Dogs can have allergic reactions just like people. Common triggers include insect stings, plants and medications (including vaccinations).
Lymphoma is a cancer of the immune system. The immune system is active throughout the whole body, and lymphoma can develop in any part of it. Symptoms vary depending on what type it is, where it is, and how aggressive it is.
Overview of the types of cancers dogs can get, how they are diagnosed and treated, as well as some questions to ask your vet if your dog is diagnosed.