Ocular manifestations of a metastatic adenocarcinoma in a horse.

This study describes a case where a horse with an iris mass and general symptoms of illness was diagnosed with metastatic adenocarcinoma, a type of cancer that had spread from another area of the body, specifically suspected of the lungs. The metastatic adenocarcinoma had affected various organs including the horse’s eyes, heart, liver, kidneys, spleen, diaphragm, and various lymph nodes.

Case Presentation

• The study is centered around a 10-year-old German Warmblood gelding that was referred to the Equine Department of the Vetsuisse Faculty, University of Zurich, Switzerland, with a mass on its iris, fatigue, intermittent fever, and a cough.
• Physical examination revealed abnormal body temperature, abnormal heart rhythm, swelling in the lower body parts, and an enlarged right mandibular lymph node.
• A further ophthalmologic examination revealed a large vascularized mass in the iris.
• The fundoscopic examination, aimed at examining the retina, revealed multifocal small, brown to black lesions with slightly elevated areas having indistinct margins surrounded by a bright or reflective zone in both eyes.

Diagnostic Testing

• Complete blood count and plasma biochemical profile were conducted, revealing mild anemia, increased white blood cells count (indicative of infection or inflammation), and reduced platelet count (which affects blood clotting).
• Abdominal ultrasound showed serious spleen disease (splenopathy) and its enlargement (splenomegaly). Thoracic radiographs showed severe lung diseases with nodules and large consolidated areas.
• Examination of samples from the enlarged lymph node showed cancerous cells, indicating a presence of neoplasm.

Clinical Outcome and Discussion

• Due to the poor prognosis, the horse was euthanized and a postmortem examination was conducted. This revealed that the horse was affected by adenocarcinoma, a type of cancer that had originated possibly in the lungs and had spread to various organs including the eyes, heart, liver, kidneys, spleen, and skeletal muscles, including various lymph nodes.
• The study concluded that metastatic adenocarcinoma should be considered as a possible diagnosis in horses presenting with the symptoms described; iris masses, multifocal chorioretinal infiltrates (spotted inflammation in the retina), and signs that are characteristic of a paraneoplastic syndrome (a set of signs arising from an immune response to neoplasia).