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Detecting degenerative joint disease-associated pain in cats

Enomoto, Masataka, et al. “Development of a Checklist for the Detection of Degenerative Joint Disease-Associated Pain in Cats.” J Feline Med Surg, Mar. 2020.

Degenerative joint disease (DJD) is a common, yet underdiagnosed, condition of cats leading to pain, impaired mobility and decreased quality of life. Up to 90% of cats have radiographic signs of DJD with an estimated 40% showing signs of DJD-associated pain. Despite this high prevalence, DJD remains underdiagnosed and thus, is frequently untreated. Several factors may contribute to this discrepancy, including the decreased number of veterinary visits for cats compared to dogs, and the difficulty of diagnosis. Owners may be less familiar with recognizing signs of musculoskeletal pain in cats, as they are distinctly different from those shown in dogs and other species. Moreover, cats typically behave differently at the veterinary clinic than they do at home, with fewer opportunities for the veterinarian to observe important behavioural signs of pain, such as difficulty navigating stairs or jumping up onto higher surfaces.

The accurate diagnosis and effective management of DJD-associated pain requires assessment and monitoring by both veterinarians and owners. Several pain metrology instruments have been described for clinical and/or research use in cats, such as the Feline Musculoskeletal Pain Index (FMPI), Client-Specific Outcome Measures, and the Montreal Instrument for Cat Arthritis (MI-CAT). However, these tools have been designed for use once the presence of DJD has been confirmed, and with the assumption that DJD-associated pain is already present. These tools are also useful for monitoring the efficacy of treatment.

The objective of the present study was to develop an evidence-based, clinically expedient screening tool to identify cats likely to have DJD-associated pain. Similar screening tools have previously developed and tested for dogs, however, there remains a critical screening gap in the detection of DJD in cats. The authors of the present study aimed to develop such a checklist using a data-driven approach that could be completed by cat owners. Their principal parameters for measuring and confirming adequate accuracy included sensitivity, specificity and predictive value.

The study used data previously compiled by the Translational Research in Pain (TRiP) Program at North Carolina State University, as well as data generated specifically for the study purposes. Scores from the previously evaluated metrology instruments, including the FMPI and MI-CAT, were converted to generate usable data to develop a prospective questionnaire-based screening tool. All cats involved in the study were also evaluated by a veterinarian and underwent radiographs to confirm the presence of DJD. Cats involved in the study were assigned to two groups: impaired (249 cats) and unimpaired (53 cats). Owners were assigned to two testing groups: DJD-informed and DJD-uninformed.

Based on the data generated, sensitivity and specificity were calculated for various owner-directed questions, and following statistical analysis, narrowed down to six questions with the highest sensitivity and specificity. The questions are shown below.

Among DJD-informed owners, the sensitivity and specificity of the questionnaire were approximately 99% and 100%, respectively. Among DJD non-informed owners, the sensitivity and specificity of the proposed questionnaire were 55% and 97%, respectively. While the authors encourage veterinarians to educate cat owners about DJD and associated pain, they also postulate that based on the study’s results, the questionnaire would still be able to identify a large proportion of affected cats, even among DJD non-informed owners.

Several potential limitations of the present study exist, including the inclusion of stairs in two of the questions; not all cats will be exposed to stairs regularly. The authors indicate, however, that when both questions involving stairs are removed, the sensitivity and specificity of the other 4 questions combined remained mostly unchanged. Another limitation exists in that the study did not evaluate cats with other diseases. The authors note that it is possible that cats with cardiovascular or neurological disease, may generate positive responses to some of the questions, but may not be experiencing DJD-associated pain. Lastly, the number of healthy non-DJD cats included in the study population was relatively low, which may affect statistical power.

In conclusion, the proposed questionnaire was designed to meet a critical need for a clinically expedient screening tool for cats with DJD-associated pain. When combined with tools designed to engage owners and monitor treatment efficacy, the proposed checklist was designed to serve a further purpose: increase awareness of DJD among cat owners. Further studies aimed at applying the questionnaire to a larger population of cats are required to validate its utility. (HM)

See also:

Bennett, D., et al. “Osteoarthritis in the Cat: 1. How Common Is It and How Easy to Recognise?” J Feline Med Surg, vol. 14, no. 1, Jan. 2012, pp. 65–75. 

Bennett, D., et al. “Osteoarthritis in the Cat: 2. How Should It Be Managed and Treated?” J Feline Med Surg, vol. 14, no. 1, Jan. 2012, pp. 76–84.