Eileen S. Hackett

Comparison of Achilles Tendon Repair Techniques in a Sheep Model Using a Cross-linked Acellular Porcine Dermal Patch and Platelet-rich Plasma Fibrin Matrix for Augmentation

The primary goal of this study was to evaluate a cross-linked acellular porcine dermal patch (APD), as well as platelet-rich plasma fibrin matrix (PRPFM), for repair of acute Achilles tendon rupture in a sheep model. The 2 surgically transected tendon ends were reapproximated in groups 1 and 2, whereas a gap was left between the tendon ends in group 3. APD was used to reinforce the repair in group 2, and autologous PRPFM was used to fill the gap, which was also reinforced with APD, in group 3. All sheep were humanely euthanized at 24 weeks after the repair, and biomechanical and histological testing were performed. Tensile strength testing showed a statistically significant difference in elongation between the operated limb and the unoperated contralateral limb in groups 1 and 3, but not in group 2. All operated tendons appeared healed with no apparent fibrosis under light and polarized microscopy. In group 1, all surgical separation sites were identifiable, and healing occurred via increasing tendon thickness. In group 2, healing occurred with new tendon fibers across the separation, without increasing tendon thickness in 2 out of 6 animals. Group 3 showed complete bridging of the gap, with no change in tendon thickness in 2 out of 6 animals. In groups 2 and 3, peripheral integration of the APD to tendon fibers was observed. These findings support the use of APD, alone or with PRPFM, to augment Achilles tendon repair in a sheep model.

A technique for central venous pressure measurement in normal horses

OBJECTIVE To investigate a technique of central venous pressure (CVP) measurement using a newly developed catheter in healthy adult horses. DESIGN Prospective experimental study. SETTING University research facility. ANIMALS Twenty healthy adult horses. INTERVENTIONS An equine central venous catheter was inserted into the jugular vein to a length of approximately 80 cm from the mid-cervical region in an attempt to catheterize the pulmonary artery. Pulmonary arterial catheterization was confirmed by echocardiography. Insertion distance and pressure were measured at this location with a disposable manometer. The catheter was then withdrawn until presence in the right atrium was confirmed by echocardiography. Insertion distance and pressure were also measured at this location. The catheter was then withdrawn in 5 cm increments until exiting the jugular insertion site with pressure measured at each location. All pressure measurements were taken with the manometer zero position at the point of the shoulder. MEASUREMENTS AND MAIN RESULTS Pulmonary artery catheterization was successful in 16 of 20 horses. Mean pulmonary arterial pressure was 23.8 cm H2O (17.5 mm Hg) (95% confidence interval [CI] 20.9-26.7 cm H2O [15.4-19.6 mm Hg]). Mean right atrial pressure was 8.3 cm H2O (6.1 mm Hg) (95% CI 7.1-9.4 cm H2O [5.2-6.9 mm Hg]). Right atrial pressure was compared with pressures recorded at sequential insertion distances and resulted in a recommendation for catheter insertion of at least 40 cm for CVP measurement in adult horses. Jugular venous pressure measurement was statistically different from CVP measurement. CONCLUSIONS This catheter measurement technique is well tolerated in normal horses. Routine clinical use of this equine central venous catheter may improve our ability to monitor patients and improve patient care and outcomes of ill horses in hospital.

Alimentary-associated carcinomas in five Vietnamese potbellied pigs

CASE DESCRIPTION 5 Vietnamese potbellied pigs were evaluated for abdominal distress that had not responded to medical treatment (4 pigs) or a draining tract of the cranial abdomen of unknown duration (1 pig). CLINICAL FINDINGS Clinical signs in the pigs included anorexia, vomiting, and constipation. Physical examination revealed a palpable abdominal mass in all pigs. Radiography revealed distended loops of small intestine in 2 pigs. TREATMENT AND OUTCOME 3 pigs were treated successfully with wide-margin excision of the abdominal masses, and 2 were euthanized. Primary tumors were diagnosed at necropsy or through histologic evaluation of biopsy specimens obtained during surgery. Types of tumor included cholangiocellular carcinoma, transmural gastric carcinoma, small intestinal adenocarcinoma, metastatic hepatocellular carcinoma, and carcinoma. The tumors involved the stomach, small intestine, spiral colon, liver, and gall bladder. All 3 surgically treated pigs survived at least 9 months after surgery. CLINICAL RELEVANCE Although rare, neoplasia of the alimentary system should be considered among the differential diagnoses for potbellied pigs with signs of abdominal distress. Wide-margin excision of the neoplastic tissue may result in a good outcome in affected pigs.

Colic: nonsurgical complications.

Colic is a serious disease of the horse and may require surgical correction. Postoperative complications may result in an increase in short-term morbidity and mortality. Commonly encountered nonsurgical complications are detailed. Anticipation and timely treatment of common postoperative complications after colic surgery may improve overall survival.

Pulmonary Gas Exchange and Plasma Lactate in Horses with Gastrointestinal Disease Undergoing Emergency Exploratory Laparotomy: A Comparison with an Elective Surgery Horse Population

OBJECTIVE To characterize pulmonary gas exchange and arterial lactate in horses with gastrointestinal disease undergoing anesthesia, compared with elective surgical horses, and to correlate these variables with postoperative complications and mortality. STUDY DESIGN Prospective clinical study. ANIMALS Horses undergoing emergency laparotomy for acute intestinal disease (n = 50) and healthy horses undergoing elective surgery in dorsal recumbency (n = 20). METHODS Arterial blood gas analysis was performed at predetermined intervals on horses undergoing a standardized anesthetic protocol. Alveolar-arterial oxygen gradient was calculated. Predictive factors for postoperative complications and death in colic horses were determined. RESULTS Arterial oxygen tension (P(a) O(2)) varied widely among horses in both groups. P(a) O(2) significantly increased in the colic group after exteriorization of the ascending colon. P(a) O(2) and alveolar-arterial oxygen gradient were not significantly different between groups, and neither were correlated with horse outcome. Arterial lactate in recovery ≥ 5 mmol/L was associated with a 2.25 times greater relative risk of complications and lactate ≥ 7 mmol/L was associated with a 10.5 times higher relative risk of death. CONCLUSION Colic horses in this population were not more likely to be hypoxemic than elective horses, nor was gas exchange impaired to a greater degree in colic horses relative to controls. Arterial lactate sampled immediately after anesthetic recovery was predictive for postoperative complications and death.

The effect of colloid formulation on colloid osmotic pressure in horses with naturally occurring gastrointestinal disease.

BackgroundNaturally occurring gastrointestinal disease is an important cause of acute hypoproteinemia in adult horses and hydroxyethyl starch colloid fluid treatment is a component of supportive care in these cases to improve plasma volume and maintain colloid osmotic pressure (COP). The objectives of the present study were to compare 2 formulations of high molecular weight hydroxyethyl starch and their relative effect on COP, acid-base status, and survival of horses with acute hypoproteinemia secondary to gastrointestinal disease.MethodsTwenty adult horses, ≥ 1 year of age, were prospectively enrolled, with informed client consent, if they developed acute hypoproteinemia, defined as a plasma total protein <5.0 g/dL or albumin <2.2 g/dL during hospitalization while undergoing treatment for gastrointestinal disease. Horses were randomly assigned to receive a rapid infusion of either 6% hydroxyethyl starch in 0.9% saline or 6% hydroxyethyl starch in lactated ringers solution at a dose of 10ml/kg. Venous blood gas analysis, COP, and PCV were evaluated before and after colloid administration.ResultsFor both groups, average COP prior to treatment was 11.0 mmHg (9.7 – 12.2 mmHg) and post colloid treatment was 13.2 mmHg (12.0 -14.7 mmHg) [Normal range 18 – 22 mmHg]. COP was significantly increased with colloid treatment (p<0.001) but this increase was not significantly different between treatment groups. Venous pH did not change significantly with treatment. Twelve horses survived to hospital discharge and survival did not differ significantly between treatment groups.ConclusionsPost-treatment COP improved approximately 20% regardless of the formulation used, however, values did not reach the normal range of COP observed in healthy horses. Acid-base parameters were not significantly impacted by either treatment. Further study is needed to determine how these two products compare with regards to other outcome measures. Evaluation of the relative effects of colloid formulation in horses with clinical disease is a future area of interest.

Pharmacokinetics and safety of silibinin in horses

OBJECTIVE To determine the oral bioavailability, single and multidose pharmacokinetics, and safety of silibinin, a milk thistle derivative, in healthy horses. ANIMALS 9 healthy horses. PROCEDURES Horses were initially administered silibinin IV and silibinin phospholipid orally in feed and via nasogastric tube. Five horses then consumed increasing orally administered doses of silibinin phospholipid during 4 nonconsecutive weeks (0 mg/kg, 6.5 mg/kg, 13 mg/kg, and 26 mg/kg of body weight, twice daily for 7 days each week). RESULTS Bioavailability of orally administered silibinin phospholipid was 0.6% PO in feed and 2.9% via nasogastric tube. During the multidose phase, silibinin had nonlinear pharmacokinetics. Despite this, silibinin did not accumulate when given twice daily for 7 days at the evaluated doses. Dose-limiting toxicosis was not observed. CONCLUSIONS AND CLINICAL RELEVANCE Silibinin phospholipid was safe, although poorly bio-available, in horses. Further study is indicated in horses with hepatic disease.

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.

Evaluation of plasma muscle enzyme activity as an indicator of lesion characteristics and prognosis in horses undergoing celiotomy for acute gastrointestinal pain

BackgroundIn horses undergoing celiotomy for acute gastrointestinal pain, identification of variables correlating with lesion severity and location, and survival provide veterinarians and owners with information that aids in making informed decisions regarding appropriate treatment. Muscle enzyme activity is often increased in horses undergoing celiotomy for acute gastrointestinal pain and it is not known if muscle enzyme activity increase is specific to lesion type or impacts prognosis for survival. The objective of this study was to evaluate the relationship of pre-operative increase in muscle enzyme activities with intestinal lesion characteristics, specifically lesion location (large versus small intestine) and whether it was strangulating versus nonstrangulating, and case survival in horses undergoing celiotomy for acute gastrointestinal pain.MethodsRecords of 241 horses undergoing exploratory laparotomy for colic were reviewed retrospectively. Evaluation of preoperative plasma aspartate aminotransferase (AST), creatine kinase (CK), sorbitol dehydrogenase (SDH), and gamma-glutamyltransferase (GGT) activities, fibrinogen and glucose concentrations, and hematocrit (HCT) and their association with gastrointestinal lesion characteristics and survival was performed.ResultsPre-operative increase in plasma CK and AST activity, and HCT and decrease in plasma bilirubin concentration were significantly associated with presence of lesions resulting in intestinal ischemia. Increase in plasma CK activity and HCT were significantly associated with a decreased probability of survival to hospital discharge. Plasma GGT and SDH activity, and glucose and fibrinogen concentration were not significantly associated with survival or severity of disease in multivariate analysis.ConclusionsPlasma muscle enyzme activity may be useful as a prognostic indicator in equine colic cases. Given that increases in plasma CK and AST activity were significantly associated with nonsurvival and the presence of intestinal ischemia, preoperative increase in these enzyme activities could assist in identification of disease severity and prognosis of horses undergoing celiotomy for acute gastrointestinal pain. Further study is indicated to elucidate the etiology of increased muscle enzyme activity in horses with surgical colic disease observed in this preliminary study.

Laparoscopic Closure of the Nephrosplenic Space in Horses with Nephrosplenic Colonic Entrapment: Factors Associated with Survival and Colic Recurrence

OBJECTIVES 1) To identify factors associated with short-term survival and time to death after hospital discharge in horses with nephrosplenic entrapment (NSE). 2) To compare the frequency of recurrent colic episodes in horses with and without laparoscopic closure of the nephrosplenic space. STUDY DESIGN Historical cohort with a nested case control. ANIMALS Client-owned horses. METHODS Medical records of horses treated for NSE from January 1, 2002 to June 1, 2014 were reviewed. Data collected included signalment, physical examination parameters, laboratory results, diagnostic findings, and treatments. Factors associated with short-term survival to discharge were analyzed with a multivariable logistic regression model and time to death after hospital discharge was analyzed with a Cox proportional hazards model. RESULTS During the study period, 211 horses had 231 NSE events and 192/211 (91%) horses survived to discharge. A positive difference in packed cell volume (PCV at admission - PCV after treatment) was associated with reduced odds of nonsurvival with each increment (OR: 0.899, 95% CI 0.816-0.991, P=.03) while the presence of concurrent alimentary lesions (OR: 8.47, 95% CI 1.42-50.4, P=.02) were significantly associated with increased odds of nonsurvival in the short term. Of 156 horses that survived to discharge for which follow-up was available, 152 (97%) were alive for ≥1 year. Increasing age (incremental years) at hospital admission was significantly associated with death after discharge (hazard ratio 1.078, 95% CI 1.002-1.16, P=.049). Recurrence of NSE was documented in 49/211 (23%) horses. The overall change in colic score indicated a reduction in colic in horses following laparoscopic closure of the nephrosplenic space compared with horses that did not have closure of the nephrosplenic space (P<0.001). CONCLUSION An increase in PCV from admission to after treatment and concurrent abdominal lesions were associated with increased odds of nonsurvival to discharge in horses with NSE. Horses that underwent laparoscopic closure had reduced colic episodes compared with horses without laparoscopic closure.