Toe cancer in dogs is one of the many types of cancer that can potentially affect dogs. Early recognition of problems associated with a dog's toes is important. Careful inspection of the dog's body when the dog owner is grooming the dog may lead to early detection of problems. Any unusual lumps and bumps on the dog's coat and toes can be identified quickly this way and brought to the vet's attention. If your dog has lost his ability to walk, has a lump on his toe, is missing a toenail, or you notice swelling, pain and deformed toenails please see your vet. Following is some important information about toe cancer in dogs.
Types of Toe Cancer in Dogs
There are several types of cancer that may affect a dog's toes. A dog's toes are often medically referred to as "digits." Toe cancers in dogs are therefore often referred to as "digital tumors."
Dog have four toes in each paw and they are each composed by three bones, known as phalanges. The nail bed is attached to the third phalange.
Different types of toe cancer in dogs produce different signs and symptoms and their treatment may vary.
Dog Toe Squamous Cell Carcinoma
This is the most common type of cancer affecting a dog's toes. Digital SCC (squamous cell carcinoma) is a malignant type of cancer that originates from the scale-like cells of the epithelium –the layer of thin tissue forming the outer layer of the dog's body surface.
Dogs predisposed to this type of tumors include large breed dogs and dogs with a black coat. Middle-aged and senior dogs around the age of 10 are more predisposed, but iSCC can also affect younger dogs.
This type of cancer commonly affects the skin around the nail often invading surrounding tissues and bones, but fortunately this type of cancer spreads rather slowly compared to other types of more aggressive cancers.
Appearance of a dog toe squamous cell carcinoma may vary. Dog owners may describe it as a small nodule, a papule, or a small blister-like growth. If allowed to grow, the affected tissue will dry and eventually ulcerate.
Dogs typically manifest swelling of the toe which can often be confused for an infection, along with lameness. This form of cancer is often suspected when the dog's toe does not improve after a course of antibiotics.
Dog Toe Malignant Melanoma
Malignant melanoma can affect a dog's toes and is the second type of cancer that is most likely to affect a dog's toes. This type of cancer originates from special pigment-producing cells that are found in the skin and are known as melanocytes.
Toe malignant melanoma is an aggressive tumor with a high tendency to invade and spread to other body parts such as the underlying bone, regional lymph nodes and lungs. This cancer may affect the nail bed of the affected toe, but can also be found affecting other parts of the toe. Growths are typically darkly pigmented, but this is not a rule set in stone, some types of melanomas may lack pigment at times and may be confused for squamous cell carcinomas.
Typically, dog owners notice that their dog has lost a nail. This tends to happens because the tumor is growing in the nail bed and ends up destroying it.
At times, what look like a melanoma turns out being the benign version, a melanocytoma. Differentiating a melanoma from a melanocytoma can be tricky since they cannot be reliably distinguished cytologically through a needle aspirate. When in doubt, the best option is to have the growth surgically removed and sent out to a pathologist for evaluation.
Other Types of Toe Cancer
Several other types of toe cancer can affect dogs. Sarcomas are cancers that can affect bone cartilage, fat, muscle, vascular, or hematopoietic tissues. Osteosarcoma most commonly affects the bones of the dog's legs, but at times may affect the bones of the dog's toe.
Soft tissue sarcomas may also affect the dog's toe or the toe's nail bed. There can be benign soft tissue tumors or malignant soft tissue tumors. Another possibility is a cancer known as hemangiopericytoma, which is a type of soft tissue sarcoma affecting the blood vessels and soft tissues. Mast cell tumors at times may also affect the dog's toe as seen in the picture.
And of course, there are several growths, or what appear to be growths, on a dog's toes that are benign, such as warts, interdigital cysts, furunculosis, digital corns, histiocytomas, abscesses or simply swelling from a small foreign body.
As seen, there are several possible causes of growths, masses or anything that may look like toe cancer in dogs. Before assuming a dog has toe cancer, the best thing to do is to have the vet see the growth sooner than later for proper diagnosis and treatment.
At the Vet's Office
Your vet will collect some medical history, asking what symptoms you have noticed and when they have started. Your vet may ask whether your dog has experienced breathing difficulties, coughing, weight loss, lack of appetite or malaise which may be symptoms associated with spread of the cancer to the lungs.
Your vet will perform a physical examination on your dog and will check your dog's body temperature, heart rate and will carefully inspect the affected area. Your vet may also look for any swelling of regional lymph nodes as this can provide an insight as to whether the dog's body is reacting to an infection or invasion.
In some cases, an x-ray of the toe may prove to be insightful and may show specific changes on the radiograph. For instance, some forms of cancer of the dog's toe affecting the bone, may show a typical moth- eaten appearance due to the cancer eating away the bone (lysis). Chest x-rays may also help confirm or rule out spread of the cancer to the lungs or chest lymph nodes.
Toe cancer in dogs is not a straightforward diagnosis and it therefore can be challenging differentiating a benign growth from a malignant one by visual inspection alone. A fine needle biopsy may at times be insightful, but the only definite way to differentiate the type of cancer is by performing a biopsy.
Treatment of Toe Cancer in Dog
In the intermediate to advanced stages of cancer, your dog may need to receive surgery. Early surgical intervention is the recommended treatment protocol of dogs with digital tumors. Depending of the cancer type, whether the cancer has spread and the grade of the tumor, the affected dog's recovery rate and prognosis may vary.
Generally dogs have a harder time recovering when the surgically removed toes are those responsible for bearing the most weight. Generally, the 2nd, 3rd, and 4th toes are the ones most responsible for bearing weight in dogs toes. Surgery on these specific toes therefore may lead to more postoperative pain due to the fact that affected dogs are forced to bear weight on a fresh surgical site, explains veterinarian Dr. Kara.
Sometimes, removing the entire toe rather than removing just a part of the toe may be less painful as no raw stump to bear weight is left behind. Melanomas of the toe typically require surgery with a wide margin to ensure tissue affected by cancer is completely removed. Chemotherapy or radiation may be suggested in addition to surgery for some malignant tumors. Consult with your vet.
- J Vet Intern Med. 2005 Sep-Oct;19(5):720-4.Canine digital tumors: a veterinary cooperative oncology group retrospective study of 64 dogs.Henry CJ1, Brewer WG Jr, Whitley EM, Tyler JW, Ogilvie GK, Norris A, Fox LE, Morrison WB, Hammer A, Vail DM, Berg J; Veterinary Cooperative Oncology Group (VCOG).