Dog owners often report to their vet that they have noticed a bump or lump on their four-legged friend. This can occur for various reasons and can be benign (non-cancerous) or cancerous. You can rest assured that most of the time, skin bumps are not cancerous. That said, in rare cases, certain types of cancer can appear on dogs’ skin, especially in older pets.
The most common causes of bumps and lumps on your dog’s skin are insect bites, abscesses, lipomas, hematomas, or acne. Other clinical signs can differ depending on the cause but can include itching and scratching, limping, hair loss, or secondary skin infections.
Take your dog to the vet if they have bumps or lumps on their body to prevent them from aggravating their condition and to diagnose the cause and get proper treatment.
What Are Lumps and Bumps on Dogs’ Skin?
Lumps and bumps can be skin inflammations or growths. Dogs of any age can develop large or small bumps and lumps, but they most often occur in older dogs.
Small bumps and lumps are usually called papules, while large ones are called nodules, a term that makes many pet owners think about cancer. However, the causes of their appearance are varied.
Any lumps and bumps that you notice on your dog’s skin should be checked by your vet.
What Are the Causes of Lumps and Bumps on Dogs’ Skin?
Lumps and bumps on dogs’ skin can be of two types:
- Malign (cancerous)
- Benign (non-cancerous)
The most common are benign, so don’t panic whenever you find one (small or big) on your dog’s body.
1. Cancerous Bumps and Lumps
Malignant skin tumors in dogs are not that common. They usually occur in older pets, but they can develop at any age and can be:
Cancerous skin masses can be of different sizes, colors, or shapes. They are generally mobile and can cause bleeding at the site, pain, loss of appetite, and weight loss. Depending on where they appear, the pain can cause lameness (if they appear on the legs), mastication problems (when they appear in the mouth), etc.
Cancer in general is a dangerous medical condition because if it is not detected and treated in time, cancer cells can migrate from the primary tumor to other organs and tissues, developing distant metastases1. Dogs can die from metastases.
For this reason, it is important to take your dog to the veterinarian when you notice a lump or bump on their body. The sooner the diagnosis is made, the better your dog’s chances of survival (if it actually is cancer).
Cutaneous Hemangiosarcoma
This skin tumor can also appear in dogs younger than 3 years old, but it is most often found in middle-aged and old dogs. The breeds most prone to cutaneous hemangiosarcoma are2:
Also, males are more prone to developing cutaneous hemangiosarcoma than females. The main causes of the appearance of this type of tumor are prolonged exposure to the sun and UV rays3.
Dogs suffering from cutaneous hemangiosarcoma will have red, painful bumps on their body. Over time, the bumps can ulcerate and cause bleeding.
Mast Cell Tumor
This type of tumor is one of the most common skin cancers in dogs. It usually affects old dogs (average age of 9 years), with the breeds most prone to it being:
Most forms of mast cell tumors have a relatively mild biological behavior, with no capacity for distant metastasis. When this type of cancer metastasizes, it first spreads to the lymph nodes, liver, spleen, and/or bone marrow.
Dogs with mast cell tumors will present a lump or bump in the skin, vomiting, lethargy, enlarged lymph centers, skin ulcers, and low appetite.
Squamous Cell Carcinoma
This type of skin cancer occurs due to prolonged exposure to the sun, especially in hairless areas such as:
The most prone breeds are:
Dogs with squamous cell carcinoma have white, red, or skin-colored bumps or lumps on their skin. If left untreated, this type of cancer can ulcerate and cause bleeding.
Although it has an aggressive evolution, squamous cell carcinoma metastasizes slowly.
Malignant Melanoma
This type of skin cancer is aggressive and metastasizes quickly. Although it can occur in any dog breed, certain ones are more prone:
They can appear anywhere on the dog’s body, especially in hairless areas. They are most often found on the lips, in the mouth, and on the nail bed.
Dogs with malignant melanoma present dark-pigmented bumps on the skin, though these can be other colors too.
2. Benign Bumps and Lumps
Benign lumps and bumps should not cause concern to dog owners because they do not invade and affect the surrounding tissues. Also, they do not spread to other organs and tissues, as is the case with certain forms of skin cancer.
Non-cancerous lumps and bumps can be any of the following.
1. Hematomas
Hematoma is an accumulation of blood outside a vessel — it is like a pouch filled with blood. It is formed most often due to an injury or trauma. An injury can lead to the rupture of the walls of the blood vessels, and the blood reaches the surrounding tissues.
It can occur anywhere on the body, but it is found most often at the level of the ear (othematoma), especially in dog breeds with long ears. These breeds risk hitting their ears when shaking their heads.
Since the ear area is not very elastic, the hematoma causes significant tension between the two sides of the auricle.
An othematoma can appear as a small mass initially until the ear swells entirely. It can be painful but it is not life threatening.
2. Sebaceous Cysts
Sebaceous cysts are membranous pockets or sacs that contain a thick, oily substance called sebum. They can develop almost anywhere on the body and appear as small white bumps on dogs’ skin.
Do not try to pop a sebaceous cyst because there is a risk of contaminating it with external bacteria and it becoming infected. Veterinarians usually recommend leaving them alone because in most cases, they resolve on their own. But if they grow, you should take your dog to the vet.
3. Enlarged Lymph Nodes
These appear as bumps of various sizes under the skin when they become inflamed. Causes of enlarged lymph nodes include:
It is recommended to take your dog to the vet for an examination if you notice that your pet’s lymph nodes are enlarged.
4. Acne
Acne is a medical condition in which the hair follicles become irritated and inflamed. It manifests as white or black pimple-like bumps on the lips and the skin of the muzzle. Other clinical signs include lesions, local pain, inflammation, and secondary infections.
The appearance of acne in dogs depends on several factors:
5. Insect Bites
Insect bites cause local allergic reactions that are manifested by the appearance of small bumps or lumps on the surface of the skin. They are red, painful, or itchy. The most common insect bites are from mosquitoes, bees, wasps, ants, or spiders (although technically, spiders are not insects but arthropods).
If your dog scratches the area intensely and often, they risk developing secondary skin infections, which may require antibiotic treatment.
6. Benign Tumors
Benign tumors do not invade the surrounding tissues and do not affect other organs. They usually appear as pink or black bumps or lumps on any area of the body, especially in older dogs. The most common benign tumors in dogs are:
Conclusion
Bumps and lumps on dogs’ skin are common and can be represented by insect bites, benign or cancerous tumors, acne, sebaceous cysts, enlarged lymph nodes, or hematomas. They occur at any age and can develop on the surface of the skin or in the skin.
Most lumps and bumps are benign, but you should still contact your veterinarian when you notice one on your dog’s body.
Featured Image Credit: KingTa, Shutterstock
