There are many different kinds of skin tumors. Some are serious but most are benign. Most skin growths are likely to be either skin papillomas (i.e. warts) or sebaceous gland adenomas. Skin papillomas are common in dogs. Their cause is unknown, although viral infections appear to be involved in some cases. These growths often appear as solitary or multiple lumps, and have a cauliflower-like surface appearan ...