High Ring Bone!!

The radiographic image below is of the right hind pastern of a 4 year old mare that presented for a prepurchase exam. The mare had only been under saddle for 6 months. During the active exam, the mare cross-cantered when lunged to the left. In addition, the pastern area was "thicker" when compared to the opposite hind limb and the mare was moderately positive to flexion of the limb in question. Due to the suspicion of a significant problem, the right hind pastern was radiographed. The yellow arrows highlight new bone growth along the edges of the pastern joint. The bone growth or osteophytes are large and proliferative. These findings are indicative of advanced osteo-arthritis of the pastern joint otherwise known as "high ring bone". 

Figure 1

In Figure 2, the same osteophytes are noted as the course around the front of the pastern joint. The yellow arrows point to the osteophytes or irregular "white" structures along the edge of the pastern joint. 

Figure 2

Figure 3 and 4 are radiographs of a normal pastern joint. There are no osteophytes noted along the margins of the pastern joint. Notice in Figure 4 the smooth, curved border of the normal pastern joint. Interestingly, the pastern imaged in Figures 3 and 4 was radiographed because it palpated "thicker" than the opposite limb. Fortunately, there was no evidence of pastern arthritis. 

Figure 3

Figure 4

 In Figure 5 there is significant new bone growth or osteophyte development along the margins of the coffin joint. This is known as "low ring bone". Generally speaking, "high" or "low" ring bone is a significant finding during a prepurchase exam. Low ring bone is more common in draft breed horses. In addition, varying degrees of coffin joint arthritis, in active sport horses, is more common than pastern arthritis.

Figure 5

 High ring bone or pastern arthritis should be a concerning finding in any horse that is expected to carry a rider. Medical management of pastern osteoarthritis is limited to intra-articular treatment with cortisone or regenerative therapies. Unfortunately, the degeneration of the joint progresses rapidly and commonly results in chronic lameness. Surgical management involves fusion of the joint either with hardware or chemicals.

Pythiosis!

The endoscopic images below are of the pharynx of a horse with a 30 day history of a bloody nose. The nasal discharge consisted of bright red blood mixed with some purulent debris. The middle-aged gelding lives in a pasture that includes multiple low-lying areas that have been flooded with stagnant water. In addition, the gelding has suffered from failure to thrive most likely due to a poor appetite.

Figure 1

The endoscopic exam revealed bleeding tissue that surrounded the pharynx but was most severe along the dorsal wall of the pharynx. There was purulent debris mixed with the bleeding tissue and multiple small, white granuoles were noted within the bleeding tissue (Figure 2) .  Possible disease processes for this condition include fungal granuloma, cancer, bacterial abscess, and pythiosis.  Pythiosis is caused by the invasion of tissues by the pathogen pythiosis insidiosum and may affect external and internal tissues. The pathogen typically gains access to the horse via exposure to stagnant water that contains p. insidiosum.  As such the lower limbs (pasterns, coronary bands, and fetlocks) are most commonly affected. Once infected, the wound becomes increasingly inflamed with persistent bloody discharge. In addition, the lesions are very puritic resulting in additional inflammation via the horse biting and scratching at the wounds. Within the large areas of inflammation are firm, yellow granuoles also known as "kunkers".  This condition can be very deadly and requires aggressive treatment. For external cases, surgical removal and topical treatment are common. In addition a vaccine is available that has proven effective for cases of equine pythiosis.

Figure 2

However, pythiosis of the pharynx is not treatable with surgical resection or the common topical medications. Fortunately, systemic antifungals have proven effective if treated early and for the appropriate amount of time. The endoscopic images below are from the same horse approximately 4 weeks into the systemic anti-fungal treatment protocol. I recommend a specific protocol that involves  6 weeks of a tapering dose and a follow up endoscopic exam. In the past 8 years I have treated nearly a dozen cases of pharyngeal pythiosis. In every case there was a body of stagnant water available to the horses and all but 1 case responded to the systemic anti-fungal medication. For more information regarding the condition and the vaccine check out the following link: http://pythium.pavlab.com/subpage5.html

Figure 3

Figure 4

Phenylbutazone Toxicity!!

The yearling pictured below was being treated with Phenylbutazone for a severe lameness. The yearling weighed approximately 750 lbs and was being treated with 2 grams of Phenylbutazone twice per day for 2 weeks! Although the lameness improved, the yearling stopped eating and developed mild colic symptoms, severe oral ulceration (Figure 1) and eventually generalized edema. 

Figure 1

The serum levels of total protein and albumin were well below normal values and an abdominal ultrasound revealed severe edema of the right dorsal colon (Figure 2) . These findings were consistent with an advanced case of right dorsal colitis secondary to excessive phenylbutazone administration. Most often, when we discuss "ulcers" in horses we are referring to gastric or stomach ulcers. These types of ulcers may be caused by drugs such as banamine and phenylbutazone or are often a result of poor nutritional management. However, colonic ulcers may also be caused by such drugs, especially phenylbutazone. These types of ulcers are poorly understood and often difficult to diagnose in a standing horse. A typical history is that of a horse that presents for mild, recurrent colic, mild to severe diarrhea, ill-thrift, and a history of recent phenylbutazone treatment. Although the dose of phenylbutazone in this case was excessive, some horses appear to be super sensitive to the drug and may develop right dorsal colitis on an accepted dose of phenylbutazone. 

Figure 2

 Sadly, the yearling described could not be saved and was euthanized. A necropsy was performed and severe ulceration of the right dorsal colon (Figure 3 and 4) was discovered along with the marked edema of the colon wall (Figure 5). These large button-like ulcers cannot be detected via an ultrasound exam and would require surgical exploration of the colon to diagnose. The edema of the right dorsal colon wall can be diagnosed via trans-abdominal ultrasound and is secondary to the significant loss of serum protein. The protein is lost through the GI tract due to the inflamed colonic surface.

Figure 3

Figure 4

Figure 5

 Phenylbutazone toxicity can range from mild to severe. Mild cases are rather common and may present as only mild colic symptoms following administration of the drug. As such, careful observation should be made at all times when treating with these types of drugs and a reduction in dose and frequency of administration should be considered sooner than later! Horses suffering from colonic ulcers do NOT respond to gastric ulcer medication such as ranitidine and omeprazole. There is no specific medication for this condition. Treatment includes termination of phenylbutazone treatment, de-bulking the diet (more pellets and less hay), and time. Prognosis is guarded for advanced cases and good for mild cases.

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

Not All Splints Are Created Equal!!

The radiographs below are from the forelimbs of a lame horse. The horse had prominent "bumps" on the inside of both canon bones and only one was sensitive to direct pressure (right front). These bumps were consistent with osseous or bony callous formation over the splint bones which are also know as "splints". The  splints had been present for over 45 days and despite moderate rest, the horse remained lame. Specifically, the horse was lame in the right front limb when trotted in a circle to the left! Careful exam of these "splints" revealed that in addition to being painful to pressure over the callous, the horse was positive to pressure over the suspensory ligament at the level of the fractured splint.

Ultrasound exam of the soft tissue structures near the fractured splint revealed an inflamed suspensory ligament. The image below highlights the suspensory ligament (yellow arrow). The areas of black are consistent with edema/fluid accumulation within the ligament and are adjacent to the bony callous. In addition  to the presence of edema/fluid, the fiber pattern is irregular. These findings are consistent with moderate inflammation of the suspensory ligament, most likely due to physical interference via the bony callous. 

The ultrasound image below compares the left and right suspensory ligaments at the level of the corresponding "splints". A clear difference can be seen between the suspensory ligaments (area under the yellow curves) of the lame leg (RF) versus the non-lame leg.

The horse was scheduled for surgery and the offending splint bone was removed. At the time of surgery, moderate inflammation of the suspensory ligament was confirmed. The gelding underwent an extensive period of rehabilitation consisting of rest and controlled exercise. Three months post surgery the gelding is back to work and completely sound. Special thanks to Dr. Tim Lynch at Peterson and Smith Equine Hospital for his surgical expertise and great collaborative effort!

This case is not unique and reminds us that we should pay close attention to ANY "splint" development. Most often, splints resolve without the development of lameness or significant complications however if the appropriate care is not considered, the likelihood of complications does increase. Appropriate care includes forced rest, ice therapy, topical Surpass, and shockwave treatment.

Venogram!

As discussed in last week's "pic of the week", laminitis or founder is a serious condition in horses that requires aggressive and frequent intervention by a veterinarian-farrier team. The radiographs below are those of a quarter horse gelding with moderate founder and approximately 10 degrees of coffin bone rotation. Although the gelding appears stable, he continues to be lame in the affected foot. Routine radiographic evaluation confirms that there has been no further rotation of the coffin bone but does not explain why the horse remains lame. 

The radiographs below are of the same horse AFTER injecting a radiopaque dye into one of the veins that removes blood from the equine foot. A tourniquet is applied at the level of the fetlock before the injection and this allows for the dye to pool within the venous vasculature. Radiographs are taken immediately after the injection and the current blood supply to the foot can be assessed. 

Careful evaluation of the above image suggests that the horse has adequate blood supply to the entire foot. This is evident by the extensive venous supply (white squiggly lines) that originate near the coronary band and essentially surround the entire foot. However, when the foot was imaged in a dorsal-palmar view (below), there appears to be a decline in blood supply to the inside of the foot versus the outside. The yellow arrows are pointing to the areas in question. Note the subjective decline in blood supply along the right side (inside) compared to the left side (outside)

Although these observations are not 100% definitive, they do suggest a reduction in blood supply to the medial aspect of the hoof. This information is important when considering the horses's prognosis and shoeing recommendations. Venograms can be easily performed in a stall-side setting but do require digital radiography and knowledge regarding the technique. The information gathered from these studies is considered an important piece of the puzzle regarding management of laminitis in the horse.

Founder!

The images below are of those of a horse with chronic "founder" or laminitis. There has been significant deterioration of the coffin bone and severe distortion of the hoof wall capsule. Clearly, there has not been adequate care of this horse's feet by a farrier/veterinarian team. Chronic founder requires careful attention and care by a veterinarian AND a farrier. The changes in coffin bone alignment must be monitored via radiographs and corrective shoeing by the farrier is critical to reduce pain and further deterioration of the foot. 

The images below are of a different horse with chronic founder that resulted in the coffin bone rotating out the bottom of the foot. Unfortunately, this is the end of the road for this horse and his condition resulted in humane euthanasia. This end result can often be avoided however sometimes despite the most attentive veterinarian/farrier team, mother nature has the last say in the matter. 

This post will be the first of several discussing chronic laminitis/founder, so stay tuned!!!

Equine Glaucoma!

The horse below presented as a 20 year-old gelding with a 1 year history of recurring eye cloudiness that was also associated with excessive tearing and squinting. When examined, the horse kept his eye partially shut and there was a moderate tinge of "blue" to the entire surface of the eye. The cornea was stained with fluorescein stain (bright green fluid pooling below the eye ball) for the presence of a corneal ulcer and non was detected. 

Closer inspection of the eye revealed a darker blue band that stretched across the cornea. This band is also known as a corneal striae and is caused by persistently increased ocular pressure.  These findings are consistent with equine glaucoma and indicate a significantly elevated pressures within the eye. The blue tint to the cornea is caused by edema and is also be associated with the increased ocular pressures. As in humans, these horses experience significant discomfort evident by their tearing and constant squinting.  Definitive diagnosis requires measuring the ocular pressure via a tonometer that can be easily performed in a stall with mild sedation. The incidence of equine glaucoma is higher than most suspect and is usually not diagnosed until after significant time has passed. Treatment includes medications to lower the ocular pressure; however, this condition is typically chronic and progressive in horses and often results in the loss of the eye. As a rule, if you find your horse with his eye half way or completely shut, it is strongly recommended that a veterinarian examine the eye and provide immediate medial treatment. 

 

Navicular bone cyst in sound horse!

 The following radiographs are of a horse's front feet. Specifically, the views are isolating the navicular bone. This horse was being evaluated as a prospect dressage horse and was completely sound during the prepurchase exam. The gelding was approximately 7 years old and there was no history of lameness.
As recommended by the examining veterinarian (me), the front feet were radiographed with plans to radiograph the hocks as well. However, a large cyst was identified in the left navicular bone.

Compared to the right navicular bone (image below), an irregularly shaped lucency (dark circle) is present in the center of the navicular bone (image above).  Although the gelding was not lame, the exam was stopped and the horse was FAILED for sale and intended use.  Everyone involved (including myself) were very surprised with the radiographic findings. However, navicular bone cysts are significant findings and will likely result in poor performance and lameness at some point in the future. As I tell my clients, my crystal ball is "cloudy" at best; however these findings are considered a deal breaker. 

This case represents another example of the importance of a thorough prepurchase exam when acquiring a horse of any price (especially a free horse). In addition, I feel strongly that foot radiographs should be a part of all prepurchase exams due to the essential role the fore feet play in equine soundness. 

Sacro Iliac Injection!

The ultrasound image above is centered over the cranial edge of the pelvic rim. The red line corresponds to the pelvic rim and the green line corresponds to the transverse process of the last lumbar vertebrae.

The picture above shows the "cranial" approach with a long spinal needle for treatment of the sacro-iliac joint (SI). From the exterior of the horse it is very difficult to visualize the SI joint however proper alignment of the spinal needle via ultrasound guidance will result in accurate treatment of the SI joint space. The needle is inserted in front of the pelvis and guided just below the rim of the pelvis (see pic below)

This technique requires ultrasound guidance of a skilled operator. The typical complaint from the rider/trainers include poor performance, no obvious lameness, unwilling to maintain a particular lead, cross-cantering, and painful response to deep pressure over the gluteous musculature. The Sacro iliac joint can be visualized per rectum and may also be evaluated via nuclear scintigraphy. The response to treatment usually requires 10-14 days before a clinical improvement is noted and it can be very significant. The most interesting aspect of SI inflammation is that these horses are rarely lame however their performance as diminished!

The above ultrasound view is per rectum and shows the SI joint. In this case, there are bony changes around the joint which are consistent with arthritis.