Disseminated lymphoma with large granular lymphocyte morphology diagnosed in a horse via abdominal fluid and transtracheal wash cytology.

The research paper describes the diagnosis and treatment of a rare case of disseminated lymphoma with large granular lymphocyte morphology in a 22-year-old Tennessee Walking Horse mare, which presented with symptoms such as weight loss, cough, colic, and respiratory issues. Despite several examinations and treatments, the horse’s condition worsened, leading to euthanasia and confirming the presence of this rare lymphoma through posthumous examination.

Background

• The article focuses on a specific case study involving a 22-year-old Tennessee Walking Horse mare. The horse displayed symptoms such as deprivation of appetite, lethargy, mild signs of colic, weight loss, and a prevailing cough. Respiration anomalies were detected, and an array of diagnostic tests was conducted.

Observations and Diagnostics

• The initial physical examination exhibited increased respiration rate along with abnormal wheezing and crackling noises during thoracic auscultation. Additionally, minor disseminated lesions were observed on the horse’s pleural surfaces during a thoracic ultrasonographic examination. However, an abdominal ultrasonographic exam did not yield any significant outcomes.
• A trans-rectal palpation revealed an impaction in the small colon which was relatively firm coupled with diarrhea. Laboratory testing showed evidence of severe neutropenia, left shift, notable acute inflammatory leukogram, signs of hepatocellular damage/necrosis, and cholestasis. The data also indicated potential mixed metabolic alkalosis and acidosis.
• A significant breakthrough came from a cytologic evaluation of a peritoneal fluid sample as well as a subsequent transtracheal wash, both showing large numbers of large granular lymphocytes (LGL). This led to the preliminary diagnosis of disseminated lymphoma with LGL morphology, a rare condition in horses.

Conclusion and Final Diagnosis

• Due to the worsening clinical signs and poor prognosis, the decision was taken to euthanize the horse. Subsequent necropsy and histopathologic examinations vindicated the preliminary diagnosis. The tests showed evidence of disseminated lymphoma with LGL morphology in various parts of the horse including the mesenteric lymph node, lungs, liver, spleen, kidneys, and right dorsal colon.
• The article underscores the rare instance of LGL lymphoma diagnosis in horses, providing valuable insights into the cytologic manifestations and post-mortem confirmation of the disease.