If you've recently noticed a lump or lesion on your beloved pet, you're no doubt worried and extremely eager to get some reassuring news from your vet. Unfortunately, approximately 30 to 40 percent of all tumors found in dogs are cancerous. In fact, more than half of dogs who live to be more than 10 years of age develop a malignant tumor at some point in their lives. However, not all tumors are bad news. There are numerous types of benign tumors that are common in dogs. But how can you tell the difference? The following are just a few of the main differences between benign and malignant skin tumors. 

Malignant Tumors

Unlike benign tumors, which usually remain localized in one small area, malignant tumors invade the surrounding tissues and continue to spread out, growing at a very rapid rate. Cancerous tumors may also bleed, ulcerate and become very painful. Unfortunately, cancerous tumors appear localized at first and can easily be mistaken for a benign skin tumor by a pet owner. For this reason, it's always a good idea to have any new growths checked by your veterinarian. 

Benign Tumors

Non-cancerous tumors usually do not cause any problems, and they are normally not painful for dogs unless the tumors become large enough to press on nerves and organs or to interfere with their range of motion. There are dozens of types of benign skin tumors in dogs, including warts, cysts, hematomas, abscesses, lymphomas, melanomas and histiocytomas. Since there are so many different types of benign tumors, they can present with a wide variety of cosmetic characteristics. However, benign tumors usually remain localized in one area. While they may grow, they usually don't start to invade other tissues. 

Even benign tumors can become cancerous over time. Therefore, it's vital that you have your dog's lumps and bumps checked each time they see a vet, especially if you've noticed changes in the mass or lesion. 

Treatments for malignant tumors vary dramatically and may include surgery, chemotherapy or radiation. Most benign tumors are not treated at all unless they start to cause problems. If a benign tumor is unsightly, you may also opt to have it removed for cosmetic reasons. 

As you can see, there are several marked differences between cancerous and non-cancerous skin tumors. However, both can have some of the same characteristics, especially during their early growing stages. The only way to know for sure that your dog's tumor is harmless is to have a vet like those at University Pet Hospital evaluate it and perform a biopsy.