Early diagnosis of feline osteoarthritis

OA in cats remains underdiagnosed and undertreated, despite its widespread prevalence; this paper looks at how we can surmount the challenge of early diagnosis, leading to better treatment interventions.

Introduction

Osteoarthritis (OA) is estimated to occur in 61-99% of cats based on radiographic studies 1,2,3 making it one of the leading causes of chronic pain in this species. The condition is characterized by progressive degradation and loss of articular cartilage (Figure 1), related to altered intrinsic mechanisms of the cartilage and influenced by changes in other intra-articular tissues such as the synovium, the subchondral bone and the menisci. The most commonly affected appendicular joints in cats include the elbow, hip, stifle, and hock joints 1,3,4. 

Despite the high prevalence, OA in cats remains underdiagnosed and undertreated. Several reasons for this have been postulated, including:

• Cats being presented to veterinarians less frequently 
• The subtle and non-specific signs of feline OA
• The poor correlation between pain and lameness in this species, which explains the lower prevalence of single limb lameness as a major clinical sign of OA
• The differing nature of interactions of owners with cats when compared to dogs 
• Altered feline behavior within the clinic environment 
• The frequent stress responses encountered during feline orthopedic examination, which render localization of pain and identification of subtle findings more complex
• Poor correlation between radiographic and clinical signs of OA

The challenges in diagnosing feline OA only become more marked when considering our desire to make an early diagnosis or detect minor changes, which are critical in facilitating early intervention. Prompt identification will have the greatest potential for providing effective management of OA, since it provides an opportunity to initiate an appropriate, tailored long-term treatment plan and disrupt the progressive vicious cycle of synovial joint deterioration 5. In this article we will address recent advances in the use of clinical metrology instruments, goniometry, diagnostic imaging and arthroscopy which will facilitate achieving that critical early diagnosis.

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