There are many signs of discomfort in a dog with lymphoma; many of the signs depend on the type of lymphoma. A few general symptoms are present in all types, and signs become more severe once the central nervous system becomes infected.
General signs of discomfort in dogs with lymphoma include vomiting, fever, weight loss, loss of appetite and depression.
Multicentric lymphoma may show few symptoms but often causes a distended abdomen or lumps on the neck, abdomen or elsewhere on your dog's body. Your dog also may begin to seem lethargic and lose its appetite. This type of lymphoma attacks the liver and spleen.
Along with the general signs listed above, gastrointestinal lymphoma can also cause diarrhea and melena, which is digested blood in your dog's stool.
Mediastynal lymphoma can show the general signs above and can cause fluid to build around the lungs. This will manifest itself as difficulty breathing and a constant cough.
More serious signs can occur as well. Bleeding within the eye, seizures and paralysis can occur if the central nervous system is involved.