A comparison of epidural buprenorphine with epidural morphine for postoperative analgesia following stifle surgery in dogs

Objective To compare the efficacy of epidural buprenorphine with epidural morphine for post‐operative pain relief in dogs undergoing cranial cruciate ligament rupture repair. Study design A randomized, double blind clinical trial. Animals Twenty client‐owned dogs with cranial cruciate ligament rupture. Methods Dogs were randomly assigned to receive either epidural buprenorphine (4 µg kg^?1) or epidural morphine (0.1 mg kg^?1) in a total volume of 0.2 mL kg^?1. Epidural injections were performed immediately after induction of anesthesia. End‐tidal halothane and CO₂ were recorded every 15 minutes from the time of epidural administration of drug to extubation. A numerical rating pain score system was used by a blinded observer to evaluate analgesia beginning at extubation and continuing at specific intervals for 24 hours after surgery. Heart rate, respiratory rate, and blood pressure were recorded noninvasively at the same times. If pain score indicated moderate discomfort, rescue morphine at 1.0 mg kg^?1 was administered intramuscularly. Results There were no significant differences between groups with respect to pain score, heart rate, respiratory rate, indirect blood pressure, end‐tidal halothane or end‐tidal CO₂ at any time point. Fifty percent of dogs in the buprenorphine group and 50% of dogs in the morphine group required rescue analgesic medication. Time of systemic rescue morphine administration did not differ significantly between the two groups. There were no clinically observable side‐effects from epidural administration of either drug in any of the dogs of this study. Conclusions Epidural buprenorphine is as effective as epidural morphine for the relief of postoperative hindlimb orthopedic pain in dogs. Clinical relevance Buprenorphine appears to be an effective opioid for epidural use in healthy dogs. Buprenorphine may offer certain advantages over morphine for epidural use, such as lower abuse potential and, in some clinics, reduced cost and less wastage of drug.     

Comparison of Plasma Fentanyl Concentrations by Using Three Transdermal Fentanyl Patch Sizes in Dogs

Objective—To compare plasma fentanyl concentrations attained after the application of three transdermal fentanyl patch sizes (50, 75, and 100 μg/hour) in dogs. Design—Repeated Latin square controlled study. Animals—Six intact, mixed-breed adult dogs (2 males, 4 females) weighing 19.9 ± 3.4 kg. Methods—Each dog was randomly assigned to receive each of three treatments: 50 (P50), 75 (P75), or 100 (P100) μg/hour transdermal patches. Patches were left in place for 72 hours. Jugular venous blood was collected at 1,2, 4, 8, 12, 24, 36, 48, 60, and 72 hours after patch application and for 1, 2, 4, 8, and 12 hours after patch removal. Plasma fentanyl concentrations were measured using a radioimmunoassay technique. After a 96-hour washout period, each dog was moved to another treatment group and received a different patch size. Results—The following results were obtained (mean ± SD): average plasma fentanyl concentration from 24 to 72 hours, 0.7 ± 0.2 ng/mL (P50), 1.4 ± 0.5 ng/mL (P75), 1.2 ± 0.5 ng/mL (P100); the total area under the concentration versus time curve (0 hours to infinity), 46 ± 12.2 ng/h/mL (P50), 101.2 ± 41.4 ng/h/mL (P75), 80.4 ± 38.3 ng/h/mL (P100); and the apparent elimination half-life, 3.6 ± 1.2 hours (P50), 3.4 ± 2.7 hours (P75), and 2.5 ± 2.0 hours (P100). There was a high degree of variability in plasma fentanyl concentrations achieved. Plasma fentanyl concentrations declined rapidly after patch removal. Conclusions—The attainment of steady-state plasma concentrations takes up to 24 hours, and there is a great deal of variability in the final concentrations reached in different individuals. In this study, the 100 μg/hour patches did not provide statistically increased plasma concentrations when compared with the 50 μg/hour patches. Clinical Relevance—Because of the interindividual and intraindividual variation in plasma fentanyl concentrations, patches should be applied 24 hours before the anticipated time that analgesia will be required. Adequacy of analgesia and potentially deleterious side effects, such as sedation and respiratory depression, should be monitored while the patches are in place. Skin reactions may occur, and the patches should be removed if such skin irritation is seen. After the patch is removed, it is expected that analgesia will wane rapidly because of the brief elimination half-life.     

The Efficacy of Mechanical Abrasion and Talc Slurry as Methods of Pleurodesis in Normal Dogs

OBJECTIVE: To determine the efficacy of mechanical abrasion and talc slurry as methods for pleurodesis in normal dogs. STUDY DESIGN: Experimental study. ANIMALS OR SAMPLE POPULATION: Ten normal beagle dogs. METHODS: Group I dogs had mechanical abrasion (MA) of the pulmonary and costal pleurae performed in one hemithorax with a dry gauze sponge with a median sternotomy approach. Group II dogs had 100 mL of a 1 g talc slurry (TS) administered into one hemithorax through a tube thoracostomy. Administration of the TS was visualized by using video thoracoscopy. All dogs were evaluated at 2, 10, 20, and 30 days postoperatively by means of thoracic radiography and ultrasonographic thoracic wall measurement. The dogs were euthanatized 30 days postoperatively and a gross necropsy was performed. Hemithoraces were assigned a pleurodesis score (0-4) and an obliteration grade (0-6). Tissues were collected for histopathologic examination of pulmonary pleura, costal pleura, and pleural adhesions. Pulmonary and costal pleurae were graded for the degree of fibrosis (0-4). RESULTS: Obliteration grade and costal pleural fibrosis score were significantly higher for the treated sides in the MA dogs compared with the TS dogs. MA Dogs: Mechanical abrasion dogs had pleurodesis, obliteration, and pleural fibrosis scores that were greater on the treated side than the untreated side, however, the differences were not statistically significant. Only two MA dogs had firm adhesion of the pulmonary pleura to the costal pleura in portions of the cranial and middle lung lobes in the treated hemithorax. Thoracic wall surface area covered with adhesions was 15% and 21% in each of these two dogs. The median pulmonary pleural fibrosis score of all MA dogs for the treated hemithorax was 3 compared to 0 on the untreated side. TS Dogs: There was no statistical difference for pleurodesis scores and obliteration grades between the treated and untreated sides. No dogs showed evidence of pulmonary to costal pleural adhesions. Histopathology showed talc crossover into the untreated side in all five dogs. Median pulmonary fibrosis score of the treated hemithorax was 1 compared with 0 on the untreated side. CONCLUSIONS: Neither method of pleurodesis produced sufficient pleural adhesions to obliterate the pleural space. It is possible that the degree of pulmonary pleural fibrosis present in MA dogs may be sufficient to limit air leakage from pulmonary blebs and bullae resulting in successful treatment of spontaneous pneumothorax.     

Intraosseous Cannulation and Drug Administration for Induction of Anesthesia in Chickens

Twenty-four chickens were randomly assigned to one of three treatments (ketamine, 30 mg/ kg; thiopental, 20 mg/kg; saline, 0.8 mL). Baseline data (heart rate, respiratory rate, systolic blood pressure, and cloacal temperature) were recorded before ulnar intraosseous cannulation and administration of drug treatment and for 30 minutes after administration. One investigator, unaware of the treatment administered, assessed the reaction to cannulation, number of attempts per cannulation, reaction to injection, time to induction and recovery, and quality of induction and recovery. Respiratory rate increased significantly (p < .05) from baseline after thiopental. Other parameters did not vary within groups or between groups. Most birds did not react or had a mild reaction to cannulation and injection, and on average fewer than two attempts were necessary. Quality of recovery was significantly (p < .05) better after thiopental. Time to recovery was significantly (p < .05) shorter after thiopental. No major histopathologic changes were noted in bone marrow samples from the injection site. This study demonstrates that the intraosseous route may be used to induce anesthesia in chickens, and that minimal changes in the variables studied were produced by ketamine and thiopental.     

Hepatic Lobe Torsion as a Cause of Colic in a Horse

A 14-year-old Arabian gelding was examined for colic. An exploratory celiotomy was subsequently performed and the left lobe of the liver was found to be twisted. The lobe was resected using a TA-90 surgical stapling instrument. Histologic examination of the resected liver indicated portal vein and sinusoid dilation and congestion with blood. There were focal areas of necrosis and bacterial cocci and rods throughout the section. The histologic findings were consistent with hepatic lobe torsion. After surgery, the horse was treated with broad spectrum antibiotics, anti-inflammatory drugs, heparin, and intravenous fluids. The horse recovered without complications, although serum liver enzymes remained elevated for more than 1 week after surgery. Seven months after surgery the horse showed no adverse affects from the disease.     

Controlled Cross Circulation in Dogs: Effects on Donor Hemodynamics

Controlled cross circulation (CCC) was performed in six pairs of dogs for 45 minutes with aortic cross clamping and cardioplegia. Data were collected in donor dogs at 10 minute intervals three times before, three times during, and three times after CCC and included arterial blood pressure, pulmonary capillary wedge pressure (PCWP), central venous pressure (CVP), cardiac index (CI), heart rate (HR), blood gas analysis, temperature, maximum rate of rise of left ventricular pressure dP/dt max/End diastolic volume (EDV), blood volume (BV), complete blood count (CBC) and activated clotting times (ACT). Pulse pressure (PP), systemic vascular resistance (SVR), oxygen delivery (Do₂), and left ventricular cardiac work (LVCW) were calculated. Arterial blood pressure, CVP, blood gas analysis, temperature, BV, CBC, and ACT were measured in recipient dogs. During CCC, donor hemodynamic changes resembled those observed in models of acute onset arteriovenous fistulas. Insidious BV shifts can occur despite the use of occlusive roller pumps. After CCC, donor hemodynamics resembled acute blood loss, characterized by decreases in mean arterial pressure (MAP), CVP, PCWP, and CI, and increases in SVR and dP/dt max/EDV. These changes were probably caused by pump imbalance and BV shift to the recipient dog.     

The Medial Saphenous Fasciocutaneous Free Flap in Dogs

The purpose of this study was to identify the angiosome of the medial saphenous artery and vein and to evaluate the use of this cutaneous angiosome as a free skin flap in the dog. In phase 1 of this study, selective angiography of the medial saphenous artery performed in six canine cadavers showed that the skin covering the entire medial femorotibial area, the distal half of the caudal head of the sartorius muscle, and the gracilis muscle were perfused by the medial saphenous artery. In phase 2, a medial saphenous fasciocutaneous island flap was raised and sutured back to the skin edges of the donor wound in three dogs. One hundred percent survival of all of the flaps occurred. In phase 3, a medial saphenous fasciocutaneous microvascular free flap was transferred to a wound that was created over the dorsal metacarpal (n = 3) or metatarsal region (n = 3). The mean length ± SD of the medial saphenous vascular pedicle was 80 ± 13 mm (n = 5); the mean diameter ± SD of the medial saphenous artery was 2.8 ± 0.2 mm (n = 5) and the mean diameter ± SD of the medial saphenous vein was 4.2 ± 0.2 mm (n = 5). One hundred percent of all flaps survived (n = 6). Selective angiography of the distal cranial tibial artery (metatarsal wounds, n = 3) and the median artery (metacarpal wound, n = 3) was performed 3 weeks after surgery. All of the vascular anastomoses were patent and neovascularization of the wound beds was present. This free flap was found to be acceptable for cosmetic reconstruction of wounds located on the distal extremity.     

Repair and Function of Synovium After Arthroscopic Synovectomy of the Dorsal Compartment of the Equine Antebrachiocarpal Joint

The reparative ability of equine synovium was determined by gross, histological, and ultrastructural examination. The functional potential of the synovium was estimated by examination of synovial cell organelles with transmission electron microscopy. Results from rested and exercised horses were compared to determine the effect of exercise on synovial healing. The response of the synovectomized joint to exercise was evaluated with a standardized lameness examination and by gross, histological, and histochemical observations of the articular cartilage. A 7-mm diameter motorized synovial resector was used to perform a subtotal synovectomy in 1 antebrachiocarpal joint of each of 8 horses; the contralateral joint served as a control. After 2 months rest, four randomly selected horses were rigorously exercised for the remainder of the study; the other four horses continued paddock rest. Lameness examinations and synovial fluid analyses were conducted at 0, 2, 30, 60, and 120 days. Synovium and articular cartilage from all horses were examined at necropsy at 120 days. None of the horses were lame during the study, and a transient synovitis occurred in the synovectomized joints. The hyaluronan concentration of treated joints decreased at 2 days but returned to normal by 60 days. Synovial fluid composition, including hyaluronan concentration, was unchanged by exercise. Significant cartilage damage was not observed in any of the joints. At 120 days, the healing synovium was devoid of villi and its subintima was fibrotic, however transmission electron microscopy confirmed that an intimal layer was present within the repair tissue. The cells within the repair tissue appeared actively engaged in both synthesis and phagocytosis. Exercise did not modify any of these findings. The results of this study suggest that 120 days after subtotal synovectomy, the joint environment was maintained and the resected synovium had evidence of restoration and increased metabolic potential. Synovectomized joints withstood exercise but synovial repair was not accelerated by exercise.     

Vaginourethroplasty for Treatment of Urethral Obstruction in the Bitch

Vaginourethroplasty was performed in six bitches with infiltrative, obstructive urethral disease. The initial clinical signs included dysuria, hematuria, pollakiuria, and stranguria. Diagnosis was based on the clinical signs, plain radiography and contrast vagino-urethrogram examination, and urethral biopsy. Five dogs were diagnosed as having urethral neoplasia; the sixth dog had granulomatous urethritis. In all six dogs, up to 50% of the urethra and the urethral tubercle were resected to ensure adequate surgical margins. One dog was euthanatized 4 months after surgery for recurrence of a transitional cell carcinoma at the surgical site. Long-term resolution of the problem (minimum of 12 months) was achieved in the other five dogs. The frequency of serious complications, including urinary incontinence and ascending lower urinary tract infections, was low.