Hip Subluxation in a Horse

A 10 year-old mare presented for sudden onset hind limb lameness. The mare was non-weight bearing on the right hind limb and within 24 hrs there was significant swelling centered over the right gluteal region. In Figure 1, the pelvis of a horse is pictured to identify the left (bottom blue arrow) and the right (top blue arrow) coxofemoral joints. In Figure 2 and 3, the pelvis has been rotated slightly to picture the area that is most commonly ultrasounded to assess the coxofemoral joint space. In Figure 3, the red line corresponds to the junction of the pelvis and the femor. The blue arrow corresponds to the coxofemoral joint space.

Figure 1

Figure 2

Figure 3

Figures 4 and 5 illustrate the views captured via ultrasound exam of the equine pelvis. This area is very difficult to adequately radiograph in a standing horse hence the ultrasound exam provides an opportunity to assess the coxofemoral joint space of a horse. As in Figure 3, the red line in Figure 5 corresponds to the juction of the pelvis and femur (coxofemoral joint space) which is also highlighted by the blue arrow. In the normal exam, the only bone structures commonly noted are the pelvis (long white line at bottom of view) and the greater trochanter of the femur (small white line at the top right of the image).

Figure 4

Figure 5

Figures 6 and 7 correspond to the right coxofemoral joint space of the lame horse. There is clearly and extra curved line in the image that corresponds to the "head" of the femur. Normally, the head of the femur is NOT visualized because it is within the acetabulum that makes up the coxofemoral joint. The ultrasound findings below are consistent with a subluxation of the coxofemoral joint space and very likely fracture of the acetabulum!  This injury carries a very poor prognosis for an adult horse; however, in miniature horses or very small ponies, surgical correction exists as an option with a guarded prognosis.

Figure 6

Figure 7

Guttural Pouch Infection in a Horse

A yearling quarter horse presented for a 30 day history of unilateral nasal discharge. The colt was not febrile, ate with a good appetite and there was a milky discharge from the left nostril only! Endoscopic exam of the guttural pouches revealed muco-purulent discharge within the left guttural pouch (Figure 1 and 2). Careful exam of the wall lining the guttural pouch revealed many small pustules (Figure 2). The colt was diagnosed with a guttural pouch infection and the fluid was analyzed for the presence and type of bacteria!

Figure 1

Figure 2

As a rule, these findings should always be considered as a likely case of equine strangles until prove otherwise. There were not enlarged lymph nodes detected within the guttural pouch of this colt and there were no other symptoms that would have suggested a case of equine strangles. Regardless, it was assumed until proven otherwise! The culture was positive for streptococcus equi zooepidemicus which is NOT the bacteria associated with equine strangles. As such, this horse was treated by lavaging the guttural pouch and the symptoms resolved.Typically, these horses do NOT respond to systemic antibiotics but will resolve with repeated lavaging of the guttural pouches. Occasionally, administration of penicillin gel directly into the guttural pouch may effective!! In my experience, >90% of the cases I diagnose with a guttural pouch infection are positive for the bacteria that causes equine strangles also known as Streptococcus equi equi
therefore, these cases are treated as highly infectious until the culture results are confirmed.

Intermitten Upward Fixation of the patella in a horse (aka Sticky stifles)

The pony in the above video presented for a history intermittent dragging of his right hind leg at the walk. Occasionally, the leg would "lock" in the extended position and the pony would drag his limb for several strides until it "unlocked". On presentation, the pony tended to have a delay in flexion of the right hind when walked in a straight line. However, when walked in a figure 8, the right hind leg would stay in the extended position for a second or two and then suddenly jerk into the flexed position. When the pony was trotted in a straight line he was completely sound however during the downward transition his right hind wound "drop out" at the moment the leg went from the extended position to the flexed position.

This pony is experiencing a condition known as intermittent upward fixation of the patella. The patella (knee cap) is controlled by three patellar ligaments (medial, middle, and lateral patellar ligaments) which originate within the quadriceps muscle. As such, the contracture and relaxation of the quadriceps muscle allows for engagement of the patella to keep the leg in extension and ALSO allow for disengagement of the patella to allow flexion of the limb.

Intermittent upward fixation of the patella is common in young horses when they are first introduced to work under saddle. It is also more common in fast growing horses that tend to have a "straight" or upright  conformation through their stifle. In my experience, this condition is more common in female versus male horses and is most often resolved by increasing the intensity of exercise, especially at the canter, uphill. However, some horses experience this condition regardless of increased exercise and require medical/surgical intervention. Years ago it was common place to transect the medial patellar ligament however long term evaluation of these horses suggested a predisposition to arthritic conditions of the stifle joint. 

More commonly, these horse are treated with hormonal therapy (estrogen) , iodine blister of the medial patellar ligament, and scarring of the medial patellar ligament via surgical intervention. Mild cases often improve with increased work plus estrogen treatment. However, horses that are "locking" their stifles most likely will need surgical intervention.

Prior to recommending medical or surgical treatment, these horses should be evaluated for soundness and the stifle joint should be radiographed. Horses that have pain associated with OCD conditions of the stifle joint may present in a similar fashion and require a different approach in managing this condition. If your horses feels like he/she is "dropping out behind" when you are at the trot, especially during the downward transition from the trot to the walk or canter to the trot, it is likely that intermittent upward fixation of the patella is playing a role in their poor performance!!

Contracted Heels in a Horse

The foot in the first two images (Figure 1 and 2)  belongs to a horse with chronic heel pain. As a result of the chronic pain, the horse's heels are severely contracted and the base of the frog has atrophied (shrunk). In Figure 2, the width of the frog is highlighted by the blue line and the length of the frog is in yellow. Normally, the width of the widest portion of the frog is 2/3 of the total length of the frog (Figure 3).

Figure 1

Figure 2

 

Figure 3

In Figure 5 and 6, a normal foot demonstrates the normal ratio between the length of the base of the frog and the over all length of the frog.This is in stark contrast to the foot in Figures 1 and 2. Normally, a horse's foot lands heel first and transfers the ground forces from the base of the frog/digital cushion thru the body of the frog. As such, the frog and digital cushion play and important role as a shock absorber.  If the base of the frog is abnormally atrophied OR the frog is NOT making contact with the ground, the ground forces are transferred to the sole and wall of the foot creating a scenario for pain over the sole and bars of the foot. This may result in further heel contracture and continued foot pain!!

Figure 4

 

Figure 5

 The development of contracted heels and an atrophied frog can be due to poor conformation and/or chronic heel pain. The chronic pain prevents the horse from fully loading the heel region and engaging the frog properly.One of the most common conditions that results in heel contracture due to chronic heel pain is in horses with navicular syndrome. Unfortunately there is no magic treatment or shoeing that will significantly reduce heel contracture in these horses. In addition, once the base of the frog atrophies as in Figure 1, it is not likely that a normal frog will ever develop. Regardless, it is important to determine if these horses have heel pain and to treat accordingly. In my experience, shoeing these horses with a full pour-in pad or a frog-support pad is key to promote normal engagement of the frog. In addition, maximizing the "break-over" will allow these horses to land heel first yet shorten the time spent weight bearing over the heel region and thus reduce heel pain. An example of such a shoeing is in Figure 6. This shoe is known as a "Roller-motion" shoe which has maximum break-over built into the toe region of the shoe. In addition, a medium-grade pour-in pad has been included for the entire length of the frog.

Figure 6

Wood Splinter Foreing Body in a Horse

A young mare presented with a baseball-size swelling on the left side of her neck that was just below the jugular groove. Two weeks prior, the mare presented with a puncture wound in the same area and the referring veterinarian removed several splinters. The mare was treated with antibiotics and the wound healed slowly; however, purulent discharge developed recently and the mare was tender to manipulation of the swelling. An ultrasound exam was performed and several linear foreign bodies (yellow arrows) were noted (Figures 1-3).

Figure 1

The linear foreign bodies were approximately 1-2 cm deep in the tissue and ranged in length from 5mm to 20mm (yellow arrows). Most concerning was the close proximity of one linear foreign body with the carotid artery (red circle in Figure 1)!!

Figure 2

Figure 3

 A 6cm incision was made directly over the linear foreign bodies followed by careful dissection of the subcutaneous tissues (Figures 4 and 5). Although the ultrasound exam suggested that the foreign bodies were big and obvious, it was quite tedious to locate the wooden offenders. In this case, 2 weeks had passed since the mare had impaled herself and her body had begun the process of forming thick scar tissue around the splinters, like a cocoon. After what seemed hours, 5 wooden splinters (Figure 6) ranging in size were removed from the mare's neck!!

Figure 4

The wound was lavaged heavily and left open to heal by second intention. It is probable that some wood fragments remain within the wound however their size and the extensive surgical exposure should allow for adequate healing without complications.

Figure 5

Figure 6