Tumor of the Thymus in Dogs

Thymoma is a rare, usually benign tumor arising from thymus tissue and sometimes associated with myasthenia gravis.

Thymus is an organ infront of the heart in the rib cage which is responsible for maturity and multiplication of T lymphocytes (a small lymphocyte that orchestrates the immune system's response to infected or malignant cells).

A thymoma is a type of tumor that originates from the layer of tissue covering the thymus (epithilium). Thymomas are rare tumors that are associated with myasthenia gravis.  Myasthenia gravis is a severe autoimmune disease (any disease in which animal's body produces antigens that are used against itself)  which causes certain muscle groups to tire easily.

Common symptoms of thymoma tumor are:


Increased breathing rate

Trouble breathing

Cranial caval syndrome — a side effect of heartworm infestation, which often leads to swelling of the head, neck, or forelimbs

Myasthenia gravis, a neuromuscular disease that leads to muscle weakness, enlarged esophagus, and frequent regurgitation

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