Lumps in Dogs
Can be frightening when you first discover them and can range in severity from harmless to life threatening

Lumps in dogs can stop any owner dead in their tracks as there is only one word that comes to your mind: cancer.

The term lump or bump usually implies that your dog has some type of a growth or swelling, and it is often designated as a tumor.

However, contrary to a lot of misconception, not all lumps are tumors, and even if they are, they are not always cancerous.

There are several different causes of a lump in your dog, and each one of them will show slightly different symptoms and have different treatments.

But there is one thing that is common in any type of lump; you need to have it tested as quickly as possible.


Acral Lick Dermatitis

One of the first causes of lumps in dogs is from a condition referred to as Acral lick dermatitis.

This is a situation where your dog self-licks themselves to the point that a lesion or lump will occur.

It is usually the result of boredom or some type of stress that your dog is undergoing, and as a result, your dog will lick so hard that they damage their own skin.

Beagle dogsLumps in dogs are not always the result of tumors

This will develop into a lesion and will also cause hair loss and usually occurs on the legs.

This is by no means a tumor and they will usually drain on their own.

If they do not, you may have to use an Elizabethan collar as well as behavior medications in severe cases.

Apocrine Sweat Gland Cyst

This form of lumps in dogs are very common and will produce a single nodule that is round and very smooth.

A nodule is a small mass of tissue or an aggregation of cells and is usually filled with liquid.

In this case, the nodule will be a have a bluish coloration and has liquid.

They can easily develop on your dog’s head, neck, or their legs. They cause no harm or damage, but they will need to be tested just to be safe.

If they are unsightly or become as issue, they can very easily be surgically removed.

Flea Allergy Dermatitis

The next potential cause of lumps in dogs is referred to as flea allergy dermatitis or flea bite hypersensitivity.

It is the result of your dog having a severe reaction to the saliva of a flea, and will cause papules, or small bumps.

Papules are smaller than a nodule, are generally very solid, but they do not contain pus.

Flea allergy can also cause very intense itching as well as hair loss, and in addition to the papules, can cause your dog’s skin to become crusty and very scaly.

They may also cause hot spots. If they are severe enough, steroids and antihistamines may have to be used.

However, flea control products can stop this cause of lumps from ever developing in most cases.

Follicular Cysts

This is considered to be one of most common cysts in dogs as well as one of the most common causes of lumps.

It is also referred to as sebaceous cysts and is a single round nodule that is either directly on the skin, or underneath the skin.

It will also have a bluish tint and may contain a yellow and grey type of material that is thick in gooey. This cyst is found on dog’s heads, their neck, as well as their truck area.

This lump should always be tested but there is one very critical factor that all owners should understand with this type of cyst; NEVER squeeze them.

They can be very dangerous to your dog if you do squeeze them they can cause a severe skin reaction.



This form of lumps in dogs may be the result of some type of an infection or a reaction to a plant such as fox-tail.

However, it could also be the result of other similar irritants.

They will appear as solid nodules but will vary in size.

If they are caused by some type of a foreign body, they will generally begin to drain, may become ulcerated, and can very easily lead to secondary infections in your dog.

These will definitely have to be tested, and if they are the result of a foreign body, they are considered very serious.

In this case they may involve major surgery as they can easily go very deep into your dog’s skin.

Mast Cell Tumors

This type of lumps in dogs is heart stopping to an owner, as they are a very common form of cancer. They are categorized as a tumor and are graded on a scale of one to four.

One is considered very slow growing, while grade four is very rapid and can spread to several parts of your dog’s body very quickly.

They are different than both nodules and papules in that they can come in several different sizes and well as numbers.

There may be just one of them, or there may be several that appear almost overnight and they will need to be tested immediately.

The grading process usually dictates the treatment, but they all will have to be surgically removed.

If they are a grade three to four, large areas of skin around the tumors will also have to be removed, and chemotherapy as well as radiation may have to be given in order for your dog to survive.


This form of lumps in dogs is equally as dangerous and is a malignant tumor found most commonly in older dogs.

They will appear as a single nodule that will be very dark in color and in most cases they will ulcerate.

They will also have to be surgically removed and large areas of skin around the tumor will also have to be removed. They are extremely dangerous.


This form of lumps in dogs is a localized collection of blood that has leaked out of your dog’s blood vessels, and is most commonly associated with ear infections as well as pendulous or long ears.

They will appear as very firm nodules, are fluid filled, and they may come in several shapes and sizes.

In most cases, they are not very dangerous and will resolve on their own.

If they do not resolve on their own, your veterinarian may have to drain them.


This is a tumor, but it is benign tumor, and almost always affects very young dogs. They will appear as a raised nodule and be strawberry red in color.

They usually affect dog’s legs, their head, or their ears.

They may have to be surgically removed, but in the vast majority of cases they resolve on their own.

Squamous Cell Carcinoma

This form of lumps in dogs is another very common malignant tumor and generally occurs when your dog’s skin becomes sun damaged or is chronically irritated.

There are two forms of these lumps; cauliflower and crusted.

If they are cauliflower like lesions, they will become ulcerated and affect your dog’s lips and nose; if they are crusted, they will appear on your dog’s legs or their body.

They are not as dangerous as other forms of malignant tumors, but they will still have to be surgically removed.

Tail Gland Hyperplasia

This form of lumps in dogs will be on their tail, as your dog has a sebaceous gland on the top of their tail very near its base.

This lump is very common in non-neutered dogs and can also be secondary to several diseases.

It will produce a very oily area around the base of the tail and may have to be surgically removed. Castration usually resolves them from reoccurring in most dogs.


This by no means is all the causes of lumps in dogs, but there is one very common theme; not all lumps are cancerous.

However, any lump should be taken very seriously and should be checked by your veterinarian as soon as you discover them.

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