Stifle OCD!!

A yearling thoroughbred presented for sudden lameness and swelling around the stifle joint. The filly had been purchased several months prior from a select thoroughbred sale and repository radiographs were performed at the time of purchase. At the time of purchase, the filly was sound, there was no effusion of the stifle joint and there were no obvious radiographic changes noted in either stifle joint. When the filly presented for lameness, the stifle radiographs were repeated. Close inspection of the lateral trochlear ridge suggested irregular contours (yellow arrows inside blue box, Figure 2) of the trochlear ridge along the mid body region (Figure 1 and 2, blue box). Based on the radiographs alone, the filly was treated with intra-articular Hylartin and forced stall rest for 30 days.

Figure 1

Figure 2

Unfortunately, the filly remained lame after 30 days of stall rest and a follow-up exam included an ultrasound evaluation of the stifle joint. The ultrasound exam revealed significant changes along the lateral trochlear ridge which were not fully appreciated on the radiographic exam. In Figure 3, the lateral and medial trochlear ridge are displayed. The bony surfaces of the trochlear ridges appear as a bright white lines and the cartilage as  thin black lines that follow the contour of the bony surface. Any disruption of the bony surface/cartilage will appear as a mix of disrupted white lines and black pockets. In Figure 3, the image on the left is of the lateral trochlear ridge and there is clearly disrupted bone and cartilage along the bony surface.

Figure 3

In Figure 4, the lateral trochlear ridge is imaged in a longitudinal plane to assess the length of the defect. Irregular bone/cartilage appears to extend for several centimeters along the length of the trochlear ridge (yellow lines). The filly was referred for arthroscopic exam and a large bone/cartilage defect was identified on the lateral trochlear ridge consistent with a osteochondritis dissecans or OCD lesion.

Figure 4

Osteochondritis dissecans is defined as a disorder that results in cracks in the articular cartilage and underlying subchondral bone. The "cracks" and cartilage separation result due to lack of blood flow to the region resulting in avascular necrosis of the tissues involved.  This condition is considered in part a hereditary disorder AND nutritional.  Unfortunately OCD lesions are common in young horses that were bred for sport such as racing thoroughbreds, performance quarter horses, and warm blood breeds.  Some cases of OCD can be managed with surgical intervention however the OCD lesion in this filly's stifle was so large that there was no hope for soundness. This case is a good example of the benefit of multiple imaging modalities in diagnosing the source of lameness in the equine stifle.

Club foot!!

The radiograph below is from a weanling colt with a severe case of a "club foot". Figure 1 is the affected foot and figure 2 is the normal foot. X-ray vision was not necessary in this case to confirm the diagnosis due to the classic distortion of the hoof capsule. Club feet in foals develop from tendon contracture or secondary to accelerated skeleton growth. As the leg bones grow in length the soft tissue structures (tendons and ligaments) cannot keep up with the rate of growth resulting in contracture of the joint spaces. In the case of a "club foot" it is the coffin joint or DIP joint that is contracted and results in abnormal hoof growth.

Figure 1

Figure 2

The yellow line below corresponds to the alignment of the short pastern bone and the coffin bone. In Figure 3, the alignment is normal. However in Figure 4 the dorsal surface of the coffin bone is not aligned with the short pastern bone. The letter "A" in figure 4 corresponds to the angle of contracture. The contracture occurs in part due to the strong pull of the deep digital flexor tendon that attaches to the bottom of the coffin bone. As the leg bones lengthen and the flexor tendons do not keep up with the growth rate, the coffin bone is pulled resulting in contracture of the joint.

Figure 3

Figure 4

Treatment of this condition in young horses varies and includes early weaning, reduced caloric intake,  repeated injections of oxytetracycline to relax the tendons, corrective trimming/shoeing, and surgical transection of the distal check ligament. In my clinical experience, many foals with mild contracture respond well to the oxytetracycline and corrective trimming protocol. However, more advanced cases such as this colt require surgical intervention. The distal check ligament attaches to the deep digital flexor tendon and essentially keeps it in "check". By cutting the ligament, there is some release of the pull by the deep digital flexor tendon on the coffin bone. This surgical procedure can be performed in a stall-side setting, in a standing patient. Once it is determined that surgery is indicated, the sooner the better!  The colt in this case was treated with oxytetracycline and corrective trimming for 2 months with minimal improvement. When he was 6 months old, the distal check ligament of the affected limb was transected. Figure 5 is the "club foot" 45 days post surgery, note the corrected alignment of the pastern and coffin bones. The colt's lameness resolved.  This case highlights the importance of early documentation with radiographs and early intervention to correct the "club foot".

Figure 5

Kissing Spines!

The radiographs below are of the dorsal spinous processes of  the vertebral bodies in the top-line of a horse. Essentially, these bones are directly below the saddle and directly below the rider's center of gravity. As such, they represent some of the most stressed areas during riding under saddle. The first two radiographs are of the same horse and the yellow circles correspond to where the spinous processes are in contact with the each other. This is also know as "Kissing spines". This horse presented for a chronic history of a tender back and unwillingness to move forward at the trot and/or canter. The 3rd radiograph is that of a normal horse. There is significant space between the spinous processes. These spinous processes are slightly cranial to the ones depicted in the previous 2 radiographs.  Unfortunately, the diagnosis of kissing spines is not favorable for the horse to have a performance career without chronic back pain. There are therapies aimed at reducing the pain and muscle spasm associated with this condition which include; saddle fitting, shockwave therapy, mesotherapy, acupuncture, chiropractic adjustment, deep message, and cortisone injections. I strongly recommend having radiographs taken of any horse with a chronic history of back pain to determine if this might be the cause!! 

Not all equine prepurchase exams are created equal!

When it comes to purchasing or acquiring a new horse, I have several "guidelines" that I strongly recommend to all prospective horse owners.

1) Have a prepurchase exam performed by a veterinarian that has no prior contact with the horse in question and does not work for the seller on a routine basis.

2) It is the veterinarian's responsibility to either PASS or FAIL the horse based on the exam.

3) Be wary of horses with no recent show or performance record, especially those that have been turned out for greater than 6 months for no good reason!

4) Consider a 2-4 week trial period prior to purchasing the horse

5) Pursue digital radiographs that can be shared via internet or CD

6) If the horse is lame at the time of the exam DO NOT PURCHASE THE HORSE


7) In case you forgot #1, have a prepurchase exam performed!! Especially if the horse is for free!!

There are a several specifics that you, as the buyer, should expect from a prepurchase exam. These include:

1: Complete physical exam to include: oral exam (via speculum and light), eye exam (cornea and lens), cardiac exam (heart rate, sound, and rhythm), lung exam (re-breathing exam),  external genitalia exam, and general conformation evaluation (hoof-pastern angles, fetlock angles, stifle-hock angles, etc).

Corneal exam revealed a slight band
of edema across the cornea suggestive
of glaucoma

2: Complete lameness exam to include: Palpation and manipulation of the horse's entire musculoskeletal system, gate evaluation at the walk-trot-canter (straight-away and circles), flexion exam of all 4 limbs (upper and lower limb flexion), and hoof tester exam of all 4 feet.

3: Radiographic evaluation to include: Front feet  (minimum), hocks, fetlocks, stifles, +/- carpi. Note: if the horse is lame during at the time of the exam, I do not recommend continuing the exam hence radiographs would not be necessary.

Chronic founder was noted on radiographs which was not
disclosed by seller and the horse was sound at the time of the exam.

4: Drug screen to include: anti-inflammatory drugs, sedatives, and corticosteroids. At a minimum, have the veterinarian collect a blood sample to be stored for 30 days in case there is a problem after purchase.

5: Complete history to include: Vaccination history, deworming history, recent travel history, dental history, recent farrier history, previous health issues (including lameness issues).

Additional diagnostics that may be warranted:

1: Upper airway endoscopy (non-sedated horse): Strongly recommended for all performance horses
2: CBC and Chemistry analysis
3: Tendon/ligament ultrasound
4: Cervical spine radiographs
5: Trans-rectal palpation of female reproductive track (brood mares)
6: Semen collection and evaluation (stallions)

The above mentioned exam, with foot radiographs, should cost no more than $500. That should be a minimum for all horses that are changing owners.  Even if the horse is for "free", discovering serious lameness issues will save you much more in the long run!

And remember....

"Unless its your own mother that is giving/selling you the horse (assuming you get along with her), it should be mandatory to have the horse examined by a veterinarian prior to completion of the transaction."