Pain Scoring in Dogs with Anxiety

Pain assessment in dogs is important for optimal management but can be challenging. Pain scales can help identify and quantify pain based on changes in behavior or facial expressions; however, anxiety and other emotional states can interfere with scoring. 

This study used Glasgow Composite Measure Pain Scale-Short Form (CMPS-SF), which is a behavior-based scale for acute pain in dogs, to investigate the relationship between anxiety and pain scores in 18 dogs undergoing surgery for stifle disease. Dogs were divided into groups based on preoperative anxiety levels evaluated by the reactivity evaluation form (REF), which is behavior based, and a visual analog scale (VAS). Fifty percent of dogs with the highest REF scores were designated high REF, and remaining dogs were designated low REF. Dogs were also designated high VAS (ie, 50% with highest VAS scores) or low VAS. Anesthetic and surgical protocols were chosen by the clinician for each case. All dogs were assessed for pain and anxiety preoperatively and 2 to 6 hours postoperatively by the same observer using CMPS-SF, REF, and VAS.

REF and VAS postoperative anxiety scores increased significantly compared with preoperative scores in the low REF and low VAS groups but not in the high REF and high VAS groups. CMPS-SF pre- and postoperative pain scores did not significantly differ between high REF and low REF groups or between high VAS and low VAS groups.

Anxiety increased after surgery, with significant increase in dogs that had lower baseline anxiety. There was no pre- or postoperative relationship between baseline anxiety levels and pain scores. 

CMPS-SF assessment of acute pain in dogs does not appear to be affected by level of anxiety.

Key pearls to put into practice:

Hospitalization and medical procedures (eg, surgery) increase anxiety in dogs. Pharmacologic and nonpharmacologic approaches to avoid and reduce negative emotional states (eg, stress, fear, anxiety) should be considered to promote patient welfare.

Pain assessment is considered the fourth vital sign, and all patients should be assessed for pain, including pre- and postoperatively, depending on the procedure performed and drugs administered.

Behavior-based or grimace scales with demonstrated scientific validity and reliability should be used for standardized pain evaluation, as they can help monitor pain scores over time and evaluate response to analgesics; cutoff scores may provide clinical guidance for administration of rescue analgesia (when available).