I Found a Hard Lump on My Dog — What is It?

Dog Health > Dog Diseases & Symptoms >
hard lump on dog

Pet owners may pet or groom their dog to suddenly feel a hard lump on their dog that they have not felt before. This can cause concern, and in some cases, downright panic.  A lump also referred to as a mass, growth, bump or tumor, can occur anywhere on the body and come in all shapes and sizes. Some hard lumps on dogs can be benign and others malignant.  In this article, will review the possible causes for hard lumps on dogs and offer recommendations for what you should do.

There are many ways to describe a skin lump on a dog. The size, shape, texture, color, location, depth, and rate of growth are all characteristics that can help determine what kind of lump it is and what level of concern you should have.

Ways to describe a hard lump on a dog include:

  • Size- Dog lumps can range from very small and huge. In fact – some tumors, such as lipomas (also known as fatty tumor) in dogs can weigh several pounds.  Learn more about What Small Bumps on Dogs Can Mean and What Large Bumps on Dogs Can Mean.
  • Shape – Some dog lumps can be regular and others can be irregular. For example, most lipomas are round in shape.
  • Texture – Some dog lumps are firm and some are soft. Some tumors can have both components with part being soft and part firm.  Lumps that are commonly soft are fatty tumors. Learn more about Fatty Cysts in Dogs.
  • Color – Some hard dog lumps are under the skin and have only the color of the skin and other skin lumps on the skin can white, red (if inflamed), or pigmented brown or black. Learn more about What Does a Black Lump on a Dog’s Skin Mean? 
  • Location – Lumps can occur anywhere on the body. Most lumps that pet owners feel are on the skin, however, lumps can also occur on organs such as on the liver, spleen, and/or kidney. Skin lumps in dogs can grow on top of the head, neck, chest, body wall, axillae, legs, tail and just about anywhere else.  Hard lumps that involve the mammary chain (breast) are one of the tumors of concern and should be evaluated immediately.
  • Depth – Skin lumps can be on the skin (such as a mole or skin tag) or they can be under the skin. Lumps that are under the skin can be attached or moveable.
  • Rate of growth – Lumps in dogs can grow at varying rates. Some lumps grow very quickly, even over days or weeks, and some grow very slowly over months to years. Histiocytomas and Mast Cell Tumors are two types of fast-growing tumors. Fatty tumors tend to grow slowly.
  • Other – Some skin lumps can be ulcerated or even become infected. This can result from trauma to the mass, poor blood supply to the tumor causing necrosis of the tumor or be associated with certain types of cancer. Histiocytomas or Mast Cell Tumor can be itchy to some dogs.

These tumor characteristics can help guide your veterinarian as to what the hard lump on your dog may be. For example, many dogs get fatty tumors that can occur anywhere but are soft and commonly attached to the body wall. Fatty tumors are rarely firm and are uncommon on certain locations such as on top of the head. A large tumor that involves the mammary chain (breast) can be suggestive of cancer.

Another factor that is commonly considered when evaluating the cause and concern for a tumor is the age of the dog.  Some hard lumps are more common in young dogs such as Histiocytomas. While young dogs (under three years of age) are more likely to get histiocytomas (especially on the face and extremities), they can happen to dogs of any age in just about any location. Other types of tumors are more common in an older dog such as mast cell tumors, lipomas, skin cancer tumors, and breast cancer.

What is this Hard Lump on My Dog?

Most dog owners worry that a hard lump could be skin cancer. Skin cancer in dogs encompasses a broad category of tumors that includes any uncontrolled growth of cells of the skin or associated structures such as glands, hair follicles and supportive tissues (fat and connective tissue). The skin is the most common site of cancer in dogs. Skin cancer frequently occurs in dogs between 6 to 14 years of age but can occur at any age.


Pg 1 of 2