Understanding Hock Arthritis: Joint Injections for Canine and Equine Patients

Hock arthritis, or osteoarthritis (OA) of the tarsal joint, is a common degenerative condition affecting both canine and equine patients. As a load-bearing joint subjected to high mechanical stress, the hock is particularly prone to wear and tear processes. Early detection, targeted therapeutic interventions, and ongoing management are crucial for maintaining mobility and quality of life in affected animals. One widely used intervention is the administration of intra-articular joint injections. In this article, we explore the clinical rationale, mechanisms of action, advantages, limitations, and costs associated with this treatment option in the UK.

Prevalence of Hock Arthritis

In Canines

Osteoarthritis affects approximately 20% of dogs over one year of age, with prevalence increasing with age and body weight (Anderson et al., 2020). The hip and stifle joints are commonly affected. However, the hock also frequently suffers, especially in active or working breeds. Breeds such as Labradors, German Shepherds, and agility dogs are particularly vulnerable. Factors contributing to hock arthritis include:

• Repetitive motion

• Previous injury

• Conformational abnormalities

• Cruciate ligament disease

  
  

In Equines

In horses, hock arthritis—specifically affecting the distal intertarsal and tarsometatarsal joints—is commonly referred to as “bone spavin.” This condition is especially prevalent in performance horses involved in disciplines requiring collection, like dressage, show jumping, and eventing. Estimates suggest that up to 60% of lameness cases in sport horses are due to hock-related issues (McIlwraith et al., 2015).

Mechanism and Application of Joint Injections

What Are Joint Injections?

Joint injections involve delivering therapeutic agents directly into the synovial space of the affected joint. The most common substances used include:

• Corticosteroids (e.g., triamcinolone acetonide, methylprednisolone acetate)

• Hyaluronic Acid (HA)

• Polyacrylamide hydrogels

• Biologic agents, such as Platelet-Rich Plasma (PRP) or Interleukin-1 Receptor Antagonist Protein (IRAP)

  
  

How They Work

• Corticosteroids function as potent anti-inflammatory agents. They suppress the production of pro-inflammatory cytokines and enzymes that contribute to cartilage degradation. They also reduce synovial fluid viscosity and joint effusion.

• Hyaluronic Acid enhances joint lubrication and viscoelasticity. It provides a cushioning effect and stimulates endogenous HA production by synoviocytes.

• PRP and IRAP are regenerative options. They modulate the inflammatory response and promote tissue repair through growth factors and cytokine inhibition (Murray et al., 2017).

  
  

The injection process is typically guided by anatomical landmarks or, more precisely, via ultrasound guidance to ensure intra-articular placement, especially in smaller joints like the canine hock.

Cost of Joint Injections in the UK for Horses and Canines

The cost of joint injections varies based on the substances used, the number of joints treated, and whether imaging guidance is employed. Here is a general breakdown:

• Canine hock injection (per joint): £250–£450

• Equine hock injection (per joint pair): £300–£600

• Biologic therapies (e.g., PRP, IRAP): £600–£1,200

  
  

These prices typically include sedation, sterile preparation, drug administration, and post-procedure evaluation. However, they may not cover diagnostics such as imaging or follow-up treatments.

Pros and Cons of Joint Injections

Pros

• Rapid Relief of Pain and Inflammation: Corticosteroid injections can provide effective pain relief within 24–72 hours (Budsberg et al., 2014).

• Minimally Invasive: Compared to surgical interventions, joint injections are less invasive and can often be performed under light sedation.

• Targeted Therapy: Direct delivery allows for a high local concentration of the drug, minimizing systemic side effects.

• Supports Rehabilitation: Reducing pain and inflammation facilitates more effective physiotherapy and exercise-based rehabilitation.

  
  

Cons

• Temporary Relief: Injections manage symptoms rather than addressing the underlying disease process. Relief may last weeks to months, necessitating repeat procedures.

• Risk of Joint Infection (Septic Arthritis): Although rare (<1% incidence with proper technique), it poses a serious complication that requires immediate veterinary attention.

• Cartilage Damage with Repeated Use: Long-term or repeated corticosteroid use may accelerate cartilage degeneration if not carefully monitored (McIlwraith et al., 2015).

• Cost Accumulation: Ongoing injections can be costly over time, particularly when paired with adjunct therapies.

  
  

Clinical Considerations in Physiotherapy

For physiotherapists, knowing when joint injections are appropriate—and when they may mask deeper biomechanical issues—is essential. Collaborating with the referring veterinary surgeon ensures integrated care. Once inflammation is managed, a tailored rehabilitation program focusing on joint mobilization, muscle strengthening, proprioceptive training, and weight management is vital. This approach can prolong the therapeutic benefits and enhance the animal’s overall well-being.

Conclusion

Joint injections remain a valuable tool in the multidisciplinary management of hock arthritis. They provide significant, albeit temporary, relief of clinical signs, supporting mobility and quality of life. However, injections should be viewed as part of a broader, holistic approach involving physiotherapy, lifestyle modification, and ongoing monitoring. By integrating scientific insight with clinical expertise, we can offer the most effective and compassionate care for animals living with joint disease.

References

• Anderson, K. L., O'Neill, D. G., Brodbelt, D. C., Church, D. B., Meeson, R. L., & Sargan, D. R. (2020). Prevalence, duration and risk factors for appendicular osteoarthritis in a UK dog population under primary veterinary care. Scientific Reports, 10(1), 1-12. https://doi.org/10.1038/s41598-020-77795-2

• Budsberg, S. C., Torres, B. T., Kleine, S. A., Sandberg, G. S., & Bergh, M. S. (2014). Evaluation of the analgesic efficacy of intra-articular administration of triamcinolone acetonide in dogs with osteoarthritis. American Journal of Veterinary Research, 75(5), 448–453.

• McIlwraith, C. W., Frisbie, D. D., Kawcak, C. E., & Fuller, C. J. (2015). Joint disease in the horse (2nd ed.). Elsevier Health Sciences.

• Murray, R. C., Clegg, P. D., & Bolt, D. M. (2017). The effects of biologic therapies on inflammation in equine joints. Veterinary Journal, 225, 44–50.