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Biomedical subjects

T S Stashak

Publications and source records attributed to T S Stashak.

At least 19 recordsLinked to original sources
PubMed2000

Removal of large fragments of the extensor process of the distal phalanx via arthrotomy in horses: 14 cases (1992-1998).

OBJECTIVE: To evaluate the outcome of horses with large fragments of the extensor process of the distal phalanx that were removed by use of arthrotomy. DESIGN: Retrospective study. ANIMALS: 14 horses with large fragments of the extensor process of the distal phalanx. PROCEDURE: Medical records for horses with large fragments of the extensor process that were removed by use of arthrotomy were reviewed. Data retrieved from medical records included signalment, use of horse, affected limb, lameness history, lameness examination findings, radiographic findings, surgical technique, and outcome. Follow-up evaluation was obtained by telephone interview. RESULTS: Most affected horses were < 5 years old and had a history of chronic lameness. Lameness grade ranged from 1/5 to 4/5. Fragments involved 20 to 45% of the dorsopalmar articular surface of the distal phalanx. Eight of 14 horses had a successful outcome. Outcome was not associated with age, duration or severity of lameness, or fragment size. CONCLUSIONS AND CLINICAL RELEVANCE: Despite involvement of a large portion of the articular surface and use of arthrotomy, joint instability and permanent soft tissue injury was not a problem in most horses. Outcome may be improved by selection of horses with lameness of < 2 years' duration and careful management after surgery. A fair prognosis may be anticipated for removal of large fragments of the extensor process via arthrotomy.

Animals↗
PubMed1997

Lateral approach for endoscopic removal of solitary osteochondromas from the distal radial metaphysis in three horses.

A lateral approach to the carpal sheath was used for endoscopic removal of osteochondromas from the distal aspect of the radius in 3 horses. Previously osteochondromas have been removed through an incision into the carpal sheath; however, endoscopy is less invasive, requires less surgery and convalescence time, provides better cosmetic results, is associated with a lower risk of infection, and allows better examination of structures within the sheath. A medial approach for endoscopic removal has been described previously; however, the lateral approach was advantageous, because it avoided the median vein, artery, and nerve and because the sheath was more easily distended from the lateral approach. Therefore, this approach may be an alternative for removal of osteochondromas from the distal aspect of the radius in horses.

Animals↗
PubMed1995

Abnormalities in oxygenation, coagulation, and fibrinolysis in colonic blood of horses with experimentally induced strangulation obstruction.

OBJECTIVE: To measure arterial and venous blood gas, coagulation, and fibrinolysis variables in blood from isolated segments of control and ischemic large colons for the purpose of identifying variables for rapid, indirect assessment of colonic mucosal injury. DESIGN: Variables were determined at specific intervals during the 4-hour study (3 hours of ischemia and 1 hour of reperfusion). ANIMALS: Seven clinically normal horses between 2 and 15 years old. PROCEDURES: Horses underwent laparotomy and occlusion of the lumen and vasculature of the mid-portion of the pelvic flexure of the large colon. During ischemia of 1 randomly-chosen colonic segment, variables were measured to determine colonic mucosal damage and were compared with histologic scores of colonic biopsy specimens. RESULTS: Significant (P < 0.05) differences from control values were observed over time for venous pH, PCO2, PO2, oxygen saturation, oxygen content, arteriovenous oxygen difference, and lactate and glucose concentrations. Mean histologic scores of biopsy specimens obtained from ischemic colons were significantly (P < 0.05) greater (indicating greater damage) than those from control colons, and increased significantly (P < 0.05) with duration of ischemia. CONCLUSIONS: Venous lactate, oxygen saturation, and PO2 values were the most significant predictors of the severity of histologic damage within the ischemic colons (R2 = 0.661). CLINICAL RELEVANCE: Venous blood gas and lactate values in the large colon are good predictors of the amount of intestinal damage incurred during 3 hours of ischemia, and may be clinically useful for the rapid determination of colonic viability.

Animals↗
PubMed1993

Reconstructive surgery of selected injuries of the head.

Traumatic injuries to the head region of the horse are a common presenting complaint. Because of a copious blood supply, these wounds typically exhibit a tremendous capability for healing. By following the basic principles of wound management and employing a few techniques unique for specific injuries, the healing of these wounds can result in a satisfactory outcome.

Animals↗
PubMed1993

Evaluation of occlusive dressings for management of full-thickness excisional wounds on the distal portion of the limbs of horses.

Two 2.5-cm2 full-thickness skin wounds were created surgically over the lateral aspect of the cannon bone of each limb of 6 horses (n = 48 wounds). Dressings evaluated were a nonadherent gauze pad (group 1); a synthetic semiocclusive dressing, (group 2); equine amnion (group 3); and a synthetic fully occlusive dressing (group 4). Wounds were assessed subjectively at each dressing change, and total wound area, area of granulation tissue, and area of epithelium in each wound were determined by computerized digital analysis of photographs of the wounds. Complete healing time (wound covered by epithelium) also was determined for each wound. Statistical comparisons were made, using Kruskal-Wallis analysis and a Mann-Whitney U test. Median time to complete healing was: group 1, 53 days; group 2, 71 days; group 3, 63 days; and group 4, 113 days. Time to complete healing was significantly longer for wounds of group-4 horses than all other groups, and wounds of group-1 horses healed faster than did those of group-2 horses (P < 0.05). Wounds in group-4 horses required significantly (P < or = 0.05) more excisions of granulation tissue (median, 11.5 times) than did those in group-1 (median, 3.5), group-2 (median, 5.5) or group-3 (median, 2.5) horses. Epithelial tissue was detected later in wounds of group-4 horses (median, 27 days) than in wounds of horses in groups 1, 2 or 3 (median, 17 days); however, this difference was not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Intestinal fibrosis with partial obstruction in five horses and two ponies.

Fibrosis of the small intestine led to recurrent colic and weight loss in 2 ponies and 5 horses. There was a reduction in the length of the small intestine to one-half normal in horses 4 to 7. Histologic examination revealed substantial small intestinal submucosal fibrosis and arteriole sclerosis. The cause was not determined, but an environmental factor was suspected because 3 horses were from the same farm and the other animals were from within a 10-mile radius of the farm. The submucosal fibrosis appeared to be secondary to sclerosis of arterioles in the submucosa and mesentery, with low blood flow state or altered vessel permeability.

Abdominal Pain↗
PubMed1992

Respiratory stridor associated with polymyopathy suspected to be hyperkalemic periodic paralysis in four quarter horse foals.

Four Quarter Horse foals ranging in age from 6 days to 2 months were determined to have upper airway stridor secondary to polymyopathy suspected to be hyperkalemic periodic paralysis. Electromyography revealed spontaneous muscle activity in all muscles examined. Electromyographic findings were similar in the dams of 3 foals (No. 1, 3 and 4). Hyperkalemia was found in foals 1 and 4. Endoscopically, the upper airway stridor in foals 1 and 3 was confirmed to be attributable to laryngeal and pharyngeal collapse or spasm. Foals 1, 2, and 3 were treated with acetazolamide. Foal 4 was not treated, at the owner's request. Foals 2 and 3 improved with treatment, foal 4's condition was static, and foal 1 required a tracheostomy and laryngeal surgery to manage its upper airway stridor.

Acetazolamide↗
PubMed1991

Traumatic injuries involving tendons of the distal limbs in horses: a retrospective study of 55 cases.

Fifty-five horses were presented to Colorado State University Veterinary Teaching Hospital between 1st of January 1980 and 31st of December 1989 for treatment of distal limb lacerations involving flexor tendons (n = 35) or extensor tendons (n = 20). Of the 35 flexor tendon lacerations, 11 horses were killed without treatment and 24 horses were treated. Twenty-two horses were included in determining outcome. Four (18 per cent) returned to their original level of use, nine (41 per cent) returned to limited riding, seven (32 per cent) returned to breeding or pasture soundness and two (9 per cent) were killed. Eighteen of the 20 horses with extensor tendon lacerations underwent treatment and 15 had sufficient follow-up to determine outcome. Seven (47 per cent) returned to their original or intended use, five (33 per cent) returned to limited use, one (7 per cent) was used for breeding and two (13 per cent) were killed. Results for horses with extensor tendon lacerations support previous reports that these injuries can be treated successfully. Results for horses having flexor tendon lacerations were better than in previous reports.

Animals↗
PubMed1991

Multivariable prediction model for the need for surgery in horses with colic.

A survey of 1,965 equine colic cases was conducted from August 1985 to July 1986 at 10 equine referral centers located throughout the United States. The purpose of this study was to develop and validate a multivariable model for the need for surgery. Two-thirds of the cases were randomly selected for model development (1,336), whereas the remaining cases (629) were used only for subsequent validation of the model. If a lesion requiring surgical correction was found at either surgery or necropsy, the case for the horse was classified as surgical, otherwise the case was classified as medical. Only variables that were significant (P less than 0.05) in an initial bivariable screening procedure were considered in the model development. Because of the large number of missing values in the data set, only variables for which there were less than 400 missing values were considered in the multivariable analysis. A multivariable logistic regression model was constructed by use of a stepwise algorithm. The model used 640 cases and included variables: rectal findings, signs of abdominal pain, peripheral pulse strength, and abdominal sounds. The likelihood ratio for surgery was calculated for each horse in the validation data set, using the logistic regression equation. Using Bayes theorem, the posttest probability was calculated, using the likelihood ratio as the test odds and the prevalence of surgery cases (at each institution) as an estimate of the pretest odds. A Hosmer-Lemeshow goodness-of-fit chi 2 statistic indicated that the model fit the validation data set poorly, as demonstrated by the large chi 2 value of 26.7 (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Failure to demonstrate reperfusion injury following ischaemia of the equine large colon using dimethyl sulphoxide.

A study was undertaken to evaluate the significance and mechanism of reperfusion injury in the equine large colon following 1 h of haemorrhagic strangulation obstruction (HSO) or ischaemic strangulation obstruction (ISO) and to assess the effect of treatment with dimethyl sulphoxide (DMSO). ISO or HSO were created 40 cm from the pelvic flexure and maintained for 60 mins under general anaesthesia. Normal saline or 20 per cent DMSO (1 g/kg bodyweight) was administered intravenously 10 mins prior to the end of the ischaemic period. Four groups of four horses in a 2 x 2 factorial design were used. Treatments of HSO or ISO and DMSO given (yes or no) were utilised. Intestinal wall biopsies and right colic arterial and venous blood samples were taken at 0, 60, 90 and 120 mins following initiation of the obstructions. Histological evaluation of the intestine using haematoxylin and eosin stained sections and immunohistochemical staining for albumin were performed. Mucosal and serum reduced glutathione (GSH) and oxidised glutathione (GSSG) levels and the amount of lymphatic dilatation with albumin and submucosal pooling of albumin were used as indirect measures of oxygen free radical production. Histopathological changes were minimal after 1 h of either type of ischaemia. Progressive changes during the post ischaemic period were minimal for ISO and moderate for HSO. Serum GSH and GSSG levels were not detectable. There was no demonstrable benefit of DMSO treatment as assessed by histology, immunohistochemistry or preservation of GSH levels in the mucosa. In conclusion, a reperfusion injury following 60 mins of ischaemia could not be detected in this study.

Albumins↗
PubMed1990

Alteration of intestinal enzyme activities associated with extensive large-colon resection in horses.

Lactase, maltase, sucrase, and alkaline phosphatase activities were determined in the intestinal mucosa from 3 locations in the small intestine and 4 locations in the large intestine 1 year after extensive large-colon resection (group 1; n = 5) and 1 year after sham operation (group 2; n = 3) in horses. Lactase, maltase, and sucrase activities were similar (P greater than 0.05) between group-1 and group-2 horses in all locations measured in the intestinal tract. Alkaline phosphatase activity in the remaining large colon of group-1 horses was significantly (P less than 0.05) greater than the activity in the large colon of group-2 horses. Decreased apparent digestion of phosphorus and a negative phosphorus balance are persistent features of large-colon resection in horses. Increases in alkaline phosphatase activity in the remaining colon of horses with extensive large-colon resection may be a specific functional adaptive mechanism that attempts to counteract the derangements in phosphorus metabolism.

Alkaline Phosphatase↗
PubMed1990

Alteration in intestinal morphologic features associated with extensive large-colon resection in horses.

Light microscopy, morphometry, and scanning electron microscopy were used to examine the mucosal morphologic features of 7 intestinal specimens (3 from the small intestine; 4 from the large intestine) from each of 8 horses 1 year after sham operation (group 1; n = 3) or extensive large-colon resection (group 2; n = 5). Qualitative light microscopic examination did not reveal differences between groups, but morphometry revealed significantly (P less than 0.05) greater intercrypt area and distance in horses with colon resection and this was most pronounced in the cecum and remaining right ventral and dorsal colon. Crypt area and depth were similar for horses with colon resection and sham operation (P greater than 0.05). Qualitative evaluation of the scanning electron micrographs revealed more prominent crypt orifices in the large intestine of horses with colon resection. The larger intercrypt distance in the colon of horses with resection was not an obvious feature of the qualitative evaluation of the surface with scanning electron microscopy. Small intestinal morphologic features were variable and significant differences were not detected between horses with sham operation and colon resection. Horses adapted to extensive large-colon resection within 1 year by increasing the absorptive (intercrypt) surface area of the remaining large intestine.

Animals↗
PubMed1989

Open joint injuries in horses: 58 cases (1980-1986).

A retrospective study was made of 58 horses with open joint injuries admitted to the veterinary teaching hospital. Twenty-five (43%) were admitted within 24 hours of injury, 15 (26%) were examined 2 to 7 days after injury, and 18 (31%) were evaluated a week or more after the initial injury. The joints of the lower portions of the limbs most commonly were affected, with injuries that varied from puncture wounds to severe lacerations with soft tissue deficits. Diagnosis was made on the basis of clinical signs and results of synovial fluid analysis and radiography. Radiography was found to be an important diagnostic tool, indicating joint involvement in 80% of horses on which it was done. Sixteen horses were euthanatized on the day of admission; of the horses treated, 53% that were examined within the first 24 hours developed septic arthritis, and the overall survival was 65%. Ninety-two percent of horses examined within 2 to 7 days of injury developed septic arthritis, with 38.5% surviving; all horses evaluated a week or more after joint injury had septic arthritis, and 50% survived. The prognosis for return to function was best in horses that were examined within the first 24 hours. Horses examined more than 24 hours after injury had a significantly (P less than 0.05) higher chance of developing septic arthritis, and thus, were significantly (P less than 0.0014) less likely to survive the injury.

Animals↗
PubMed1989

Correlative morphometry and morphology of normal equine intestinal mucosa and comparison after adaptation to extensive large colon resection.

Light microscopy, morphometry and scanning electron microscopy (SEM) were used to examine the mucosal morphology of seven intestinal specimens (three from the small intestine and four from the large intestine) from two horses not subjected to surgery and three horses one year after sham-operation for colon resection. Qualitative and quantitative evaluation revealed similar morphology for all horses except that the unoperated horses had significantly (P < 0.05) fewer goblet cells in the crypts of the large intestine. In the small intestine, SEM demonstrated that villus shape varied and ranged from coned to broad and flat. In the large intestine, SEM of the right ventral and dorsal colon revealed more prominent crypt openings than in the caecum. The small colon contained the most prominent crypt openings with the least variation among horses. In the small intestine, light microscopy and morphometry revealed a greater number of goblet cells and a decreased width to the enterocytes in an aboral direction from the cranial jejunum to the ileum. In the large intestine, the crypt area and crypt depth increased significantly and the intercrypt area decreased significantly in an aboral direction from the caecum to the small colon (P < 0.05). In comparison to the normal morphology, horses one year after extensive large colon resection had significantly greater intercrypt area in the caecum and remaining large colon.

Adaptation, Physiological↗
PubMed1989

Evaluation of two techniques for large intestinal resection and anastomosis in the horse.

Six normal adult horses had large colon resections at the sternal and diaphragmatic flexures. Stainless steel staples were used to close the stumps of the dorsal and ventral colons in all six. Intestinal continuity was restored with a side-to-side anastomosis of the dorsal and ventral colons. Three of these anastomoses were performed with staples, and three with a double inverting suture pattern. After one month, the horses were surgically reevaluated, and the anastomotic sites were examined. There was no significant difference between the stoma sizes in the two groups. No complications were observed with either of the methods. However, the stapling procedure was faster to perform and resulted in less contamination of the surgical field. For these reasons, the authors preferred the stapling technique. No adverse effects from large colon resection were observed. Although the results described are quite good, resection of more extensive portions of the large colon can be more demanding and more problematic.

Anastomosis, Surgical↗