Ask the Vet: Joint Injections and Soft Tissue Injury Treatments

Answered by, Amy Poulin-Braim, VMD, DACVS-LA, Neshanic Station, NJ

Question: I would like to ask about ringbone. Are there treatment options for ringbone and if so, how do they work?

The history is on a 2-year-old horse that the ringbone appeared at 7 months of age. He was always in the paddock and suddenly I saw the ringbone begin.

Answer: Your question regarding ring bone in a young horse is a challenging one, without seeing and evaluating your horse or having any additional information.

Generally speaking, ring bone (arthritis of the coffin joint (low ring bone) or pastern joint (high ring bone) is a chronic progressive osteoarthritic disease in middle to older aged horses. It is usually secondary to chronic repetitive trauma or soft tissue instability of the joint.

In young horses, ring bone usually develops secondary to trauma to the bone, growth plates or surrounding soft tissue structures that give the joint stability. Additionally, conformational abnormalities, which places abnormal stress and strain across the joint, can also cause progressive arthritis.

Evaluation by your veterinarian is critical. This would include a physical and lameness examination. Also the extent of bony remodeling across the joint can only be assessed by radiographs, this will also help to identify which type and extent of ring bone your horse has (low or high). The surrounding soft tissue structures should also be evaluated by ultrasound, as they may have originally been damaged requiring a different form of treatment or they may become damaged by impingement of the new bone growth from the ring bone.

There are various treatments available that should be prescribed by your veterinarian. Systemic anti-inflammatory medication to help alleviate pain related to chronic arthritis is a good first step. Additionally, intra-articular joint injections with corticosteroids can help ease inflammation and pain associated with chronic arthritic pain. There is a topical anti-inflammatory cream that can be applied temporarily as well as shock wave therapy. Lastly, surgical fusion of the joint with plates and screws is also an option, which eventually can provide pain relief by inhibiting motion across the joint space and fusing the two bones together.

Your veterinarian will be able to best guide you in the decision making process after evaluating your horse. Best of luck with your horse and I would encourage you to contact your veterinarian for further discussion.

Question: We use to be told that the joints would fuse at a certain age and there would be no need for injections. True or False?

Answer: Normal joints, without evidence of osteoarthritis, trauma and/or inflammation should continue to function with normal gliding motion between cartilage surfaces without the need for joint injections.

Normal joints can become temporarily inflamed secondary to trauma/inflammation. This could be from a bad step, twist, strain, overuse. This cycle of inflammation can be mitigated by joint injections, reducing pain, swelling, effusion (increased production of abnormal joint fluid) restoring the internal joint fluid back to normal color and viscosity.

If trauma/inflammation is persistent secondary to chronic overuse, cartilage breakdown, supporting soft tissue injury and conformational defects, which leads to improper loading of the joint, the cartilage surfaces start to break down (beginning stage of arthritis), underlying subchondral bone may become damaged which leads to chronic pain and lameness.

The body then starts to produce new bone in efforts to stabilize the joint. While this is occurring it can be a painful and prolonged process and often times, joint injections help to reduce some of the clinical signs to some extent, but do not resolve the underlying problem.

Joint fusion can occur naturally, chemically or surgically with the goal being to stop motion between two bone/cartilage surfaces.

To answer your question, there is no age that this happens in all horses in all joints. In general, advanced arthritis (most commonly- low or high ring bone or bone spavin in the hock (arthritis of the two lower hock joints)), takes a very long time for natural complete fusion to occur, if it occurs at all and is painful during this process. Usually, this type of arthritis is seen in older horses from wear and tear of performance, but can be seen in younger horses secondary to trauma or conformational abnormalities.

Chemical fusion works by injection of an agent that destroys or melts the cartilage surfaces such that bone on bone remains behind and eventually, over time, these two bone surfaces fuse together. Again, this can be a very painful procedure that takes several months to complete.

Surgical fusion is a procedure performed under general anesthesia that removes the cartilage surfaces between two bones and uses a combination of plates and screws to stabilize across the joint to allow for healing of the bone ends to one another. Again, this is a painful procedure, with involvement of surgery, but tends to get a more controlled and quicker response to healing due to stabilization of the bones between the joint.

Out of all of the joints in the horse, the lower hock joints is the most common location that has the possibility to naturally fuse over time. However, the age and time frame is highly variable and dependent on the horse and may require joint injections 1-2 times/year to help reduce inflammation and pain while this is happening.