Development of a vision impairment score for the assessment of functional vision in dogs: Initial evidence of validity, reliability, and responsiveness.

AIM: To describe the development and initial validation of a questionnaire measuring functional vision in dogs. METHODS: A 17-item survey was designed to quantify functional vision in dogs. The Vision Impairment Score (VIS) was determined by summing responses to each question. Questions were assigned to one of five subcategories: overall vision, daily activities, peripheral vision, near vision, and distance vision. Content validity was established during development phases, and construct validity via comparing results of known groups (blind vs sighted; normal vs impaired vision; surgery to improve vision vs nonrestorative surgery), and through factor analysis. Concurrent criterion validity was determined with use of a validated health-related quality-of-life (HRQL) assessment tool. Reliability and responsiveness assessments were investigated using intraclass correlation coefficient (ICC) and effect size (ES), respectively. RESULTS: Responses (221) from 201 dog owners were included. Compared to sighted dogs (n = 153), blind dogs (n = 48) had a higher VIS and greater impairment in all subcategories. Among sighted dogs, a higher VIS was obtained in dogs with low vision compared to those with normal vision (P < 0.001). A higher VIS was associated with poorer HRQL (P < 0.001). Perfect reliability was obtained for 6/17 questions, and excellent reliability for 11/17 questions (intraclass correlation 1.0 and >0.9, respectively), and the VIS was highly responsive to therapeutic intervention (effect size 1.46). CONCLUSION: Results suggest the VIS may be clinically useful in assessing and obtaining a quantifiable measure of functional vision in dogs. Ongoing validation of the tool for clinical use is needed.

Development, initial validation and reliability testing of a web-based, generic feline health-related quality-of-life instrument.

OBJECTIVES: The objective of this study was to develop a valid, reliable, web-based generic feline health-related quality-of-life (HRQoL) questionnaire instrument to measure the affective impact of chronic disease. METHODS: A large initial item pool, obtained through interviews with cat owners, was reduced using predetermined criteria, survey scores for relevance and clarity, and the ability of individual items to discriminate between healthy and sick cats when owners completed a prototype questionnaire. Using these data, factor analysis was used to derive a scoring algorithm and provide evidence for factorial validity. Validity was demonstrated further in a field trial using a 'known groups' approach (sick vs healthy cats will have a different HRQoL profile, and the HRQoL profile of cats will deteriorate as comorbidities increase). Test-retest reliability was assessed using intra-class correlation coefficients (ICCs). RESULTS: In total, 165 items were reduced to 20 and, on the basis of a factor analysis that explained 72.3% of the variation in scores input by 71 owners of 30 healthy and 41 sick cats using the prototype, these were allocated to three domains (vitality, comfort and emotional wellbeing [EWB]) with a scoring algorithm derived using item loadings. Subsequently, the owners of 36 healthy and 58 sick cats completed one or two (n = 48) assessments. Median scores (healthy vs sick) for all domains were significantly different ( P <0.001), 78% of cats were correctly classified as healthy or sick and for comorbidities the correlation coefficients were moderate (vitality 0.64; comfort 0.63; EWB 0.50). Test-retest reliability was good (ICC vitality 0.635; comfort 0.716; EWB 0.853). CONCLUSIONS AND RELEVANCE: This study provides initial evidence for the validity and reliability of a novel HRQoL instrument to aid the assessment and management of chronic diseases of cats.

When is the right time?

Veterinary medicine is veering further towards prolongation of life at all costs, without the safeguard of being able to robustly measure quality of life. Jacky Reid, Andrea Nolan and Marian Scott discuss major steps forward in the ability to measure changes in health-related quality of life.

Application of a scaling model to establish and validate an interval level pain scale for assessment of acute pain in dogs.

OBJECTIVE: To establish interval level measurement in a prototype composite measure pain scale (CMPS) for assessment of acute pain in dogs and to investigate the scale's validity. ANIMALS: 20 clinically normal dogs, 20 dogs with medical conditions, and 117 dogs undergoing surgery. PROCEDURE: First, a scaling model was applied to the CMPS descriptors to establish weights for each and create a continuous scale. Subsequently, 5 observers independently used the scale to score signs of pain in 4 groups of dogs (control dogs, dogs with medical conditions, and 40 dogs undergoing soft tissue or orthopedic surgery). Scores from each group and from groups of conditions perceived to cause no, mild, moderate, and severe pain were compared. In addition, the scale was applied to 77 dogs undergoing orthopedic or soft tissue surgery and scores were compared with simultaneously derived numeric rating scale (NRS) scores; comparisons were made between surgical groups and with time after surgery. RESULTS: Calculated scale descriptor weights ranged from -2.0 to 2.0 and were transformed to create a continuous scale from 0 to 10. Median CMPS scores differed significantly among the 4 study groups and among pain severity groups and were typically greater with increasing perceived pain severity. Agreement was determined between CMPS and NRS scores, and there was a significant and expected time effect and difference between the CMPS scores of dogs undergoing orthopedic and soft tissue surgery. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that this interval level measurement scale is a valid measure of acute pain in dogs.