatment afterwards, such as radiation therapy or chemotherapy.

Monitoring

In many cases, benign lumps may simply require periodic checks by your vet to ensure they’re not changing or growing.

Cryosurgery

This is when extreme cold (liquid nitrogen) is used to remove very superficial skin lesions.

Radiation therapy

This is used for malignant lumps and bumps that can’t be surgically removed, or to 'mop up' any remaining tumour cells after lumpectomy of some types of locally invasive malignant masses. It uses high energy radiation to shrink or kill cancer cells.

Chemotherapy

This is the use of drugs to kill cancer cells that have spread around the blood or lymphatic system, or to hopefully clear remaining tumour cells after surgical removal of a malignant mass.

Diagnostic procedures for lumps on dogs

While your vet will often be able to make an educated guess on the type of lump your pet may have (based on factors such as your dog’s age and breed and the appearance of the lump), many canine lumps can only be definitively diagnosed through microscopic assessment of the cells involved.

Depending on their diagnostic suspicions, your vet might recommend performing one or more of the following tests to determine the type of lump or bump your dog has:

• Fine needle aspiration (FNA): This test involves a small needle being inserted into the lump to collect some of its cells and/or fluid, which are then deposited onto a microscope slide. The slide is then stained and viewed under a microscope to look for particular types of body cells, bacteria or fungi. Sometimes your regular vet may be able to make a diagnosis in clinic, but other times your pet’s sample may have to be sent to a specialist pathologist in a laboratory for confirmation of the lump type. FNA can usually be performed on conscious pets, but if your pup’s lump is painful or if your pup is particularly wriggly, they may require sedation.
• Impression smear: If your pet’s lump discharges fluid, your vet may be able to rub a microscope slide onto the lump, and then stain the collected fluid and examine it for cells as with an FNA.
• Biopsy: If an FNA doesn’t contain enough numbers of useful cells for diagnosis (which can sometimes happen with certain types of lumps), your vet might need to take a surgical biopsy instead. Generally, your dog will receive a sedative or anaesthetic, so that a small section of the lump or the entire lump can be removed. This sample is then placed in formalin (a preservative) and sent to a lab, where thin slices of it are examined under a microscope.

Other common causes for new lumps on dogs

Ticks

Nobody likes them! But, ticks are present in bushy or scrubby areas in many regions of Australia. Depending on your geographic location, your furry friend may be exposed to paralysis ticks, brown dog ticks or bush ticks.

A tick on your dog will appear as a cream, brown or grey coloured lump attached to the surface of your pet’s skin. They can range from the size of a pinhead to the size of a small grape, depending on how much blood they have ingested. If you look closely, you will see the tick’s short, threadlike legs protruding from under the base of the embedded tick, near your pet’s skin. Ticks that have already fallen off will leave a small red 'crater' in your pet’s skin.

Brown dog ticks and bush ticks can be irritating to your furry friend and can unfortunately spread certain infectious diseases. Paralysis ticks can cause progressive muscular weakness, leading to symptoms such as wobbliness or an inability to walk, laboured breathing, a weakened bark, and vomiting or retching. Unfortunately, tick paralysis can be deadly. It’s always best to consult with your vet for advice on which ticks are prevalent in your area, what symptoms to look for, and the most effective tick prevention products for your pooch.

If you see a tick on your furry mate, it’s best to remove it ASAP using a tick removal tool and check your pet over for any remaining ticks. If paralysis ticks are in your area, your dog should be closely monitored for any symptoms of tick paralysis. If they demonstrate any concerning signs, do not hesitate to get in touch with your vet immediately.

What to do if you discover a sudden lump under your dog’s skin?

If you notice a new lump on your pet’s skin, it’s a good idea to first check that it isn’t a tick. Once this is (hopefully!) ruled out, it’s helpful to take a photo of the lump, with something nearby for scale, such as your thumb. That way you can recheck it every few days for the next two to four weeks to see if it is changing in size or appearance - pretty easy right?

For anything underneath the skin, it’s best to very gently feel around the mass (provided this isn’t painful for your pooch) and try to determine its size (e.g. pea sized, grape sized, ping pong ball sized, etc). You should then recheck the mass regularly over the next two to four weeks to see if it’s getting bigger.

Any new lump or bump that hasn’t resolved in four weeks, is bothering your dog, or is visibly growing or changing should ideally be assessed by your vet.

When to see the vet

While finding a lump or bump on your dog can be worrying, don’t panic but do be proactive! A prompt check up with your trusted vet can bring you peace of mind; either through your vet’s professional reassurance that your pet’s lump is nothing to worry about, or by ensuring that you have given your pet the best chance of a recovery with early intervention.

Your furry friend’s health is more than fur-deep! Those little lumps and bumps could be nothing – or something worth checking. While the right diet, treats, and supplements help keep them in tip top shape, unexpected vet visits can happen.