You’ve probably heard of several types of cancer – the names typically end in “oma,” some of the most common being sarcoma, melanoma, and carcinoma. To help your vet in detecting and fighting cancer, make a habit of running your hands over your dog with the intent to find any abnormalities that weren’t present before. Once you’re familiar with how your pooch feels on a usual day, it’ll be much easier to detect things that are unusual both on and below the skin.
Lipomas are growths comprised of fat cells and are both benign and painless for your dog. Lipomas form under the skin and grow continuously, sometimes reaching large sizes. Your vet may want to perform a biopsy to be certain the growth hasn’t developed into the malignant (but very rare) liposarcoma, but he will probably only want to remove benign growths if they are somehow interfering with your dog’s quality of life. Melanomas are usually benign and are typically dark lumps on the skin accompanied by a light crust. If you detect what you think may be a melanoma near the nail bed or in your pup’s mouth, it’s time to see the vet as these locations can indicate malignant melanomas.
Papillomas are also benign. These appear as small pink warts, usually with the cauliflower appearance typical in standard warts. While large areas may develop at once and look somewhat icky, you only need to worry if the area starts bleeding or becomes infected.
Papillomas typically disappear on their own.
Osteosarcomas are painful tumors that develop in older dogs’ legs, jaw, or ribs. You may notice your dog yelps or becomes upset when you place pressure on a certain area of his body. If
so, a vet can determine whether or not it truly is a tumor through an X-ray. The treatment is typically amputation above the affected portion. Sarcomas are malignant tumors in the soft tissue of your dog’s body and usually include a prefix that indicates the location
(fibrosarcomas form in the fibrous connective tissue, lymphosarcomas in the lymphatic tissue). These tumors often require several methods of examination before diagnosis and are nearly always removed surgically.
Prostate tumors are rare in older dogs who have not been neutered, while those who are neutered are at a far greater risk for prostate cancer (but a much lower risk for prostate enlargement). These tumors can be both benign and malignant and are difficult 
to detect without a full examination. Malignant tumors require removal of the prostate gland.
Mammary tumors most commonly occur in unspayed, older females, and they occur in multiple
instances near the dog’s teats. They can be either benign or malignant, but most are painless. You can typically feel these tumors just under the skin of your female, so if you detect a small, harder area of tissue, get your pup to the vet. Treatments for breast cancer can vary according to severity.