Objective-To use computed tomography (CT) to provide a detailed description of elbow joint structures in clinically normal dogs. Animals-6 clinically normal adult mixed-breed dogs weighing 24 to 37 kg and one 12-month-old Labrador Retriever weighing 27 kg. Procedure-To perform CT of both elbow regions, dogs were anesthetized and placed in lateral recumbency. One- and 2-mm contiguous slices were obtained by use of a third generation computed tomographic scanner. Good resolution and anatomic detail were acquired from the computed tomographic images by use of a bone (window width, 3,500 Hounsfield units; window level, 500 Hounsfield units) and soft-tissue setting (window width, 400 Hounsfield units; window level, 66 Hounsfield units). After euthanasia, the forelimbs from the Labrador Retriever were removed and frozen in water at -18oC. Elbow joints were sectioned into approximately 1- mm-thick slab sections by use of an electric planer. Anatomic sections were photographed and compared with the corresponding computed tomographic images. Computed tomographic reconstructions of the elbow joint were created in sagittal and dorsal planes. Results-Structures on the computed tomographic images were matched with structures in the corresponding anatomic sections. The entire humeroradioulnar joint surface could be evaluated on the reconstructed images in the sagittal and dorsal plane. Conclusions and Clinical Relevance-Computed tomographic images provide full anatomic detail of the bony structures of the elbow joint in dogs. Muscles, large blood vessels, and nerves can also be evaluated. These results could be used as a basis for evaluation of computed tomographic images of the forelimbs of dogs with elbow joint injuries.

Objective-To determine whether changes in amplitude of the reflex-evoked muscle action potential (REMP) elicited by noninvasive dental dolorimetry (electrical stimulation of the tooth pulp) in anesthetized dogs may be used to objectively evaluate the effectiveness of IV and intrathecal (IT) administration of morphine. Animals-6 male Beagles that were 2 to 6 years old. Procedure-Dogs were used in a crossover design with at least a 5-day washout period between treatments. Each dog received morphine, saline (0.9% NaCl) solution, and oxytocin via the IV and IT routes of administration; however, only results for morphine and saline treatments were reported here. Dogs were anesthetized and prepared for noninvasive dental dolorimetry. After IV or IT administration, electrical stimulation was applied to a tooth, and REMPs of the digastricus muscle were recorded at 5-minute intervals for 60 minutes. To determine differences in REMP amplitude between treatments, a linear regression line was fitted for each dog-treatment combination. Results-The IV administration of morphine significantly inhibited REMP amplitude, compared with IV administration of saline solution. Intrathecal administration of morphine significantly inhibited REMP amplitude, compared with IT administration of saline solution. Conclusions and Clinical Relevance-Noninvasive dental dolorimetry in anesthetized dogs has promise as a technique for use in evaluating the analgesic potential of drugs administered IV and IT through evaluation of their effect on REMP amplitude recorded for the digastricus muscle.

Objective-To determine whether the hyoepiglotticus muscle has respiratory-related electromyographic activity and whether electrical stimulation of this muscle changes the position and conformation of the epiglottis, thereby altering dimensions of the aditus laryngis. Animals-6 Standardbred horses. Procedure-Horses were anesthetized, and a bipolar fine-wire electrode was placed in the hyoepiglotticus muscle of each horse. Endoscopic images of the nasopharynx and larynx were recorded during electrical stimulation of the hyoepiglotticus muscle in standing, unsedated horses. Dorsoventral length and area of the aditus laryngis were measured on images obtained before and during electrical stimulation. Electromyographic activity of the hyoepiglotticus muscle and nasopharyngeal pressures were measured while horses exercised on a treadmill at 50, 75, 90, and 100% of the speed that produced maximum heart rate. Results-Electrical stimulation of the hyoepiglotticus muscle changed the shape of the epiglottis, displaced it ventrally, and significantly increased the dorsoventral length and area of the aditus laryngis. The hyoepiglotticus muscle had inspiratory activity that increased significantly with treadmill speed as a result of an increase in phasic and tonic activity. Expiratory activity of the hyoepiglotticus muscle did not change with treadmill speed in 4 of 6 horses. Conclusions and Clinical Relevance-Findings reported here suggest that contraction of the hyoepiglotticus muscle increases dimensions of the airway in horses by depressing the epiglottis ventrally during intense breathing efforts. The hyoepiglotticus muscle may be an important muscle for dilating the airway in horses, and contraction of the hyoepiglotticus muscle may induce conformational changes in the epiglottis.

Objective-To develop a laparoscopic-assisted technique for cystopexy in dogs. Animals-8 healthy male dogs, 7 healthy female dogs, and 3 client-owned dogs with retroflexion of the urinary bladder secondary to perineal herniation. Procedure-Dogs were anesthetized, and positive pressure ventilation was provided. In the healthy male dogs, the serosal surface of the bladder was sutured to the abdominal wall. In the healthy female dogs, the serosa and muscular layer of the bladder were incised and sutured to the aponeurosis of the external and internal abdominal oblique muscles. Dogs were monitored daily for 30 days after surgery. Results-All dogs recovered rapidly after surgery and voided normally. In the female dogs, results of urodynamic (leak point pressure and urethral pressure profilometry) and contrast radiographic studies performed 30 days after surgery were similar to results obtained before surgery. Cystopexy was successful in all 3 client-owned dogs, but 1 of these dogs was subsequently euthanatized because of leakage from a colopexy performed at the same time as the cystopexy. Conclusion and Clinical Relevance-The laparoscopic-assisted cystopexy technique was quick, easy to perform, and not associated with urinary tract infection or abnormalities of urination.

Objective-To develop laparoscopic-assisted techniques for enterostomy feeding tube placement and full-thickness biopsy of the jejunum in dogs. Animals-15 healthy dogs. Procedure-Dogs were anesthetized, and positive pressure ventilation was provided. A trocar cannula for the laparoscope was inserted on the ventral midline caudal to the umbilicus. For enterostomy tube placement, a second trocar cannula was placed lateral to the right rectus abdominis muscle, and a Babcock forceps was used to grasp the duodenum and elevate it to the incision made for the cannula. The duodenum was sutured to the abdominal wall, and a feeding tube was inserted. For jejunal biopsy, a third trocar cannula was placed lateral to the left rectus abdominis muscle. A portion of jejunum was elevated to the incision for the second or third cannula, and a full-thickness biopsy specimen was obtained. A second specimen was obtained from another portion of jejunum, and retention sutures for the 2 biopsy sites were tied so that serosal surfaces of the biopsy sites were apposed to each other. Dogs were euthanatized 30 days after surgery. Results-The enterostomy tube was properly positioned and functional in all 8 dogs that underwent laparoscopic-assisted enterostomy tube placement, and sufficient samples for histologic examination were obtained from all 7 dogs that underwent laparoscopic-assisted jejunal biopsy. None of the dogs had any identifiable problems after surgery. Conclusion and Clinical Relevance-Results suggest that in dogs, laparoscopic-assisted procedures for enterostomy tube placement and jejunal biopsy are an acceptable alternative to procedures performed during a laparotomy.

Objective-To evaluate the effect of 2 cyclooxygenase (COX)-2 inhibitors on contractile activity of the circular smooth muscle layer of the equine dorsal and ventral colon. Sample Population-Samples of the dorsal and ventral colon obtained from 10 healthy horses. Procedure-Full-thickness tissue samples were collected from the dorsal colon in the area of the diaphragmatic flexure and the ventral colon in the area of the sternal flexure. Samples were cut into strips oriented along the fibers of the circular muscle layer and mounted in a tissue bath system for determination of contractile strength. Incremental amounts of etodolac, nabumetone, and indomethacin ere added, and contractile activity was recorded. Results-Response of the dorsal and ventral colon to nonsteroidal anti-inflammatory drugs (NSAIDs) was variable. Indomethacin induced the greatest reduction in contractile activity, followed by nabumetone. For etodolac, the difference from baseline values was only significantly reduced at the highest concentration used (1 × 10(-5)M) for the ventral colon. Conclusions and Clinical Relevance-The NSAIDs that are designed to target the COX-2 isoform appeared to have variable effects on the contractile activity of the equine dorsal and ventral colon. Etodolac appeared to have the least effect on contractile activity, compared with the effects attributable to nabumetone, and would potentially have the fewest adverse effects relative to motility of the dorsal and ventral colon.

Objective-To determine significant molecular and cellular factors responsible for differences in secondintention healing in thoracic and metacarpal wounds of horses. Animals-6 adult mixed-breed horses. Procedure-A full-thickness skin wound on the metacarpus and another such wound on the pectoral region were created, photographed, and measured, and tissue was harvested from these sites weekly for 4 weeks. Gene expression of type-I collagen, transforming growth factor (TGF)-β1, matrix metalloproteinase (MMP)-1, and tissue inhibitor of metalloproteinase (TIMP)-1 were determined by quantitative in situ hybridization. Myofibroblasts were detected by immunohistochemical labeling with α-smooth muscle actin (α-SMA). Collagen accumulation was detected by use of picrosirius red staining. Tissue morphology was examined by use of H&E staining. Results-Unlike thoracic wounds, forelimb wounds enlarged during the first 2 weeks. Myofibroblasts, detected by week 1, remained abundant with superior organization in thoracic wounds. Type-I collagen mRNA accumulated progressively in both wounds. More type-I collagen and TGF-β1 mRNA were seen in forelimb wounds. Volume of MMP-1 mRNA decreased from day 0 in both wounds. By week 3, TIMP-1 mRNA concentration was greater in thoracic wounds. Conclusions and Clinical Relevance-Greater collagen synthesis in metacarpal than thoracic wounds was documented by increased concentrations of myofibroblasts, type-I collagen mRNA, TGF-β1 mRNA, and decreased collagen degradation (ie, MMP-1). Imbalanced collagen synthesis and degradation likely correlate with development of exuberant granulation tissue, delaying healing in wounds of the distal portions of the limbs. Factors that inhibit collagen synthesis or stimulate collagenase may provide treatment options for horses with exuberant granulation tissue.

Objective-To determine whether intrathecal (IT) or IV administration of oxytocin will diminish amplitude of the reflex-evoked muscle action potential (REMP) in the digastricus muscle during electrical stimulation of the tooth pulp in anesthetized dogs, thus suggesting an analgesic effect for oxytocin. Animals-6 male Beagles that were 2 to 6 years old. Procedure-Dogs were used in a crossover design with at least a 5-day washout period between treatments. Each dog received morphine, saline (0.9% NaCl) solution, and oxytocin by both the IT and IV routes of administration. Noninvasive dental dolorimetry was used to assess changes in pain threshold following administration of treatments. Effectiveness of analgesia was determined on the basis of change in REMP amplitude in the digastricus muscle. Results-Morphine administered IV significantly inhibited REMP amplitude, compared with IV administration of saline solution or oxytocin. There was not a significant change in REMP amplitude between saline solution and oxytocin administered IV. Intrathecal administration of morphine significantly inhibited REMP amplitude, compared with IT administration of saline solution or oxytocin. Intrathecal administration of oxytocin significantly increased REMP amplitude, compared with IT administration of saline solution or morphine. Conclusions and Clinical Relevance-Although IV administration of oxytocin did not have an effect on REMP amplitude, compared with IV administration of saline solution, IT administration of oxytocin had the opposite effect of morphine and increased REMP amplitude of the digastricus muscle. These data do not support the use of oxytocin as an analgesic agent in dogs.

Objective-To determine the effect of a commercially available nasal strip on airway mechanics in exercising horses. Animals-6 horses (5 Standardbreds and 1 Thoroughbred). Procedure-Horses exercised on a treadmill at speeds corresponding to 100 and 120% of maximal heart rate with and without application of a commercially available nasal strip. Concurrently, tracheal pressures, airflow, and heart rate were measured. Peak inspiratory and expiratory tracheal pressures, airflow, respiratory frequency, and tidal volume were recorded. Inspiratory and expiratory airway resistances were calculated by dividing peak pressures by peak flows. Endoscopic examination of the narrowest point of the nasal cavity (ie, nasal valve) was performed in 1 resting horse before, during, and after application of a nasal strip. Results-During exercise on a treadmill, peak tracheal inspiratory pressure and inspiratory airway resistance were significantly less when nasal strips were applied to horses exercising at speeds corresponding to 100 and 120% of maximal heart rate. Application of the nasal strip pulled the dorsal conchal fold laterally, expanding the dorsal meatus. Conclusions and Clinical Relevance-The commercially available nasal strip tented the skin over the nasal valve and dilated that section of the nasal passage, resulting in decreased airway resistance during inspiration. The nasal strip probably decreases the amount of work required for respiratory muscles in horses during intense exercise and may reduce the energy required for breathing in these horses.

Objective-To evaluate postexposure prophylaxis (PEP) in dogs experimentally infected with rabies. Procedure-29 Beagles. Procedure-Dogs were sedated and inoculated in the right masseter muscle with a salivary gland homogenate from a naturally infected rabid dog (day 0). Six hours later, 5 dogs were treated by administration of 2 murine anti-rabies glycoprotein monoclonal antibodies (mAb) and commercial vaccine; 5 received mAb alone; 5 received purified, heat-treated, equine rabies immune globulin (PHT-ERIG) and vaccine; 5 received PHT-ERIG alone; 4 received vaccine alone; and 5 control dogs were not treated. The mAb or PHTERIG was administered at the site of rabies virus inoculation. Additional vaccine doses for groups mAb plus vaccine, PHT-ERIG plus vaccine, and vaccine alone were administered IM in the right hind limb on days 3, 7, 14, and 35. Results-All control dogs and dogs that received only vaccine developed rabies. In the PHT-ERIG and vaccine group, 2 of 5 dogs were protected, whereas none were protected with PHT-ERIG alone. Use of mAb alone resulted in protection in 4 of 5 dogs. Administration of mAb in combination with vaccine provided protection in all 5 dogs. Conclusions and Clinical Relevance-Current national guidelines recommend euthanasia or a 6- month quarantine for unvaccinated animals exposed to rabies. Findings from this study document that vaccine alone following severe exposure was unable to provide protection from rabies. However, vaccine combined with mAb resulted in protection in all treated dogs, revealing the potential use of mAb in PEP against rabies in naïve dogs.