Lumps on Dogs - Should I Worry?

As a pet owner, it is easy to think the worst when you find a lump on your dog. However, lumps come in all forms and can mean many different things for your canine companion.

Read on for guidance on how to identify different kinds of lumps, so you can have a better idea of what you're dealing with and get some advice on what you can do next.

Our article will cover:

• What causes lumps on dogs?
• Types of different lumps on dogs
• What you can do at home
• What your vet can do

Are you worried your dog might need emergency care?

If in any doubt, please use our free Felcana Symptom Checker to triage your pet and find out if your pet needs emergency veterinary care.

How do I check for lumps on my dog?

This video below provides a brilliant guide on how to feel for lumps on your dog, and how to measure them. 

What can cause lumps on your dog? 

Lumps can occur for a number of reasons. Although they can be variable, many have typical appearances. The way they look and feel can give you some important information on how nasty they are likely to be. In the following sections we are going to detail common types of lumps you might find, how to identify them and whether you need to rush to your vet.

1. Abscesses

Why do they occur?

Abscesses are a build up of pus under the skin. They happen because of an infection at a site where the skin barrier has been broken. 

Risk factors 

Does your dog: 

• Have walks off the lead 
• Love playing fetch/picking up sticks
• Run around in tall grass 
• Recently had a scuffle - often with the neighbourhood cat

Identification checklist 

• Found at wound or injection sites
  
  • Injection site abscess are uncommon as vets are very sterile. Commonly injections are given in the scruff (just between the shoulder blades) or in the muscles of the spine or thigh, making these common locations for injection site abscesses.
  • Bite wounds, scratches or stick injuries often result in abscess formation
  • They can also happen if a foreign body tracks through the skin of your dog - a common one to occur is grass seeds, especially in summer
• Not draining or draining with pus and/or blood
  
  • If it is draining, you may see thick yellow/green tinged pus with or without blood coming out of the lump
  • If it is non-draining, it will gradually increase in size without anything coming out of it
• Variable in size 
  • If the abscess is non-draining, it is likely to keep increasing in size as all the gunk builds up in a contained space
  • If the abscess then becomes draining, it is likely to reduce in size as all the gunk comes out
• Feel soft and fluid filled, or hard and walled
  • Early abscesses, especially before they start to drain, are likely to feel soft and fluid filled. Imagine poking a water balloon - it'll feel just like that
  • As abscesses stick around for longer the walls start to feel firm and thickened
• Have a smooth and regular texture
• They can be recurring or a be a one time thing 
  • This depends on whether the cause of the abscess (like a foreign body) remains in the site
• Abscesses are benign, non-cancerous lumps

Do you need to visit the vets? 

We suggest visiting the vets if you suspect your dog has an abscess - especially if it is not draining so that your vet can lance it, clean it and prescribe treatment if necessary. Seeking veterinary advice is especially important if the abscess is recurring or non-resolving.

In the meantime, you can help your dog out by cleaning the sight with a dilute salt solution (if they allow it) and if the abscess is in a site they can lick, pop a buster collar on to stop them from getting at it. 

2. Lipomas (Fatty Lumps)

Why do they occur?

Fatty lumps or Lipomas are caused by benign increases in the number of fat cells, which are normally produced by your dog, collecting in a specific location.

Risk factors 

Is your dog:

• Overweight
• Older
• Female
• A Weimaraner, Cocker Spaniel, Dobermann, Labrador Retriever, Miniature Schnauzer or Dachshund

Identification checklist 

• Can be found anywhere 
  
  • They can occur everywhere and anywhere and form as separate pockets of skin so feel like a movable lump
  • Rarely, they can spread down into the muscle making then infiltrative lipomas which are trickier to remove
• Non-draining 
• Variable in size
  • They range in size and can be very small to ginormous 
  • Lipomas generally increase in size over time however, they may get smaller if your dog starts to loose weight 
• Soft and squishy consistency
  • Lipomas are just lumps of fat and that is exactly what they feel like
• Smooth, regular texture and they can be pedunculated
  • Lipomas are often smooth and regular, without changes in skin texture
  • Lipomas can be pedunculated - meaning that they are attached to your dog by stalk of skin and often move freely
• Can have one or multiple
  
  • Note that if your dog has multiple lumps just because you identify one as a lipoma it doesn't mean they all are!
• Persistent and recurring
  
  • Once a lipoma is there even if it changes in size it is there, it won't completely go away unless surgically removed
  • Once surgically removed lipomas can recur in different sites or at the same location

• Lipomas are benign, non-cancerous fatty tumours 
  • Very rarely lipomas can actually be liposarcomas which are malignant and cancerous, although these do not spread around the body in the same way as other cancers. They can be particularly challenging or even impossible to remove.

Do you need to visit the vets?

Lipomas are generally harmless to your dog unless they cause difficulty in moving around, eating or drinking. Lipomas may reduce in size if your dog looses weight. They can be left alone or surgically removed by a vet which will cure them.

3. Sebaceous Cysts 

Why do they occur? 

 A Sebaceous Cyst is a collection of fluid or debris that blocks the sebaceous gland (oil gland) and clogs it up similar to a pimple.

Risk factors

Is your dog: 

• Older

Identification checklist

• Most commonly found along your dog's back 
  • However, sebaceous glands are found throughout the skin and any one of them can get blocked
• Non-draining 
  • They are not draining which is why the gland gets clogged up 
  • If the cyst were to burst white pasty material will come out
• Small in size
• Hard and firm consistency with a smooth in texture 
• Dark/red in colour
  • They are usually dark in colour but can become red and sore - especially if they become infected
• They can be recurring or a one time thing and your dog can have multiple at once or only one
  • They may persist or self resolve and can recur at the same site or appear at different sites or never reappear - in summary it is variable!
• Sebaceous cysts are benign, non-cancerous lumps

Do you need to visit the vets?

Sebaceous cysts are harmless lumps and can be left alone unless they become infected or irritated. If they appear infected, you can clean the site with a warm, dilute salt solution. If the infection persists take your dog to the vets for advice. 

4. Warts/Papillomas 

Why do they Occur? 

Warts (Papillomas) are common in dogs (like in people) and are caused by a very contagious viral infection that your dog can catch from other dogs.

Risk factors 

Is your dog:

• A puppy or an older dog
• Immunocompromised 
• In close contact with other dogs

Identification checklist

• Located on the face, eyelids, mouth, groin, lower legs and feet
• Non-draining
• Have a firm consistency, with a cauliflower like appearance and roughened texture
• Commonly your dog will have multiple warts in clusters
• Recurring
  • Warts appear suddenly (e.g. lump appeared overnight on your dog) and self resolve, clearing up on there own
  • They can recur in your dog especially at times of stress
  • Your dog may develop an immunity to the virus with time
• Papillomas are benign masses caused by a persistent viral infection

Do you need to visit the vets?

Warts (Papillomas) do not require veterinary treatment unless they are causing irritation, are infected, or are making it difficult for you dog to eat, drink or walk comfortably. They should self resolve with time - it could take up to a few months. 

5. Histiocytomas 

Why do they occur? 

Histiocytomas are a benign, non-cancerous tumour that occur in dogs due to an abnormal overgrowth of histiocytes, which are a type of immune cell. 

Risk factors 

Is your dog: 

• Under the age of six

Identification checklist

• They commonly occur on the limbs or face of dogs
  • However they can occur anywhere
• Non-draining
• Small in size (less than 2.5cm)
• Red in colour and hairless
• Firm in consistency and smooth in texture
  
  • Like a small raised button
• Only one usually appears at a time 
• Histiocytomas are a benign tumour 

Do you need to visit the vets?

Histiocytomas usually go away on their own in a few months. However, they need to be seen by your vet to make sure they are not a different kind of nastier tumour.

6. Mast Cell Tumours

Why do they occur? 

Mast cell tumours are the most common malignant cancerous growths in dogs. They are caused by a change and overgrowth of mast cells, which are a type of immune cell that normally contribute to inflammation. 

Risk factors 

Is you dog

• Older
• A Boxer, Boston Terrier, English Bull Dog, Mastiff, Labrador Retriever, Golden Retriever, Shar Pei, Fox Terrier, Dachshund or Weimaraner

Identification checklist

• Can be seen anywhere on the body but most commonly on the trunk or hind limbs and appear in or just under the skin
  • The form of mast cell tumours that appear on the skin is the most common 
  • Less commonly, they can occur on internal organs such as the spleen, liver or bone marrow. This is known as the visceral form and is considered a more aggressive type of cancer
• Appearance of mast cell tumours are variable, they can be: 
  
  • Raised
  • Red 
  • Ulcerated
  • Attached by a stalk 
  • Cause focal thickening of the skin 
• A feature of mast cells is that they can change from day to day 
  • They can appear more benign one day and angrier the next 
  • They can look like benign lumps for a while and then suddenly grow and ulcerate
• They are usually solitary lumps
• Mast cell tumours are cancerous and malignant

Do you need to visit the vets?

If you suspect a mast cell tumour it needs to be seen by your vet so they can stage it. This allows your vet to determine how dangerous it is to your dog's health and what treatment options are available to you. You should see your vet as soon as possible if your dog also has decreased appetite, weight loss, vomiting, diarrhoea, lethargy, coughing, difficulty breathing or enlarged lymph nodes. This could suggest systemic involvement which requires veterinary attention.

7. Melanomas 

Why do they occur? 

Melanomas are caused by an abnormal overgrowth of melanocytes - which are the cells in skin that produce pigment. They can be malignant, cancerous tumours or benign, non-cancerous tumours.

Risk factors

Is your dog:

• A Visla, Miniature Schnauzers, Doberman Pinschers, Airedale Terriers, Schnauzer, Scottish Terrier or Bay Retrievers
• Older

Identification checklist

• Non-draining
• Pigmented
• Benign Melanomas 
  • Single lesion most commonly on the feet, face, trunk or scrotum 
  • Small and slow growing 
• Malignant Melanomas
  • Single lesion more commonly found on the lips, eyelids, digits or scrotum 
  • Can become ulcerated appearing rough in texture
  • Grow rapidly 

Do you need to visit the vets?

If you suspect a malignant melanoma you should seek veterinary advice as soon as possible. They are very fast growing and can spread to internal organs quickly so require rapid treatment. If you suspect a benign melanoma it is suggested to still seek veterinary advice to determine if it is truly benign and monitor it in case it changes to the malignant form.

8. Squamous Cell Carcinomas

Why do they occur? 

Squamous Cell Carcinomas are the second most common skin cancer in dogs. They happen because of an abnormal overgrowth of squamous cells which are part of the structure of the skin. They are locally invasive and destructive.

Risk factors

Is your dog:

• Older 
• A Staffordshire Bull Terrier, English Bull Terrier, Beagle, Poodle, Dalmatian, Harlequin Great Dane, Whippet, Beauceron Sheepdog, Bouvier Des Flanders, Briad, Black Labrador Retriever or a Black Giant Schnauzer 
• A depigmented or spotted breed 
• A large pigmented breed 
• Suffered from papilloma virus (warts) previously

Identification checklist

• More commonly occurs in poorly pigmented or hairless regions on the digits, head and neck, trunk, scrotum and back end
  • Due to the association of UV radiation
• When not on the digits 
  • Can be ulcerative 
  • Raised and firm with an unclear border
  • Can be roughened and have a cauliflower appearance
  • Range in size up to 5 cm across
  • Reddened and crusty
  • Common to become infected and bleed
• When found on the digits 
  • Can occur on several toes normally on the same leg
  • Often starts with the nail getting longer, followed by swelling and ulceration at the nail base 
  • It can be seen as swelling of the toe and the cracking of the nail
  • The entire nail may fall out 
  • Your dog may be lame and walk with a limp

Do you need to visit the vets?

If you suspect a squamous cell carcinoma you should seek veterinary advice. Treatment is needed to prevent this aggressive tumour causing further damage to the area.

What can you do? 

Firstly, check if your dog needs emergency veterinary care using our free Felcana symptom checker.

Monitor your dog's skin lump. Make a record of changes in size, colour, texture, shape, consistency and whether anything comes out of it. The best way to do this is by taking pictures and recording the dates.

Seeking veterinary advice is the best thing you can do for you dog. That way you can be sure what the lump is and your dog can receive treatment if indicated/possible.

Going to the vets is especially recommended if you suspect the following: a non-resolving abscess, any cancerous lump (such as a mast cell tumour, melanoma, squamous cell carcinoma etc.) a histiocytoma or benign melanoma (to confirm that they are not another kind of tumour.)

You should also seek veterinary advice if the lump is causing discomfort to your dog, impairing their: breathing, movement, eating or drinking, has change appearance, feels different, looks ulcerated or infected or is bleeding.

And finally, veterinary investigation is needed if along with the lump your dog also has weight loss, a decreased appetite, enlarged lymph nodes or is lethargic.

What can your vet do?

Investigate

1. Fine Needle Aspirate (FNA) 

A Fine Needle Aspirate is where a vet will poke a sterile needle into your dogs lump to collect some material, then push out the needle aspiration onto a glass slide to assess under a microscope. Many lumps can be diagnosed in this way, as it gives information on what cells are making up the lump. 

2. Biopsy 

A Biopsy is where the vet takes a piece or all the lump off of your dog and sends it for lab analysis - to look at the layout and type of cells. This is important for diagnosis of certain lumps and differentiation of cancerous and non-cancerous lumps.

3. Surgery 

This can include procedures like surgical biopsy - to make sure they take out the whole thing (which is very important for cancerous lumps.) As well as surgical exploration of abscess - to make sure there isn't any foreign material stopping the abscess from healing.   

Treat

1. Surgery

This can be done to investigate as described above but may also be curative in some cases.

2. Prescriptions

Your vet can prescribe specific medication for the management and treatment of lumps depending on what they are.

3. Chemotherapy/Radiation therapy 

Your vet can discuss/refer you for chemotherapy and radiation therapy options if indicated. They can discuss and make a plan that best suits you are your canine companion.

Remember Not to Panic!

Identification of the lump is one of the most important steps to helping your dog and not all lumps are life threatening. Many of the lumps listed above can self-resolve or be helped along the way with non-invasive treatments. Even if it is something more menacing, early identification is the best thing for your dog and means you can start treatment as soon as possible. Of course, if you have any doubts or worries, contact your vet as soon as you can for advice specific to your dog. 

This article was written by Sumuduni Theminimulle. Sumuduni is a final year vet student at the University of Bristol. She is set to graduate in 2022 and start her first role as a small animal vet in Essex.