why do my dog have a big ball in his side?

why do my dog have a big ball in his side

It could be canine lipoma, which isnt bad. Our 8 yr old lab has six on the sides of her chest... they range in size from a marble to about 60% the size of a golf ball. None are cancerous and could be removed via surgery.

Take your dog to the vet. Yes, it could be a lipoma, but it could be a cancerous type of tumor as well. No matter what it is, it is better to have that checked out early, before it either grows very large and starts to cause your dog pain, or before the cancer spreads and kills your dog.