Nasal adenocarcinoma with diffuse metastases involving the orbit, cerebrum, and multiple cranial nerves in a horse.

This research article examines the case of a 9-year-old Trakehner gelding horse that displayed neurological complications due to a nasal adenocarcinoma with widespread metastases affecting the eye socket, brain, and multiple cranial nerves.

Introduction to the Case

• The case presented in the research study revolves around a 9-year-old Trakehner gelding, a breed of horse, which was showing symptoms of exophthalmus or protrusion of the eye on the right side.
• The symptoms observed included lack of response to threats in the right eye, diminished direct and consensual pupillary light reflexes on the right side, skewed placement of the right eye, minor asymmetry on the right side of the face, an inclination of the head to the left, and increased muscle tension in the right limbs. These clinical signs led to the suspicion of multiple pathological lesions affecting certain areas and nerves of the brain.

Diagnostic Procedures

• A differential diagnosis was conducted via an ultrasonographic examination of the right eye. The results revealed the presents of a vascularized retrobulbar mass, indicating a tumor or lesion behind the eyeball.
• Further confirmation of the condition was achieved through computed tomographic (CT) imaging. The imaging showed the presence of a mass that has filled the nasal cavity of the horse and invaded the forebrain.

Post-mortem Findings

• A necropsy of the horse was conducted to gather further data. The results demonstrated the presence of a poorly differentiated nasal adenocarcinoma. This is a type of cancerous tumor affecting the base of the nose, which had metastasized to the eye socket or orbit.
• The metastases also spread to various areas including the right parotid gland, cranial cervical lymph nodes, the fascial planes of the neck, and the lungs.
• Although the clinical signs suggested the involvement of the right facial and left vestibulocochlear nerves, no evidence of direct involvement was discovered. This discrepancy suggested the possibility of paraneoplastic peripheral neuropathy which is a condition resulting from the cancer’s effect on the nervous system, rather than direct involvement of the nerves by the cancer.