Objective—To determine epidemiologic characteristics,
clinical findings, and treatment outcome of 5-hydroxytryptophan (5-HTP) toxicosis in dogs.
Animals—21 dogs with evidence of accidental 5-HTP
Procedure—Information was retrieved from the
National Animal Poison Control Center database.
Records of dogs ingesting 5-HTP between January
1989 and February 1999 were reviewed for information
on signalment, dose ingested, clinical signs
(onset, severity, duration), treatments administered,
Results—Clinical signs of toxicosis developed in 19 of
21 (90%) dogs. Neurologic signs included seizures (9
dogs), depression (6), tremors (5), hyperesthesia (5),
and ataxia (4). Gastrointestinal tract signs included
vomiting or diarrhea (12 dogs), signs of abdominal
pain (3), and hypersalivation (2). Other clinical signs
were hyperthermia (7 dogs) and transient blindness
(3). Three dogs died. No important clinical laboratory
or necropsy findings were reported. The doses of 5-HTP ingested ranged from 2.5 to 573 mg/kg (1.1 to
260 mg/lb) of body weight; the minimum toxic dose
reported in our study was 23.6 mg/kg (10.7 mg/lb),
and the minimum lethal dose was 128 mg/kg (58.1
mg/lb). Onset of signs ranged from 10 minutes to 4
hours after ingestion, and signs lasted up to 36 hours.
Of 17 dogs with clinical signs of toxicosis that
received treatment, 16 recovered; treatment consisted
of decontamination, seizure control, thermoregulation,
fluid therapy, and supportive care.
Conclusions and Clinical Relevance—Ingestion of
5-HTP in dogs can result in a potentially life-threatening
syndrome resembling serotonin syndrome in
humans, which requires prompt and aggressive care.
(J Am Vet Med Assoc 2000;216:1937–1940)