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Methylphenidate toxicosis in dogs: 128 cases (2001–2008)

David W. Genovese DVM1, Sharon M. Gwaltney-Brant DVM, PhD, DABVT2, and Margaret R. Slater DVM, PhD3
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  • 1 Veterinary Diagnostic Laboratory, College of Veterinary Medicine, University of Illinois, Urbana, IL 61802.
  • | 2 American Society for the Prevention of Cruelty to Animals, Animal Poison Control Center, 1717 S Philo Rd, Ste 36, Urbana, IL 61802.
  • | 3 American Society for the Prevention of Cruelty to Animals, Animal Poison Control Center, 1717 S Philo Rd, Ste 36, Urbana, IL 61802.

Abstract

Objective—To determine clinical signs and outcomes of methylphenidate hydrochloride (MPH) toxicosis in dogs; to assess effects of amount (ie, dose) and formulation (immediate or extended release) of ingested MPH on onset, duration, and severity of clinical signs; and to describe management of MPH intoxication.

Design—Retrospective case series.

Animals—128 dogs with MPH toxicosis or exposure.

Procedures—Data from an Animal Poison Control Center (APCC) database from November 1, 2001, to November 30, 2008, were reviewed. Records of dogs were searched for APCC classifications of confirmed (n = 71) or suspected (39) MPH toxicosis; dogs (18) that ingested MPH but did not develop clinical signs of toxicosis were also included. Signalment, dose, clinical signs, treatment, and outcome were evaluated.

Results—Clinical signs of toxicosis were reported in 107 of 128 (84%) dogs that ingested MPH; these included hyperactivity in 42 (33%), tachycardia in 27 (21%), vomiting in 19 (15%), agitation in 16 (13%), and hyperthermia in 13 (10%). Doses ranged from 0.36 mg/kg (0.164 mg/lb) to 117.0 mg/kg (53.18 mg/lb). Severity of clinical signs was not strongly associated with dose. More severe and prolonged clinical signs were associated with ingestion of extended-release formulations of MPH; 3 dogs that consumed these formulations (doses, 10.2 mg/kg [4.64 mg/lb], 15.4 mg/kg [700 mg/lb], and 31.1 mg/kg [14.14 mg/lb]) died. Favorable outcomes were reported for most (31/34 [91%]) dogs.

Conclusions and Clinical Relevance—Ingestion of even small amounts of MPH can cause severe clinical signs in dogs. Monitoring and supportive care are recommended regardless of dose.

Abstract

Objective—To determine clinical signs and outcomes of methylphenidate hydrochloride (MPH) toxicosis in dogs; to assess effects of amount (ie, dose) and formulation (immediate or extended release) of ingested MPH on onset, duration, and severity of clinical signs; and to describe management of MPH intoxication.

Design—Retrospective case series.

Animals—128 dogs with MPH toxicosis or exposure.

Procedures—Data from an Animal Poison Control Center (APCC) database from November 1, 2001, to November 30, 2008, were reviewed. Records of dogs were searched for APCC classifications of confirmed (n = 71) or suspected (39) MPH toxicosis; dogs (18) that ingested MPH but did not develop clinical signs of toxicosis were also included. Signalment, dose, clinical signs, treatment, and outcome were evaluated.

Results—Clinical signs of toxicosis were reported in 107 of 128 (84%) dogs that ingested MPH; these included hyperactivity in 42 (33%), tachycardia in 27 (21%), vomiting in 19 (15%), agitation in 16 (13%), and hyperthermia in 13 (10%). Doses ranged from 0.36 mg/kg (0.164 mg/lb) to 117.0 mg/kg (53.18 mg/lb). Severity of clinical signs was not strongly associated with dose. More severe and prolonged clinical signs were associated with ingestion of extended-release formulations of MPH; 3 dogs that consumed these formulations (doses, 10.2 mg/kg [4.64 mg/lb], 15.4 mg/kg [700 mg/lb], and 31.1 mg/kg [14.14 mg/lb]) died. Favorable outcomes were reported for most (31/34 [91%]) dogs.

Conclusions and Clinical Relevance—Ingestion of even small amounts of MPH can cause severe clinical signs in dogs. Monitoring and supportive care are recommended regardless of dose.

Contributor Notes

Dr. Genovese's present address is the Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32608.

Dr. Gwaltney-Brant's present address is 501 N Dorchester Ct, Mahomet, IL 61853.

Dr. Genovese was a fourth-year veterinary student at the time of the study.

Address correspondence to Dr. Gwaltney-Brant (sharon.brant@yahoo.com).