Early Identification of Intestinal Strangulation: Why It Is Important and How to Make an Early Diagnosis.

Horses with colic caused by intestinal strangulation can have an excellent outcome with early surgical correction of the obstruction. The expense associated with surgery is typically less with early lesion correction. The challenge is making an early diagnosis of intestinal strangulation. Although for some horses with a strangulating obstruction, the need for surgery is made based on severe colic signs or lack of response to analgesia, in other horses, it is less obvious. Signalment, history, and meticulous physical examination, combined with some targeted diagnostic procedures can help with early diagnosis of intestinal strangulation. Improving the outcome of these horses requires diligence and a team-based approach from the owner or caregiver, primary care veterinarian, and specialists.

Experimental crossover study on the effects of withholding feed for 24 h on the equine faecal bacterial microbiota in healthy mares.

BACKGROUND: An association between equine gastrointestinal disease causing colic signs and changes in faecal bacterial microbiota has been identified. The reasons for these changes and their clinical relevance has not been investigated. Withholding feed, which is an integral part of managing horses with colic, may contribute to the observed changes in the microbiota and impact interpretation of findings in horses with colic. Study objectives were, therefore, to determine the effect of withholding feed for 24 h on equine faecal bacterial microbiota in healthy mares to differentiate the effects of withholding feed from the changes potentially associated with the disease. RESULTS: Species richness and Shannon diversity (alpha diversity) were significantly lower at the late withheld (10-24 h post withholding feed) and early refed (2-12 h post re-feeding) time points compared to samples from fed horses (P < 0.01). Restoration of species richness and diversity began to occur at the late refed (18-24 h post re-feeding) time points. Horses having feed withheld had a distinct bacterial population compared to fed horses (beta diversity). Bacteroidetes BS11 and Firmicutes Christensenellaceae, Christensenella, and Dehalobacteriaceae were significantly increased in horses withheld from feed primarily during the late withheld and early refed time points. Bacteroidetes Marinilabiaceae and Prevotellaceae, Firmicutes Veillonellaceae, Anaerovibrio, and Bulleidia, and Proteobacteria GMD14H09 were significantly decreased in horses with feed withheld at late withheld, early refed, and late refed time periods (P < 0.01). Changes in commensal gut microbiota were not significant between groups. CONCLUSIONS: Withholding feed has a significant effect on faecal bacterial microbiota diversity and composition particularly following at least 10 h of withholding feed and should be taken into consideration when interpreting data on the equine faecal bacterial microbiota in horses.

Outcomes of pregnant broodmares treated for colic at a tertiary care facility.

OBJECTIVE: To evaluate, following colic admission during pregnancy, (1) broodmare survival; (2) the frequency of recurrent colic in broodmares and its associated variables, and (3) pregnancy outcome and the variables associated with a negative pregnancy outcome. STUDY DESIGN: Ambidirectional observational cohort study. ANIMALS: One hundred and four client-owned broodmare admissions. METHODS: Admissions of pregnant mares from June 2010 until October 2016 were included. Data were collected until November 2017. Cox proportional hazards regression analysis was performed to evaluate variables associated with broodmare survival. Logistic regression analysis was used to examine the variables associated with recurrent colic and pregnancy outcome. RESULTS: Broodmares from 73/104 (70.2%) admissions were discharged alive. Lesion category, admission hyperlactatemia (hazard ratio (HR) 3.24, 95%, CI 1.28-8.22, P = .013), and admission high packed cell volume (HR 2.89, 95% CI 1.29-6.47, P = .010) were associated with reduced survival. Recurrent colic was observed in broodmares from 33/70 admissions (47.1%). The final multivariable model for recurrent colic included Thoroughbred breed (OR 5.09, 95% CI 1.58-16.4, P = .006) and age (OR .876, 95% CI .747-1.03, P = .105). Overall, negative pregnancy outcome was 14/65 (21.5%). Lesion category, evidence of systemic inflammatory response syndrome (SIRS) in hospital (OR 31.2, 95% CI 2.09-466.5, P = .013), and diarrhea in hospital (OR 379.3, 95% CI 97.1-1482.0, P < .001) were associated with increased negative pregnancy outcome. Altrenogest administration was inversely associated with negative pregnancy outcome (OR 0.029, 95% CI .004-.222, P = .001). CONCLUSION: Pregnant broodmares admitted for colic had lower survival than anticipated and were at risk of recurrent colic. Markers of broodmare disease severity were associated with pregnancy outcome. CLINICAL SIGNIFICANCE: Lesion category, hematologic variables (packed cell volume and l-lactate concentration), evidence of SIRS, and diarrhea were useful for predicting broodmare and pregnancy outcomes.

Clinical findings associated with development of postoperative reflux and short-term survival after small intestinal surgery in geriatric and mature nongeriatric horses.

OBJECTIVE: To determine risk factors, especially age, associated with postoperative reflux (POR; >2 L of reflux present upon intubation), high-volume POR (≥20 L in 24 hours), and short-term outcome after small intestinal (SI) surgery. STUDY DESIGN: Retrospective case-control study. SAMPLE POPULATION: Horses aged ≥16 years (geriatric; range, 16-30; n = 44) and <16 years (mature; range, 2-15; n = 39) with an SI surgical lesion that survived general anesthesia and did not have a second exploratory celiotomy during the same visit. METHODS: Medical records (2009-2015) were reviewed; perioperative variables were evaluated for associations with outcomes by using multivariable logistic regression. RESULTS: Postoperative reflux was associated with an increasing packed cell volume at admission (odds ratio [OR], 1.08; 95% CI, 1.00-1.16; P = .042) and presence of nasogastric reflux at admission (OR, 4.61; 95% CI, 1.3-15.69; P = .014). High-volume POR was associated with an increasing glycemia at admission (OR, 1.19; 95% CI, 1.01-1.40; P = .041), presence of nasogastric reflux at admission (OR, 10.05; 95% CI, 2.21-45.74; P = .003), and SI resection (OR, 10.52; 95% CI, 1.81-61.25; P = .009). Increasing surgical time (OR, 2.50; 95% CI, 1.16-5.29; P = .019) and high-volume POR (OR, 6.37; 95% CI, 2.12-19.12; P = .001) were associated with nonsurvival. CONCLUSION: Age, considered as both a continuous variable and a categorical variable, was not associated with the development of POR, high-volume POR, or nonsurvival. CLINICAL SIGNIFICANCE: Age does not influence the occurrence of POR and should not negatively impact an owner's decision to pursue surgery in aged horses.

Use of perioperative variables to determine the requirement for repeat celiotomy in horses with postoperative reflux after small intestinal surgery.

OBJECTIVE: To determine whether perioperative variables can be used to differentiate a medical vs a surgical reason for postoperative reflux (POR) after small intestinal (SI) surgery in horses. STUDY DESIGN: Retrospective study. SAMPLE POPULATION: Horses >1 year of age that recovered from SI surgery and had POR. METHODS: Medical records of horses that underwent SI surgery and developed POR from 2009-2015 were reviewed. Surgical reasons for POR were defined as an anastomosis complication, mechanical obstruction, or nonviable intestine identified at repeat celiotomy/necropsy. A medical reason for POR was presumed when the POR improved with medical treatment or when no surgical reasons were identified at repeat celiotomy/necropsy. Perioperative variables were analyzed and used to develop a logistic regression model. RESULTS: Fifty-one horses had POR after SI surgery. After initial SI surgery, 14 horses had surgical reasons for POR diagnosed at repeat celiotomy or necropsy. Thirty-seven horses were considered to have medical reasons for POR because their POR resolved with medical management or functional ileus was diagnosed at repeat celiotomy/necropsy. A greater volume and a greater duration of POR were not associated with a surgical reason for POR. Rather, a postoperative (PO) fever and the timing of colic in the PO period were associated with a surgical reason for POR. CONCLUSION: Horses that developed a fever and colic in the PO period after SI surgery were more likely to have a surgical reason for POR. CLINICAL SIGNIFICANCE: These findings may provide guidance for clinicians when they are making decisions about repeat celiotomy in horses with POR after SI surgery.

Serum amyloid A concentration in postoperative colic horses and its association with postoperative complications.

OBJECTIVE: To determine serum amyloid A (SAA) concentrations in the postoperative (PO) colic horse and its association with PO complications and infection. STUDY DESIGN: Prospective case series. ANIMALS: Fifty-one horses after colic surgery. METHODS: Blood samples from horses undergoing exploratory celiotomy were analyzed for quantitative SAA and fibrinogen concentrations and for neutrophil count at days 0, 1, 2, and 4-6 and at hospital discharge. RESULTS: Complications developed in 35 (69%) horses and included PO colic (n = 13, 25%), PO reflux (n = 11, 22%), intravenous catheter (IVC) complications (n = 11, 22%), low-grade fever (n = 11, 22%); surgical site infection (SSI; n = 9, 18%), high-grade fever (n = 7, 14%), and diarrhea (n = 4, 8%). There was an association between day 2 SAA and PO colic (P = .004), diarrhea (P = .042), IVC complications (P = .008), and PO reflux (P = .008) as well as day 4-6 SAA and PO colic (P = .004) and diarrhea (P = .018). Discharge SAA concentration was associated with SSI (P = .001). Fibrinogen concentrations at days 4-6 and at discharge were associated with PO colic (P = .003), diarrhea (P = .004), IVC complications (P = .002), and PO reflux (P = .023). No differences were seen in SAA, fibrinogen, or neutrophils between horses with PO infection vs those with non-infection-associated complications. CONCLUSION: Serum amyloid A was markedly increased in the PO period in all horses but did not differ between PO infection and noninfection complications. The amount of inflammation associated with PO colic and colic surgery was high and may have affected the predictive value of SAA for early PO infection. CLINICAL SIGNIFICANCE: Although increases occurred earlier, measurement of SAA with a point-of-care analyzer may not be a more sensitive indicator of infection in the early PO colic horse than fibrinogen concentration. Serum amyloid A may help detect SSI in the late PO period.

Influence of Salmonella status on the long-term outcome of horses after colic surgery.

OBJECTIVE: To compare long-term outcome of Salmonella-positive versus Salmonella-negative horses discharged from hospital after colic surgery. STUDY DESIGN: Retrospective case-control. ANIMALS: Horses discharged from the hospital after colic surgery. For each horse with positive culture for Salmonella enterica (SAL-POS, n = 59), at least 2 horses testing negative for S. enterica (SAL-NEG, n = 119) were enrolled. METHODS: Owners were interviewed via phone at least 12 months after surgery regarding: (1) complications after discharge from the hospital; (2) duration of survival; and (3) return to prior or intended use. Association between immediate postoperative clinical variables such as Salmonella status and long-term measures of outcome was tested via ratios (odds ratio [OR]) and 95% confidence intervals. Data were analyzed for survival using a Cox proportional hazards model and for return to use using multivariable logistic regression. RESULTS: SAL-POS horses had a higher OR of surgical site infection (2.7 [1.1-6.9] P = .027) and weight loss (6.8 [1.8-26.1] P = .002). At the time of follow-up, there were 53/56 (95%) SAL-POS and 99/118 (84%) SAL-NEG horses alive. The final multivariable model for nonsurvival included postoperative colic (hazard ratio 7.6 [2.8-19.2] P = .002) and the interaction between Salmonella status and duration of rectal temperature > 103°F postoperatively (SAL-POS 1.04 [1.01-1.07] and SAL-NEG 1.16 [1.06-1.25], P = .005). The majority of horses returned to their intended use regardless of their SAL-POS (38/50, 76%) or SAL-NEG (77/96, 80%, P = .498) status. CONCLUSION: Salmonella-positive horses that survive to discharge from the hospital after colic surgery have similar risks of long-term complications (colic/diarrhea), survival, and return to function than Salmonella-negative horses.

Short-term complications after colic surgery in geriatric versus mature non-geriatric horses.

OBJECTIVE: To compare in geriatric and mature horses the occurrence of short-term complications and short-term outcome associated with complications after colic surgery. STUDY DESIGN: Retrospective case-control study. SAMPLE POPULATION: Horses aged ≥20 years (geriatric, n = 78) and 4-15 years (mature non-geriatric, n = 156) that had exploratory celiotomy for colic and survived recovery from general anesthesia. METHODS: Medical records (2000-2010) of horses that recovered from general anesthesia after colic surgery were reviewed. Postoperative complications evaluated included postoperative reflux (POR), diarrhea, inappetence, fever, leukopenia, incisional infection, incisional dehiscence, thrombophlebitis, colic, repeat celiotomy, pneumonia, and laminitis. Short-term outcome (alive vs. dead at hospital discharge) of geriatric and mature horses with these complications were compared. Data were analyzed using a χ(2) or Fisher's exact test or an ANOVA. Level of significance P < .05. RESULTS: Geriatric horses had higher odds of having a small intestinal strangulating lesion than mature horses. A higher proportion of geriatric horses had POR and inappetence; however, there was no difference in the proportion of geriatric and mature horses with small intestinal strangulating lesions having POR. Short-term outcome with and without complications was similar between the 2 age groups. CONCLUSION: Geriatric and mature horses have similar occurrences of short-term complications and short-term outcomes associated with complications after colic surgery.

Outcome of Surgical and Medical Management of Cecal Impaction in 150 Horses (1991-2011).

OBJECTIVE: To evaluate short- and long-term outcome after medical and surgical management of horses with cecal impaction and to determine reasons for death or euthanasia. STUDY DESIGN: Retrospective case series. ANIMALS: Horses (n = 150). METHODS: Data collected from medical records (1991-2011) of horses with a diagnosis of cecal impaction, included signalment, history of recent disease/surgical procedure, admission data, management (medical, typhlotomy alone, jejunocolostomy), complications, and outcome. Short-term outcome (alive or dead at discharge) and long-term outcome (alive or dead at ≥1 year) were determined by telephone interview. Data were analyzed using a χ(2) or Fisher's exact test. Level of significance was P < .05. RESULTS: Of 150 horses hospitalized with a diagnosis of cecal impaction, 102 (68%) had a history of recent disease or a surgical procedure. Thirty-eight horses (25%) had cecal perforation at admission and 3 horses (2%) were euthanatized without treatment. Of 109 horses treated, 59 (54%) were managed medically and 50 (46%) surgically (typhlotomy [26]; jejunocolostomy [24]). The proportion of horses alive at hospital discharge was significantly lower for horses managed medically (61%) compared with surgically (82%; P = .02) but there was no difference between horses managed with typhlotomy alone (77%) or with jejunocolostomy (88%; P = .47). There were 57% of horses managed medically alive at 1 year. There was a similar proportion of horses alive at 1 year after typhlotomy alone (73%) and jejunocolostomy (70%; P = .86). CONCLUSIONS: Compared to the recent reports, the proportion of horses alive at hospital discharge was lower for both medically and surgically managed horses with cecal impaction. There was decreased survival for horses treated medically than those treated surgically; however, no significant difference was seen in survival between horses managed with typhlotomy alone versus jejunocolostomy.

Current treatment of ascending colon volvulus in horses: a survey of ACVS Diplomates.

OBJECTIVE: To report the results of a survey of opinions on current treatments and estimated outcomes of ascending colon volvulus in horses. STUDY DESIGN: Web-based survey. SAMPLE POPULATION: American College of Veterinary Surgeons (ACVS) Diplomates (n = 151) who perform gastrointestinal surgery in horses. METHODS: ACVS Diplomates with credentials in the large animal specialty obtained by examination in 2010 or earlier (n = 410) were solicited by e-mail to complete a web-based survey designed to determine ascending colon volvulus treatment preferences and outcomes. RESULTS: Responses were obtained from 162 ACVS Diplomates, of which 151 currently performed gastrointestinal surgery in horses. Horses surgically treated with ascending colon volvulus accounted for ≤ 20 cases/year and primary treatment was most often anatomic reduction with or without pelvic flexure enterotomy. Median estimated survival rate was 70% and surgical treatments were not associated with estimated survival (P = .27). Diplomates identified early surgical correction as the single most important factor impacting survival of horses surgically treated for ascending colon volvulus. CONCLUSIONS: Reported survival rates for horses with ascending colon volvulus were good. Respondents indicated this might be due in part to early surgical treatment. Survey investigations can provide preliminary data for future prospective studies and facilitate a consensus among Diplomates in treatment of surgical disease.

End-to-Side Versus Side-to-Side Jejunocecostomy in Horses: A Retrospective Analysis of 150 Cases.

OBJECTIVES: To determine factors associated with postoperative reflux, postoperative colic, repeat celiotomy, and survival in horses after end-to-side (E2S) or side-to-side (S2S) jejunocecostomy. STUDY DESIGN: Retrospective, multicenter study. SAMPLE POPULATION: Horses (n = 150). METHODS: Admissions, intra- and postoperative data were collected from medical records of horses that had E2S or S2S jejunocecostomy. Descriptive statistics were calculated and data were analyzed using parametric and nonparametric tests, linear and multivariate logistic regression with significance set at P < .05. Kaplan-Meier estimate of the survival function was performed. RESULTS: One hundred fifty horses (S2S = 90, E2S = 60) were included. S2S procedures were performed using staples (n = 57) or hand-sewn (33). Method of anastomosis was not significantly associated with development of postoperative reflux or colic, repeat celiotomy, whether the horse was alive at hospital discharge or 12 months after discharge. The number of years that the principal surgeon was boarded by the American College of Veterinary Surgeons significantly affected whether the horse was discharged from the hospital alive (P = .003). Age (P = .006) was significantly associated with 12-month survival. Increased age (P = .013) and administration of prokinetic medication (P = .0006) were significantly associated with development of postoperative reflux. Sixty-eight (76%) horses with S2S and 52 (87%) horses with E2S were discharged alive. CONCLUSION: Age, patient related variables, and surgeon experience may influence morbidity and mortality more than method of jejunocecostomy.

Use of multiple admission variables better predicts intestinal strangulation in horses with colic than peritoneal or the ratio of peritoneal:blood l-lactate concentration.

BACKGROUND: Early identification of strangulating obstruction (SO) in horses with colic improves outcomes, yet early diagnosis of horses requiring surgery for SO often remains challenging. OBJECTIVES: To compare blood and peritoneal fluid l-lactate concentrations, peritoneal:blood l-lactate ratio, peritoneal minus blood (peritoneal-blood) l-lactate concentration and other clinical variables for predicting SO and SO in horses with small intestinal lesions (SO-SI) and then to develop a multivariable model to predict SO and SO-SI. STUDY DESIGN: Retrospective cohort. METHODS: A total of 197 equids admitted to a referral institution for colic between 2016 and 2019 that had peritoneal fluid analysis performed at admission were included. Twenty-three admission variables were evaluated individually for the prediction of a SO or SO-SI and then using multivariable logistic regression. Odds ratios (ORs) with 95% confidence intervals (CI) and area under the curve of the receiver operator characteristic (AUC ROC) were calculated. RESULTS: All variables performed better in the model than individually. The final multivariable model for predicting SO included marked abdominal pain (OR 5.31, CI 1.40-20.18), rectal temperature (OR 0.30, CI 0.14-0.64), serosanguineous peritoneal fluid (OR 35.34, CI 10.10-122.94), peritoneal-blood l-lactate (OR 1.77, CI 1.25-2.51), and peritoneal:blood l-lactate ratio (OR 0.36, CI 0.18-0.72). The AUC ROC was 0.91. The final multivariable model for predicting SO-SI included reflux volume (OR 0.69, CI 0.56-0.86), blood l-lactate concentration (OR 0.43, CI 0.22-0.87), serosanguineous peritoneal fluid (OR 4.99, CI 1.26-19.74), and peritoneal l-lactate concentration (OR 3.77, CI 1.82-7.81). MAIN LIMITATIONS: Retrospective, single-hospital study design. CONCLUSIONS: Blood and peritoneal fluid l-lactate concentrations should be interpreted in conjunction with other clinical variables. The relationship between peritoneal and blood l-lactate concentration for predicting SO or SO-SI was complex when included in a multivariable model. Models to predict SO probably vary based on lesion location.

Effect of intraperitoneal PERIDAN™ concentrate adhesion reduction device on clinical findings, infection, and tissue healing in an adult horse jejunojejunostomy model.

OBJECTIVE: To evaluate the effect of PERIDAN™ Concentrate on clinical findings, infection, and tissue healing in adult horses undergoing celiotomy and jejunojejunostomy. STUDY DESIGN: Block randomized blinded experimental in vivo study. ANIMALS: Adult horses (n = 12). METHODS: Horses had jejunojejunostomy at 2 sites and were administered 5 L of diluted PERIDAN™ Concentrate (6 horses) or Lactated Ringer's Injection (LRS) control intraperitoneally (6 horses) before body wall closure. Postoperative monitoring comprised physical examinations, serial hematology, coagulation and chemistry panels, and ultrasonographic examination. Horses were euthanatized 10 days postoperatively. Anastomoses and linea alba incisions were tested for mechanical strength; and tissue healing, inflammation, and infection were assessed by histological evaluation. Data were analyzed using a mixed model ANOVA. Level of significance was P < .05. RESULTS: No physical examination differences were observed between groups. Statistically significant differences were observed in leukocyte and neutrophil counts, prothrombin time, antithrombin III activity, intestinal bursting pressures, and histologic healing grade in the mid region of the linea alba. These differences were minimal, and of no observable clinical significance. Other blood variable and histologic differences between groups were not significant. CONCLUSIONS: PERIDAN™ Concentrate was safely administered intraperitoneally to healthy horses undergoing celiotomy and anastomosis.

Evaluation of direct in vivo gene transfer in an equine metacarpal IV ostectomy model using an adenoviral vector encoding the bone morphogenetic protein-2 and protein-7 gene.

OBJECTIVE: To evaluate gene transfer in an equine metacarpal IV (MCIV) ostectomy model using adenoviral vectors encoding the human bone morphogenetic protein-2 and protein-7 gene (Ad-BMP-2/-7). EXPERIMENTAL ANIMALS: Healthy adult horses (n = 15). METHODS: A plate stabilized, critical size 1.5 cm ostectomy was created in left and right MCIV. The ostectomy site was injected with either Ad-green fluorescent protein (Ad-GFP) or Ad-hBMP-2/-7 at completion of surgery; the same treatment was assigned to both the left and right forelimb of each horse (n = 5 horses/group). Bone healing was evaluated radiographically every 2 weeks for 16 weeks. Horses in a pilot study (n = 5) were used as untreated controls for radiographic evaluation to 8 weeks. After euthanasia at 16 weeks bone healing was evaluated using dual energy X-ray absorptiometry (DEXA) and histomorphometry. Data were analyzed using an ANOVA or Kruskal-Wallis test. Level of significance was P < .05. RESULTS: At 4 and 6 weeks, the Ad-GFP group had a significantly lower percentage defect ossification compared with the untreated control group. There was no significant difference between untreated and Ad-hBMP-2/-7 groups at any time point and no significant difference in bone healing radiographically, histologically, or using DEXA between any groups at 16 weeks. CONCLUSIONS: Ad-hBMP-2/-7 did not improve bone healing in horses at 16 weeks.

Changes in the faecal bacterial microbiota during hospitalisation of horses with colic and the effect of different causes of colic.

BACKGROUND: Previous studies have identified alterations in the faecal microbiota of horses with colic; however, further work is needed to interpret these findings. OBJECTIVES: To compare the faecal microbiota of horses presenting for colic at hospital admission, day 1 and day 3/discharge and with different colic duration and lesion locations. STUDY DESIGN: Prospective observational clinical study. METHODS: Faecal samples were collected from 17 colic cases at hospital admission, on day 1 and on day 3 post-admission or at the time of hospital discharge if prior to 72 hours. Faecal samples were extracted for genomic DNA, PCR-amplified, sequenced and analysed using QIIME. Species richness and Shannon diversity (alpha diversity) were estimated. The extent of the relationship between bacterial communities (beta diversity) was quantified using pairwise UniFrac distances, visualised using principal coordinate analysis (PCoA) and statistically analysed using permutational multivariate analysis of variance (PERMANOVA). The relative abundance of bacterial populations at the different time points and in different types of colic was compared using ANCOM. RESULTS: There was a decrease in species richness from admission to day 3/hospital discharge (P < .05), and a lower species richness (P = .005) and Shannon diversity (P = .02) in horses with colic ≥60 h compared to <60 h. Based on PCoA and PERMANOVA, there was a significant difference in bacterial community composition for horses with different colic duration (P = .001) and lesion location (P = .006). Several differences in bacterial phyla and genera were observed at different time points and with different types of colic. MAIN LIMITATIONS: Relatively low numbers and a diverse population of horses. CONCLUSIONS: The microbiota change from hospital admission to day 3/discharge in horses with colic and horses with colic ≥60 h and large colon lesions have a distinct bacterial population compared to horses with colic <60 h and small intestinal lesions.

Acute abdominal dehiscence following laparotomy: A multicentre, international retrospective study.

BACKGROUND: Incisional complications are a common cause of morbidity following laparotomy. Although uncommon, acute abdominal dehiscence (AAD) is a potentially fatal post-operative complication. However, few AAD cases are described in the literature. OBJECTIVES: To describe common features of cases of AAD following ventral midline laparotomy, management and outcomes. STUDY DESIGN: Retrospective case series. METHODS: Hospital records of horses that underwent a ventral midline laparotomy at nine hospitals in the UK, Ireland and USA over a 10-year period (2009-2019) were reviewed. Data were collected for pre-, intra- and post-operative factors that were considered relevant. Descriptive statistical analysis was performed. RESULTS: A total of 63 cases of AAD were identified. AAD occurred due to tearing of sutures through the linea alba or rupture of the body wall adjacent to the suture line in 46 horses (73%). AAD occurred at a median of 5 days (0.5-70 days) post-operatively and broodmares accounted for 25% of the cases (n = 16). Surgical site infection developed prior to AAD in 28 horses (44%); leakage of peritoneal fluid occurred in 5% of horses prior to AAD being identified. Surgical repair was performed in 27 horses (43%), 10 (16%) were treated conservatively and 26 (41%) were euthanised immediately. Repair was most frequently performed using suture (n = 14), wire (n = 5) or a combination (n = 5). Overall survival to hospital discharge was 39% (24/63). Where surgical repair was performed, 15 horses (56%) survived to hospital discharge; 9 horses (90%) managed conservatively survived to hospital discharge. MAIN LIMITATIONS: Follow-up was not performed for all cases following hospital discharge and some data were incompletely recorded in hospital files. CONCLUSIONS: Previously stated causative factors for AAD were not consistent features in the present study. Surgical site infection following laparotomy and pregnant or early post-partum mares may be important risk factors for AAD and warrant further investigation.

Acquired jejunal pseudodiverticula in a yearling Arabian filly.

OBJECTIVE: To report a case of multiple acquired jejunal pseudodiverticula managed successfully by resection and jejunojejunostomy. STUDY DESIGN: Clinical report. ANIMALS: Arabian filly. METHODS: The filly was referred for signs of acute colic of several hours duration and had a 2-week history of inappetence and weight loss. Three meters of thickened, edematous, and dilated jejunum removed during exploratory celiotomy had an intussusception and numerous diverticula; jejunojejunostomy performed. The pathoanatomic diagnosis was proliferative enteropathy with pseudodiverticula formation and jejunal muscular hypertrophy and diverticulosis. The diverticula appeared to be acquired; however, the exact cause was not determined. RESULTS: There were no postoperative gastrointestinal complications and 1 year later, the filly was doing well. CONCLUSION: Multiple acquired jejunal pseudodiverticula not associated with classic muscular hypertrophy can occur in young horses. Long-term prognosis seemingly can be excellent after resection and jejunojejunostomy. CLINICAL RELEVANCE: Compared with other reports of small intestinal diverticula in horses, this case is unique because it was not congenital or associated with classic muscular hypertrophy.

In vitro comparison of a novel external fixator and traditional full-limb transfixation pin cast in horses.

OBJECTIVE: To compare the mechanical properties and failure modes of a standardized short oblique distal radial metaphyseal osteotomy stabilized using either a transfixation pin cast (TPC), a modular-sidebar external skeletal fixator (ESF), or a solid-sidebar ESF (modular- or solid-ESF, respectively) using static or cyclic axial loading to failure. STUDY DESIGN: In vitro study. ANIMALS: Equine cadaver forelimbs. METHODS: A 30 degrees oblique distal radial osteotomy was created and stabilized using 1 of the 3 fixation methods: (1) TPC, (2) modular-ESF, or (3) solid-ESF. Limbs were tested using static (TPC, modular-ESF, and solid-ESF) or cyclic (TPC and solid-ESF) axial loading to failure. The stiffness, yield load, yield displacement, failure load, and failure displacement for static loading and the cycles to failure for cyclic loading at 75% failure load were obtained. Data were analyzed using a Kruskal-Wallis test. Level of significance was P<.05. RESULTS: The solid-ESF had a greater stiffness, higher yield and failure load and a lower yield and failure displacement than the TPC (P=.01) and the modular-ESF (P=.02). TPC had a higher yield load, failure load, and yield displacement than the modular-ESF (P=.01). Mean cycles to failure for TPC was 2996+/-657 at a load of 16,000 N and for solid-ESF 6560+/-90 cycles at a load of 25,000 N. CONCLUSIONS: The solid-ESF was stiffer and stronger than the TPC and modular-ESF and failed at a greater number of cycles in axial loading compared with the TPC. CLINICAL RELEVANCE: This study is an initial step in evaluating the solid-ESF. Further testing needs to be performed, but this fixation may offer a viable alternative to the traditional TPC for stabilization of long bone fractures in adult horses.

Right dorsal colon resection and bypass for treatment of right dorsal colitis in a horse.

OBJECTIVE: To describe a novel surgical technique for management of right dorsal colitis in the horse. STUDY DESIGN: Clinical report. ANIMALS: 14-year-old Warmblood gelding. METHODS: The horse was referred for treatment of a stromal abscess and signs of right dorsal colitis. Plasma chemistry revealed marked hypoproteinemia. Abdominal ultrasonographic examination showed a thickened right dorsal colon (RDC). Medical treatment was unsuccessful. With the horse in left lateral recumbency under general anesthesia, an approach to the right side of the abdomen through a 16th rib resection was made. The thoracic cavity was entered during the approach. Surgical resection of the RDC and side-to-side anastomosis of the diaphragmatic flexure to the small colon (bypass) was performed. The thoracic cavity was closed by attaching the diaphragm to the body wall and air was removed at the completion of surgery. RESULTS: Resection of the RDC and bypass of the resected area was successfully performed. The colic signs and hypoproteinemia resolved. Complications of surgery included a deep surgical site infection with development of a large intrathoracic abscess. The abscess was managed with drainage and long-term antimicrobial treatment. CONCLUSION: Right dorsal colitis can be treated successfully with resection and bypass of the RDC. In cases where the thoracic cavity is penetrated during the abdominal approach, the diaphragm should be sutured to the body wall at the beginning of surgery to avoid development of an infection within the thoracic cavity. CLINICAL RELEVANCE: RDC resection and bypass may be an alternative approach for management of horses with right dorsal colitis.