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Nitric oxide (NO) is an endogenous gas that serves as a biologic messenger in many physiologic processes including neurotransmission, blood-pressure control, the immune system's ability to kill tumor cells, and wound healing. NO is produced after oxidation of L-arginine by a family of nitric oxide synthase (NOS) enzymes. Two of the NOS enzymes are present continuously and are thereby termed constitutive NOS. One of the enzymes, inducible NOS, is not typically expressed in resting cells and is induced by various substances including endotoxin, some cytokines, and microbial products. Thus, NO often has paradoxical activities. When NO is over- or underproduced, it can result in potentiation of disease states with disastrous results. This review discusses the biochemistry of NO, its functions in normal and disease states, and therapy for modulating NO production in disease states.

This study compared three methods of pain relief in dogs that had total ear canal ablation with lateral bulla osteotomy. The hypothesis was that systemic opioids with preoperative local nerve blocks would provide superior pain relief. Thirty-one dogs with chronic otitis externa were included in the study. Dogs were randomly assigned to one of three protocols: systemic opioids alone (10 dogs, group 1), systemic opioids with bupivacaine splash block (11 dogs, group 2), and systemic opioids with preoperative local bupivacaine nerve blocks (10 dogs, group 3). Twenty-one dogs had bilateral ear ablation and 10 had unilateral ablation. Pain was assessed preoperatively, at extubation, 2 hours postextubation, and 1 day postoperatively by a single observer blinded to the analgesic protocol used. Pain scores were not significantly different within or between groups, nor did unilateral versus bilateral ablation have a significant effect on the score. Mean scores were less than 3 (scale 1 to 5) for all groups at all observation times. Rough recoveries were noted in 30% of group 1 dogs, 0% of group 2, and 20% of group 3 dogs. Ninety-four percent of dogs were moderately to heavily sedated at extubation. Sixty percent of group 3 dogs remained moderately to heavily sedated 2 hours postextubation. Rectal temperature, pulse rate, respiratory rate, and postoperative change in serum cortisol levels were not significantly different between groups. Postoperative increase in blood glucose was significantly higher in groups 1 and 3 compared with preoperative levels. Twenty-three percent of the dogs required additional analgesia or tranquilization after surgery, as determined by the anesthetist; 1 dog in group 1, 2 in group 2, and 4 in group 3. Each of the three analgesic protocols provided similar pain relief in dogs undergoing total ear canal ablation.

Five dogs were diagnosed as having unilateral separation of the otic cartilages (auricular and annular). Four dogs had sustained prior trauma (hit by a car). Clinical signs were typical of ear canal stenosis and included swelling at the base of the ear (n = 2), periotic fistulation (n = 2), head tilt toward the affected side (n = 2), and pain when opening the mouth (n = 1). Palpation revealed separation of the horizontal and vertical ear canals. Otoscopic findings included a shallow ear canal and a pseudotympanic membrane across the proximal end of the auricular cartilage. Findings at surgery confirmed the diagnosis of cartilage separation and included an exudate-filled horizontal ear canal and a blind-ending vertical ear canal. Surgical treatment involved isolating the distal end of the annular cartilage (horizontal ear canal), opening and evacuating the horizontal ear canal, and suturing the open end of the annular cartilage to the skin. The length of annular cartilage was variable among the dogs, although each dog had sufficient horizontal canal to appose skin to otic epithelium. The vertical ear canal was not surgically dissected or manipulated. The mean follow-up period was 46 +/- 14 months (range, 31 to 68 months). All five dogs had patent horizontal ear canals when examined at the follow-up examination.

Two hundred dogs and cats undergoing exploratory celiotomy for reasons other than trauma were grouped by disease classification and by body system affected. There were 61 animals in which infection or inflammation predominated, 63 animals with neoplasia, and 76 animals with noninflammatory and non-neoplastic conditions. Body systems affected were digestive, lymphatic, urinary, reproductive, other, and undetermined. Seventy-three percent of the animals survived the hospitalization period; survival rates for animals with infection or inflammation, neoplasia, and other disorders were 69%, 60%, and 86%, respectively. Within the same groups, the exploratory celiotomy provided strictly diagnostic information in 72%, 79%, and 24% of the animals, and surgical treatment was provided to 28%, 21%, and 58% of the animals, respectively. Intraoperative cytologic and histologic diagnoses were consistent in 78% of the animals; the consistency rates for animals with infection or inflammation, neoplasia, and other disorders were 81%, 88%, and 59%, respectively. Complications after surgery were observed in 30% of the animals, with 60% of the complications disease related. Complications were observed in six animals with reproductive disorders (67%), six animals with urinary disease (46%), 35 animals with digestive disease (29%), and three animals with lymphatic disease (13%).

Short bowel syndrome occurred in four dogs after extensive (74% to 88%) small intestinal resection. Weight loss and diarrhea were the principal clinical signs. Treatment was based on the severity of clinical signs. One dog is alive after 27 months. Three dogs died within 3 months. The prognosis depends on the extent and site of resection, degree of intestinal adaptation, preoperative condition, and postoperative care.

Twenty-three canine pelves were tested bilaterally to determine the stiffness and strength of intact ilium and stabilized oblique iliac osteotomies that simulated a common clinical fracture. Fixation systems tested were three 4.0 mm cancellous screws inserted ventral to dorsal across the osteotomy site and one laterally placed five hole 3.5 mm dynamic compression plate. Specimens were mechanically tested to failure under torsional, axial, or axial plus bending loads. Lag screw fixation was stiffer and stronger than plate fixation in all testing modes. The differences were statistically significant (p less than .05) in the torsional and axial plus bending loading modes. Fatigue testing was performed on implanted specimens with low-level cyclic loading under axial plus bending loading conditions. Physiologic loading conditions failed to produce mechanical failure of either fixation system after 100,000 cycles.

Biomechanical analysis was performed on the cranial cruciate ligament (CCL) and three autogenous tissues used for CCL reconstruction in the canine stifle. The autogenous tissues were patellar ligament-based autografts described for over-the-top CCL replacement and included the central one third of the patellar ligament, the medial one third of the patellar ligament, and the lateral one third of the patellar ligament with fascia lata. Tension testing produced abrupt failure of the central and medial autografts but sequential failure of the lateral autograft. Structural properties were determined for the overload condition and within the load range of normal activity for the CCL (physiologic range). None of the autograft systems approached the stiffness, maximum load, and energy absorbed to maximum load of the CCL. The central and lateral autografts were stiffer, had greater maximum loads, and absorbed more energy to maximum load than the medial autograft. The central and lateral autografts had an elastic range, as defined by proportional limit, which corresponded to the physiologic range of loading for the CCL. Loads that corresponded to physiologic displacement of the lateral and central autografts were near the maximum load of the fixation site, which underscored the need for postoperative support of the repaired stifle.