Stephanie S. Caston

Congenital Fetal Rhabdomyoma in a Foal

An Appaloosa filly was born with a ventral midline, approximately 8 × 12 × 15 cm subcutaneous cervical mass. The nonencapsulated mass was composed of interlacing and haphazard bundles of spindle cells on moderate to abundant loose myxomatous stroma. A moderate number of cells showed cross striations with minor nuclear variation and a low mitotic rate. Immunohistochemical staining for myoglobin, desmin, actin, vimentin, and S-100 was positive and negative for glial fibrillar antigen and keratin. Rhabdomyomas are rare benign tumors of striated muscle. Rhabdomyomas described previously in the veterinary literature are analogous to the “adult form” of human rhabdomyoma. This is the first report of a veterinary case that 1) clinically and histologically parallels the “fetal form” in human rhabdomyoma and 2) describes a congenital extracardiac rhabdomyoma.

Wound Care in Horses

Care of equine wounds in the field can be a challenging endeavor. Many times, wound care is complicated by chronicity or by prior inappropriate care in addition to the great degree of tissue trauma that occurred when the horse was wounded. Recognizing involvement of synovial structures, loss of skin, and damage to bone are critical in the initial examination of wounds and will guide future care. Education of clients is also important in that preparing them for possible outcomes during healing may help improve compliance and proper treatment of wound. Owners and trainers often perform much of the daily care and monitoring of equine wounds and thus can greatly assist or impede the progress. Bandaging is important to management of equine wounds-especially on the limbs-and is sometimes overlooked because of its labor-intensive nature and the desire for a spray, ointment, or salve that will heal the wound. The practitioner that improves and utilizes his or her understanding of the wound-healing process in concert with his or her knowledge of local anatomy will be the one who is best equipped to care for wounds in ambulatory practice.

Retrospective evaluation of facilitated pastern ankylosis using intra‐articular ethanol injections: 34 cases (2006–2012)

REASONS FOR PERFORMING STUDY While surgical arthrodesis is the treatment of choice for osteoarthritis of the proximal interphalangeal joint, some clients are unable to pursue surgery due to costs. A more economical technique was sought using intra-articular ethyl alcohol injections to facilitate ankylosis. OBJECTIVES To describe the technique and outcome of intra-articular ethyl alcohol injections for facilitated ankylosis of proximal interphalangeal joints with osteoarthritis. METHODS As a retrospective case series, the medical records (2006-2012) of clinical cases diagnosed with proximal interphalangeal joint osteoarthritis treated with intra-articular ethyl alcohol injections were reviewed. Cases with follow-up of at least 6 months were included. Technique and outcome were determined. Evaluation of outcome was assessed using return to previous performance or intended use and owner satisfaction as the indicators of success. Soundness and level of work are also reported. RESULTS Thirty-four horses were included in the study. At the time of follow-up, 17 horses (50%) were sound, while 13 horses (38%) were improved but not sound. One horses lameness was unchanged, and 3 horses were lost to follow-up. The median time until horses became sound or returned to work was 8 months. Six horses had complications, 4 of which were mild and transient. CONCLUSIONS AND POTENTIAL RELEVANCE The use of intra-articular ethyl alcohol in the proximal interphalangeal joint in horses affected by osteoarthritis appears to be a viable method for facilitated ankylosis if surgical management is not an option.

Outcome of horses undergoing navicular bursotomy for the treatment of contaminated or septic navicular bursitis: 19 cases (2002–2016)

BACKGROUND Contaminated or septic navicular bursitis has been reported to have a guarded prognosis after surgical treatment with navicular bursotomy only. In our experience, the use of navicular bursotomy for the treatment of this disease in combination with systemic and local delivery of antimicrobials can provide a good prognosis, even in horses with chronic disease. OBJECTIVE To report the outcome of horses undergoing navicular bursotomy for the treatment of contaminated or septic navicular bursitis. STUDY DESIGN Descriptive case series. METHODS Navicular bursotomy was performed in combination with systemic and local antimicrobial therapies. Medical records (2002-2016) were reviewed. Follow-up information was obtained from owners or referring veterinarians. Horse outcome was divided into two groups. A successful outcome (Group 1) was assigned to horses that were able to return to the same level of use or performance as before contamination/infection. A satisfactory outcome (Group 2) was assigned to horses that survived but did not return to their previous function or level of performance. RESULTS All horses survived to hospital discharge. Follow-up was obtained from 4 months to 12.75 years after surgery. Sixteen horses were able to return to their previous level of use (84.2%) and three horses were able to return to a lower level of performance or were pasture sound (15.8%). All 19 owners were satisfied with the outcome. MAIN LIMITATIONS Small sample size and retrospective nature of the study. Follow-up was limited to telephone contact with owners and referring veterinarians, and there is potential for recall bias. CONCLUSIONS Navicular bursotomy in combination with systemic and local antimicrobial therapies is an effective treatment for contaminated or septic navicular bursitis. The success rate in this population makes navicular bursotomy worthy of consideration in cases of contaminated or septic navicular bursitis, especially with chronicity and/or where equipment or expertise for bursoscopy is unavailable.

Efficacy of Teaching the Gambee Suture Pattern Using Simulated Small Intestine versus Cadaveric Small Intestine

OBJECTIVE To determine if instruction using simulated small intestine (SSI) is as effective as using cadaveric small intestine to teach the Gambee suture pattern to second year veterinary students. STUDY DESIGN Prospective, randomized, blinded study. SAMPLE POPULATION Second year veterinary students (n=59). METHODS Students were randomly assigned to groups using SSI or equine cadaver small intestine (CSI) to learn the Gambee suture pattern. The same educator, an experienced surgical instructor, instructed all students. Instruction consisted of verbal description of the technique with a schematic diagram followed by a demonstration. Students then practiced the technique with supervision and verbal feedback. One week later, 3 board certified surgeons experienced in surgical instruction evaluated each student suturing equine CSI and scored them using a rubric developed and validated for surgical skills assessment. RESULTS Fifty-nine students were enrolled (4 students were absent for the lab during which the assessment was performed; 55 students were available for evaluation). Of the 55 students evaluated, 26 were in the SSI group and 29 were in the CSI group. There was no significant difference between CSI and SSI groups in ability to perform the Gambee suture pattern using equine CSI 1 week following training. CONCLUSION SSI is as effective as equine cadaveric small intestine tissue to teach the Gambee suture pattern to second year veterinary students. If cadaver tissue is unavailable or undesirable, SSI could be used to instruct suture placement techniques.

Tenotomy of the semitendinosus muscle under standing sedation versus general anesthesia: Outcomes in 20 horses with fibrotic myopathy

OBJECTIVE To compare outcomes after semitendinosus tenotomy performed under standing sedation versus general anesthesia. STUDY DESIGN Retrospective case series. SAMPLE POPULATION 20 horses with fibrotic myopathy of the semitendinosus muscle. METHODS Medical records (2002-2015) of horses undergoing tenotomy of the semitendinosus muscle for the treatment of fibrotic myopathy were reviewed. Signalment, history, affected muscles, restrain method, surgical procedures, and short-term outcome as well as complications were retrieved from records. Long-term outcome (gait and athletic function) was assessed at least 6 months postoperatively by conversation with the owners. Pearsons χ2 statistical analysis was used to compare restrain method and affected muscles with overall outcome. Significance was set at P < .05. RESULTS Tenotomy of the semitendinosus muscle was performed under standing sedation in 8 horses and under general anesthesia in 12 horses. Follow-up period ranged from 9 months to 10 years. Gait was improved to variable degrees in 8 of 14 horses when the semitendinosus muscle alone was affected and in 4 of 6 horses when both the semitendinosus and semimembranosus muscles were involved (P = .11). Six of 8 horses treated under standing sedation and 6 of 12 horses treated under general anesthesia exhibited some improvement in the characteristic fibrotic gait (P = .4473). Five of 6 athletic horses treated under standing sedation and 6 of 9 athletic horses treated under general anesthesia returned to their preinjury level of athleticism. Horses treated under standing sedation had no incisional complications; 2 of 12 horses treated under general anesthesia exhibited incisional drainage. CONCLUSION Tenotomy of the semitendinosus muscle in horses with fibrotic myopathy leads to similar improvement in gait, whether performed under standing sedation or general anesthesia.

CD47 expression in cryopreserved equine cutaneous masses and normal skin

We investigated CD47 expression in cryopreserved sections of equine cutaneous masses and normal skin. CD47 is a cell surface protein expressed on many cell types and overexpressed in some tumors. Interaction of CD47 and signal regulatory protein–alpha (SIRPα) inhibits phagocytosis by macrophages. Formalin-fixed tissues from horses prospectively enrolled in the study were used to establish a histologic diagnosis. Immunohistochemical assays were performed on cryopreserved tissues using anti-CD47 antibodies or IgG control antibodies. CD47 was not expressed on equine normal skin but positivity to CD47 was present in 13 of 24 (54%) masses. Immunotherapy with anti-CD47 antibodies for equine cutaneous tumors that express CD47 warrants further investigation.