Effects of Halothane, Enflurane, and Isoflurane on Supraventricular and Ventricular Rate in Dogs With Complete Atrioventricular Block

Complete atrioventricular (AV) block was produced in 32 chloralose-anesthetized autonomically intact dogs to determine the effects of halothane, enflurane, and isoflurane on supraventricular and ventricular rate. Halothane (n = 17), enflurane (n = 6), and isoflurane (n = 9) were administered in three separate experiments in sequential minimum alveolar concentration (MAC) multiples of 0.5, 1.0, 1.5, 2.0, 1.5, and 1.0. Supraventricular rate, ventricular rate, and mean arterial blood pressure (MAP) were measured and recorded at baseline and after a 20-minute equilibration period of each inhalation anesthetic at each MAC multiple. Increasing concentrations of enflurane and isoflurane significantly decreased supraventricular rate ( P < .05). Ventricular rate was not significantly changed by sequential MAC multiples of halothane, enflurane, and isoflurane. Increasing concentrations of halothane, enflurane, and isoflurane significantly decreased MAP with enflurane producing the most significant decrease ( P < .05). Ventricular arrhythmias occurred in 5 of 17 dogs anesthetized with halothane and 1 of 9 dogs anesthetized with isoflurane. Inhalation anesthesia can significantly decrease supraventricular rate and MAP, does not alter ventricular rate, and can produce ventricular arrhythmias in dogs with complete AV block.     

Penetration of the small intestine by an unusual foreign body resulting in colic in a horse: A case report

A nine-year-old Arabian gelding was evaluated for acute abdominal pain. Based on clinical signs and the results of the diagnostic work-up, surgical exploration of the abdominal cavity was performed. An adhesion was found involving a section of jejunum, its mesentery, and the omentum. Passage of gas and/or ingesta was obstructed at that point. On closer examination of the involved bowel, a porcupine quill which had perforated throught the intestinal wall from the lumen was identified. This was believed to have been the inciting cause for the formation of the adhesion and subsequent intestinal obstruction.     

Comminuted First Phalanx Fractures in 30 Horses: Surgical vs. Nonsurgical Treatments

Comminuted first phalanx fractures were diagnosed in 30 horses. One leg was involved in each horse. Five horses were presented with open fractures. Nine horses had a portion of intact cortex (strut) extending from the proximal to distal joint. Ten horses were euthanized, including one with an open fracture, without treatment. The remaining 20 horses were treated by open reduction with a neutralization plate (8 horses, including one with an open fracture), open reduction with lag screw fixation (3 horses), lag screw fixation through stab incisions (2 horses), external coaptation with a cast (3 horses), and external skeletal fixation using a weight supporting shoe (4 horses, including 3 with open fractures).
Thirteen horses were euthanized following treatment because of persistent infection (9), chronic lameness (2), and third metacarpal bone fractures (2). Seven horses survived longer than 1 year after treatment. Six were lame and used as breeding animals, and one horse went on to race successfully. All four horses with open fractures that were treated were subsequently euthanized.
Significantly more horses with an intact strut of bone survived after treatment (4 of 7 [57%]) when compared to horses without an intact strut of bone that were treated (3 of 13 [23%]) (p < 0.05).
Invasive surgical approaches used for the repair of comminuted first phalanx fractures in this study were associated with an unacceptable infection rate (55%). Techniques involving less trauma to the compromised soft tissue around the fracture should afford a better chance for a successful outcome.     

Radiographic aspects of exercise-induced pulmonary hemorrhage in racing horses

Abnormal pulmonary radiopacities were identified in 13 racing horses in which a diagnosis of exercise-induced pulmonary hemorrhage (EIPH) had been confirmed. The lesions were in the caudal lung lobe in all horses; seven were on the right and three on the left, and the laterality for three could not be determined. In ten horses the opacities, which were large and peripherally located, obliterated the thoracophrenic angle. They merged with the silhouette of the diaphragm and had a circular or ovoid surface directed toward the hilum. The intensity of opacification of the consolidated areas varied, and they often were not sharply marginated. Dorsal displacement of the pulmonary arteries was noted in the region of the radiopacity in seven horses. Varying volumes of pleural effusion were observed in nine horses. Serial radiographic examinations were performed in seven horses. The pulmonary radiopacities cleared within ten days in two horses. In the remaining five horses, gradual resolution, characterized by a reduction in lesion size with improved margination, occurred during several months. The central region of the radiopaque lesion commonly had a patchy appearance, suggesting cavitation. Normal pulmonary vascular and interstitial markings were evident following complete resolution of these lesions. The cause of these abnormal pulmonary opacities has not been determined. Pathologic-radiologic correlations will be required to improve understanding of the pathophysiology of EIPH in the racing horse.     

TENESMUS AND STRANGURIA FROM A CYSTIC UTERINE REMNANT

A 14-year-old domestic short hair spayed female cat was examined for tenesmus and stranguria. The abdominal mass discovered was removed and found to be a cystic uterine remnant. Tenesmus and stranguria resolved following mass removal.     

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.     

Physiologic responses of feral horses to succinylcholine chloride immobilization

Five captive feral horses were immobilized at 72 hour intervals for 30 days by intramuscular administration of succinylcholine chloride (SCh) using a capture gun and dart system. The serum enzyme activities of creatine phosphokinase, glutamate-oxaloacetate transaminase, and lactate dehydrogenase and serum cortisol concentrations were monitored to assess the response to chemical immobilization in feral horses over time.Reference values for these parameters in feral horses were found to be in close agreement with those of normal, rested horses not in training. The results suggest that single, or infrequently repeated, use of succinylcholine-chloride by intramuscular administration to captive feral horses, or to otherwise unapproachable horses, could be efficiently and practically employed in field situations without major physiologic alterations and with minimal stress occurring in these horses.     

A Novel Pin Distraction Device for Arthroscopic Assessment of the Medial Meniscus in Dogs

Objective— To describe an extra-articular joint distractor for meniscal examination and treatment during canine stifle arthroscopy.
Study Design— Case series.
Animals— Dogs ≥20 kg with suspected cranial cruciate ligament (CrCL) deficiency.
Methods— A custom designed linear side bar was constructed to allow invasive pin distraction of the stifle joint. Its design efficacy for distraction of the medial joint compartment, observation and probing of the medial meniscus, and value during meniscal surgery was evaluated by clinical use.
Results— Application of the stifle distractor medial to the stifle joint using 2 negative threaded pins was easily performed percutaneously without the need of power equipment; however, unintended intra-articular placement of 1 threaded pin occurred in 2 stifles, without appreciable consequence to joint function. Observation as well as thorough probing of the caudal horn of the medial meniscus, even in the presence of a prominent remnant of the CrCL or severe periarticular fibrosis, was possible. Partial meniscectomy was effectively performed as needed without apparent damage to the associated articular surfaces.
Conclusions— Distraction and translation of the medial compartment of the stifle joint using invasive pin distraction allowed observation and palpation of the caudal horn of the medial meniscus so that assessment and treatment were readily accomplished without apparent morbidity.
Clinical Relevance— With careful attention to accurate pin placement, invasive pin distraction of the medial compartment of the canine stifle joint may improve arthroscopic evaluation and treatment of meniscal pathology.