Paraneoplastic pruritus and alopecia in a horse with diffuse lymphoma.

This research paper discusses a case of a horse that experienced severe itching and hair loss, and was later diagnosed with widespread lymphoma. Lymphoma was considered by the veterinarians due to persistent high levels of calcium in the horse’s blood. Ultrasonography revealed lumps within the spleen and liver, and further microscopic evaluation suggested lymphoma. The horse’s condition worsened leading to euthanasia, and a post-mortem examination confirmed the diffuse lymphoma diagnosis. This case indicates that serious internal diseases, including cancers like lymphoma, need to be considered when a horse presents with unexplained generalized itching.

Condition of the Horse

• The study presents a case of an 8-year-old gelding Paint Horse, which was brought in for medical evaluation due to generalized itching (pruritus), hair loss (alopecia), and intermittent fever.
• The initial examination of the skin and microscopic evaluation of skin scrapings didn’t suggest any specific diagnosis. Skin biopsy showed the presence of vasculitis, an inflammatory condition affecting blood vessels.

Lymphosarcoma Consideration and Confirmation

• The horse had a constant high calcium level in its blood (hypercalcemia), which led to lymphosarcoma—a type of lymphoma in animals—as a probable diagnosis.
• Ultrasonography was performed, revealing presence of hypoechoic (less reflective of ultrasound waves) nodules within the parenchyma (functional parts) of the liver and spleen.
• Microscopic evaluation of aspirate obtained from a splenic nodule indicated the presence of lymphosarcoma cells, supporting the initial suspicion.
• Unfortunately, the horse’s health deteriorated, leading to euthanasia. A subsequent postmortem examination revealed widespread lymphoma, confirming the earlier diagnoses.

Implications for Veterinary Practice

• In humans, generalized pruritus can be a symptom of serious internal diseases, including cancer. Similarly, in veterinary medicine, particularly for horses, unexplained generalized itching should be considered as a potential symptom of internal health conditions.
• This case specifically draws attention towards lymphoma, suggesting its inclusion in differential diagnoses for horses presenting with generalized itchiness for which no other cause can be established.
• Moreover, due to this case, veterinarians are made aware of lymphoma’s association with paraneoplastic symptoms such as pruritus and alopecia.