Equine lymphoma, also known as lymphosarcoma, is a form of cancer which involves the horse's lymphatic system. It most often starts in one lymph node but will eventually spread throughout the body.

There are many types of lymphoma. Typically, tumors are multicentric and involve lymph nodes and thoracic and abdominal organs. They are most common in horses age 5 to 10 years of age but can occur at any age. Equine lymphoma presents in four different anatomic forms.

	Generalized	Cutaneous	Alimentary	Mediastinal
Clinical signs:	Chronic and progressive	Multifocal to generalized exfoliative dermatitis Focal areas of nodules or ulcerations Pruritis	Weight loss Intermittent colic Fever Chronic diarrhea	Dyspnea Coughing Recurrent pleural effusion