ObjectiveTo evaluate thermal antinociception from intravenous (IV) administration of hydromorphone alone or followed by butorphanol or naloxone in cats. Study designRandomized, controlled, masked, crossover design. AnimalsA group of eight adult female cats. MethodsCats were administered six treatments of two IV injections 30 minutes apart: treatments S–S, two 0.9% saline; H–S, hydromorphone (0.1 mg kg−1) and saline; H–LB, hydromorphone and butorphanol (0.02 mg kg−1); H–MB, hydromorphone and butorphanol (0.1 mg kg−1); H–HB, hydromorphone and butorphanol (0.2 mg kg−1); H–N, hydromorphone and naloxone (0.04 mg kg−1). Skin temperature (ST), thermal threshold (TT) and sedation score (SS) were recorded before (baseline) and for 8 hours after the first injection. Percentage maximum possible effect (%MPE), thermal excursion (TE), TT, SS and ST were compared using two-way repeated measures anova or Friedman test followed by Tukey’s or Dunn’s multiple comparisons test when appropriate. Significance was set at p ≤ 0.05. ResultsData from seven cats were analyzed. There were no significant differences among treatments in baseline values, SS and within S–S over time. Compared with respective 0.5 hour values following hydromorphone administration, %MPE was significantly lower at 4–8 hours for H–S; at 3–8 hours for H–LB; at 4–8 hours for H–MB; at 6–8 hours for H–HB and at 1–8 hours for H–N. Compared with respective 0.5 hour values, TE was significantly lower at 4–8 hours for H–S; at 3–8 hours for H–LB; at 2 and 4–8 hours for H–MB; at 6 and 8 hours for H–HB and at 1–8 hours for H–N. Conclusions and clinical relevanceButorphanol and naloxone reduced hydromorphone-induced thermal antinociception. Butorphanol preserved hydromorphone antinociceptive properties better than naloxone. Butorphanol is recommended during non-life-threatening scenarios as a partial reversal agent for hydromorphone in cats.