Implementation of a prospective in-clinic validated Feline Osteoarthritis Checklist

Abstract

Objectives

The goal of the present study was to screen two cat populations for osteoarthritis. There are an estimated 60 million cats in the USA, with a growing body of evidence identifying a high percentage of them as suffering from osteoarthritis (OA); however, many are undiagnosed. New tools, such as the Feline Osteoarthritis Checklist, are available for use in practice to help screen cats for OA.

Methods

Working with the same general small animal practice, one population of cats was retrospectively screened for OA using historical methods, including physical examination and owner engagement. These results were then numerically evaluated to a similar prospective population using the Feline OA Checklist as a screening tool. Five general practice veterinary clinics with feline patients participated in both parts of this study, providing a total of 502 cat medical records for the retrospective phase of this study and 437 completed screening forms in the prospective phase of this study.

Results

Of the cats in the retrospective phase of the study, 1% had orthopedic-related issues when methods of identification such as oral history and physical examination were used. When the Feline OA Checklist was used as a screening tool in a prospective population, 39% of cats were identified as demonstrating at least one behavior consistent with OA.

Conclusions and relevance

Pain recognition is the first step of pain management, and the use of the Feline OA Checklist can help improve feline health and welfare by easily and readily identifying these patients. Utilizing tools such as the Feline OA Checklist to screen all cats in practice offers veterinary practitioners an efficient way to identify the impact of feline OA and begin alleviating pain-related suffering.

Introduction

In the USA, the cat population is estimated at over 60 million, with increasing evidence suggesting that a high percentage suffer from osteoarthritis (OA);^{1 –4} however, this disease remains significantly underdiagnosed for several reasons. First, studies have identified that 44–65% of cats in the USA see their veterinarian annually, and another 22% see their veterinarian every other year, leaving many adult cats vulnerable to undetected onset of chronic disease.^1,2 Second, most cats seen by veterinarians are either aged under 3 years or over 12 years, leaving a substantial age gap in between.^5,6 As cats age, they are affected by several diseases, including OA, chronic kidney disease and other ailments. ⁷ Research has estimated that 60% of cats aged 6 years and older are affected by degenerative joint disease (DJD), including OA; however, cats at this stage of life may not be receiving annual care and rarely exhibit lameness.^3,6 Indeed, when they are seen by a veterinarian, they do not demonstrate physical examination findings associated with canine OA, such as joint effusion and crepitus.^3,6 In addition, radiographs, which many consider the gold standard for identifying joint changes consistent with OA, are often inconsistent with feline (and canine) clinical signs associated with OA.^8,9 Several studies found that only 4–16.7% of cats with radiographic changes consistent with OA demonstrated any degree of lameness.^6,9 Although researchers recognize the need to assess behaviors at home, it was not until 2019 that researchers at North Carolina State Veterinary School developed the Feline Musculoskeletal Pain Screening Checklist (referred to as the Feline OA Checklist here).^10,11 This screening tool contains six activities that, when difficult for a cat to complete, demonstrate 97% specificity for DJD; therefore, a positive response to any question indicates a high likelihood of DJD-associated pain. ¹⁰ The tool is intended for pet owner engagement in a clinic setting, as cats are more likely to display OA behaviors at home, making identification in the clinic more challenging.

Given the known limitations for assessing feline OA, ¹⁰ this study proposed that real-world use of the Feline OA Checklist would identify a larger number of cats with activities indicative of OA when numerically compared with existing methods most commonly used in practice (ie, oral history, physical examination, orthopedic examination, radiographs). The goal of this study was to numerically compare a screened feline population to a random, but similar, unscreened population from the same clinic.

Materials and methods

Study procedures

This observational study was conducted in two parts, including a retrospective assessment and a prospective active pet owner checklist response. Clinics across the USA were offered the study opportunity and were selected based on their willingness to participate, their ability to provide consistent data and the number of cats seen as part of their patient population. Each clinic provided retrospective and prospective information for evaluation.

Each clinic was asked to participate in both parts. Initially, a retrospective record review of up to the last 100 cats was undertaken at general veterinary clinics (Figure 1 and the data collection form in the supplementary material). Clinics were asked to share only the patient ID and signalment to ensure anonymity of owner information. Cats presented for euthanasia were excluded from both parts of the study. Cats of any age, breed, sex or health status were eligible for inclusion in the study. Once the cats were identified, clinics were asked to review the record and determine the reason for the visit, any diagnostics undertaken or recommended during the visit, any current diagnoses for the patient and any treatments that were recommended or in use for any current diagnosis.

Figure 1.

Procedural design: explanatory sequence of procedures for each portion depicted horizontally

The prospective study component was performed for up to 100 cats per clinic (excluding cats presenting for euthanasia) presenting for a sick or well visit (Figure 1). In the reception area, before the cat’s examination, pet owners were provided with a paper copy of the Feline OA Checklist for review and completion. Pet owners were asked to consider their cat’s activities in the past week and check any activities they had observed. The six activities included climbing up stairs, climbing down stairs, chasing moving objects, jumping up, jumping down and running (Figure 2a).

Figure 2.

(a) Feline Osteoarthritis Checklist and (b) Feline Osteoarthritis Checklist health-related quality of life questions

In addition, pet owners were asked to complete three health-related quality of life (HRQoL) questions (Figure 2b). ¹² These HRQoL questions or domains within the Feline Vetmetrica Health Related Quality of Life tool have been validated and scores demonstrate a significant difference between healthy and sick cats. ¹² The three HRQoL questions ask owners to think about their cat’s behavior in the past week and use a scale from 0 (my cat couldn’t be less) to 6 (my cat couldn’t be more) to score their cat’s energy and enthusiasm (vitality), activity and comfort (comfort), and happiness and contentment (emotional wellbeing). Each question was scored individually on a Likert scale from 0 (minimum score reflecting low vitality, comfort or emotional wellbeing) to a maximum of 6 (representing high vitality, comfort or emotional wellbeing). This tool was selected based on the abundance of evidence supporting its ability to demonstrate differences between healthy and sick cats. ¹²

The final section of the checklist focuses on three general behavior questions (Figure 3). These questions inquire about changes in the cat’s personality and sociability, urination and defecation habits, and hiding or slowing down behaviors. Owners selected a yes or no response for each question.

Figure 3.

Feline Osteoarthritis Checklist general behavior questions

Phase 1

The retrospective phase collected cat signalment (age, sex, neuter status, breed and weight), medical history, treatment history, diagnostic testing history and any treatment history. Information regarding well and sick visits was summarized, including any treatments and diagnostic testing results. No identifiable pet owner information was included.

Phase 2

The prospective phase collected cat signalment (age, sex, neuter status, breed and weight), medical history, treatment history, diagnostic testing history and treatment history for prior visits as well as the current visit. In addition, each pet owner completed the Feline OA Checklist at presentation and three QoL and three behavior questions. No identifiable pet owner information was included.

All respondents of the prospective phase of the study were informed in writing that by completing the Feline OA Checklist, they were agreeing to provide informed consent before their participation. Each clinic provided cat signalment, medical, treatment and diagnostic history, which was attached to the completed Feline OA Checklist. Pet owners were compensated by the clinic at the completion of each interaction. Clinics were asked to ensure each respondent population was unique and there was no crossover between the two participant groups.

Data collection

Data collection took place between April 2019 and July 2021. As this research was purely non-interventional in nature for both animals and humans, formal ethics approval was not required. All respondents provided expressed informed consent to participate after receiving information on study aims, procedures and confidentiality of personal data. Participating veterinary clinics provided compensation to pet owners for their participation in the survey.

Survey forms

For the retrospective part of the study, all documentation was provided electronically via data capture devices. For the prospective part of the study, the Feline OA Checklist was completed on paper and all paper copies were returned for analysis.

Study size determination

Since this observational analysis utilized summary statistics, a convenience sample was determined using conventions from prior research as well as practical constraints based on the number of clinics and study participants.^3,6,7,10,13

Statistical analysis

Demographic characteristics were summarized using standard descriptive summaries. Continuous variables were summarized but not statistically analyzed using SAS Freq and Proc Means (SAS 9.4; SAS Institute) to calculate range, minimum, maximum and frequency.

Results

Study population

Five privately owned general practice small animal clinics were identified in the Northeast and Midwest areas of the USA (Figure 1). Clinics were all located in urban/suburban areas and were identified as providing general veterinary care for cats.

In the retrospective phase, 502 cat medical records were provided with 100 records from three clinics and 101 records from two clinics. The cats’ ages were in the range of 8 weeks to 20 years (mean age 6.1 years) (Table 1). Slightly less than half (241/502, 48%) of the cats were seen for wellness visits, including vaccination. For those that presented for non-wellness-related examinations, reasons for presentation included upper respiratory infections, ocular issues, hyperthyroidism, skin infections/abscesses, parasites and chronic renal disease.

Table 1.

Demographics of the study participants

	Retrospective (n = 502)	Prospective (n = 437)
Age of the youngest (weeks)	8	6
Age of the oldest (years)	20	20
Mean age (years)	6.1	8.7
Sex (M/F)	245/257	222/215
Breed	Domestic shorthair: 358 Domestic mediumhair: 65 Domestic longhair: 47 Pure breed: 32	Domestic shorthair: 334 Domestic longhair: 44 Domestic mediumhair: 25 Pure breed: 30 Unknown: 4

Cats presenting for orthopedic-related issues constituted less than 3% of cases, with 10 cats presenting for acute orthopedic injuries and five (1%) cats presenting for chronic orthopedic changes. For the 10 cats presenting with acute orthopedic injury, all were aged 6 years or under. For those cats presenting with chronic orthopedic changes, all were aged 10 years or older (Table 2).

Table 2.

Descriptive statistics of outcome variables for the retrospective patient group

Age group (years)	n	Mean age (years)	Age range (years)	% with chronic OA	% with acute pain
<6	348	2.12	0.2–5	0	2
6–12	88	8.78	6–12	2	2
>12	66	14.83	13–20	5	0
Total	502	–	–	1	2

OA = osteoarthritis

In the prospective phase, 437 cats were examined, with clinics providing 49–100 medical records per site. Cats ranged in age from 6 weeks to 20 years (mean age 8.7 years), with slightly more male cats when numerically compared with female cats (Table 1). Slightly more cats were seen for wellness visits, including vaccination, in the prospective arm of the study, with 231/437 (53%) cats presenting for wellness visits. The remaining cats presented for similar non-wellness reasons as observed in the retrospective case review, including upper respiratory infections, hyperthyroidism, skin infections/abscesses, parasites and chronic renal disease.

Each of the six activities reviewed by the owners as part of the Feline OA Checklist align with an activity that has been validated to screen cats for OA pain. ¹⁰ When utilizing the checklist, owners identified 9% of cats under the age of 6 years with one or more activities consistent with OA pain (numerically compared with 0% in the retrospective group), while 38% of cats aged 6–12 years had one or more activities consistent with OA pain (Tables 2 and 3). However, 71% of cats over the age of 12 demonstrated activities consistent with OA pain. Overall, 39% of cats in the study demonstrated at least one sign consistent with OA pain (as numerically compared with the 1% in our retrospective record review) (Tables 2 and 3).

Table 3.

Descriptive statistics of outcome variables for the prospective patient group

Age group (years)	n	Mean age (years)	Age range (years)	% with OA
<6	208	2.39	0.2–5	9
6–12	149	8.66	6–12	38
>12	80	15.13	13–20	71
Total	437	–	–	39.1

OA = osteoarthritis

Pet owners also completed three QoL questions evaluating their cat’s vitality, comfort and emotional wellbeing. Because of smaller sample sizes, we utilized the age of 6 years as our cutoff for the analysis of the QoL results. Healthy cats under the age of 6 years had the highest QoL scores, while sick cats aged 6 years or older had the lowest QoL scores (Tables 4 and 5).

Table 4.

Descriptive statistics of quality of life variables for sick cats

Sick cats	n	Vitality	Comfort	Emotional wellbeing
Age <6 years	83	4.8	5.0	5.1
Age ⩾6 years	123	3.6	3.9	4.4
Total	206	4.0	4.3	4.6

Table 5.

Descriptive statistics of quality of life variables for healthy cats

Healthy cats	n	Vitality	Comfort	Emotional wellbeing
Age <6 years	125	5.4	5.6	5.7
Age ⩾6 years	106	3.9	4.4	4.8
Total	231	4.4	4.8	5.1

Even tools such as the general behavior history included in the Feline OA Checklist are designed to assist the veterinary healthcare team to focus on additional, often ‘hidden’, issues. Recognizing the time limits placed on clinics due to limited staffing and increased demand, this information may help the veterinary healthcare team focus on otherwise unidentified issues and determine the need for additional diagnostic workup (Table 6). In fact, general behavior questions about hiding, slowing down or changes in defecation or urination habits may be some of the first signs of OA. When the cats that demonstrated hiding and slowing down were included in our totals, 58% (86/149) of cats aged 6–12 years and 90% (72/80) of cats over the age of 12 years demonstrated one or more behaviors that may indicate changes due to OA (Tables 3 and 6).

Table 6.

Descriptive statistics of general behavior history variables

Age (years)	n	Personality change	Urinary or defecation changes	Hiding or slowing down
<6	208	9	18	10
6–12	149	15	20	29
>12	80	14	12	40
Overall	437	38	50	79

Discussion

The purpose of this study was to numerically compare a screened feline population with a random, but similar, unscreened population from the same clinic. This study identified that 39.1% of cats demonstrated at least one sign consistent with OA pain as numerically compared with the 1% in our retrospective record review. As we noted within this study, before using this tool, if we consider only the chronic cats identified, we have a prevalence of 1% (5/502) which is similar to the 0.9% previously reported by Banfield (https://www.banfield.com/state-of-pet-health). ¹⁴ This low identification rate demonstrates the real challenge feline OA presents to the veterinary healthcare team.

Since OA and the pain associated with this disease are often overlooked in our feline patients, the Feline OA Checklist provides an opportunity to positively change this trend. Historically, many tools and methods used to identify OA in dogs do not work as intended in cats. Some of these methods fail because of the very solitary nature of the cat, and only through observation of the animal in its natural environment do we see observable changes. ⁶ Therefore, the prevalence of OA in cats has varied widely, often dependent on the method of diagnosis used in the study (92% Lascelles; 22% Godfrey; 23% Clarke).^4,8,9 In fact, changes in behavior and lifestyle indicative of OA are often interpreted as age-related changes, and for many pet owners are perceived as not concerning. ⁶ In addition, surveyed owners of cats report that they are less likely to seek veterinary care if they do not detect a medical issue; thus, missed signs of OA lead pet owners to believe their pets are healthy. ² Cat behavior is often complex, and activities such as hiding and slowing down or changes in defecation habits may be indicative of issues like OA. ¹³ General behavior questions such as those in the Feline OA Checklist may be used as part of validated questionnaires such as the Client-Specific Outcomes Measure (CSOM), which allows pet owners to select behaviors that they identify as difficult for their cat to complete. ¹³

Recent guidelines ¹⁵ recommend that pain should be evaluated in every patient, and pain recognition is the first step. When used in a clinical setting, the Feline OA Checklist allows pet owners to quickly screen their cat and is intended to be utilized as part of the screening for all cats presenting to the veterinary clinic. ¹⁰ With a specificity of 97%, it is uncommon for this tool to generate false positives. ¹⁰ Once a cat is identified as being at risk of having OA, the veterinary team can discuss diagnostic options and expectations of treatment with the owner. Having these discussions early in the disease process and addressing client concerns can help with owner engagement. ¹⁶ In addition, when the Feline OA Checklist is employed as a screener, the veterinary health team then has validated tools such as the CSOM ¹³ or the Feline Musculoskeletal Pain Index ¹⁷ available to monitor treatment efficacy. With a growing list of treatment options, once OA is identified, pet owners are no longer constrained by oral medication selections, which broadens the population of cats that can be treated and monitored. Indeed, non-steroidal anti-inflammatory drugs and anti-nerve growth factor monoclonal antibodies are considered first-line analgesic treatments and are available to veterinarians to provide multimodal treatment of OA. ¹⁵ Certainly, as we utilize tools such as the Feline OA Checklist and newer treatment options, we can identify these patients earlier in the disease process and contribute to improved quality of life and better health outcomes.

Tools measuring HRQoL are also important for understanding the impact of pain in feline patients. The development of the Vetmetrica HRQoL instrument has traditionally focused on sick versus well populations, but our study also considered age. As expected, owners of healthy cats aged under 6 years reported the highest vitality, comfort and emotional wellbeing scores, while owners of sick cats aged over 6 years reported the lowest scores.

In the prospective part of this study, clinics were asked to screen any cat presenting to the veterinary clinic. Proportionally, there were more cats over the age of 6 years in the prospective population compared with the retrospective population, suggesting possible selection bias. Although this may have increased the overall percentage of cats with OA in the final results, it remains important to recognize that all cats, especially those aged over 6 years, should be screened for OA and offered treatment.

Study limitations

This study was limited to the use of the Feline OA Checklist in a clinic-based population and, therefore, does not include information on owner acceptance of OA, additional diagnostics performed to confirm findings or subsequent treatment of these cats. The results represent data from these specific clinics, and without statistical analysis, they may not reflect outcomes in other practices. In addition, since the most common feline population seen in veterinary practice is aged under 2 years, the study population skewed younger. As retrospective work is inherently observational, and the information reviewed was not originally collected for the purposes of this study, the results may be subject to confounding bias. Opportunities to improve the checklist include incorporating timelines for behavior changes to help the veterinary team better assess a cat’s current lifestyle. Future studies should ideally include a larger sample of cats aged over 6 years, particularly those aged 6–15 years, and cats with comorbidities, to better identify OA prevalence in these middle-aged populations.

Conclusions

Pain recognition is the first step in pain management, and the Feline OA Checklist can improve feline health and welfare by readily identifying affected cats and enabling a focused medical approach to OA. In this study, the use of the Feline OA Checklist increased the identification of cats at risk of OA from 1% to 39% in a general practice population. Utilizing tools such as the Feline OA Checklist to screen all cats in practice offers veterinary practitioners an efficient way to address the impact of feline OA and begin mitigating pain-related suffering.