Rhabdomyosarcoma of the tongue in a horse.

The research discussed in this article investigated the case of a 5-year-old Quarter Horse mare that exhibited symptoms of quidding and nasal discharge. A soft tissue mass was discovered at the base of the horse’s tongue, which was later diagnosed as rhabdomyosarcoma following surgical removal and histopathologic examination.

Discovery and Diagnosis of the Condition

• The study subject was a 5-year-old Quarter Horse mare, known to have a six-month history of quidding — where the horse drops food from its mouth while chewing — and a nasal discharge containing feeding material.
• Upon physical examination, the horse showed signs of weight loss. An abnormal movement of the soft palate — a part of the body that helps in swallowing and speaking — was observed, identified as dorsal displacement. This instability in the soft palate’s normal function was due to a soft tissue mass at the base of the horse’s tongue. The tumor, viewed as a significant health concern, caused discomfort and changes in eating habits, resulting in weight loss.

Surgical Intervention and Histopathological Examination

• The diagnosed mass was surgically removed via an oral approach. The surgical method chosen ensured minimal invasive damage, and likely contributed to the overall success of the operation.
• Post-surgery, the specimen was tested in what is called a histopathological examination. This type of examination is generally performed on a sample of the tumor tissue after it has been surgically removed, allowing doctors to view the tissue under a microscope with greater detail and understand the exact nature of the disease.
• Through the histopathological evaluation, the research team diagnosed the horse’s disease as rhabdomyosarcoma. Rhabdomyosarcoma is a form of muscle cancer that grows from immature muscle cells and is unusual in equines. The discovery of rhabdomyosarcoma in the horse’s tongue is rare, enhancing the significance of this case.