chronic

Objective

To clinically evaluate previously developed pain scales [Donkey Chronic Pain Composite Pain Scale (DCP-CPS), Donkey Chronic Pain Facial Assessment of Pain (DCP-FAP), and combined Donkey Chronic Pain Scale (DCPS)], including behavioural and facial expression related variables, for the assessment of chronic pain in donkeys.

Study design

Prospective, blinded clinical study.

Animal population

A group of 77 donkeys (34 patients and 43 healthy control animals)

Methods

Animals were assessed by two observers that were blinded to the condition of the animals.

Results

Both DCP composite pain scale (CPS), DCP facial assessment of pain (FAP) and resulting Donkey Chronic Pain Scale (DCPS) scores showed good inter-observer reliability (Intra Class Correlation (ICC) coefficient = 0.91, confidence interval (CI) = 0.86–0.95, p < 0.001; ICC = 0.71, CI = 0.50–0.83, p < 0.001 and ICC = 0.84, CI = 0.72–0.91, p < 0.001 respectively). All scores (DCP-CPS, DCP-FAP and the resulting combined DCPS) were significantly higher for patients compared to controls at all time points (p < 0.001 for all three scales). Sensitivity and specificity for identification of pain (cut-off value > 3) was 73.0 and 65.1% for DCP-CPS, while for DCP-FAP this was 60.9% and 83.3%, respectively. For the combined DCPS, sensitivity was 87.0% and specificity 90.9% (cut-off value > 6).

Conclusions and clinical relevance

The DCPS, based on behavioural and facial expression-based variables, proved a promising and reproducible tool to assess different types of chronic pain in donkeys. The combination of behavioural and facial expression-based variables showed the best discriminatory characteristics in the current study. Further studies are needed for refinement of these tools.

Assessment of chronic pain is very important for monitoring and improving welfare and quality of life in donkeys. Freedom from disease and pain is one of the ‘five freedoms’ underlying animal welfare. The aim of the current study was to develop a pain scale for assessment of chronic pain in donkeys (Donkey Chronic Pain Scale; DCPS), including behavioural and facial expression-related parameters. The scale was applied to 77 donkeys (38 donkeys diagnosed with chronic health problems by means of clinical examination and additional diagnostic procedures and 39 healthy control animals). Animals were assessed twice daily for three consecutive days by two observers that were not masked to the condition of the animals but were unaware of the analgesic treatment regimens. Both composite, facial expression-based and combined DCPS pain scales showed excellent inter-observer reliability (Cronbach’s alpha = 0.98, 0.96 and 0.98 respectively; P < 0.001). Individual composite and facial expression-based pain scores and the resulting combined DCPS showed significant differences between donkeys with chronic conditions and control donkeys at all time points (P < 0.001). A DCPS cut-off of 6 showed good sensitivity and specificity (92% and 82.5% respectively) for presence of a chronic painful condition. Facial expression-related parameters separately showed low sensitivity. In conclusion, it is possible to use a composite pain scale for assessment of chronic pain in donkeys, based on behavioural and facial expression-based parameters. Further studies are needed to validate this pain scale before it can be used in veterinary practice.