Risk factors associated with gastrointestinal dysfunction in horses undergoing elective procedures under general anaesthesia.

REASONS FOR PERFORMING STUDY: Gastrointestinal dysfunction occurs commonly following elective anaesthesia. Identification of risk factors may allow implementation of preventative measures to reduce the prevalence of colic following elective anaesthetic procedures. OBJECTIVES: To examine risk factors associated with gastrointestinal dysfunction or post anaesthetic colic for horses undergoing elective surgical or diagnostic procedures under general anaesthesia. STUDY DESIGN: Retrospective case series. METHODS: Medical records were collected from adult horses undergoing general anaesthesia from 1 January 2008 to 31 December 2010 using a retrospective cohort design. Potential risk factors were examined using univariable logistic regression with a limit of a P<0.25. Through backward elimination, the final multivariate model was created to identify variables significantly associated with gastrointestinal dysfunction. RESULTS: Colic or delayed faecal output was reported in 36 out of 416 (8.7%) horses undergoing general anaesthesia in the study period. In the final multivariable model, horse breed (P = 0.05), intraoperative peripheral blood lactate (P = 0.02), right lateral recumbency during general anaesthesia (P = 0.04), post anaesthetic rectal temperature (P = 0.03) and hours to first passage of faeces (P<0.01) were statistically significant between horses that exhibited colic compared with those that did not. Arabians were more likely to develop colic compared with other horse breeds (4/13, 30.8%). Horses that exhibited gastrointestinal dysfunction passed faeces later than those that did not (7.2 ± 0.8 h and 5.4 ± 0.2 h, respectively). As blood lactate increased at the end of anaesthesia, the odds of colic occurring also increased (odds ratio:1.4, 95% confidence interval: 1.04-1.83, P = 0.02). CONCLUSIONS: This study demonstrated the prevalence of colic in horses undergoing elective general anaesthetic procedures in our hospital population. Arabian horses, increasing blood lactate and delayed passage of faeces were significantly associated with an increased risk of gastrointestinal dysfunction.

Clinical features and prognostic variables in 109 horses with esophageal obstruction (1992-2009).

BACKGROUND: Esophageal obstruction is common in horses and can result in life-threatening complications. Previous studies have described clinical findings in horses with esophageal obstruction, but there are no reports that attempt to make correlations of clinical findings with outcome. HYPOTHESIS: Specific clinical features of horses with esophageal obstruction are associated with increased likelihood of complications. ANIMALS: One hundred and nine horses with esophageal obstruction. METHODS: Retrospective cross-sectional study. All clinical records of horses admitted between April 1992 and February 2009 for esophageal obstruction were reviewed. The association among 24 clinical, hematological, biochemical, therapeutic variables and the likelihood of complications was investigated by a univariable logistic regression model, followed by multivariable analysis. RESULTS: Multiple logistic regression analysis revealed that intact males (P= .02), age >15 years (P < .01), and a need for general anesthesia (P < .01) were associated with the development of complications after an episode of esophageal obstruction. Increased respiratory rate (>22 breaths/min) and moderate or severe tracheal contamination, although not associated with complications as a whole, significantly increased the risk of developing aspiration pneumonia (P≤ .01). CONCLUSIONS AND CLINICAL IMPORTANCE: Signalment, clinical variables, and endoscopic findings were confirmed as important tools in assessing the severity of the esophageal lesion and pulmonary involvement. Knowledge of risk factors for the development of complications will aid in making informed decisions to optimize treatment and assist in the assessment of prognosis.

Association between hyperglycemia and survival in 228 horses with acute gastrointestinal disease.

BACKGROUND: Glucose homeostasis is dysregulated in critically ill humans resulting in hyperglycemia and decreased survival. Hyperglycemia is common in horses presenting with abdominal crisis, and this might be associated with a worse prognosis for survival. OBJECTIVE: To determine if hyperglycemia in horses with acute abdominal disease is associated with increased odds of failure to survive to hospital discharge. ANIMALS: Two hundred and twenty-eight adult horses with acute gastrointestinal disease. METHODS: Observational retrospective study. Records of horses > 1 year of age presenting for treatment of colic over a 3-year period were reviewed. Data collected included age, duration of colic, glucose, heart rate, PCV, total protein, anion gap, cost of hospitalization, breed, sex, pain at admission, diagnosis, whether surgery was performed, and life status at hospital discharge. Potential risk factors for nonsurvival were screened by univariable logistic regression and the best-fitting univariable model was used as the basis for multivariable regression modeling. RESULTS: Mean blood glucose was 155 mg/dL (8.5 mM) with 45% of the population above the reference range; 16.7% (38 of 228) of horses had severe hyperglycemia (>195 mg/dL; 10.7 mM). Factors associated with increased odds of failure to survive included glucose, severity of pain at admission, heart rate, PCV, anion gap, and diagnosis. The best-fitting multivariable model included glucose and diagnosis, with age included as a confounding variable. The model correctly classified outcome for 92.5% of horses. CONCLUSIONS AND CLINICAL IMPORTANCE: This study has confirmed prior reports that hyperglycemia is common in horses with colic and is associated with a worse prognosis for survival to hospital discharge.

Evaluation of dietary and management risk factors for enterolithiasis among horses in California.

Enteroliths are intestinal calculi that result in intestinal obstruction and colic in horses. Equine enterolithiasis occurs worldwide, but the disease is particularly prevalent in some geographic locations, including California. The objectives of this study were to evaluate dietary and environmental risk factors for the disease. This was accomplished through a case-control study by comparing horses with colic from enterolithiasis presenting to the University of California, Davis VMTH, to horses with colic of other causes. Data were collected on 61 horses with enterolithiasis and 75 controls via evaluation of patient records and questionnaires completed by owners at the time of admission. Following multiple logistic regression analysis, the following factors were found to be significantly associated with enterolithiasis: feeding > or = 50% of the diet as alfalfa; feeding <50% of the diet as oat hay; feeding <50% of the diet as grass hay; and lack of daily access to pasture grazing.

Petrographic and geochemic evaluation of equine enteroliths.

OBJECTIVE: To characterize the texture, mineralogic features, and chemical features of enteroliths obtained from horses. SAMPLE POPULATION: Enteroliths from 13 horses with colic. PROCEDURE: Enteroliths were harvested from 13 horses that underwent ventral midline celiotomy for treatment of colic or necropsy because of colonic obstruction and rupture caused by enteroliths. Dietary and environmental history were determined via questionnaires or evaluation of medical records. In 7 horses that underwent surgical treatment for enterolithiasis, samples of colonic contents were obtained via an enterotomy in the pelvic flexure. Colonic concentrations of magnesium (Mg), phosphorus (P), sulfur (S), sodium (Na), calcium (Ca), and potassium (K) were determined. Enteroliths were analyzed via electron microprobe analysis and X-ray diffraction. RESULTS: Enteroliths varied widely regarding degree of porosity, presence and distribution of radiating texture, and composition and size of the central nidus. A distinct concentric banding was identifiable in all enteroliths. Struvite was the predominant component of all enteroliths, although Mg vivianite was identified in 5 enteroliths, and there were variable quantities of Na, S, K, and Ca in the struvite within enteroliths. Despite an abundance of Ca in colonic fluids, Mg-phosphate minerals were preferentially formed, compared with Ca-phosphates (apatite), in equine enteroliths. CONCLUSIONS AND CLINICAL RELEVANCE: Enteroliths comprise 2 major Mg phosphates: struvite and Mg vivianite. There is wide variability in macrotexture and ionic concentrations between and within enteroliths.

Disseminated hemangiosarcoma in the horse: 35 cases.

Thirty-five cases of disseminated hemangiosarcoma (21 clinical cases and 14 previously reported cases) were reviewed to describe the disease in horses. Hemangiosarcoma occurred in mature, particularly middle-aged horses, with no apparent sex predilection. Thoroughbreds seemed to be overrepresented (13 cases) but a true breed predilection could not be established. The respiratory and musculoskeletal systems were most commonly affected and presenting complaints included dyspnea (26%), subcutaneous or muscular swelling (24%), epistaxis (17%), and lameness (12%). Heart and respiratory rates were usually increased and mucous membrane color was frequently pale or icteric. Capillary refill time and rectal temperature were often normal. Anemia (88%), neutrophilic leukocytosis (62%), and thrombocytopenia (48%) were common. Examination of tissue samples collected by fine-needle aspirate or biopsy established an antemortem diagnosis in 4 horses. The diagnosis was made during postmortem examination in the remaining 31 horses. The lung and pleura (77%), skeletal muscle (46%), and spleen (43%) were most commonly affected. A primary site of tumor involvement could be identified in 22 horses. Hemangiosarcoma should be included as a differential diagnosis for horses with evidence of hemorrhage into body cavities, skeletal muscle, or subcutaneous locations.

Evaluation of enterolithiasis in equids: 900 cases (1973-1996).

OBJECTIVE: To identify breed, age, sex, physical findings, history, and outcome of treatment in horses and other equids with enterolithiasis. DESIGN: Retrospective study. ANIMALS: 900 equids with enterolithiasis. PROCEDURE: Medical records from equids with enterolithiasis admitted between 1973 and 1996 were reviewed. Data on signalment, history, physical examination and clinicopathologic findings, surgical findings, and outcome were compiled from records and from telephone interviews with owners. Sex and breed predilections were determined by comparison of the study population with the general hospital population of equids during the same time period. RESULTS: Equids with enterolithiasis represented 15.1% of patients admitted for treatment colic, and 27.5% of patients undergoing celiotomy for treatment of colic. Arabian and Arabian crosses, Morgans, American Saddlebreds, and donkeys were significantly overrepresented, and Thoroughbreds, Standardbreds, warmbloods, and stallions were significantly underrepresented in the study population, compared with the hospital population. The mean age of equids with enterolithiasis was 11.4 years. The most common historic findings were signs of intermittent colic (33.3%) and passage of enteroliths in the feces (13.5%). Physical examination findings were similar to those found in equids with other forms of nonstrangulating large colon obstructive disease. Fifteen percent (131) developed gastrointestinal tract rupture caused by an enterolith that necessitated euthanasia. Short-term and 1-year survival rates for equids undergoing celiotomy for treatment of enterolithiasis and recovering from anesthesia were excellent (96.2 and 92.5%, respectively), and postoperative complications were uncommon. Recurrence of enterolithiasis was identified in 7.7% of the study population. CLINICAL IMPLICATIONS: Results indicated that shortterm and 1-year survival rates for equids undergoing surgery for enterolithiasis are excellent. Identification of signalment, history, and management factors may help identify equids with a high risk for development of enterolithiasis.

A modified teniotomy technique for facilitated removal of descending colon enteroliths in horses.

OBJECTIVE: To describe a method for facilitating movement of enteroliths obstructing the proximal portion of the descending colon. STUDY DESIGN: Prospective report. SAMPLE POPULATION: 15 horses. METHODS: A seromuscular incision through the antimesenteric taenia of the proximal portion of the descending colon was used to facilitate movement of enteroliths. RESULTS: Teniotomy allowed proximal descending colon enteroliths located within the abdomen or close to the abdominal wall to be advanced 4 to 15 cm in an aboral direction so that they could be exteriorized for safe removal. CONCLUSIONS AND CLINICAL RELEVANCE: Teniotomy is a feasible method for mobilizing enteroliths in the proximal descending colon in locations that cannot otherwise be exteriorized.

Endoscopy of the auditory tube diverticula in four horses with otitis media/interna.

Endoscopic examination of the auditory tube diverticula was a diagnostic aid in the evaluation of 4 horses with otitis media/interna and associated osseous changes of the stylohyoid and petrous temporal. One of the horses was examined because of persistent head shaking; the other 3 were examined because of an acute onset of facial and vestibulocochlear nerve dysfunction. Proliferative lesions involving the petrous temporal bone and proximal portion of the stylohyoid bone were identified endoscopically in all 4 horses. Endoscopy is a noninvasive procedure that provides an alternative to skull radiography and tympanocentesis in the diagnosis of otitis media/interna in horses. In addition, risks associated with general anesthesia are avoided.