Use of charcoal hemoperfusion and hemodialysis in the treatment of methotrexate toxicosis in a dog

Objective: To describe the successful use of charcoal hemoperfusion (HP) and hemodialysis (HD) in a dog in the treatment of methotrexate (MTX) toxicosis.

Case summary: An American Pit Bull Terrier accidentally ingested 56.8 mg/m² of MTX. The patient's initial serum MTX concentration was 0.11 μmol/L. At this dosage, myelosuppression and gastrointestinal epithelial necrosis have been reported. Charcoal HP and HD in series were used to enhance elimination of MTX. Serial serum samples were obtained during the session at 0, 30, 60, 90, 120, 150, and 180 minutes and 12 hours after the session. These were later analyzed for MTX concentrations. Clearance of MTX was 73% and extraction ratio was 63% within the first 30 minutes of HP/HD. A 3-hour session eliminated all detectable traces of MTX. The dog tolerated the session well and did not develop any clinical signs of MTX toxicosis.

New or unique information provided: HP and HD together were highly effective in enhancing elimination of MTX from this patient. The prompt use of extracorporeal techniques decreased toxic concentrations of MTX to safer values, which prevented myelosuppression and gastrointestinal injury. HP and HD in conjunction or in place of traditional therapy may be a viable option for the treatment of acute toxic exposures to MTX.