Dorsal Laminectomy in the Horse III. Results in Horses With Cervical Vertebral Malformation

Subtotal dorsal cervical laminectomy was used to relieve spinal cord compression due to cervical vertebral malformation in 16 horses. The majority were Thoroughbred or Quarter Horse males, 1 to 4 years old. The caudal cervical vertebrae were involved in all but two instances. A Funkquist type B laminectomy was performed and the defect filled with a free autogenous nuchal fat graft. All horses recovered from surgery without complication or deterioration in neurological status. Neurological improvement occurred in 12 cases, including six that became sound. Three horses fractured a vertebral articular process and were euthanized. A modification to the shape of the laminectomy was adopted to reduce this complication.     

Evaluation of the Palmaz Stent in the Trachea and Mainstem Bronchi of Normal Dogs

Objective — This study evaluates the efficacy of the Palmaz balloon expandable intraluminal stent in the trachea and mainstem bronchi of normal dogs. Study Design — Effects of the stent were evaluated by physical examination, thoracic radiography, respiratory tract fluoroscopy and endoscopy, tracheal diameter measurement, postmortem examination, and airway histomorphometry. Animals or Sample Population — Ten normal beagle dogs. Methods — Stent size was estimated from thoracic radiographs in awake dogs. Group I dogs (n = 4) had two stents placed: one in the thoracic trachea (TT) plus a randomly chosen mainstem bronchus (MB). Group II dogs (n = 3) had stents placed in the MB (one stent), TT (one stent), and mid- or proximal cervical trachea (CT) (one or two stents). Three dogs were used as sham-operated controls (group III). Temperature, pulse, respiration, and cough were measured twice daily. Dogs were evaluated at 21 and 49 to 56 days after stent placement, euthanatized, and tissues were collected for histomorphometric analysis of stent integration and epithelial pathology. Results — Mean tracheal diameters of awake (10.5 ±1.7 mm) and anesthetized dogs before stent implantation (13.9 ± 2.0 mm) were significantly different (P <.01). Complications associated with stent placement included acute pulmonary edema (n = 2), stent migration (n = 7), stent collapse (n = 4 CT, 2 TT, and 1 MB), and positive tracheal culture (n = 10). Group II dogs coughed more at rest, exercise, and with tracheal palpation than dogs in other groups (P <.01). Group I dogs coughed more at rest than group III dogs (P <.01). Stent integration ranged from 0 to 91.3%. Squamous metaplasia and epithelial ulceration associated with stents ranged from 0 to 57.5% and 0 to 32.7%, respectively. Conclusions — Determination of stent size should be based on measurements taken on anesthetized dogs because use of inappropriately sized stents may promote stent migration, squamous metaplasia, and/or ulceration. Epithelialization over stent struts may occur if the stent is closely associated with tracheal epithelium. Clinical Relevance — Palmaz stents do not appear to be appropriate for placement in the CT of dogs; however, with technical modifications, application in the TT and MB may be feasible.     

Cystotomy Closure: A Comparison of the Strength of Appositional and Inverting Suture Patterns

Dorsal cystotomies were performed in 60 healthy dogs. Twenty bladders were closed with a single-layer interrupted appositional suture pattern, 20 with a two-layer interrupted appositional suture pattern, and 20 with a two-layer continuous inverting suture pattern. Four dogs from each group were euthanatized at hours 0, 3, 12, 18, and 24. Mechanical strength of the cystotomy closures was evaluated by calculating the circular bursting wall tension. The single-layer interrupted appositional suture pattern was as strong as both two-layer suture patterns at hours 3, 12, 18, and 24. The two-layer interrupted appositional suture pattern was as strong as the two-layer continuous inverting suture pattern during the first 24 hours.     

XERORADIOGRAPHIC ANATOMY OF THE EQUINE DIGIT AND METACARPOPHALANGEAL REGION

The purpose of the project was to use xeroradiography to provide a reference for radiographic anatomy of the equine digit and metacarpophalangeal region. The left foredigits and metacarpophalangeal joints of a mature horse and a 30-day-old foal were radiographed, using xeroradiographic techniques. Fifteen xeroradiographs, illustrating standard projections of each area, were selected and appropriately labeled to demonstrate normal radiographic anatomy of these regions. These xeroradiographs have been used successfully for several years to teach radiographic anatomy of these areas to first-year veterinary students at North Carolina State University.     

Contact Dermatitis in Dogs and Cats: Pathogenesis,Histopathology, Experimental Induction and Case Reports*

Résumé— Une revue de la physiopathologie et de Thistopathologie des dermites de contact par allergie et irritation est présentée. Le rôle des lymphocytes, des cellules de Langerhans, des basophiles et des éosinophiles est discuté. Des résultates précédents non-publiés de dermites de contact expérimentales chez le chien sont présentées. Les résumés des cas cliniques de dermites de contact spontannées chez le chien et le chat présentées lors du 9e congrès de l'AAVD sont inclus. Les cas cliniques sont comparés aux cas expérimentaux et aux aspects histopathologiques décrits chez 1'homme. Des lésions avec un infiltrat riche en éosinophiles ont été retrouvées dans trois cas; une discussion sur la possibilité d'existence d'IgE à la surface des cellules de Langerhans entrainant à la fois une réponse de type I et de type IV chez ces patients est développée. [Walder, E. J., Conroy, J. D. Contact dermatitis in dogs and cats: pathogenesis, histopathology, experimental induction and case reports (Dermite de contact chez le chien et le chat: pathogénie, histopathologie, induction expérimentale et cas cliniques). Resumen— Se revisa la fisiopatología e histopatología de la dermatitis por contacto alérgica y por irritación en la especie humana y en los animales. Se discute el papel de los linfocitos, las células de Langerhans, los basófilos y los eosinófilos. Se presentan datos sobre la dermatitis por contacto alérgica y por irritación en el perro no descritos hasta la fecha. Se incluyen los resumenes de los casos clinicos presentados en las das jornadas de la Academia Americana de Dermatología Veterinaria. Se comparan los casos clinicos con los hallazgos expérimentales en el perro y con las caracteristícas histopatológicas recientemente descritas en la especie humana. En tres casos se descubrieron vesiculo-pústulas con abundantes eosinófilos; se especula con la posibilidad de que células de Langerhens cargadas con IgE induzcan reacciones mixtas de hipersensibilidad de tipo I y IV (“atopia por contacto”). [Walder, E. J., Conroy, J. D. Contact dermatitis in dogs and cats: pathogenesis, histopathology, experimental induction and case reports (Dermatitis por contacto en el perro y en el gato: patogénesis, histopatología, reproducción experimental y casos clínicos). Zusammenfassung— Es erfolgt eine übersicht über Pathophysiologie und Histopothologie der irritativen und allergischen Kontakdermatitis das Mensch und Tier. Es werden die Rollen der Lymphozyton, Langerhans Zellen, basne und eosinophilen Granulozyten diskutiert. Es werden unveröffentlichte Daten über experimentelle irritative und allergische Kontaktdermatitis bei Hunden vorgestellt. Die Zusammenfassungen von Fallstudien spontaner Kontaktdermatitis bei Hund und Katze, veröffentlicht beim 9. Jahrestreffen der American Academy of Veterinary Dermatology werden miteingeschlossen. Die Fallstudien werden mit den experimentellen Ergebnissen beim Hund und mit den klassischen und kürzlich beschriebenen histopatholo-gischen Bildern beim Menschen verglichen. In drei Fällen wurden vesikulopustulöse Veränderungen, reich an ensinophilen Granulozyten, festgestellt; es werden Mutmaßungen über die Möglichkeit von IgE-tregenden Langerhans-Zellen angstellt, die überlappende Typ I- und Typ IV-Reaktionen (“Kontaktatopie”) bei diesen Patienten induzieren. [Contact dermatitis in dogs and cats: pathognesis, histopathology, experimental induction, and case reports (Kontaktdermatitis bei Hund und Katze: Pathogenese, Histopathologie, experimentelle Induktion und Fallstudien). Abstract— The pathophysiology and histopathology of irritant and allergic contact dermatitis in man and animals are reviewed. The roles of lymphocytes, Langerhans cells, basophils and eosinophils are discussed. Previously unreported data on experimental irritant and allergic contact dermatitis in dogs are presented. The abstracts of case reports of spontaneous contact dermatitis in dogs and cats presented at the Ninth Annual American Academy of Veterinary Dermatology Meeting are included. The case reports are compared to the experimental findings in dogs and to classical and recently-described histopathologic features in humans. Eosinophil-rich, vesiculopustular lesions were found in three cases; speculation is made regarding the possibility of lgE-bearing Langerhans cells inducing overlap Type I and Type IV hypersensitivity reactions (“contact atopy”) in these patients.     

Surgical Treatment of Priapism in a Stallion

Priapism occurred in a stallion after the administration of acetylpromazine. When conservative measures failed, the corpus cavernosum penis (CCP) was drained and irrigated, and a vascular shunt between the erectile bodies was created. Subsidence of erection resulted, but subsequently, the stallion was unable to retract or erect the penis. The stallion was castrated and the penis was surgically retracted into the sheath.     

Exposure and Postoperative Stability of Three Medial Surgical Approaches to the Canine Elbow

Articular cartilage exposure and immediate postoperative stability provided by three medial surgical approaches in canine cadaver elbows were compared. The approaches evaluated were a desmotomy of the medial collateral ligament (DMCL) that included a tenotomy of the pronator teres muscle, a longitudinal myotomy of the flexor carpi radialis (MFCR), and an osteotomy of the medial epicondyle (OME). Nondestructive biomechanical testing was performed before the surgical approach and repeated after surgery. The stiffness at 13 valgus deviation of the elbow and energy absorption up to 13 valgus deviation of the elbow were determined from the pre-operative and postoperative torque-rotation curves. The perimeters of the ulnar and humeral articular cartilage that were visualized through the approach were scored with a dental pick. Latex casts were made of articular surfaces of the elbow. The humeral and ulnar articular exposures were determined by computerized planimetric analysis of latex cast photocopies. The humeral cartilage exposure of the OME approach was significantly greater than either the MFCR or DMCL approaches. The DMCL approach provided a significantly greater humeral cartilage exposure than the MFCR approach. All three approaches provided statistically similar percentages of ulnar cartilage exposure. The stiffness and energy absorption of the OME and MFCR approaches were similar and significantly greater than the DMCL approach. The OME approach provided the best combination of exposure and immediate postoperative stability.     

Cardiopulmonary effects of clenbuterol in the horse

Clenbuterol, a bronchospasmolytic agent (β₂ agonist) was studied in terms of its hemodynamic and airflow response in eight, healthy horses. Four animals were instrumented to record intrapleural pressure and air flow, these were used to compute pulmonary resistance, peak flow rates, and tidal volumes. Four animals were instrumented to record pulmonary arterial pressure, carotid arterial pressure, cardiac output, and arterial gas tensions. After control values were recorded, clenbuterol (0.8 μg/kg) was intravenously administered to each horse in each experiment group.
Following clenbuterol administration, non-elastic resistance of the lung or pulmonary resistance significantly decreased, 33.6% reduction at 10 min post-clenbuterol. Pulmonary resistance remained lowered during the entire procedure and showed no tendency of returning toward control values by 3 h post-clenbuterol. Within 30 sec following clenbuterol injection carotid arterial pressure decreased (mean pressure decrease 28.2%). Accompanying the change in arterial pressure, the heart rate drastically increased, 99.0%. Both changes were transient and returned to control ranges within 2 min.
Clenbuterol appears to be effective in reducing non-elastic resistance of the lung, however intravenous administration to an animal with pre-existing cardiovascular or cardiopulmonary disease should be avoided.     

ULTRASONOGRAPHIC FINDINGS IN CAIRN TERRIERS WITH PRECLINICAL RENAL DYSPLASIA

Renal dysplasia is a hereditary disease characterized by abnormal differentiation of renal tissue. The ultrasonographic appearance of dysplastic canine kidneys has been reported in the late stage of the disease where inflammatory and degenerative changes are already present and the dogs are in chronic renal failure. In this study, we describe the ultrasonographic appearance of the kidneys of five related Cairn Terriers affected with renal dysplasia before the onset of clinical or laboratory evidence of renal failure. Common findings included poor corticomedullary definition and multifocal hyperechoic speckles in the renal medulla, or a diffusely hyperechoic medulla. Severity of ultrasonographic changes was related to the severity of histopathologic findings. The ability to detect dysplastic changes before clinical signs develop makes ultrasound a potentially useful screening method for canine renal dysplasia.