Successful surgical removal of a pheochromocytoma in a mare via trans-costal approach.

BACKGROUND: Pheochromocytomas have been previously reported in horses, but successful antemortem diagnosis and surgical removal without recurrence of clinical signs have not been described. OBJECTIVE: To report the clinical presentation, diagnostic evaluation, surgical technique, anaesthetic management and post-operative care of a mare diagnosed with pheochromocytoma. STUDY DESIGN: Clinical case report. METHODS: An 18-year-old Quarter Horse mare presented for recurrent episodes of colic, profuse sweating, muscle fasciculations and agitation over a 2-month period. Clinical, clinicopathologic and ultrasonographic (transcutaneous, transrectal) abnormalities were consistent with a unilateral left-sided adrenal mass. Surgical removal of the mass was performed via a trans-costal approach with removal of the 18th rib and retraction of the left kidney to improve exposure. Associated vasculature was ligated, and the adrenal mass was removed and submitted for histopathology and immunohistochemistry. RESULTS: A trans-costal surgical approach provided excellent visualisation of the adrenal mass and allowed for identification and ligation of associated vessels. Total surgical and anaesthesia time were 86 and 114 min, respectively. Several intraoperative (hypertension, tachycardia) and post-operative (colic with tachycardia, tachypnea, large colon pelvic flexure impaction and nasogastric reflux) complications were encountered and managed successfully. Immunohistochemistry demonstrated positive labelling for synaptophysin and chromogranin A, confirming diagnosis of pheochromocytoma. The mare had recovered well at 6-week recheck post-operatively and returned to training at 6 months post-operatively. No further clinical signs consistent with pheochromocytoma have been observed following removal. CONCLUSIONS: The trans-costal approach allowed for surgical removal of a pheochromocytoma in a mare. Surgical removal of adrenal masses in horses may be associated with complications yet was successfully performed without subsequent recurrence of clinical signs associated with tumour presence and return to athletic use in this mare.

Transcutaneous Detection of Intramural Microchips for Tracking the Migration of the Equine Large Colon: A Pilot Study.

Colic remains the number one cause of mortality in horses, and large colon displacement including colonic volvulus is one of the leading causes for equine hospitalization and surgery. Currently, there is not an adequate model to study the pathophysiology of this condition. The objective of this proof-of-concept study was to determine if subserosal implantation of bioinert microchips in the large intestine would be detectable by a RFID (radio-frequency identification) receiver when the implanted microchips were adjacent to the body wall, thus identifying the location of the colon within the abdomen. A horse with no history of gastrointestinal disease underwent a ventral midline celiotomy to implant twelve bioinert microchips into the subserosa at predetermined locations within the large colon and cecum. A RFID scanner was used to monitor the location of the colon via transcutaneous identification 1-3 times daily for a one-month period. Following humane euthanasia, a postmortem examination of the horse was performed to assess microchip implantation sites for migration and histologic assessment. Eleven out of the 12 implanted microchips were successfully identified transcutaneously at occurrences as high as 100%. Odds ratios were calculated for the likelihood of identifying each chip in a location different from its most common location. Microchips implanted into the subserosa of the equine large colon can be used as a means of identifying the approximate location of the equine large colon via transcutaneous identification with an RFID scanner.

Multi-Institutional Retrospective Case-Control Study Evaluating Clinical Outcomes of Foals with Small Intestinal Strangulating Obstruction: 2000-2020.

Lower survival has been reported in foals than adults with small intestinal strangulating obstruction (SISO), but age-dependent outcomes have not been examined directly. Hospital records were collected from five US academic referral hospitals. It was hypothesized that foals would exhibit lower survival than case-matched adults. Foal cases 6-months-of-age or younger, and adult cases between 2- and 20-years-of-age were collected. Data revealed 24 of 25 (96.0%) foals and 66 of 75 (88.0%) adults that were recovered from surgery for SISO survived to hospital discharge. Sixteen of the total 41 (39.0%) foals studied were euthanized intraoperatively, whereas 30 of 105 (28.6%) adults were euthanized intraoperatively. Common lesions in foals that were recovered from surgery were volvulus (n = 13) and intussusception (n = 5), whereas common lesions in adults were volvulus (n = 25) and strangulating lipoma (n = 23). This study was limited by incomplete medical records, relatively small sample size, and lack of long-term follow-up. Unexpectedly, short-term survival tended to be higher in foals than adults and may have been partly driven by case selection prior to referral or surgery or decision-making intraoperatively. More optimism toward surgical treatment of foals with SISO may be warranted.

Combined tube cystostomy and urethrotomy for the treatment of urethral obstruction due to urolithiasis in goats.

OBJECTIVE: To describe the treatment of goats with urethral obstruction secondary to urolithiasis by combining tube cystostomy and urethrotomy. ANIMALS: Eight male goats. STUDY DESIGN: Short case series. METHODS: Medical records (September 2012-September 2017) of male goats treated for obstruction secondary to urolithiasis with tube cystostomy and urethrotomy were reviewed. Data collected included signalment, history, physical examination findings, diagnostic results, perioperative treatments, operative details, hospitalization duration, intraoperative and postoperative complications, urolith analysis, and time to restoration of urethral patency. Long-term follow-up (>12 months) was obtained by email or telephone interviews of owners or by clinical examination. RESULTS: Seven of eight goats were castrated males of various of breeds. All goats were tachycardic with urethral pulsation at admission. Uroliths were composed of calcium carbonate in four goats and silica in one goat. All goats regained urethral patency during hospitalization, and all were discharged alive from the hospital. Seven goats were alive at long-term follow-up. Postoperative complications included persistent urethral obstruction requiring a second urethrotomy 2 days postoperatively, premature dislodgement of the bladder catheter and jejunal obstruction secondary to adhesions, and recurrence of obstructive urolithiasis within the proximal perineal urethra requiring a second surgery 8 months later (1 each). Long-term outcome was good, with urethral patency beyond 12 months in six of eight goats. CONCLUSION: Combining tube cystostomy and urethrotomy restored urethral patency in goats with urethral obstruction from uroliths. Although none of the complications seemed directly related to the urethrotomy, formation of abdominal adhesions and recurrence of urolithiasis affected long-term outcomes. CLINICAL SIGNIFICANCE: Uroliths that do not dissolve in acidic urine may be more frequent in some practices. The combined approach of tube cystostomy and urethrotomy appears to successfully restore urethral patency with promising long-term outcomes.

Retrospective evaluation of the effect of intravenous fluid administration on development of postoperative reflux in horses with colic (2004-2012): 194 horses.

OBJECTIVE: To evaluate the role of intravenous fluid volume and electrolyte supplementation on the development of postoperative reflux (POR) in horses undergoing celiotomy for colic. DESIGN: Case-control study spanning 2004-2012 for horses undergoing celiotomy for colic. SETTING: University teaching hospital. ANIMALS: Sixty-seven client-owned horses >1 year of age with POR were each matched to 2 controls with similar surgical lesions that did not demonstrate POR. MEASUREMENTS AND MAIN RESULTS: Survival was significantly lower in cases (65.7%) than controls (96.1%). Factors found to be associated with POR included decreased net fluid volume administered on day 1 postoperatively, increased age, and performing a resection and anastomosis. Mean time until onset of POR was 20.4 hours postoperatively. PCV was significantly higher immediately following surgery and at 24 hours postoperatively in horses that developed POR compared with matched controls. There was no association between electrolyte values at presentation or administration of potassium, calcium, or magnesium in the postoperative period and the subsequent development of reflux. CONCLUSIONS: In the perioperative period, IV fluid volume overload and electrolyte abnormalities were not contributing factors in the development of POR in this population of surgical colic patients. Close postoperative monitoring with consideration and correction of pre- and postoperative fluid deficits is recommended.

Reactive mesothelial hyperplasia associated with chronic peritonitis in a 20-year-old Quarter horse.

A 20-year-old gelding was diagnosed with peritonitis and severe reactive mesothelial hyperplasia. Exploratory laparotomy findings were suggestive of a neoplastic etiology; however, additional diagnostics ruled this out and the horse made a full recovery. This report demonstrates the difficulty and value of differentiating between reactive and neoplastic mesothelial processes.

Hyperplasie mésothéliale réactive associée à une péritonite aiguë chez un cheval Quarter horse âgé de 20 ans. Une péritonite et l'hyperplasie mésothéliale réactive grave ont été diagnostiquées chez un hongre âgé de 20 ans. Les résultats d'une laparatomie exploratoire ont suggéré une étiologie néoplasique. Cependant, des diagnostics additionnels ont éliminé cette possibilité et le cheval s'est complètement rétabli. Ce rapport démontre la difficulté et la pertinence de différencier entre les processus mésothéliaux réactif et néoplasique.(Traduit par Isabelle Vallières).

Concentrations of serum amyloid A and plasma fibrinogen in horses undergoing emergency abdominal surgery.

OBJECTIVE: To compare the perioperative response of serum amyloid A (SAA) to fibrinogen in horses requiring exploratory celiotomy for colic and to determine if SAA could be used to predict complications and outcome. DESIGN: Prospective observational clinical study. SETTING: University teaching hospital. ANIMALS: Eighteen horses undergoing exploratory celiotomy for colic. Inclusion criteria for the study included survival and anesthetic recovery from exploratory celiotomy, no history of surgery within the past year. INTERVENTIONS: Blood was obtained via jugular venipuncture before surgery (time 0) and at 24, 48, 72, and 96 hours after recovery from anesthesia. MEASUREMENTS AND MAIN RESULTS: Quantitative and semiquantitative fibrinogen, SAA, total nucleated cell counts, and total protein were evaluated at each time point. Multivariable linear regression was used to assess differences at each time point and after grouping horses according to duration of colic prior to surgery, strangulating surgical lesion or not, presence of systemic inflammatory response syndrome (SIRS) on admission, and postsurgical complications. Significant (P < 0.05) increases in SAA concentrations occurred in all cases after surgery compared to fibrinogen concentration, which only demonstrated a mild, clinically insignificant increase postsurgery. SAA concentrations were also significantly increased (P < 0.05) in cases identified with SIRS prior to surgery and postoperatively at 48 (P = 0.05) and 72 hours (P = 0.02) in horses that developed complications. CONCLUSIONS: Measurement of SAA is a more sensitive indicator of inflammation than fibrinogen in the perioperative period of horses requiring exploratory celiotomy for colic. Serial measurement of SAA at 48, 72, and 96 hours after surgery may be helpful to determine risk of complications and guide postoperative management. Measurement of SAA on admission also allows for quantification of SIRS when it is detected clinically.

In vitro comparison of V-Loc™ versus Biosyn™ in a one-layer end-to-end anastomosis of equine jejunum.

OBJECTIVE: To compare a unidirectional barbed suture (V-Loc™) to its suture material equivalent (Biosyn™) in a single-layer end-to-end anastomosis of equine jejunum. STUDY DESIGN: Experimental in vitro study. ANIMALS: Jejunal sections from adult horses (n = 5) without gastrointestinal disease. METHODS: Jejunal end-to-end anastomoses (n = 9) were performed for each group (V-Loc™, Biosyn™) with a continuous Lembert pattern with an interruption every 120°. Anastomosis construction time, luminal diameter, and number of suture bites were recorded. Anastomosis constructs were distended with fluid at 1 L/min until failure. Location and intraluminal pressure at failure were recorded and all measurements were compared between groups. RESULTS: V-Loc™ anastomoses were significantly faster to perform (13.1 ± 0.35 minutes) when compared to the Biosyn™ group (15.6 ± 0.72 minutes; P = .0004). No differences were observed for anastomotic index or number of suture bites. V-Loc™ anastomosis constructs had a significantly decreased bursting pressure (160 ± 11.6 mmHg) compared to Biosyn™ constructs (184 ± 16.9 mmHg; P = .01). CONCLUSIONS: V-Loc™ allowed faster construction time and did not cause a decreased anastomosis luminal diameter when compared with Biosyn™. V-Loc™ had a decreased bursting strength compared with Biosyn™, albeit well above pathologic pressures encountered clinically. Use of V-Loc™ may be beneficial for decreasing the amount of exposed suture material because of the absence of knots after construction and has the potential to result in decreased adhesions.

Measurement of urinary F2-isoprostanes as markers of in vivo lipid peroxidation: a comparison of enzyme immunoassays with gas chromatography-mass spectrometry in domestic animal species.

F(2)-isoprostanes are useful markers for assessing oxidant injury; however, the validity of measuring urinary 15-F(2t)-isoprostane concentration by enzyme-linked immunosorbent assay (ELISA) has not been evaluated in veterinary species. The current study assesses the agreement between 2 commercially available urinary isoprostane kits and gas chromatography and negative ion chemical ionization-mass spectrometry (GC/NICI-MS). The results indicate that only feline urinary isoprostane measurement by glucuronidase (GL)-ELISA has acceptable agreement with GC/NICI-MS. Urinary isoprostane concentration was highly variable in critically ill animals, but there were too many variations between healthy and critically ill animals to draw meaningful conclusions. Currently, GC/NICI-MS is the only method that can be recommended for the assessment of urinary isoprostanes in dogs, cattle, and horses. Feline urinary isoprostanes can be assessed by GL-ELISA, but caution is still warranted when comparing data from manuscripts using different methods given the relatively low Spearman rank correlation coefficient. Future studies may require large sample sizes or focused inclusion criteria to account for variability in isoprostane concentration.

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.

Dietary risk factors and colonic pH and mineral concentrations in horses with enterolithiasis.

A prospective, unmatched case control study was performed to identify dietary and environmental risk factors for enterolithiasis in horses in California and to determine whether colonic ingesta analyses differed between horses with and without enteroliths. Forty-three horses with enterolithiasis were compared with 19 horses with surgical colic attributable to nonstrangulating obstruction of the colon without enteroliths. Colonic ingesta samples were collected at surgery from horses with enteroliths and control horses. Colonic pH and colonic concentrations of magnesium, phosphorus, sulfur, sodium, calcium, potassium, and nitrogen were measured. Questionnaires were distributed to owners to determine diet and management practices. Student's t-test and Mann-Whitney tests were used to evaluate differences in pH, dry matter content, percent nitrogen, and mineral content. Associations between dietary and management risk factors and enterolith occurrence were quantified by odds ratios. Mean pH of colonic contents from horses with enterolithiasis was significantly higher than for control horses. Horses with enterolithiasis had significantly lower percent dry matter in colonic fecal samples and higher mean mineral concentrations than controls. On the basis of reported feeding and management practices, horses with enterolithiasis were fed a significantly higher proportion of alfalfa in their diet and were less likely to have daily access to pasture grass than horses without enteroliths. Results suggest that decreasing alfalfa consumption and allowing daily access to pasture grazing might reduce the risk of enterolithiasis. Dietary modifications promoting acidification of colonic contents and dilution of minerals might be beneficial as preventive measures for enterolithiasis in horses.