Factors affecting incisional complication rates associated with colic surgery in horses: 78 cases (1983-1985).

From May 1, 1983 to April 1, 1985, 142 operations were performed on horses with signs of acute abdominal pain (colic), using a ventral midline incision. Seventy-eight horses lived for at least 15 days after surgery or had acute dehiscence and were included in the study. Seventy horses had surgery once, and 8 horses had surgery 2 or more times. Six-month follow-up evaluation was obtained for 66 horses that had 1 surgery and for 6 horses that had multiple surgeries. Incisional complications included drainage (including infection), acute dehiscence, hernia, and suture sinus formation. The effects of preoperative peritoneal fluid presence, enterotomy or resection, suture material and pattern used in the linea alba, type of skin closure and use of a sutured-on stent bandage on the incidence of incisional complications were investigated. The complication of incisional infection rate associated with a near-far-far-near suture pattern vs simple interrupted pattern in the linea alba was the only statistically significant (P less than 0.05) difference observed.

Attempts to restore abduction of the paralyzed equine arytenoid cartilage. I. Nerve-muscle pedicle transplants.

The purpose of this project was to adapt a surgical technique from humans and dogs to horses in which a portion of an accessory muscle of respiration and its nerve supply is transplanted to a denervated dorsal cricoarytenoid muscle. Anatomical dissections in seven horses revealed two possible donor nerve-pedicle grafts: the omohyoid and the sternothyrohyoid, both innervated by a branch of the first and second cervical nerves. Histochemical evaluations in two ponies of the dorsal cricoarytenoid, omohyoid and sternothyrohyoid muscles revealed similar proportions of fiber types 1 and 2 in all three muscles. Electromyographic studies in these two ponies revealed that the omohyoid and sternothyrohyoid muscles contract synchronously with respirations during forced inspiration under general anesthesia. Based on surgical ease of access, a 1 cm2 portion of the omohyoid muscle at the point of penetration of the second cervical nerve was used as a nerve-muscle pedicle graft in an attempt to reinnervate the left dorsal cricoarytenoid muscle in four ponies. These four ponies (as well as three others which served as controls) had previously undergone left recurrent laryngeal nerve transection. All seven ponies endoscopically showed signs of complete left laryngeal hemiplegia immediately postoperatively. Animals were monitored endoscopically for 30 weeks after surgery. The three control ponies showed no abduction of the arytenoid cartilage. In addition, in these three ponies, histological and histochemical expected changes of muscle fiber atrophy and fibrosis were present in the dorsal cricoarytenoid muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Attempts to restore abduction of the paralyzed equine arytenoid cartilage. II. Nerve implantation (pilot study).

The purpose of this project was to attempt restoration of abduction of a recently experimentally denervated left dorsal cricoarytenoid muscle by implanting a transected nerve-end into the paralyzed muscle. In six ponies the cut end of the second cervical nerve was implanted into a slit made in the left dorsal cricoarytenoid muscle. The nerve end was secured in place with one 5-0 polypropylene suture connecting the epineurium to the epimysium. The left recurrent laryngeal nerve was transected during this procedure. All six ponies showed signs of complete left laryngeal hemiplegia immediately after surgery. Postoperatively all ponies were evaluated qualitatively on a monthly basis by subjective examination for evidence of abduction of the arytenoid cartilages on endoscopy and quantitatively by measurement of the cross sectional area of the left and right half of the rima glottidis. Subjective endoscopic evidence of partial abduction was seen in four of the six ponies six months postoperatively. Measurement of the cross sectional area of the rima glottidis revealed a total loss of 38% of the area immediately postoperatively. There were no significant changes in cross sectional areas of the rima glottidis between the immediate postoperative evaluation to the six months postoperative evaluation. Gross postmortem examination revealed partial dorsal cricoarytenoid muscle atrophy as evidenced by a 24-55% decrease in muscle mass compared to the right dorsal cricoarytenoid muscle. Histopathological studies revealed regions with clusters of large muscle fibers.(ABSTRACT TRUNCATED AT 250 WORDS)

Attempts to restore abduction of the paralyzed equine arytenoid cartilage. III. Nerve anastomosis.

The purpose of this project was to attempt restoration of abduction of a recently denervated left dorsal cricoarytenoid muscle in the horse by anastomosing the first cervical nerve to the abductor branch of the left recurrent laryngeal nerve. Ten horses were used in the study. In six horses the left recurrent laryngeal nerve was transected and ligated while the ventral branch of the left first cervical nerve was anastomosed to the abductor branch of the left recurrent laryngeal nerve. The remaining four horses also had the left recurrent laryngeal nerve transected and ligated but had no nerve anastomosis performed. Each horse was evaluated preoperatively, and at one week, three and six months after surgery, by endoscopy and determination of upper airway resistance. The endoscopy was performed with the horses breathing room air and while breathing 10% carbon dioxide. All ten horses showed endoscopic signs of complete laryngeal hemiplegia immediately postoperatively. Starting at three months postoperatively clonic movements of the left arytenoid cartilage were observed in four of the six reinnervated horses but not in the sham operated horses. At the sixth postoperative month five reinnervated horses had clonic movements of the left arytenoid cartilage. The comparison of upper airway resistance measurements before surgery and at one week, three and six months after surgery showed no significant differences in either control or experimental horses. Following euthanasia at six months postoperatively, the left and right dorsal crioarytenoid muscles were compared for evidence of reinnervation. No significant difference in weight was noted in the reinnervated horses but the left dorsal cricoarytenoid muscle weighed less than the control horses.

Use of high-speed cinematography and computer generated gait diagrams for the study of equine hindlimb kinematics.

High-speed cinematography with computer aided analysis was used to study equine hindlimb kinematics. Eight horses were filmed at the trot or the pace. Filming was done from the side (lateral) and the back (caudal). Parameters measured from the lateral filming included the heights of the tuber coxae and tailhead, protraction and retraction of the hoof and angular changes of the tarsus and stifle. Abduction and adduction of the limb and tarsal height changes were measured from the caudal filming. The maximum and minimum values plus the standard deviations and coefficients of variations are presented in tabular form. Three gait diagrams were constructed to represent stifle angle versus tarsal angle, metatarsophalangeal height versus protraction-retraction (fetlock height diagram) and tuber coxae and tailhead height versus stride (pelvic height diagram). Application of the technique to the group of horses revealed good repeatability of the gait diagrams within a limb and the diagrams appeared to be sensitive indicators of left/right asymmetries.

Colonic atresia in cattle: A prospective study of 43 cases.

This prospective study was initiated to document the success rate obtained in the treatment of colonic atresia in calves, identify factors that influence survival rate, and to report the histopathological appearance of the proximal blind end of the ascending colon. Forty-three calves with intestinal obstruction due to colonic atresia were admitted to the Ontario Veterinary College between September 1982 and May 1986. Parameters recorded prospectively in this study included age, breed, sex, history, vital signs, acid-base and electrolyte status, location of intestinal atresia, medical and surgical management, and outcome. The typical history and clinical signs included failure to pass meconium or feces, decreased appetite, and progressive depression and abdominal distension. The most common site of colonic atresia was the midportion of the spiral loop of the ascending colon (n = 25). Of the 43 calves, three (7%) were euthanized at surgery, 21 (49%) died in the hospital, and 19 (44%) survived and were discharged from the hospital. Four of the surviving calves died subsequent to discharge giving an overall long-term (mean 15.9 months) survival rate of 35%. No significant risk factors were identified, although experienced surgeons showed a trend towards increased survival rate.

Equine Colic: Seventy-six Cases Resulting from Incarceration of the Large Colon by the Suspensory Ligament of the Spleen.

Incarceration of the large colon by the suspensory ligament of the spleen was diagnosed and surgically corrected on exploratory celiotomy in 76 horses exhibiting abdominal pain. The condition was diagnosed most frequently during the winter months in mature males of mean age 4.7 years. Clinical signs progressed slowly and included mild to moderate abdominal pain and distension with moderate tachycardia. The mean duration of colic prior to surgical intervention was 20.7 hours. The mild nature of the colic, the findings on palpation per rectum, and the continued passage of feces in 40% of horses, frequently led to the diagnosis and treatment of colonic impaction prior to admission. The condition was correctly diagnosed prior to exploratory celiotomy, by palpation per rectum, in only 18% of cases. Two types of displacement were identified. Sixty-six (86.8%) animals survived and were discharged from the hospital; the longterm survival rate was 78.9%.

Invasive teat surgery in dairy cattle: part I - surgical procedures and classification of lesions.

A prospective study was performed to identify the nature and management of teat abnormalities in cows presented to a referral teaching hospital during a three year period. All cattle (n = 60) admitted to the Ontario Veterinary College for teat problems were evaluated by physical examination; in 53 teats, contrast radiography or xeroradiography were obtained. Surgery was performed on 52 teats from 51 cows and a prosthesis was implanted in 27 teats. Short term (under two weeks) complications included intraoperative bleeding (n = 6), milk leakage through the incision (n = 4), and failure to milk by machine in 26 cases. Histopathological diagnosis of sections taken from obstructive lesions included fibrous tissue (n = 8), normal mammary tissue (n = 3), fibropapilloma, mammary polyps, and inflamed mucosa (one each). The lesion could be classified into five types: 1) focal teat cistern obstruction, 2) diffuse teat cistern obstruction, 3) membranous obstruction, 4) diffuse teat and gland cistern obstruction, or 5) leakage of milk through an abnormal route (i.e. teat fistula, webbed teat, or lacerations).

Invasive Teat Surgery in Dairy Cattle: II - Long-term Follow-up and complications.

A prospective study was performed on 52 teats that were operated upon at the Ontario Veterinary College over a three year period for various problems. Long-term postsurgical follow-ups were obtained to assess milking ability. Sixty-three percent of all the cows that had surgery were classified by the Canadian Holstein Association as "good" or better. The implantation of a prosthesis was required in 32 teats and was found to be associated with: a higher prevalence of chronic mastitis, a lower long-term milking success rate, and an increased prevalence of abnormal milking times. Of the five types of teat lesions encountered, Type I (<30% of teat cistern involved) and Type V (lacerations, webbed teats, fistulae) had the best short and long-term prognosis for lactation. Overall, 60% of the operated teats were milking one month after surgery, and 41% at the end of the lactation.

Extension large colon resection in 12 horses.

Extensive resection (50-75%) of the large colon was performed in 12 horses. Indications for resection were: loss of viability due to large colon volvulus (seven), thromboembolic episode (three), impairment of flow of ingesta due to adhesions (one), or congenital abnormalities (one). The time required to correct the primary cause of abdominal pain and complete the resection ranged from 2.5 to 4.75 hours. Three horses had severe musculoskeletal problems postoperatively and were euthanized in the recovery stall. Four other horses were euthanized early in the postoperative period because of: further large colon infarction (two), ileus (one), or small intestinal problems (one). Five horses survived with no apparent nutritional or metabolic problems during two to three weeks of hospitalization. Clinical data were obtained from these horses from nine months to eighteen months postoperatively and revealed no clinical or clinicopathological abnormalities in four of them; the fifth horse exhibited diarrhea and weight loss four months postoperatively but responded to diet change.

Histology of the normal and retained equine testis.

Abdominal, inguinal and scrotal testes of horses were examined grossly and by light microscopy. An average of 1.5, 2.3 and 4.6 layers of spermatogenic cells, and mean seminiferous tubule diameters of approximately 66.2, 83.6 and 146.6 micron in the abdominal, inguinal and scrotal testes, respectively, were recorded. The interstitial spaces and the number of interstitial cells (of Leydig) seemed to be increased while spermatogenesis appeared to be arrested in the retained testes. Early spermatocytes were the most mature stages of the spermatogenic cells in the retained testes. An extensive vacuolation of spermatogenic cells was evident in these testes. The changes may result due to a high temperature of the abdominal environment in concert with the altered production of androgens.

Extensive large colon resection in the pony. I. Surgical procedures and clinical results.

The effect of resection of 75% (length measurement) of the large colon in ponies was studied. Ten ponies in good physical condition were divided into two groups: group I consisted of the six experimental ponies and group II of four control ponies. Preoperatively and postoperatively for five months, ten clinicopathological parameters were determined: body weight, venous blood pH, plasma bicarbonate, total plasma protein concentration, serum electrolyte values (sodium, potassium, chloride), and fecal osmolarity. Subjective assessment of attitude and appetite revealed no difference between the groups or within groups at any time. Resection of a major portion of the large colon did not significantly influence the clinicopathological parameters evaluated. The hematocrit of the ponies in group I did decrease during the first postoperative month and this was attributed to whole blood loss associated with the resection procedures. The results of this investigation indicated that resection of 75% of the large colon in ponies is compatible with life.

Extensive large colon resection in the pony. II. Digestibility studies and postmortem findings.

The nutritional implications and adaptive processes resulting from resection of 75% of the length of the large colon in ponies were investigated. Ten ponies in good physical condition were divided into two groups: six in the experimental group and four in the control group. During the sixth postoperative month, two digestibility studies were conducted, and phosphate fractional renal excretion and serum biochemical profiles were determined in both groups. The ponies (N = 10) were euthanized six months postoperatively, and gross and histopathological examinations were performed. Results of the serum biochemical profiles, phosphate fractional renal extraction and digestibility studies showed no statistically significant difference between groups except for the serum phosphate concentration. However, large colon resection was associated with hypophosphatemia in three of the six ponies and produced an overall significantly lower phosphate concentration in the experimental ponies. This hypophosphatemia suggests that some dietary modifications may be needed postoperatively in ponies or horses undergoing this surgical procedure. Postmortem examination and histopathological examination failed to demonstrate differences between groups. Adaptive mechanisms, specifically mucosal hypertrophy or hyperplasia, were not observed.

Retrospective evaluation of xylazine/halothane anesthesia in 125 cattle.

A retrospective morbidity and mortality study was carried out on 125 case records of cattle involving xylazine/halothane anesthesia at the Ontario Veterinary College, Guelph between May 1979 and February 1983.One hundred and six animals were given xylazine intramuscularly with a mean dose of 0.22 mg/kg and the remaining 19 were given a mean dose of 0.17 mg/kg intravenously. When the animals became recumbent, they were intubated and connected to an anesthetic machine which delivered halothane in oxygen.Anesthetic complications were recorded for ten cattle (8%) in the series and were mainly associated with regurgitation of ruminal contents, with or without aspiration. Three animals died as a result of the anesthetic procedure and in three other instances there were complications which were potentially fatal. Two of the anesthetic deaths were directly attributable to faulty technique rather than a specific drug response.The use of xylazine/halothane was judged to be clinically satisfactory and did not produce an unacceptable complication rate, although it is evident there is a significant risk associated with general anesthesia in ruminants.

Pheochromocytoma in the horse and measurement of norepinephrine levels in horses.

Ten cases of pheochromocytoma in horses were obtained from the literature and a computer search of medical records. The clinical, laboratory and pathological features of pheochromocytoma in horses were reviewed. Pheochromocytoma is a catecholamine secreting tumor which tends to occur in older horses without breed or sex predisposition. It is usually unilateral adrenal medullary in location and benign. Malignancy was present in one horse. The most common clinical signs were sweating, tachycardia, tachypnea, muscle tremor and anxiety; however the tumor may be asymptomatic. Clinical signs were nonspecific and could be confused with other diseases, especially abdominal pain. Hyperglycemia is a consistent finding. Venous norepinephrine levels were measured in normal horses. Norepinephrine measurements may prove to be a diagnostic aid in horses with pheochromocytoma.

Surgical treatment of paraphimosis in a pony.

Circumcision (or reefing operation) was performed on an aged pony stallion to remove excessive granulation tissue involving the preputial integument following an injury and subsequent paraphimosis. Postoperative swelling of the penis and prepuce was reduced daily with gentle massage. Initially, an improvised suspensory was used to support the penis postoperatively. The pony was able to voluntarily retract its penis six months following surgery.

The treatment of transection of the extensor carpi radialis muscle as a result of a lacerating wound in a horse.

A 16 month old filly was presented with the complaint of a severe laceration to the right foreleg with resultant transection of the extensor carpi radialis. Normal principles of wound treatment were followed and a bandage and splint were used for support and immobilization. The return to partial function of the damaged extensor carpi radialis was evidenced by resolution of the wound and an improvement in the patient's gait four months after the time of injury.