How to Identify and Manage Bog Spavins & Bone Spavins
The most important quality in a dressage horse is soundness. If your horse is unlevel or irregular, you will be heavily penalized by every good dressage judge, and your dressage career will be over before it’s begun!
But how about “cosmetic” blemishes?
Can a horse with a few lumps and bumps still be suitable for dressage?
In this article, we take a look at spavins, a common hock blemish, and discuss the wisdom of buying a horse with this condition.
What is a spavin?
There are two forms of spavin; bog spavin and bone spavin. Essentially, a spavin is a swelling or hard lump that forms around the horse’s hock area.
Bog spavins
A bog spavin is the term that’s used to describe a collection of excess fluid in the upper part of the hock (tibiotarsal) joint.
The tibiotarsal joint is responsible for flexion of the hock.
What causes bog spavins?
There are many causes of bog spavins.
In some types of horse, notably warmbloods, spavins are caused by osteochondrosis (OCD). OCD is a condition that results in small fragments of bone and cartilage being present in the hock joint. It’s this floating debris that can cause irritation of the joint, leading to the accumulation of fluid that forms the bog spavin.
Bog spavins can also be caused by trauma and injury to the joint.
Another cause of bog spavin is an imbalance in the carbohydrate to protein ratio.
Overwork can also cause a strain of the collateral ligaments and inflammation of the hock joint lining.
Can bog spavin cause lameness?
OCD itself does not generally cause lameness, but the effect that the spavin has on the hock joint depends very much on the size and precise location of the spavin.
For example, the most common site for OCD in the tibiotarsal joint is at the distal intermediate ridge of the tibia.
Fragments from that area can cause the formation of a bog spavin, although the horse is rarely lame. That’s because the location of the debris is not greatly involved in the movement of the joint.
That said, the veterinary advice that’s generally given in such circumstances is to remove the fragments to prevent future problems in the joint.
However, if the spavin is affecting the lateral trochlear ridge of the tibiotarsal bone, large areas of bone and cartilage loss can occur, resulting in a very irregular joint surface and chronic lameness.
Note that even horses who have had loose bone fragments removed from the hock joint can still develop a bog spavin.
Treatment and prognosis of a bog spavin
In general, the prognosis is pretty good for a horse with a bog spavin that doesn’t affect the animal’s soundness.
In cases where the hock appears normal, the prognosis is more guarded. That’s because, in cases where the defect has been present for some time, the capacity of the hock joint is increased. Joint fluid is then produced to fill the extra space, so the joint remains distended.
The good news for horses with bog spavin is that the condition doesn’t preclude any horse from competing in high level dressage. However, you should be aware that the condition may indicate joint weakness or a previous injury.
So, if you go to view a potential purchase that has a bog spavin, ask your vet to carefully examine the horse before you proceed.
Bone spavins
Bone spavins affect the lower part of the hock joint.
Bone spavin is also more correctly known as osteoarthritis.
The two lower joints of the hock have relatively little movement, although a high degree of force is transmitted through them.
What causes bone spavin?
Like bog spavin, the cause of bone spavin is not fully understood. However, certain heavier breeds do demonstrate a predisposition to the condition.
It’s also thought that trauma, injury, and conformation can play a role in the formation of bone spavin. The condition can affect animals of all ages.
Can bone spavin cause lameness?
In some horses, osteoarthritis can interfere with the movement of the hock joint, and the resulting lameness can be career-ending.
Other cases involve more destructive changes that occur within the actual joints. In cases of cartilage loss where the joint space is narrowed, regardless of bone loss in adjacent areas, affected horses are often much more lame than others.
Treatment in these cases is much more difficult and generally less successful.
Diagnosis of bone spavin
Many horses develop bone spavins without ever becoming lame. Consequently, the condition is not diagnosed until X-rays are carried out for some unrelated condition.
However, in cases of persistent lameness, it’s essential to establish that the lameness is sited in the hock and not elsewhere.
Nerve blocks (intra-articular anesthesia) are generally used to isolate the site of the lameness. X-rays will also be taken to pinpoint the precise location and type of the bone spavin.
These procedures are essential, as those factors will influence the horse’s likely response to any treatment that’s prescribed.
Sometimes, spurs of bone appear around the small joints that make up the lower part of the hock joint.
Treatment of bone spavin
In many cases of bone spavin, the condition can be managed using low-dosage anti-inflammatory and pain-killing drugs. However, that efficacy of such a course of treatment depends on the degree of lameness present and the job the horse is expected to do.
Bone spavins cannot be cured. However, the condition can be managed via drug therapy and light exercise to keep the joint mobile and flexible.
However, if you intend to compete a dressage horse that’s affected by bone spavins, be sure to check your national federation’s rules on permitted and non-permitted drugs.
In conclusion
Both bog and bone spavins affect the horse’s hock joint.
Bog spavins manifest themselves as puffy swelling at the top part of the hock, whereas bone spavins are typically hard, bony growths on the lower part of the hock.
Sometimes, spavins don’t affect the horse’s soundness. However, in other cases, the horse may become mildly irregular in his movement or he could be markedly lame, depending on the precise location of the spavin and the part of the hock joint it affects.
Does your horse have spavins? How has the condition affected your dressage career?
Tell us about your experience in the comments box below.
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