Closeup of dog paws
Finding a broken toenail on your pet’s foot can easily be attributed to vigorous backyard digging or an exuberant session on the scratching post, but a broken nail may sometimes signal something more serious and should always merit at least a call to your veterinarian. Here are some examples of problems that a broken toenail or painful toe can signal.

1. Nail Infections

Bacterial, fungal and yeast infections are common in the feet and nail beds of dogs and cats, especially those with allergies to substances in the environment like dust, mold and pollen. A botched nail trim or a broken toenail can also lead to a nail infection if the site is exposed to contaminants. Signs of an infection may include excessive foot licking or limping. You may notice redness and oozing from the junction between the nail and toe. Severe infections can cause nail discoloration and the nail may become brittle. Your veterinarian may advise soaking the area and may prescribe oral antibiotics or antifungal medications to resolve these conditions.

2. Squamous Cell Carcinoma

Veterinarians have long been aware that large breed, dark-coated dogs like black Labradors, Briards and black standard Poodles have an increased risk of developing a certain type of malignant (cancerous) tumor in the toes. These tumors, called squamous cell carcinomas, can destroy the bone and cause the nail to break easily. You might notice some blood spots on the carpet or your dog licking at one particular toe. An interesting feature of toe squamous cell carcinoma is the fact that light-colored (white, cream, apricot and red) purebred standard Poodles seem resistant to developing this tumor (although keep in mind light-colored dogs of other breeds can and often do). A fascinating recent genetic study explored the connection between toe squamous cell carcinoma and coat color in Poodles and identified two genes linked to coat color that are involved in the manifestation of this worrisome tumor. The researchers found that one of the genes, which is protective against the tumor, is lacking in black-coated Poodles. Since the study was limited to Poodles, the information cannot be generalized to all light-colored dogs. Additionally, whether this seeming immunity to toe squamous cell carcinomas extends to some of the designer Poodle mixed breeds, such as Goldendoodles and Labradoodles, is unknown at this time. Regardless of coat color, any dog with toe swelling should be examined by a veterinarian, who may recommend radiographs (X-rays) and possibly a biopsy of the toe.

3. Melanoma of the Toe

Melanoma, a cancerous tumor of pigment cells, behaves differently in dogs than in humans. We fret about freckles and other pigmented spots on our human skin. However, in dogs, pigmented spots on the skin are usually benign because malignant melanoma occurs in the mouth and at the junction between the nail and the first toe bone. Like toe squamous cell carcinoma, melanoma of the toe can destroy the bone, weaken the nail and cause the nail to break off. In the early stages of this deadly tumor, you may see redness or weepiness at the junction between the nail and the toe. If left untreated, toe melanoma tends to spread throughout the body, making early detection a lifesaver. As with squamous cell carcinomas, detection requires a visit to a veterinarian, where a radiograph of the toe and potentially a biopsy are likely interventions.

4. Feline Toe Tumors and Lung Cancer?

Melanoma is extremely rare in cats and, while squamous cell carcinoma does occur in kitties, it does not typically do so in the feline toe. But in a strange twist of cancer behavior, cats can get toe tumors. These bizarre tumors just happen not to originate in the toe. When a cancer specialist like me examines a cat with a swollen toe, our first impulse may seem strange to the cat’s family because we are very anxious to X-ray the cat’s chest. The reason for this is that the chest X-ray will determine if the toe swelling has spread (or metastasized) from feline lung cancer. This odd occurrence in cats is well known to veterinary oncologists as lung-digit syndrome. Identifying lung-digit syndrome is critical since there is no real treatment and palliative care measures should be instituted immediately.

Bottom Line: Be on Your Toes When It Comes to Toes 

For all these reasons, if you notice your pet licking his feet beyond normal grooming behavior or if you come across a broken nail, check each one of his toes for swelling, oozing or pain. Licking at one particular toe, especially if there is swelling or redness, should not be ignored and a trip to your veterinarian is in order. Early detection of a toe tumor can increase the chance that successful treatment can be employed to make your pet a cancer survivor or at least help extend the length and quality of his or her life.

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