All dogs can be prone to moles and general lumps and bumps on the skin, but cocker spaniels in particular, are somewhat predisposed to some of them. If you have recently noticed moles under your cocker spaniel's chin, it is best to have a veterinarian take a look at them to rule out any malignancies. Often, a quick diagnosis is difficult because there may be several causes for the moles, and this is why various diagnostic tests, such as biopsies, may need to be performed.
Cysts are benign growths that can appear virtually anywhere on your dog's body. Cocker spaniels are prone in particular to sebaceous cysts which are growths about 1 inch in size and filled with dead skin cells and oil. Other possible benign growths include lipomas, fatty lumps under the skin, and histiocytomas which are red, dome-shaped growths commonly found on the ears, face and feet of younger dogs. Other mole-like lesions that can be found on a cocker spaniel's chin may be due to bacterial or fungal skin infections, and skin conditions such as acne.
There are other noncancerous growths that may be seen on your cocker spaniel's chin. Warts can be caused by a papilloma virus or by an irritant and can be contagious to other dogs. They are commonly found around the face, chin, mouth, lip, neck and limbs. Skin tags are other benign growths often appearing like "bits of chewing gum" stuck to the skin. Hematomas consist of accumulations of blood under the skin and may appear from physical trauma.
Moles that appear to grow at a faster rate, have irregular borders and tend to bleed, are often suspected of being cancerous growths. Melanomas comprise malignant cells that typically develop in an older mole and the cocker spaniel breed appears to be predisposed to them. Sebaceous adenomas, another type of cancer cocker spaniels are prone to, consist of moles that are light in colour and are typically smaller but primarily affect the sebaceous glands. Skin carcinomas and mast cell tumours are other possibilities even though the chin area is not the preferred location for such growths.
A sample of cells collected from your cocker spaniel's mole will be necessary to perform a biopsy and determine if the mole is benign or not. Treatment will vary depending on the cause. The mole might be removed if it tends to bleed and bother the dog. Should the mole result to be malignant, surgical excision is recommended in the early stages. If the cancer has spread, affecting other organs, surgery may not be effective and chemotherapy would be recommended.