title: Analgesic efficacy of tramadol in cats with naturally occurring osteoarthritis.
abstract: OBJECTIVE
  This study aimed to (1) compare outcome assessments in normal and osteoarthritic cats and (2) evaluate the analgesic efficacy of tramadol in feline osteoarthritis (OA), in a prospective, randomised, blinded, placebo-controlled, crossover design.
  
  
  METHODS
  Twenty cats were included after clinical examination, blood work and full body radiographs were performed. In Phase 1, outcome assessments aimed to differentiate normal (n = 5; i.e. exempt of any radiographic and clinical sign of OA) from OA (n = 15) cats. In Phase 2, OA cats were treated twice daily with a placebo (PG: cornstarch 15 mg) or tramadol (TG: 3 mg/kg) orally for 19 days, with a 3-month washout period between treatments. Evaluations were performed in normal and OA cats at baseline and consisted of: 1) peak vertical force (PVF) after staircase exercise; 2) telemetered night-time motor activity (NMA); and 3) response to mechanical temporal summation (RMTS). After treatment, PVF, NMA and RMTS evaluations were repeated in OA cats. Data were analysed with mixed model methods with an alpha-threshold of 5%.
  
  
  RESULTS
  Phase 1: 1) PVF (% of body weight; mean ± SD) was higher in normal (59 ± 10.5) than in OA cats (50.6 ± 5.7) (p = 0.005); 2) NMA (no unit) was not different between groups; 3) RMTS (number of stimuli; median (range)) was higher in normal [29.5 (23.5-30)] than in OA cats [14 (8.5-28)] (p < 0.0001). Phase 2: PVF, NMA and RMTS presented a treatment effect (p = 0.024, p = 0.008 and p = 0.018, respectively). No clinically important adverse-effects were observed.
  
  
  CONCLUSIONS
  Outcome assessments such as kinetics (PVF) and evaluation of central sensitisation (RMTS) are discriminant of OA status. Mobility measured by NMA was not discriminant of OA status, however it increased in OA cats with tramadol treatment. Nociceptive hypersensitivity quantified by RMTS was evident in OA cats and was responsive to tramadol treatment.
authors.affiliation: GREPAQ (Animal Pharmacology Research Group of Quebec), Faculty of Veterinary Medicine-Université de Montréal, Saint-Hyacinthe, QC, Canada.
authors.forename: Beatriz P
authors.initials: BP
authors.lastname: Monteiro
authors.affiliation: GREPAQ (Animal Pharmacology Research Group of Quebec), Faculty of Veterinary Medicine-Université de Montréal, Saint-Hyacinthe, QC, Canada.|Osteoarthritis Research Unit, Research Center of the University of Montreal Hospital Centre, Montreal, QC, Canada.
authors.forename: Mary P
authors.initials: MP
authors.lastname: Klinck
authors.affiliation: GREPAQ (Animal Pharmacology Research Group of Quebec), Faculty of Veterinary Medicine-Université de Montréal, Saint-Hyacinthe, QC, Canada.|Osteoarthritis Research Unit, Research Center of the University of Montreal Hospital Centre, Montreal, QC, Canada.
authors.forename: Maxim
authors.initials: M
authors.lastname: Moreau
authors.affiliation: GREPAQ (Animal Pharmacology Research Group of Quebec), Faculty of Veterinary Medicine-Université de Montréal, Saint-Hyacinthe, QC, Canada.|Osteoarthritis Research Unit, Research Center of the University of Montreal Hospital Centre, Montreal, QC, Canada.
authors.forename: Martin
authors.initials: M
authors.lastname: Guillot
authors.affiliation: Department of Clinical Sciences, Faculty of Veterinary Medicine-Université de Montréal, Saint-Hyacinthe, QC, Canada.
authors.forename: Paulo V M
authors.initials: PV
authors.lastname: Steagall
authors.affiliation: Osteoarthritis Research Unit, Research Center of the University of Montreal Hospital Centre, Montreal, QC, Canada.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Pelletier
authors.affiliation: Osteoarthritis Research Unit, Research Center of the University of Montreal Hospital Centre, Montreal, QC, Canada.
authors.forename: Johanne
authors.initials: J
authors.lastname: Martel-Pelletier
authors.affiliation: GREPAQ (Animal Pharmacology Research Group of Quebec), Faculty of Veterinary Medicine-Université de Montréal, Saint-Hyacinthe, QC, Canada.
authors.forename: Dominique
authors.initials: D
authors.lastname: Gauvin
authors.affiliation: GREPAQ (Animal Pharmacology Research Group of Quebec), Faculty of Veterinary Medicine-Université de Montréal, Saint-Hyacinthe, QC, Canada.
authors.forename: Jérôme R E
authors.initials: JR
authors.lastname: Del Castillo
authors.affiliation: GREPAQ (Animal Pharmacology Research Group of Quebec), Faculty of Veterinary Medicine-Université de Montréal, Saint-Hyacinthe, QC, Canada.|Osteoarthritis Research Unit, Research Center of the University of Montreal Hospital Centre, Montreal, QC, Canada.
authors.forename: Eric
authors.identifier: http://orcid.org/0000-0003-0209-5261
authors.initials: E
authors.lastname: Troncy
mesh_terms: D000701:Analgesics, Opioid / Q000494:pharmacology / Q000627:therapeutic use*; D000818:Animals; D002371:Cat Diseases / Q000188:drug therapy*; D002415:Cats; D018592:Cross-Over Studies; D005260:Female; D008297:Male; D010003:Osteoarthritis / Q000188:drug therapy / Q000662:veterinary*; D011446:Prospective Studies; D016037:Single-Blind Method; D014147:Tramadol / Q000494:pharmacology / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D000701:Analgesics, Opioid; D014147:Tramadol