title: Inconsistency of allometric scaling for dissociative anesthesia of wild felids.
abstract: OBJECTIVE
  To evaluate allometric scaling for ketamine-xylazine (KX) anesthesia in wild felids using domestic cats for reference.
  
  
  METHODS
  Prospective single-phase non-blinded study.
  
  
  METHODS
  Six domestic cats and 13 wild felids (five Leopardus pardalis, five Puma concolor, one Panthera onca and two Panthera leo).
  
  
  METHODS
  Six domestic cats (4.1 ± 0.8 kg, REF1) were anesthetized by intramuscular administration of ketamine (15 mg kg(-1) ) and xylazine (1 mg kg(-1) ). Wild cats were divided into three groups based on body weight: 12.9 ± 2.4 kg (G1; n = 7), 43.0 ± 15.7 kg (G2; n = 4) and 126.0 ± 7.8 kg (G3; n = 2). Ketamine and xylazine doses were calculated based on allometric scaling of the basal metabolic rate (BMR = 70 × body mass(0.75) ). Afterwards, the six domestic cats were administered mean KX doses calculated for G1 and G2 (REF2). The heart rate, systolic arterial pressure, respiratory frequency, pH, the venous partial pressure of carbon dioxide, bicarbonate and lactate concentrations were recorded for up to 60 minutes.
  
  
  RESULTS
  Additional doses were required in 12 out of the 13 wild cats. Anesthesia was not achieved in G3. Latency periods in wild felids were longer than REF1 and REF2. Anesthesia duration in REF1 was longer than that in the other groups. Recovery from anesthesia in REF1 and REF2 was longer than G1 and G2. Physiological variables remained within the range limits for the species. G1 baseline lactate concentration was higher than in the other groups.
  
  
  CONCLUSIONS
  KX anesthesia established by allometric scaling of BMR from doses administered to domestic cats did not predict reliable anesthetic doses for wild cats. Dose rates calculated with this method must not be applied to these species.
authors.affiliation: School of Animal Science and Food Engineering, University of São Paulo, São Paulo, SP, Brazil.
authors.forename: Adriano B
authors.initials: AB
authors.lastname: Carregaro
authors.affiliation: Veterinary Medicine Course. Federal University of Southern Border, Realeza, PR, Brazil.
authors.forename: Gabrielle C
authors.initials: GC
authors.lastname: Freitas
authors.affiliation: School of Animal Science and Food Engineering, University of São Paulo, São Paulo, SP, Brazil.
authors.forename: Shayne P
authors.initials: SP
authors.lastname: Bisetto
authors.affiliation: School of Animal Science and Food Engineering, University of São Paulo, São Paulo, SP, Brazil.
authors.forename: Nathalia V
authors.initials: NV
authors.lastname: Xavier
authors.affiliation: Mourão Ecological Park, Leme Zoo, Leme, SP, Brazil.
authors.forename: Elton V
authors.initials: EV
authors.lastname: Sterzo
mesh_terms: D000818:Animals; D000835:Animals, Wild; D001835:Body Weight; D002415:Cats / Q000601:surgery*; D004305:Dose-Response Relationship, Drug; D007649:Ketamine / Q000008:administration & dosage*; D008954:Models, Biological; D011446:Prospective Studies; D014991:Xylazine / Q000008:administration & dosage*
chemical_list: D014991:Xylazine; D007649:Ketamine
keywords: allometric scaling; dissociative anesthesia; ketamine; metabolic rate; xylazine