i'm a big lover of animals, so just want to post stories to make people aware. dogs can get cancer too:
"Testicular tumors are very common in older dogs that have not been neutered. Male dogs of any age can develop testicular tamers.
There are three types of testicular tumors and they are sertolicell tumors, seminomas and interstitial cell tumors they are all three treated the same.
Sertoli cell tumors show a swelling of the testicle and scrotal area. Sertoli tumors may metastasize to the abdomen, lungs and brain. Seminomas will also appear as swellings of the testicle and scrotum. They can go to the abdomen. Interstitial cell tumors show few symptoms. They do not produce estrogen or metastasize. They are not usually a problem. If a dog has cancerous tentacle tumors they need to have abdominal and chest x-rays to check for metastasis. They will also need to have blood work done."
read more here: http://www.examiner.com/dog-health-in-sacramento/dogs-get-testicular-cancer