SUBTRACTION PORTAL VENOGRAPHY

Photographic subtraction was made of 38 canine portal venograms to remove the images of the overlying abdominal structures and enhance the radiographic contrast of portal veins. The improved visual quality of the subtracted portogram aided in the detection of portosystemic shunts and intrahepatic portal veins. The subtraction studies revealed portosystemic shunts not detected on the initial portal venogram.     

Femoral Capital Physeal Fractures in 25 Foals

The medical records of 25 horses 1 year of age or younger affected with femoral head and neck fractures during an 18 year period were reviewed. Each fracture involved the capital physis. The foals were 11 days to 12 months of age (mean, 5 months). No femoral capital physeal fractures occurred in horses older than 1 year of age during the same period. The history in each case included acute onset of severe unilateral hindlimb lameness, 3 hours to 2 months (mean, 12 days) before presentation. Injuries observed were violent falls, struggles, and kicks. Crepitation, swelling, pain with manipulation or palpation or both, and apparent fracture fragment displacement were inconsistently noted. Tentative clinical diagnoses were confirmed by radiography in 24 foals and by necropsy alone in one foal. Twenty-one foals were euthanatized due to poor prognosis. One foal sent home for stall rest was lost to follow-up. Surgical repair was attempted in three foals. Two fractures were repaired with multiple intramedullary pins and the foals were euthanatized within 2 weeks due to surgical failure and, in one case, contralateral limb breakdown. The third fracture was repaired with a compressing screw and plate device; the animal was pasture sound at month 20.     

Spatial Labor Markets and the Rural Labor Force

Functional economic areas have long been recognized as the appropriate unit of analysis for examining the spatial organization of regional economic activity. While easily defined conceptually, few fine-tuned empirical delineations based on either trading or commuting patterns have been produced. In this paper, labor market areas (LMAs) based on commuting patterns of Saskatchewan residents are constructed for two points in time, 1981 and 1991. Detailed Statistics Canada data on place of work and place of residence for the experienced labor force were used 38 distinct LMAs were identified for 1991, and 37 for 1981. The 15 largest LMAs, which included just under one-half of all rural municipalities (RMs) in southern Saskatchewan, grew in absolute terms and gained in relative importance during the decade. Another 23 (22) smaller LMAs in 1991 (1981), provided jobs for modest but declining numbers of both commuters and noncommuters. The remaining 30 percent of all RMs had such low or diffused levels of commuting that they were not included in any LMA in either year. A pattern apparent for all LMAs was an intensification of commuting within the labor market area. Although there was a reduction in the number of commuters from centers of employment to surrounding areas between 1981 and 1991, there was an even larger increase in commuters to centers of employment. While commuting to a job in an urban center is still a distinct possibility for the rural labor force living within the 15 largest LMAs, it is increasingly less likely for those residing elsewhere in rural Saskatchewan. In these remote areas, alternatives to urban-based employment are required.     

MAGNETIC RESONANCE IMAGING OF THE NORMAL EQUINE DIGIT AND METACARPOPHALANGEAL JOINT

Magnetic resonance (MR) images were made in sagittal and transverse planes through the metacarpophalangeal joint and digit of a horse. The images accurately depicted gross anatomic structures in the leg. Soft tissue structures were defined as separate entities on the images. Histologic varlation in tissues correlated with signal intensity differences on the MR images. Magnetic resonance imaging appears to be a promising imaging modality for evaluating musculoskeletal structures in equine limbs.     

Dorsal Laminectomy in the Horse II. Evaluation in the Normal Horse

Subtotal dorsal cervical laminectomy was performed on nine normal horses to evaluate positioning, refine the surgical technique, and assess the immediate and long-term effects of this procedure in the horse. Funkquist type B laminectomies were performed at various levels from C3-C4 to C6-C7. Absorbable gelatin sponge or autogenous nuchal fat was placed over the exposed dura mater. Surgery times varied from 2 to 3 hours, and all horses recovered without complication. Rapid primary intention wound healing occurred, with two horses showing neck pain. All remained neurologically normal. The horses were euthanized 6 weeks, 3 months, or 6 months postoperatively. Myelograms performed just prior to euthanasia demonstrated normal or expanded dye column widths. Necropsy revealed that all surgical sites had healed well. The laminectomy membrane was soft and pliable and could be easily separated from the underlying dura mater when fat was used as interpositional material. When gelatin sponge was used, the laminectomy membrane was firmly bonded to the dura. Spinal cords at the level of laminectomy appeared normal and moved freely within the vertebral canal. Histological evaluation of the laminectomy sites and associated spinal cord revealed no abnormalities attributable to the surgery. It was concluded that dorsal cervical laminectomy can be performed in horses without untoward sequelae. The procedure may be useful for the treatment of equine cervical compressive myelopathies.     

Evaluation of Continuous Infusion of Lidocaine on Gastrointestinal Tract Function in Normal Horses

Objective— To determine the effect of continuous infusion of lidocaine on fecal transit time in normal horses.
Study Design— Experimental randomized cross-over study.
Animals— Healthy horses (n=6).
Methods— Barium-filled microspheres were administered to horses by nasogastric intubation and feces were collected every 2 hours for 4 days. A bolus of 2% lidocaine (1.3 mg/kg) was administered randomly, followed by a continuous infusion of lidocaine (0.05 mg/kg/min) for 3 days or an equivalent volume of saline. The washout period was 10 days. Variables assessed included defecation frequency, weight of feces produced, intestinal transit time (number of microspheres observed on radiographs), fecal moisture content, borborygmus score, heart and respiratory rate, and signs of lidocaine toxicity (e.g., ataxia, CNS depression).
Results— During the first 24 hours of lidocaine administration, mean (±SD) fecal output (10.8±6.9 kg) was decreased compared with controls (15±4.9 kg). Mean (±SEM) time for passing 50% of the barium-filled microspheres was shorter in controls (42±1.13 hours) compared with the lidocaine group (50±1.32 hours).
Conclusions— Continuous infusion of lidocaine increases the transit time of feces in normal horses.
Clinical Relevance— Clinicians need to be aware of the effects of using a continuous infusion of lidocaine on the transit time of feces in normal horses, with a potential for exacerbating those effects when combined with drugs that decrease motility and in horses with medical colic (e.g., impaction) or where a diagnosis has not been made.     

Postoperative Examination of the Biceps Femoris Muscle Sling Used in Excision of the Femoral Head and Neck in Dogs

Twenty-four dogs underwent unilateral excision of the femoral head and neck. An adjunctive biceps femoris muscle sling procedure was done in 16 dogs. In eight dogs (controls), the flap was dissected and returned to its original position. Four dogs with muscle slings were euthanatized on days 2, 5, 30, and 60, respectively. Four control dogs were euthanatized on day 2 and four dogs on day 5. Limb function did not differ consistently between dogs with muscle slings and control dogs. There was marked swelling and edema of the affected limb in half the dogs with muscle slings but not in the controls. Postoperative temperature elevations were significantly higher in dogs with muscle slings on days 1 and 2 (p less than 0.05). Infection was documented in four dogs with muscle slings. Flaps from control dogs had only minor gross and histologic abnormalities. On days 2 and 5, flaps from dogs with muscle slings appeared congested and swollen beneath and distal to the ostectomy site, with infarction involving 50 to 90% of the muscle mass. On days 30 and 60, the muscle slings were atrophic and fibrous, and by day 60 a synovial membrane covered the surfaces of all slings within the pseudarthrosis. Muscle fiber loss was attributed to infarction, necrosis, and disuse atrophy.     

Nasal Septoplasty for Correction of Septal Deviation in a Foal

Objective — This article reports an alternative to septal resection in nasal septal deviations involving the rostral 7 to 10 cm of the nasal septum.
Study Design — Case report.
Sample Population — One client-owned foal.
Methods — A nasal approach with mucosal elevation was used to gain access to the cartilaginous portion of the nasal septum. Once exposed, a series of parasagittal incisions in the cartilage allowed the septum to be repositioned while providing some intrinsic stabilization.
Results — The nasal approach provided good access to the rostral 7 cm of the nasal septum. The technique resulted in minimal hemorrhage from the site. Bleeding was reduced with the use of ephedrine to vasoconstrict the mucosal vessels, and primary closure of the mucosa.
Conclusions — Use of an intrinsically stabilized septoplasty should be considered as a means of decreasing the airway obstruction caused by nasal septal deviation in foals while allowing for normal development of facial contour.     

Evaluation of an Interfragmentary Compression System for the Repair of Equine Femoral Capital Physeal Fractures

Femoral neck and proximal epiphyseal lengths were measured in 37 femurs from 19 cadaver foals that were 1 day to 12 months old to determine the applicability of a human interfragmentary compression system to equine femoral capital physeal fractures. Because components of the implant system are available only in fixed sizes, its use was possible in foals older than 5 weeks of age, but not in younger foals. The 135 degree angle plate conformed best to the equine femur. Femoral capital physeal fractures were created surgically and repaired with the implant system in three foals. Fracture stability was evident clinically and radiographically in all three foals until euthanasia at month 3. At necropsy, the treated femurs were 4, 8, and 27 mm shorter than their mates. Epiphyseal viability was verified in all three foals by tetracycline deposition and new appositional bone growth comparable with that in the contralateral control epiphyses. The treated capital physis was open but reduced in thickness in one foal, disorganized in one foal, and closed in one foal. Fixation by compression with the implant system resulted in stability sufficient for fracture healing and maintenance of epiphyseal viability, although it was associated with reduced longitudinal femoral growth.