A multicenter retrospective case-cohort study on the prevalence of incisional morbidities in late pregnant mares following exploratory celiotomy (2014-2019): 579 cases.

OBJECTIVE: To report the prevalence and risk factors for incisional morbidities in late pregnant and nonpregnant/early pregnant control mares following colic surgery. DESIGN: Multicenter, retrospective, cohort study from January 2014 to December 2019. SETTING: Two university teaching hospitals and 1 private referral center. ANIMALS: Five hundred and seventy-nine fillies and mares ≥2 years old that underwent celiotomy. Pregnant mares (n = 54) were >240 days in gestation from the last known breeding date and were compared to control females (n = 525) undergoing colic surgery. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Morbidity rates were not different between mare groups with 56% of pregnant mares and 51% of control mares reporting at least 1 morbidity. Incisional swelling was the most common reported complication in both groups. Incisional swelling was associated with shorter hospital stays (odds ratio [OR], 0.18; P < 0.01), and drainage was associated with a longer hospital stay (OR, 1.27; P ≤ 0.01) and with use of an abdominal bandage (OR, 4.4; P < 0.01). Herniation was associated with hypercapnia under anesthesia (OR, 1.1; P = 0.048), previous abdominal surgery (OR, 8.3; P = 0.003), and with use of an abdominal bandage (OR, 56; P = 0.006). Body wall dehiscence was associated with longer hospital stay (OR, 1.2; P < 0.01). Nonsurvival was higher in pregnant mares (13%) compared to control mares (5%; P = 0.02). CONCLUSIONS: The prevalence of incisional morbidities did not differ between pregnant and control mares undergoing colic surgery. Several factors were associated with incisional morbidities, including the duration of surgery and anesthesia, anesthetic variables, abdominal bandage use, previous ventral abdominal incision, and longer duration of hospitalization.

Comparison of the zip skin closure system with conventional suture for skin closure of ventral midline incisions in horses.

OBJECTIVE: To compare the application and healing of the zip skin closure system (ZSCS) with sutured closure by use of a split-scar model of ventral midline incisions in horses in a prospective, randomized experimental study. ANIMALS: 8 adult horses. PROCEDURES: All horses underwent an exploratory ventral midline celiotomy with a standardized 30-cm skin incision. Each horse was randomized to have either the cranial 15 cm closed with suture and caudal 15 cm with the ZSCS or vice versa (split-scar model). Skin closure time was recorded and compared. Photography and skin biopsies were taken preoperatively and 14 days postoperatively. Cosmetic appearance was assessed by use of a proposed equine celiotomy incision score. Healing at 14 days was assessed by histopathology. RESULTS: Skin closure times were faster with the ZSCS compared to sutured incisions. At 14 days postoperatively, the cosmetic appearance (equine celiotomy incision scores) for ZSCS incisions were better than sutured closure and histologic healing scores were not different between methods of closure. Subcuticular sutures were associated with deep dermal inflammation and necrosis independent of epidermal closure methods. CLINICAL RELEVANCE: While limitations to the utility of the ZSCS are recognized, the potential benefits of expedient closure, good cosmetic outcome, and satisfactory healing make this method viable for closure of linear wounds or incisions in horses.

Comparative results of 3 treatments for medial femoral condyle subchondral cystic lesions in Thoroughbred racehorses.

OBJECTIVES: To compare 3 different methods for treatment of medial femoral condyle (MFC) subchondral cystic lesions in Thoroughbred horses <24 months old based on the criterion of ability to race post-treatment. STUDY DESIGN: Retrospective cohort study. ANIMALS: Thoroughbreds (n = 107, age < 24 months) diagnosed with MFC subchondral cystic lesions. METHODS: Medical records between January 2004 and December 2017 were reviewed. Three treatment methods were used in these horses during that time frame: arthroscopic debridement, intralesional autologous mesenchymal stem cell (MSC) injection, and intralesional corticosteroid injection. The outcome evaluated was the ability to compete in a pari-mutuel race. RESULTS: Seventy-eight of 107 Thoroughbreds (73%) raced post-treatment; 41/57 (72%) of horses treated by arthroscopic debridement raced; 16/19 (84%) of horses treated with intralesional MSCs raced; 21/31 (68%) of horses treated with intralesional corticosteroids raced. There was no difference between groups in the ability to start a race. Sex, limb affected, and lesion size also had no effect on the ability to start a race. There was a trend for increasing lesion size reducing the probability of racing. CONCLUSIONS: Seventy-three percent of the horses raced, but there was no difference in the ability of unraced Thoroughbreds to race after treatment of MFC subchondral cystic lesions with arthroscopic debridement, intralesional mesenchymal stem cells, or intralesional corticosteroids. CLINICAL SIGNIFICANCE: The 3 reported treatment options may be considered for treatment of MFC subchondral cystic lesions with a good prognosis for racing post-treatment. Owners should be advised that increasing lesion size decreases the probability of racing.

Use of Polyamide (Nylon) Cable Ties for Vascular Ligation of Healthy Equine Jejunal Mesentery.

Jejunal vascular ligation is an essential step in performing jejunojejunostomy. Hand sewn ligation is typically used and can increase operative time with long sections of bowel to be removed. Nylon cable ties (NCT) have been used for vascular ligation in horses but are yet to be investigated for application on the mesenteric vasculature of the gastrointestinal tract. Our objective was to evaluate the efficacy and short-term safety of NCT jejunal mesenteric vessel ligation in healthy horses. Eight healthy adult horses underwent midline celiotomy. A segment of jejunal mesentery was identified (≥4 arcades). Briefly, three fenestrations (proximal, middle, distal) were made 5-10 mm apart adjacent to the first and last vascular arcade to be ligated. Two sterilized NCT were passed to encircle the mesentery through the proximal and middle fenestrations, separated by intact mesentery. NCT were closed tightly and the vascular pedicle transected with Mayo scissors through the distal fenestration. Jejunojejunostomy was then performed and the mesentery sutured closed. The number of vascular arcades and time to ligate using NCT were recorded. At 2 weeks, horses underwent repeat celiotomy to assess the healing of the NCT ligation site and an equal number of vascular arcades were hand sewn double ligated using 2-0 Polyglactin 910 as a timed comparison. NCT mesenteric ligation was significantly faster than hand sewn methods (P < 0.01). Effective hemostasis was achieved in all cases. There was no evidence of local infection or adhesions at 14 days post-operatively. Further investigation in the long-term effects in horses as well as horses with strangulating jejunal lesions are needed for clinical application.

Comparison of one-layer Utrecht pattern with two-layer (simple continuous/Cushing) pattern for jejunojejunostomy in healthy horses in vivo.

OBJECTIVE: To compare end-to-end jejunal anastomoses with a one-layer (Utrecht) and two-layer (simple continuous/Cushing) patterns. STUDY DESIGN: Experimental study. ANIMALS: Eight healthy adult horses. METHODS: Jejunal end-to-end anastomoses were performed in randomly assigned one-layer or two-layer patterns. Horses were recovered from surgery and monitored for complications. At 14 days, the opposite pattern was performed (cross-over design) prior to euthanasia. Duration of closures was compared between patterns. Serosal width was measured before harvesting anastomotic sites from the first procedure. Luminal diameter was measured, and sections were collected for histological evaluation of heating after routine and immunohistochemical staining. RESULTS: One-layer closure was faster (716 ± 86 s) than two-layer closures (1136 ± 111 s). Postoperative complications were minimal. No difference was detected in lumen size between groups. The lumen was reduced by 18% after one-layer and 15% after two-layer closures (p = .34). Serosal adhesions to the mesentery without clinical evidence of obstruction were observed in two horses with two-layer closure. Histopathological scores for inflammation, infection, and healing did not differ between groups. CONCLUSION: Jejunal anastomosis with one-layer Utrecht technique was about 7 min faster and led to similar luminal reduction and histological healing scores as two-layer jejunojejunostomies. CLINICAL SIGNIFICANCE: The outcomes of one-layer Utrecht jejunojejunostomies in healthy horses justify clinical evaluation of this technique.

Use of polyamide cable ties during experimental omentectomy in adult horses with histopathological assessment.

OBJECTIVE: To report the use of nylon cable ties (NCT) for omentectomy in the horse. STUDY DESIGN: Experimental study. ANIMALS: Eight healthy adult horses. METHODS: Horses underwent nylon cable tie (NCT) ligation of the greater omentum after ventral midline celiotomy. The time required to complete the omentectomy was recorded. Horses were recovered for 14 days before repeat celiotomy, adhesions assessment, and histological examination of the omentectomy site using a proposed histologic grading scheme. The total time for omentectomy procedure and histologic score was assessed for normality. Data are expressed as mean ± standard deviation. RESULTS: NCT ligation provided sufficient hemostasis to complete the omentectomy (28 ± 15 s), without rescue ligation. No gross evidence of intra-abdominal adhesion or morbidity was associated with the omentectomy site 14 days after surgery. NCT were intact at the site of application, covered with smooth fibrous connective tissue. Adiponecrosis with minimal inflammation and fibrovascular occlusion of omental vessels was present at the surgical site. Mild inflammation was present at the NCT-tissue interface. CONCLUSION: The use of NCT resulted in fast and effective omentectomy in healthy horses without short-term evidence of inflammatory reaction or intra-abdominal adhesion. CLINICAL SIGNIFICANCE: The described technique provides an alternative for omentectomy in healthy adult horses.

Effect of 3% chloroprocaine hydrochloride when used for median and ulnar regional nerve blocks in lame horses.

OBJECTIVE: To assess onset of analgesia for 3% chloroprocaine hydrochloride and 2% mepivacaine hydrochloride when used for median and ulnar nerve blocks in lame horses. ANIMALS: 6 naturally lame horses. PROCEDURES: A crossover experiment was conducted. Horses were assigned to 1 of 2 treatment groups (3% chloroprocaine or 2% mepivacaine first). Median and ulnar nerve blocks were performed in the lame limb with the assigned treatment. Lameness was objectively evaluated before treatment administration and at various points for 120 minutes after treatment with a wireless inertial sensor-based motion analysis system. Following a 7-day washout period, horses then received the other treatment and lameness evaluations were repeated. RESULTS: Median and ulnar nerve blocks performed with 3% chloroprocaine resulted in more consistent, rapid, and profound amelioration of lameness than did blocks performed with 2% mepivacaine. Lameness decreased more between 20 and 40 minutes after injection when 3% chloroprocaine was used than when 2% mepivacaine was used. Complete resolution of lameness was detected a mean of 9 minutes after injection when median and ulnar nerve blocks were performed with 3% chloroprocaine and a mean of 28 minutes after injection when performed with 2% mepivacaine. CONCLUSIONS AND CLINICAL RELEVANCE: 3% chloroprocaine had a more rapid onset and provided better analgesia for median and ulnar nerve blocks in horses with naturally occurring lameness, compared with 2% mepivacaine. These favorable properties suggest that 3% chloroprocaine would be useful for performance of median and ulnar regional nerve blocks during complicated lameness evaluations.