Fractured Scapula in a Horse

A 5 year-old miniature horse presented to PHD Veterinary services for the complaint of forelimb lameness. The mini had been charged and mounted by a full grown horse 4 weeks prior and subsequently the mini was a grade 4 out 5 lame in the right forelimb at the walk. The referring veterinarian examined the mini on the day of the injury and radiographed the shoulder joint. There were no radiographic abnormalities noted. Although the lameness was slowly resolving, the owner and referring veterinarian elected for an ultrasound of the shoulder region. On presentation, the mini was a grade 3/5 lame in the right forelimb at the walk. There was a firm swelling over the center of the right scapula and the mini was painful to direct pressure. There was no muscle atrophy noted and the ambulation of the limb was normal.
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Figure 1

In Figure 1, the spine of the scapula is imaged. The white structures correspond to bone. The yellow arrows point to multiple bone fragments. These ultrasound findings suggest that the spine of the scapula was crushed when the full grown horse mounted the mini. The image in Figure 2 corresponds to an equine scapula and the yellow arrows highlight the spine of the scapula as it extends nearly the length of the scapula.  In addition to the bone fragments of the spine of the scapula, the longitudinal scan of the scapula in Figure 3 suggests a fracture of the body of the scapula. There is a "step" or interruption of the bony margin which is indicated by the red arrow in Figure 3. 

Figure 2

Figure 3

 In Figure 4, the abnormal scapula (left image) is compared to the normal scapula (right image). Clearly, there are multiple bone fragments present at the site of the fractured scapula. The prognosis for this mini is good given time to heal. The mini is developing a firm, bony callous over the fracture site to stabilize the scapula and it's soundness has improved since the injury. It remains possible that the mini may develop a sequestrum (dead bone) due to the multiple bone fragments which would result in a draining wound. In addition, the fracture of the body of the scapula will need significant time to stabilize before the mini can return to full soundness. This type of injury would likely be more serious in a full size horse due to the weight of the horse. In addition, the radial and suprascapular nerves are often involved in these types of injuries resulting in muscle atrophy and difficulty in proper ambulation of the limb.

Figure 4

Resolved Fibrosarcoma in a horse!

Several months ago I presented a case involving a gelding that presented for lameness and soft tissue swelling along the outside of the right knee (carpus). The gelding was lame at the walk and hesitant to flex the limb at the carpus. Ultrasound exam revealed a well demarcated soft tissue mass (dark tissue inside blue circle) that was centered over the carpus (Figures 1-3). The histopathology report was consistent with a fibrosarcoma.

Figure 1

Because the tumor was located immediately adjacent to the joint capsule of the carpus, surgical removal was considered high risk. As such, the tumor was injected with a chemotherapy agent called Cisplatin via ultrasound guidance. The tumor was injected twice, approximately 30 days apart. There was a moderate reduction in the size of the tumor just 3 weeks after the first injection and the gelding was no longer lame at the walk and was more willing to flex the limb at the carpus.

Figure 2

Figure 3

 The gelding's limb was evaluated 4 weeks after the second Cisplatin treatment. There was no evidence of the fibrosarcoma on the outside of the carpus AND under the skin (Figure 5). The ultrasound exam only noted normal subcutaneous tissue and joint capsule between the ultrasound probe and the carpus. The gelding was sound at the walk, trot, canter and has returned to full work!! The case is a good example of the benefits of intra-lesional injection of tumors that are non-operable with chemotherapy agents. There are several chemotherapy agents available and the procedure can be performed at the barn with ultrasound guidance.

Figure 4

Shoulder swelling in a Horse

The mare in Figure 1 presented for a complaint of sudden onset severe swelling at the point of the right shoulder and near non-weight bearing lameness of the same limb. The mare is normally kept with other horses and there is no history of a "equine dispute" or evidence of external trauma. On presentation, the swelling consists of significant edema and the mare is considerably "tender" to pressure and palpation of the swelling. Manipulation of the limb was limited due to the significant pain response that resulted. Radiographic exam of the horse's shoulder is a viable option however due to the pain on manipulation and significant soft tissue swelling, an ultrasound exam was more highly indicated.

Figure 1

The images in Figure 2 and 3 correspond to the soft tissue swelling noted in Figure 1. A large, fluid filled pocket was noted deep to the skin surface. The fluid had a mixed pattern of echogenicity suggesting that the fluid consisted of cellular debris mixed with blood/serum. These findings are most consistent with a large subcutaneous abscess. The two most likely causes for abscess formation in this area would be trauma induced or abscess formation from a bacteria called corynebacterium pseudotuberculosis. This condition is also known as "Pigeon's fever". Pigeon's fever is a serious condition due to the highly infectious nature of the bacteria AND the fact that once the bacteria is present on the premises, it is very difficult to remove from the environment. Correct diagnosis depends on collecting a sample of fluid from the abscess and submitting for laboratory evaluation. Treatment of either condition requires establishing drainage of the abscess and daily  lavage for 10-14 days after drainage. Microbiological identification in this case is pending and the horse is in quarantine on the farm! The abscess was opened and drainage established.

Figure 2

Figure 3

Interestingly, within 7 days of examining the mare above, a gelding presented for similar symptoms. He was found non-weight bearing lame in the pasture with severe swelling of the shoulder region. The referring veterinarian provided digital radiographs which did not identify the cause of the lameness/swelling. On ultrasound exam, a bright, bone-like structure (red dotted line) was noted extending into a fluid filled mass that appeared to be a hematoma (Figure 4 and 5). The bone-like structure was the humerus bone (red dotted line) and it was fractured plus displaced. This gelding was humanely  immediately euthanized!

Figure 4

Figure 5

Although these cases are quite different in outcome, they demonstrate the benefit of soft tissue ultrasound with regards to assessing "swellings". As demonstrated it is possible to evaluate soft tissue changes as well as bony changes.

Fibrosarcoma in a horse!

A 14 year old gelding presented for a complaint of recent lameness and swelling of the right knee or carpus. There was no history of trauma but a plumb size swelling was palpated along the outside of the knee. The gelding resented direct pressure over the knee and any manipulation of the knee. When radiographed, there were no significant abnormalities noted with regards to the bones or articular surfaces that make up the carpus. However, a moderate soft tissue swelling was noted along the dorsal (front) and lateral (outside) aspect of the carpus (Blue circles in Figures 3-4). 

Figure 1

Figure 2

Figure 3

Figure 4

An ultrasound exam was performed on the soft tissue swelling and a hypoechoic (dark) soft tissue structure was identified (Figure 5). This structure appeared well demarcated and was consistent with a mass or tumor which was below the surface of the skin yet outside the joint capsule of the carpus.

Figure 5

When the ultrasound image is flipped into the same projection as the radiograph, the soft tissue mass aligns perfectly with the soft tissue swelling noted on the digital radiograph (Figure 6). The red line corresponds to the middle carpal joint and helps demonstrate how close the tumor is to the joint yet does NOT communicate with the joint.

Figure 6

A core biopsy was taken of the soft tissue mass through a small skin incision directly over the area in question and submitted for analysis.  The histopathology report indicated that the core biopsy was consistent with a fibrosarcoma. This type of tumor is not common in horses and although it does not commonly spread to other regions of the horse, it can be locally destructive and aggressive. As such, it was determined that the immediate course of action was intra-lesional injections of a potent chemotherapy drug. Due to the close proximity with the joint capsule, surgery was considered too risky at this point. The gelding has been treated 1x with a chemotherapy medication and a follow-up exam is expected within 2-3 weeks. To be continued...

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.