Neck Injections/Cervical Facet Injections

Neck Injections/Cervical Facet Injections

Look carefully at this radiograph.  These are the fourth, fifth and sixth cervical (neck) vertebrae of a 14 year old equitation horses with severe left forelimb lameness.  Let your eye move along the top edge of the bones from left to right.  Do you see the fracture fragment, irregular boney growth (exostoses), and loss of joint architecture (degenerative joint disease) at the top joint (dorsal facets) between the last two vertebral bodies? This is arthritis, and it can develop in the neck in the same way it can in any other joint in the body. 

The joints between each of our vertebrae, whether horse or human, have the same function as any other joint in the body, which is to cushion compression forces during motion .  In the horse, particularly jumping and dressage horses, flexion of the neck during athletic performance increases the compressive forces on the lower neck joints, or C3 through C7.  Over time, this repetitive trauma can overcome the body's natural ability to dampen these concussive forces.  Inflammation results, with subsequent degradation of joint fluid and intervertebral disc material.  Ultimately, in an effort to stabilize the joint, the body begins to lay down additional bone.  What was once a dynamic, spring-like mechanism, becomes brittle and rigid.  This is degenerative joint disease (DJD), commonly called arthritis.  In the neck, DJD can be responsible for clinical signs as subtle as occasional tripping, progressing up through severe neurologic instability.  Primary forelimb lameness is an unusual, but well documented, clinical sign occasionally caused by cervical DJD.  All other causes of forelimb lameness must be ruled out with a careful lameness evaluation and localizing nerve blocks before such lameness is attributed to cervical DJD.

The dorsal facets are the knobby boney structures at the top of each cervical vertebral body.  The positive clinical outcome of injecting anti-inflammatory and lubricating medications (steroids and hyaluronic acid) into the space between the dorsal facets is well documented.  The sterile injection procedure is done with ultrasound guidance in the standing, sedated horse.  The response to injections varies considerably from horse to horse, both with respect to effectiveness and duration. 

In addition to intra-articular facet injections, modalities including acupuncture, laser therapy and physical therapy by a QUALIFIED equine physical therapist can provide important  benefits to horses with cervical DJD.

 The horse with the radiographic changes pictured here improved 75% after facet injections, however, the severity of these radiographic changes and of his lameness were cause for retirement to pasture turn out.  His owner and trainer were happy to honor him with this option in return for his years of service as a show jumper and equitation horse.

If your horse has unexplained stiffness, difficulty turning, repeated tripping, or undiagnosed forelimb lameness, ask your veterinarian about the possibility of a neck problem.



I believe that education is the key to evolution. I believe that animals are the key to compassion. I believe the learning never stops.

February 9, 2010 - Injectable Joint Therapies

Vet Tip of the Day: Injectable Joint Therapies
Key Words: Adequan, Legend, PSGAG, Hyaluronic Acid

To finish our segment on the hock, here is a brief discussion of the two FDA licensed injectable agents to improve joint health.  The first, Adequan, is used more commonly for osteoarthritis of the hock (bone spavin).  Adequan is a large molecule with the chemical name polysulfated glycosaminoglycan (PSGAG) which cannot be absorbed when given orally and so is administered by intramuscular injection.  Adequan has been shown repeatedly in controlled clinical trials to improve lameness associated with chronic degenerative joint disease, however, on an individual animal basis, it's effectiveness is quite variable.   Its mechanism of action is similar to chondroitin and glucosamine.  Remember that these oral supplements are building blocks used by the body in the construction of cartilage.  Adequan is a very large molecule, more complex than either chondroitin or glucosamine, and is further along the construction pathway in the formation of cartilage matrix.  The PSGAG molecule is incorporated into cartilage, giving it elasticity and shock abosorbing capacity.

I use the brand name Adequan, although there are generic PSGAG products available, as well as compounded products.  However, as with oral supplements, the molecular construction of the generics and compounded products are not necessarily equivalent to Adequan, and have not stood the test of clinical or experimental study.  In fact, Luitpold Pharmaceuticals, the manufacturer of Adequan, has spent quite a bit of money conducting quality research on their product, and in the comparison studies performed to date, Adequan has outperformed generics.  Once again, you get what you pay for.

Legend is injectable hyaluronic acid (HA).  And yes, just like PSGAG,  hyaluronic acid comes in many molecular weights and qualities, and so far, for intravenous administration, Legend is the gold standard.  While Adequan is used most commonly for hock arthritis, it is not uncommon to combine Adequan and Legend as joint therapies.  In the joint environment, hyaluronic acid and PSGAG have complex actions.  In addition to acting as structural components of joint fluid and cartilage, both HA and PSGAG have anti-inflammatory effects within the joint.  On top of that, when used together, each component enhances the activity of the other, so 1+1=3!  Therefore, in performance horses with joint issues, it may be advisable to use combination therapy. 

There is a standard protocol for initiation of Adquan therapy, established by the manufacturer.  The recommendation is to give 1 vial every 4 days for 28 days followed by one vial every 2-4 weeks thereafter. Legend is often given once monthly intravenously as maintenance therapy, with additional doses given around the time of competition.

Oral and injectable chondroprotectant agents are widely used in treating osteoarthritis of the hocks.  They often are used in conjunction with intra-articular (directly into the joint space) injections of similar products in combination with corticosteroids, as well as oral adminstration of non-steroidal anti-inflammatories such as phenylbutazone.  Finally, a topical anti-inflammatory cream is now available which provides local, temporary pain relief and can be effective to control hock pain during exercise.  This product is Surpass, or diclofenac acid.

We've covered a lot of information on the hock.  If you are interested in learning more,  use the key words provided as Search words in Google and you will find LOTS more to read.

Have a great day,
Chrysann

Monday, February 1 - Ringbone

Vet Tip of the Day: High & Low Ringbone
Key Words: Pastern, arthritis

Continuing our examination of the leg, let's look at another disease that is common in the foot/pastern region. Remember that there are three pastern bones located below the fetlock: the long pastern bone (P1), the short pastern bone (P2) and the coffin bone (P3). Ringbone is a common degenerative joint disease that occurs in two locations: high ring bone results when the joint surfaces between the first and second pastern bone become irregular and eventually proliferative (arthritis). Low ring bone occurs when similar changes take place at the joint between the second pastern bone and the coffin bone.

Horses with short, upright pasterns and narrow feet are predisposed to ringbone, as are those whose occupations involve repeated concussion on hard surfaces. Because the joint between the second pastern bone and the coffin bone is inside the rigid hoof capsule, low ring bone is more difficult to manage than high ring bone.

Ring bone is diagnosed using a combination of diagnostic nerve blocks and radiographs. It is a chronic progressive disease that is treated with corrective shoeing, injections of anti-inflammatory medication into the affected joint, administration of chondroprotective (joint protecting) medications and oral supplements such as chondrotin sulfate and hyaluronic acid, and administration of non-steroideal anti-inflammatory drugs such as phenylbutazone. In severe cases of high ring bone, the joint between P1 and P2 can be surgically fused.