Effect of Ketorolac Tromethamine on Atracurium-Induced Neuromuscular Blockade in Anesthetized Dogs

Objective —The purpose of this study was to determine the effect of ketorolac tromethamine or placebo on the neuromuscular blockade induced by an infusion of atracurium in isoflurane-anesthetized dogs. Design —Randomized, controlled trial. Animals —Six healthy, adult mixed-breed dogs (five female, one male) weighing 24.8 ± 2.8 kg. Methods —Dogs were studied on two occasions with a minimum of 7 days between studies. Dogs were induced with 5% isoflurane in oxygen and maintained with 1.6 ± minimum alveolar concentration (MAC) end-tidal isoflurane. Neuromuscular blockade was assessed using the train of-four response. Once 50% depression of the first twitch (T₁) was achieved, the atracurium infusion rate was held constant for 30 minutes. Then ketorolac, 0.5 mg/kg, or the same volume of placebo (0.9% sodium chloride solution) was administered intravenously and the atracurium infusion maintained for an additional 60 minutes. Before and at 2, 5, 10, 15, 30, and 60 minutes after ketorolac or placebo, the percent depression of T₁ and the fourth twitch to the first twitch (T₄/T₁) ratio were recorded. The atracurium infusion was discontinued and the time for T₁ to recover from 50% to 75% of its original value was recorded. At 75% T₁, edrophonium, 0.5 mg/kg intravenously, was administered to antagonize the residual blockade. Results —There was no significant difference in T₁%, T₄/T₁ ratio, or recovery time after ketorolac administration compared with placebo. Conclusions —Ketorolac, 0.5 mg/kg intravenously, has no significant effect on either atracuriuminduced neuromuscular blockade or recovery time for T₁ in isoflurane-anesthetized dogs. Clinical Relevance —The concurrent use of atracurium should not be a contraindication for the administration of ketorolac for intraoperative or postoperative analgesia.     

Xylazine-Ketamine and Detomidine-Tiletamine-Zolazepam Anesthesia in Horses

Eight horses were anesthetized three times, by intravenous administration of xylazine (1.1 mg/kg) and ketamine (2.2 mg/kg), detomidine (0.02 mg/kg) and tiletamine-zolazepam (1.1 mg/kg), or detomidine (0.04 mg/kg) and tiletamine-zolazepam (1.4 mg/kg). The sequences were randomized. The duration of analgesia and the times to sternal and standing positions were recorded. Heart rate, arterial pressure, pHa, PaCO2, and PaO2 were measured before and during anesthesia. The duration of analgesia with the two doses of detomidine-tiletamine-zolazepam, 26 +/- 4 minutes and 39 +/- 11 minutes, respectively, was significantly longer than the 13 +/- 6 minutes obtained with xylazine-ketamine. Bradycardia occurred after administration of detomidine, but heart rates returned to baseline values 5 minutes after administration of tiletamine and zolazepam. Arterial pressure was significantly higher and PaO2 significantly lower during anesthesia with detomidine-tiletamine-zolazepam than with xylazine-ketamine. Some respiratory acidosis developed with all anesthetic combinations. The authors conclude that detomidine-tiletamine-zolazepam can provide comparable anesthesia of a longer duration than xylazine and ketamine, but hypoxemia will develop in some horses.     

Rectal and Colonic Injury in the Llama Anatomic Considerations and Surgical Management in Four Llamas

Transrectal palpation in llamas can result in iatrogenic rectal and colonic injury. The purpose of this report is to define the caudal extent of the peritoneal cavity in llamas and to describe the surgical management of rectal or colonic injuries in four llamas. Measurements were made of six adult llamas during necropsy. The mean distance from the peritoneal reflection to the anus was 3.9 ± 0.1 cm (3.4 - 4.3 cm). Four llamas were examined for rectal or colonic perforations. One laceration was of partial thickness and three lacerations were of full thickness. Two of the defects were repaired by a transanal approach and two by celiotomy to facilitate removal of fecal debris and abdominal lavage. Successful repair of the rectal or colonic tears was achieved in all four llamas. Wound infection and incisional hernia occurred in both llamas that underwent celiotomy. Two llamas died 3 and 18 months later, and two llamas have survived 2 years. Rectal tears in llamas are accompanied by a high risk of peritoneal contamination, and primary closure is recommended. If fecal contamination of the abdomen has occurred, celiotomy is indicated to allow mechanical removal of fecal debris and peritoneal lavage.     

Correlation of Clinical, Radiographic, and Surgical Localization of Intervertebral Disc Extrusion in Small-Breed Dogs: A Prospective Study of 50 Cases

Objective —To compare prospectively clinical, radiographic, and surgical findings of intervertebral disc extrusion (IDE) localization in small-breed dogs and to determine the best means of lesion localization for the purpose of hemilaminectomy. Study Design —Clinical, radiographic, and surgical findings of small-breed dogs with thoracolumbar IDE were prospectively compared for agreement on lesion localization. Sample Population—50 small-breed dogs with IDE treated at the three participating veterinary hospitals were included in the study if no other confounding diseases were identified and if the owner gave permission for diagnostic tests and surgery. Methods —Clinical and surgical findings were recorded by the surgeon assigned to the case. Radiographic studies were evaluated independently by two radiologists blinded as to the clinical and surgical findings. values and 95% confidence intervals were calculated for agreement on lesion localization by clinical, radiographic, and surgical means and for agreement between radiologists. Results —K values for agreement of lesion localization were as follows: clinical versus surgical, 0.595; radiologist A versus radiologist B, 0.81; radiologist A versus surgical findings, 0.60; radiologist B versus surgical findings, 0.71. Both radiologists' interpretation of IDE localization agreed with surgical localization in 60% of cases. Conclusions —Clinical lateralization of IDE was found to be the least reliable factor of those studied for determining on which side the hemilaminectomy should be performed. Results of this study differ from those of previous studies examining the reliability of myelography to localize the site of IDE accurately. The results of this study further suggest that surgery may not be an absolute standard for determination of the localization of IDE in small-breed dogs. Clinical Relevance —Intervertebral disc extrusion in small-breed dogs frequently results in bilateral distribution of extruded material. Computed tomography or magnetic resonance imaging may be necessary to delineate completely the distribution of extruded disc material in IDE.     

Canine Axial Skeletal Osteosarcoma A Retrospective Study of 116 Cases (1986 to 1989)

Axial skeletal osteosarcomas were evaluated retrospectively in 116 dogs. Thirty-one tumors occurred in the mandible, 26 in the maxilla, 17 in the spine, 14 in the cranium, 12 in the ribs, 10 in the nasal cavity and paranasal sinuses, and 6 in the pelvis. Medium-sized and large dogs were most commonly affected. Females outnumbered males 2.1:1, but this varied with tumor location. The mean age was 8.7 years. Osteosarcomas of the rib occurred in significantly younger dogs (mean age, 5.4 years) than osteosarcomas at any other axial skeletal site. Pulmonary metastasis was diagnosed radiographically in 11.1% of the dogs. The median survival for dogs treated surgically was 22 weeks, the 1-year survival was 26.3%, and the 2-year survival was 18.4%. The tumor recurrence rate was 66.7%. Most dogs (79.6%) died or were euthanatized for problems associated with the primary tumor.     

Reverse Saphenous Conduit Flap in Cats: An Anatomic Study

The vascular anatomy of the reverse saphenous conduit flap in cats was denned by contrast radiography of both hindlimbs of 18 feline cadaver specimens. In all 36 flaps, flow of contrast medium from the femoral artery to the distal end of the flap was documented. Direct anastomosis of the superficial branch of the cranial tibial artery with the cranial branch of the saphenous artery and communication of the caudal branch of the saphenous artery with the perforating metatarsal artery, via the medial and lateral plantar arteries, was documented. The cranial branch of the medial saphenous vein was shown to anastomose with the cranial branch of the lateral saphenous vein. The presence of these anastomoses support the feasibility of the reverse saphenous conduit flap as an option for reconstruction of wounds of the metatarsus in cats.     

Flexible External Fixation for Craniodorsal Coxofemoral Luxations in Dogs

An external fixator consisting of two Ellis pins connected by a flexible band was developed and evaluated as a treatment for craniodorsal coxofemoral luxations in dogs. The technique for closed application of the fixator without injury to the coxofemoral joint or sciatic nerve was developed in six dog cadavers. The coxofemoral joints were then surgically destabilized and the limbs were manipulated through a full range of motion to assess the efficacy of the fixator in maintaining joint reduction. The fixator maintained joint reduction and stability after a surgically created craniodorsal luxation except when the femur was externally rotated 90d?. A flexible external fixator was then applied unilaterally in four healthy dogs. The dogs tolerated the fixator well and were bearing weight on the limb within 2 days after surgery; the range of motion was not limited by the fixator. The efficacy of a flexible external fixator in maintaining joint reduction after craniodorsal coxofemoral luxation was then evaluated in eight large dogs. The right coxofemoral joint in each dog was luxated surgically by removal of the dorsal joint capsule and transection of the ligament of the head of the femur and deep gluteal muscle. The joint was reduced and the fixator pins were applied in a closed fashion. In four dogs, a flexible external band was applied to the pins. Luxation did not reccur in these four dogs. The bands were not applied initially in four control dogs. Luxation occurred in three of the four control dogs within 24 hours of surgery. The joints that luxated were reduced and the flexible bands applied. Luxation did not recur after the bands were in place. The dogs tolerated the external fixators well, were bearing weight within 2 days of surgery, and walking with only minimal lameness 5 days after surgery. Luxation of the coxofemoral joints did not occur during the 2-week period in which the fixators were in place. The joints remained stable 1 week after removal of the fixators, at which time the dogs were euthanatized. Necropsy evaluation identified inflammation surrounding the pins and fibrous thickening of the dorsal joint capsule. The flexible external fixators were applied closed, maintained reduction of the coxofemoral joint after replacement of a craniodorsal luxation, and allowed weight bearing and limb usage soon after surgery. The flexible external fixator has several advantages over other methods of treating craniodorsal coxofemoral luxations. Complications noted in this study included pin tract drainage, pin loosening, and disruption of the flexible bands.     

The Effect of Trans-Stifle External Skeletal Fixation and Hyaluronic Acid Therapy on Articular Cartilage in the Dog

Transarticular external skeletal (TES) fixators were applied unilaterally to the stifle joints of 10 young adult dogs. After 4 weeks, the fixators were removed from all dogs. Two dogs were not allowed a remobilization period, whereas 8 dogs were provided with 4 additional weeks of weight-bearing activity in a kennel run. Four dogs were given high-molecular weight hyaluronic acid by intra-articular injection weekly during the remobilization period. Clinical gait evaluations and range of motion were determined during the remobilization period. Articular cartilage samples from both stifle joints of all dogs were evaluated histologically and histochemically. No significant differences in gait scores or range of motion were noted between treated and untreated dogs. Articular cartilage proteoglycan content was reduced after 4 weeks of trans-stifle external skeletal fixation as determined by loss of alcian blue (AB) histochemical staining. Improved homogeneity of histochemical staining was observed after remobilization. However, remobilization was associated with histological damage to the surface and tangential layers of articular cartilage. Remobilization combined with hyaluronic acid (HA) therapy improved histochemical staining and reduced structural damage to articular cartilage when compared with remobilization alone.     

Gradual Occlusion of Extrahepatic Portosystemic Shunts in Dogs and Cats Using the Ameroid Constrictor

Gradual occlusion of the splenic vein, using a specialized device (ameroid constrictor), was evaluated experimentally in three normal beagle dogs. Splenoportograms were used to verify that total occlusion of the splenic vein had occurred in all dogs within 4 to 5 weeks after application of the device. The ameroid constrictor (AC) was also evaluated as a method of gradual vascular occlusion in 12 dogs and two cats with single, extrahepatic, portosystemic shunts (PSS). Serum bile acid (SBA) concentrations were measured and portal scintigraphy (PS) was performed on all 14 animals preoperatively and 10, 20, 30, and 60 days postoperatively. Two dogs (14%) died from portal hypertension in the early postoperative period. One dog and one cat developed multiple acquired PSS, confirmed by mesenteric portography 90 days after the operation. Portal scintigraphy confirmed total occlusion of the primary shunt in the other 10 animals. Shunt fractions (SF), as measured by PS on postoperative days 30 and 60, declined significantly from preoperative values. Significant decreases were noted between preoperative and postoperative values for preprandial SBA on postoperative day 60 and for postprandial SBA on postoperative day 30. SBA concentrations did not correlate with SF. Based on this study, gradual vascular occlusion using the AC is recommended as a method for treatment of single, extrahepatic, PSS.