Lumps on Your Dog: Common Types & What You Should Know

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If you find yourself worrying about finding a lump on your dog or wondering what the lump under your dog's skin is, try not to panic — there are many possible causes for lumps on your pet. While dogs can develop cancerous tumors, if you find a growth on your dog's skin, many are treatable. A lump or bump can even be as simple as an inflamed hair follicle.

The most important thing for you to do is stay alert to any lumps on your pooch and let your veterinarian know about them; that way, they can determine if treatment is necessary.

How Do I Monitor a Bump on My Dog?

Skin tumors are the most commonly seen tumor in dogs, reports the Merck Veterinary Manual. By regularly examining your dog's skin, you can take a lead role in caring for their health. Establish a weekly routine of inspecting your dog from the tip of their nose to the end of their tail. Make sure to hone in on commonly overlooked spots, like between the toes, under the tail and even in your dog's mouth — if they're cooperative. Chances are your pooch will enjoy these extra pets and rubs.

If you find a mass on your dog, make sure to note where it is, and not just mentally. Grab your phone to snap a quick photo or two. A dog's lumps and bumps can change over time, and keeping a log of their locations and sizes will help your vet more effectively manage your dog's health.

Young man in plaid shirt rubbing the ear of a smiling Bernese mountain dog.

Diagnosing a Lump on My Dog

"What should I do if I find a lump on my dog?" It's a common question pet parents ask. The best thing you can do if you discover a bump on your dog is to schedule an appointment with the vet. While Dr. Google provides a wealth of pet health information, it's easy to go down a rabbit hole of misinformation and panic. Instead, go straight to the expert. Even if your dog is due for an exam in a few months, don't wait. Even noncancerous masses can worsen and get infected if you wait too long to bring your dog in for treatment.

Your vet will need to take some tests to accurately diagnose your dog's lump. They may recommend a fine needle aspirate and cytology — one of the least invasive procedures to evaluate a lump or bump, during which a vet uses a small needle to collect cells. The cells are placed on glass slides and stained for microscopic review. Depending on the type of mass, the vet may be able to diagnose it quickly. Or, your vet may send out the slides to a laboratory to have them reviewed by a specialist.

While a fine needle aspirate is usually helpful, in some cases, with particular types of masses, your vet may need to take a larger biopsy and excise tissue with a scalpel or punch blade. This is a more invasive procedure than a fine needle aspirate and might require sedation or anesthesia. However, biopsies are usually performed at a vet's office and your dog should be able to return home the same day.

Common Types of Lumps on Dogs

As Petco mentions, lumps or bumps can often be categorized into two classifications: skin growths and tumors.

Skin Growths

A skin growth is a benign (non-cancerous) lump of tissue that projects out from the surrounding skin. Below are some of the more common skin growths on dogs:

  • Abscesses: These are lumps that form as a result of an infection from a bite, wound or foreign object. They are often painful and can contain large amounts of blood and pus with the possibility of rupturing.
  • Apocrine Cysts: These cysts are caused by obstructed skin glands. Think of them much like a human pimple. They may also rupture, which often helps clear them up.
  • Hematomas: These occur when blood accumulates beneath the skin following a trauma. These too can be painful for your dog.
  • Injection-Site Reactions: Following an injection, your dog may develop a small knot beneath the skin. These can be tender, but often fade within a couple of days or weeks.
  • Hives and Other Allergic Reactions: Hives are itchy, swollen pockets of skin as the result of allergic reaction. Other types of bumps can form from different types of allergic reactions.

Types of Skin Tumors in Dogs

The word tumor is one of the scariest words a pet parent can hear. However, not all tumors are cancerous, and even those that are can still be treated. A tumor, simply, is a mass of tissue that forms as the result of the accumulation of abnormal cells. Read on to learn about some of the different types of tumors and where they might form on your dog's body:

  • Histiocytomas: These small, hard and dome shaped benign growths often appear in younger dogs on their head, ear flaps or legs. They can often disappear, even without treatment.
  • Lipomas: These are most commonly found in overweight dogs — they are benign tumors consisting of soft and smooth clumps of fat cells that can grow very large, found most often around the chest, abdomen and front legs.
  • Sebaceous Gland Hyperplasia: This type of tumor forms when the glands that secrete sebum (the oily substance that lubricates your dogs skin) grows rapidly. These are also benign tumors that have a wart-like appearance often found on your dog's legs, torso or eyelids.
  • Malignant Skin Tumors: These types of tumors are cancerous, and appear as noticeable lumps or sores on the skin that won't heal. The most common type of malignant skin tumors are mast cell tumors. Early detection is key to keeping your dog happy and healthy.

Can a Skin Lump or Tumor Be Treated?

After the lump is diagnosed, your vet will walk you through your treatment options. Know that even when a mass is diagnosed as cancer, your dog can have a great outcome if the lump is treated early and aggressively. Proper nutrition may help manage (and prevent) mild skin bumps and irritation. The right balance of essential fatty acids in dog food can calm sensitive skin and support healthy skin and a shiny coat.

The key to a positive outcome is early treatment, and early treatment can't happen without early detection. If you find a bump, take a picture, note when it appeared and take your dog in to see the vet. The power to help your dog live a longer, healthier life is at your fingertips.

Contributor Bio

Dr. Laci Schaible

Dr. Laci Schaible, is a small-animal veterinarian and veterinary writer. She has won numerous awards for her commitment to pet owner education and is considered a leading veterinary telehealth expert.

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