Introduction

Melanoma in companion canines unfortunately is fairly common, especially on the eyelids but also in many other locations. Most dogs with melanoma show no systemic signs of illness – at least not unless and until the disease has metastasized to vital organs.

Symptoms of Melanoma in Dogs

Melanoma typically presents as single or multiple brown or black nodules on areas of darkly-pigmented skin – especially on the eyelids. These tumors also commonly occur on the toes (in the nail bed), on the lips, in the mouth or on the skin of the trunk or limbs. Sometimes, the mass is not pigmented, although this is uncommon. The tumors usually are detected either by an owner or by a veterinarian during a routine examination.

Oral melanoma usually is seen as a raised mass during a dental examination or other veterinary check-up. Oral melanomas almost always are invasive, aggressive, malignant and extremely metastatic. They may be accompanied by:

• Noticeable bad breath (halitosis)
• Excessive salivation (ptyalism)

Nail bed melanomas tend to be locally invasive but only moderately metastatic. When the toes and/or nail beds are affected, owners may notice:

• Swelling
• Lameness
• Licking at the affected area

In dogs, melanomas of the skin are usually but not always benign. Cutaneous (skin) melanoma may appear as:

• Raised dark bumps (single or multiple)
• Raised skin sores (single or multiple)

Melanomas around the eye and those in the eye itself usually are benign and rarely metastasize. Owners of dogs with ocular melanoma may observe:

• Change in the appearance of the eye
• Eye redness
• Eye cloudiness
• Swelling around the eye
• Darkening of the iris of the eye
• Mass on or near the eye
• Mass on or near the eyelid
• Ocular pain
• Twitching of muscles around the eye (blepharospasm)
• Impaired vision (bumping into objects in familiar places; difficulty navigating in unfamiliar places)

Dogs at Increased Risk

Both the benign and malignant forms of melanoma occur most commonly in older dogs, usually after 9 years of age, depending on the breed. Certain breeds appear to be predisposed to developing melanoma, including the Doberman Pinscher, Irish Setter, Gordon Setter, Cocker Spaniel, Schnauzer (miniature and giant), Golden Retriever, Miniature Poodle, Boston Terrier and Scottish Terrier. As domestic dogs age, their owners should be especially conscientious about looking for any new lumps or bumps – especially in the mouth, around the eyes, under or around the toenails and on the footpads.