Comparison of Certain Intrarectal versus Intramuscular Pharmacodynamic Effects of Ketamine, Dexmedetomidine and Midazolam in Cats

SIMPLE SUMMARY: The chemical immobilization of cats is widely required in veterinary clinical practice; sedative drugs are administered intramuscularly and routinely, but this is painful and uncomfortable. The intrarectal route is commonly used in humans for the sedation of uncooperative patients and is very safe, but it is not investigated in cats. In the present study, twenty owned cats were included, ten underwent intramuscular sedation, and the other ten intrarectal sedation. Cardiorespiratory values, pulse oximetry, body temperature, sedation score, and the feasibility of venous catheter placement were compared between the two groups at pre-established time points. Cats that received the intrarectal administration showed a shorter and superficial state of sedation than intramuscular ones, but in the intrarectal group, the maintenance of SpO₂ values was >95% during the experimental period and the recovery of the quadrupedal station was faster. According to these results, the intrarectal route appears to have a high efficacious option for performing minimally invasive clinical and diagnostic procedures in cats. ABSTRACT: The aim of this clinical trial was to evaluate the impacts of administration via the intrarectal route (IR) in cats on their heart and respiratory rates, blood pressure, body temperature, and sedation quality compared to the intramuscular route (IM). The intramuscular group (IMG) received 0.003 mg kg(−1) dexmedetomidine, 2 mg kg(−1) ketamine, and 0.2 mg kg(−1) midazolam while the intrarectal group (IRG) protocol was 0.003 mg kg(−1) dexmedetomidine, 4 mg kg(−1) ketamine, and 0.4 mg kg(−1) midazolam. Cardiorespiratory values, temperature, and sedation score were measured 2 min after administration and then every 5 min up to the 40th minute. Cats belonging to IRG reacted less strongly to the drug, as opposed to those receiving intramuscular administration (2/10 in IRG vs. 8/10 in IMG). Average time between drug administration and standing position was 44.9 ± 5.79 in IRG and 57 ± 9.88 min in IMG. In IRG, maintenance of SpO₂ values is >95% at each time point. Median and range peak of sedation {7 (5)} in IMG occurs at 20th, 25th, and 30th minutes post drug administration while was lower in IRG. Cardiorespiratory values were slightly lower in IMG than in IRG, but always constant in both treatments. Temperature did not differ between groups. At this dosage, although sedation score was higher in IMG, intrarectal route could be efficacious for performing minimally invasive clinical and diagnostic procedures in cats.