Solid Bumps in Cats
Can be the result of a myriad of different conditions

Solid bumps in cats can be the result of several different conditions that will range from allergic reactions to much more serious conditions such as tumors or cancer.

When your cat does develop a bump or a lump of some type, it will fall into two different classifications: Papules or nodules.

A papule is technically described as a circumscribed solid elevation of your cat’s skin with no visible fluid. They can vary in size from the shape of a pinhead to as large as one centimeter.


They can also appear in several different colors including brown, purple, pink, or red in some cases.

These forms of solid bumps may open up when they are scratched by your pet and as a result become infected or crusty.

A nodule is much larger than a papule, and is technically described as a solid collection of tissue in your cat.

Deep blue eyes in catsSolid bumps in cats can be life treatening in some cases

They usually start at one centimeter and can grow to almost two centimeters in some cases.

These forms of solid bumps or lumps can occur in your cat’s epidermis, dermis, or their subcutis, which refers any level of their skin.

Solid bumps in cats have different causes, but the most common are as follows:



An abscess is your cat is the accumulation of pus, and it may or may not be the result of an infection.

These forms of solid bumps will appear as firm, fluid filled nodules that will vary in both size and shape.

They will almost always have a crusty area at or near the actual puncture site of the bump.

If they do become infected, it can cause your cat to develop a fever and rapidly lose their appetite.

If it is scratched by your cat, they can also open up and start to drain. If this does occur, it will spread the infection, if that is the cause.

To treat them, they will have to be surgically drained and flushed, and than treated with antibiotics.

Allergic Dermatitis

This cause of solid bumps in cats is the result of an allergic reaction, with the most common cause being a reaction from some type of antibiotic that has been applied directly to their skin.

It may also be the result of a reaction to the metal nickel or wool.

However, one of the single largest causes of this reaction is from plastic, which is one reason you should always use metal or ceramic feeding bowels for your cat.

his condition may also be the result of a reaction to certain dyes or carpet deodorizers, which are quite dangerous to cats.

When allergic dermatitis attacks your cat, it will cause their skin to become red with small bumps or blisters.

These will usually affect areas where your cat does not have a lot of hair to act as protections.

They will become extremely itchy to your cat and can very easily cause hair loss.

The best form of treatment will be to find and then eliminate the cause, and then treat your cat with antihistamines.

Steroids may be used, but you should always get a second opinion, as they can have severe side effects.

Feline Acne

Another common cause of solid bumps in cats is Feline acne.

This is a condition that has no actual known cause, and it may occur only once in your cat, or it can become a chronic condition.

It is almost always found on the chin and it should be treated very seriously, as it can easily become deep forms of infections.

It will appear first as small blackheads, but can very easily develop into either pustules or nodules.

If it becomes aggravated, it can cause swelling and secondary infections.

It is usually treated with mild forms of medicated shampoo, antibacterial creams, or topical forms of Vitamin A.

If it becomes severe, antibiotics will have to be used. Fatty acids are also used as both a treatment and a preventive form of medication.


This is one of the most dangerous causes of solid bumps in cats.

This is a very rapid growing form of tumor that is extremely invasive in your cat.

It may be caused by Feline leukemia virus or it may also be the result of a recent vaccination.

This dangerous growth, if caused by a vaccination, will almost always appear at the exact site of the vaccination.

It will first appear as nodules that are very irregular in shape that can ulcerate easily.

They will have to be surgically removed, and because of their tenacity to be invasive, large areas surrounding the growth will also have to be removed.

If the tumor is on your cats legs, in most cases the only way to effectively treat it is with amputation.

Radiation and chemotherapy may also have to be utilized, and it can become extremely expensive.

Mammary Cancer

This form of solid bumps in cats is almost always found in non-spayed females and it is extremely dangerous.

It is estimated that over 90 percent of all cases are malignant, and they will appear as single or multiple nodules under your cat’s skin.

They will vary in size, almost always be irregular in shape, and can very easily ulcerate and spread.

They are extremely dangerous and surgery is the only form of treatment.

Mast Cell Tumors

This form of solid bumps in cats is also extremely dangerous, and is graded on a scale of one to four, with four being the most deadly.

However, in cats, most forms are only a grade one. Theses tumors will appear as nodules in varying sizes, shapes, as well as numbers. They will also have to be removed by surgery.

Miliary Dermatitis

These forms of solid bumps are most often associated with infections, auto-immune diseases, hormonal disorders, or nutritional deficiencies.

They will appear as multiple small bumps and usually appear on your cat’s hips, neck, back, or their thighs.

They will cause moderate to severe itching, and are very effectively treated with fatty acid supplements. In severe cases, corticosteroids may have to be used.


This form of solid bumps is caused by the larvae of the Cuterebra fly and will occur in the late summer months.

They will be nodule in size, and will almost always affect your cats head and neck areas.

These nodules will have a very small opening which the larvae use to breath.

These nodules are extremely dangerous and they will have to be surgically removed by a professional.

If you attempt to remove them and they break, the allergic reaction can be so severe it can take your cats life within a few hours.

Tick Bites

Tick bites can cause nodules, even once the tick is removed. They will become extremely red, very itchy, and become crusty very rapidly.

In most cases, once the tick has been removed, the nodule will heal on its own.


Solid bumps in cats have several more causes, but these are the most common.

Any bump should be treated very seriously, as some of the causes may cost your cat their life in not treated as quickly as possible.

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