Spotting and Understanding Melanoma in Cats and Dogs

With summer and warmer weather approaching, it's important to remember that pets can also develop sun-induced tumours such as melanoma. Although your pet, whether a dog, cat, or other furry companion has a coat of fur, it does not fully protect them from harmful sun exposure and skin cancers including melanoma.

Melanoma is a malignant cancer originating from melanocytes, the pigment-producing cells in the skin and mucous membranes. Detecting it early in cats and dogs can be difficult because fur conceals lesions, but recognising key signs is vital for prompt veterinary care and improving outcomes.

1. Recognising Suspicious Spots and Lumps on Your Pet

The appearance of dark or pigmented lumps or spots on your pet’s skin can indicate melanoma or other skin conditions. In cats, particularly orange tabbies, benign pigmented lesions called "lentigo simplex" often appear as harmless spots on gums, nose, eyelids, and lips. These do not progress to melanoma. In dogs, pigmented areas called macules can form after skin infections, usually on less-haired belly skin. These are non-cancerous but require veterinary diagnosis to rule out melanoma.

Because benign and malignant lesions can look similar, any new, changing, or unusual spots should be examined by your vet as soon as possible for an accurate diagnosis.

2. Melanoma Can Be Hard to Detect Under Fur

Unlike humans, pets’ fur coverage makes it difficult to spot melanoma visually. The most common melanomas in dogs occur inside the mouth, while oral melanomas are less frequent but still serious in cats. If your pet tolerates mouth examination, check for dark, raised, or bleeding areas on gums. Bad breath (halitosis) or difficulty eating can also be warning signs. It’s best to rely on professional veterinary checks to identify oral melanomas early and accurately.

3. Feline Ocular Melanoma: Spotting Eye Changes

One subtle and challenging form of melanoma in cats affects the coloured part of the eye (the iris). Initially, it may look like a freckle and gradually enlarge, covering more of the iris. If you observe dark spots or growths on your cat's eye, arrange for an ophthalmologist assessment. If the tumour is malignant, enucleation (eye removal) is often recommended to prevent spread and prolong your cat’s life. Despite the difficulty of this decision, most cats adapt well after surgery.

4. Broken Toenail or Limping Could Signal Melanoma in Dogs

In dogs, melanoma can develop at the nailbed, sometimes mistaken for a broken nail. The tumour weakens the nail, causing it to snap and leading to swelling and pain in the toe. If your dog limps or has a swollen toe with no obvious injury, consult your vet promptly. Diagnostic x-rays often reveal melanoma, and amputation of the affected toe may be necessary to stop the tumour spreading.

5. Signs and Symptoms to Watch For

• Unexplained new lumps or masses on skin or mucous membranes
• Persisting bad breath or oral bleeding
• Visible dark spots or pigmented masses on skin, gums, or eyes
• Changes in eating behaviour, drooling, or pain
• Limping or swelling in toes or nailbeds

6. Diagnosis and Veterinary Care

Your veterinarian will perform a thorough physical exam, including checking areas such as the mouth, skin, eyes, and lymph nodes. Diagnostic procedures often include fine needle aspiration (FNA) to sample suspicious cells, biopsy for definitive diagnosis, and imaging tests such as X-rays or ultrasounds to check if the melanoma has spread.

Early veterinary intervention is crucial for managing melanoma effectively. Treatments may include surgical removal, radiation therapy, chemotherapy, or immunotherapy. Recent advances include vaccines for oral melanoma in dogs, though these are treatments rather than cures.

7. Regular Health Checks and Responsible Pet Ownership

Since melanoma can be aggressive and hard to detect, regular health checks with your vet are essential. Observing your pet’s behaviour and physical condition closely, especially during warmer months, helps catch potential issues early. Always seek veterinary advice if your pet develops unusual spots, lumps, or changes in health.

Conclusion

Melanoma is a serious but treatable cancer in cats and dogs when caught early. As responsible pet owners, understanding the warning signs and ensuring regular veterinary care can make a significant difference in your pet’s health and longevity. Remember to protect pets from excessive sun exposure and monitor their skin and overall wellbeing diligently.