Tachypnea and antipyresis in febrile horses after sedation with alpha-agonists.
BACKGROUND
Signs of tachypnea after sedation of febrile horses with alpha2-agonists have been noted previously but have not been further investigated.


OBJECTIVE
To examine the effects of xylazine and detomidine on respiratory rate and rectal temperature in febrile horses and to investigate if either drug would be less likely than the other to cause changes in these variables.


METHODS
Nine febrile horses and 9 healthy horses were included in the study.


METHODS
Horses were randomly assigned to sedation with xylazine 0.5 mg/kg or detomidine 0.01 mg/kg. Heart rate and respiratory rate were recorded before sedation and at 1, 3, and 5 minutes after injection. Hourly measurements of rectal temperature were performed starting before sedation.


RESULTS
All febrile horses experienced an episode of tachypnea and antipyresis after sedation. Rectal temperature in the febrile group was significantly lower at 1, 2, and 3 hours after sedation. In several measurements, the decrease was >1 degrees C. Respiratory rate in the febrile group was significantly increased after sedation. All febrile horses were breathing>40 breaths/min and 3 horses>100 breaths/min 5 minutes after sedation. No differences were noted between the 2 treatments. No significant changes in respiratory rate or temperature were noted in the reference group.


CONCLUSIONS
Febrile horses can become tachypneic after sedation with detomidine or xylazine. The antipyretic properties of alpha2-agonists need consideration when evaluating patients that have been sedated several hours before examination.
Kendall
A
A
Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden. anna.kendall@kv.slu.se
Mosley
C
C
Bröjer
J
J
D000316:Adrenergic alpha-Agonists / Q000009:adverse effects / Q000627:therapeutic use; D000818:Animals; D005334:Fever / Q000188:drug therapy / Q000662:veterinary*; D006734:Horse Diseases / Q000188:drug therapy*; D006736:Horses; D006993:Hypnotics and Sedatives / Q000009:adverse effects / Q000627:therapeutic use; D007093:Imidazoles / Q000009:adverse effects / Q000627:therapeutic use*; D012119:Respiration / Q000187:drug effects*; D014991:Xylazine / Q000009:adverse effects / Q000627:therapeutic use*
D000316:Adrenergic alpha-Agonists; D006993:Hypnotics and Sedatives; D007093:Imidazoles; D014991:Xylazine; C041255:detomidine