Suspected cytosine arabinoside induced interstitial lung disease in a dog with meningoencephalitis

An 11-year-old neutered male Dachshund dog weighing 7 kg presented with acute onset of respiratory distress after subcutaneous administration of cytosine arabinoside (CA).The patient previously diagnosed with meningoencephalitis of unknown origin and was being treated with oral prednisolone, levetiracetam, potassium bromide, gabapentin, and periodic subcutaneous CA administration (50 mg/m 2 , q 12 h, subcutaneous, 4 times, every 3 weeks).The patient developed tachypnea with labored respiratory effort after 9th CA administration.Thoracic radiograph revealed bilateral diffuse interstitial to alveolar pulmonary opacities, and echocardiogram indicated no evidence of leftsided heart failure.Based on the onset coinciding with the administration of CA, low possibility of other pulmonary disease, remission of symptom showed after discontinuation of CA, we suspected CA-induced interstitial lung disease.The patient's pulmonary opacities on the radiograph improved to a similar degree as before the adverse event over time, but respiratory symptoms were not fully resolved.Sildenafil (2 mg/kg, per oral, q 12 h) was given as therapeutic trial to manage possible pulmonary hypertension, suspected a sequela of the lung disease, based on an echocardiographic evidence and clinical signs.The patient's respiratory symptom was well managed since, and achieved discontinuation of sildenafil.