Wound Drainage from Under Full-thickness Skin Grafts in Dogs Part II. Effect on Cosmetic Appearance

Four skin grafting procedures were performed on both sides of the chests of 12 dogs to evaluate the effect of wound drainage on the survival and cosmetic appearance of the grafts. The techniques evaluated were a sheet graft, (control), continuous low level suction, piecrust incisions, and nonexpanded mesh graft. Graft viability was assessed on the 10th postoperative day by visual inspection. The mean survival rate for all grafts was 90%. No significant difference between graft types was observed.
Hair growth on each graft was assessed 3 months postoperatively as "normal" (resembled that on the surrounding skin), "moderate" (thickness of hair growth was less than normal but would nearly conceal the underlying skin), "sparse" (a few hairs were present and the skin below was easily visible), and "none" (no hair growth). No statistical differences in categories of hair growth were detected within types or between types of grafts. Hair growth also was assessed as "acceptable" (those areas having normal and moderate hair growth) and "nonacceptable" (hair growth sparse or none). No difference between graft types was noted. All types exhibited a significantly greater area of acceptable than nonacceptable hair growth.     

The Effect of Hyperbaric Oxygen Treatment on a Compromised Axial Pattern Flap in the Cat

A pedicle skin flap based on the caudal superficial epigastric artery was created in 12 cats. The artery was ligated and the vein left intact. Six cats were treated with hyperbaric oxygen at 2 atm absolute for 90 minutes daily for 14 days, starting the day after surgery. Skin flap color was significantly better in the treated cats on days 1, 2, and 3. The amount of exudate was significantly less in the treated cats on day 3. There was no difference in the amount of swelling between treated and nontreated control cats. Although five of six of the treated cats had 100% skin flap survival, there was no significant difference in total flap survival between treated and nontreated control cats.     

Hemodynamic Effects of Atropine and Glycopyrrolate in Isoflurane-Xylazine-Anesthetlzed Dogs

Alterations in parasympathetic tone are partially responsible for xylazine's hemodynamic effects. The purpose of this study was to evaluate and compare the hemodynamic changes caused by the administration of intravenous (IV) atropine or glycopyrrolate after IV xylazine in isoflurane-anesthetized dogs. Six healthy beagles (8.2 to 10.7 kg) were used in two trials separated by 7 days. Anesthesia was induced and maintained with isoflurane in 100% oxygen with controlled ventilation. Once constant end-tidal isoflurane (1.8%) and arterial partial pressure of carbon dioxide (35 to 45 mm Hg) values were reached, baseline data were recorded and xylazine (0.5 mg/kg, IV) was given. In trial 1 atropine (0.1 mg/kg, IV) was given 5 minutes after xylazine, and in trial 2 glycopyrrolate (0.025, mg/kg, IV), was given 5 minutes after xylazine. Hemodynamic variables were recorded 3 minutes after xylazine and 3 minutes after anticholinergic administration. In trial 2, bilateral vagotomies were performed 10 minutes after glycopyrrolate, and hemodynamic variables were recorded 3 minutes later. Heart rate, cardiac index, and stroke index decreased; arterial pressure and systemic vascular resistance increased after xylazine. Heart rate, cardiac index, and rate pressure product increased after anticholinergic administration. Significant differences between atropine and glycopyrrolate were not observed in any of the hemodynamic parameters. Similarly, significant differences between glycopyrrolate and bilateral vagotomy were not observed. The authors conclude that intravenous atropine and glycopyrrolate have equivalent hemodynamic actions during the increased pressure phase after IV xylazine in isoflurane-anesthetized dogs; that intravenous atropine and glycopyrrolate produce comparable increases in heart rate and that both may increase the risk of myocardial hypoxia associated with an increase in rate pressure product; and that vagal blockade produced by high-dose glycopyrrolate (.025 mg/kg, IV) is similar to that produced by bilateral vagotomy.     

The Accuracy of Intraoperative Diagnoses Based on Examination of Frozen Sections A Prospective Comparison with Paraffin-Embedded Sections

The accuracy of diagnoses based on examination of frozen sections was determined by comparing the results to those obtained by examination of tissues prepared using conventional methods (formalin fixation, paraffin-embedded tissue). One hundred ninety-four specimens were examined using the frozen section technique; 37 were examined to confirm a tentative diagnosis or to document lymph node metastasis and the remainder were examined to diagnose an unknown pathologic process. Of the 194 specimens examined, an accurate, specific diagnosis was obtained in 161 (83%); in 19 (10%), the pathologic process was correctly identified, but a specific diagnosis was not obtained; and in 2 (1%) the diagnosis was deferred. The remaining 12 (6%) were incorrectly diagnosed by the frozen section technique. When the number of specimens in which a specific diagnosis was obtained was combined with the number of specimens in which the pathologic process was correctly identified, the overall accuracy rate of the frozen section technique was 93%. There was no difference in the accuracy of the frozen section technique based on the reason for submission of the sample, source of tissue submitted, or the type of pathologic process (i.e., inflammatory or neoplastic). Of the 12 incorrect diagnoses, 4 (33%) were because of sampling errors and 8 (67%) were caused by interpretation errors. The proposed indications for the use of intraoperative frozen sections are: 1) to determine the nature of a pathologic process for which a preoperative diagnosis has not been established, 2) to determine the extent of spread of neoplastic tissue to lymph nodes and other organs, 3) to evaluate resection margins of a neoplastic process, and 4) to clarify situations where a discrepancy exists between the preoperative cytologic or histologic diagnosis and intraoperative gross pathology.     

Treatment of Low Arterial Oxygen Tension in Anesthetized Horses with Clenbuterol

Clenbuterol (0.8 microgram/kg intravenously) was administered to 10 anesthetized horses with an abnormally low PaO2 (less than 90 mm Hg) despite controlled ventilation with an oxygen-rich gas mixture. Results were compared with those from 10 controls to which no clenbuterol was given and in which conventional methods to increase PaO2 were ongoing. Horses treated with clenbuterol had higher PaO2 values for at least 90 minutes. Clenbuterol was associated with increased heart rate and profuse sweating. Clenbuterol can be administered intravenously to increase the PaO2 of mechanically ventilated horses that have low arterial oxygen tension while under inhalation anesthesia. Further studies are warranted to define more precisely the circumstances under which clenbuterol may be used safely.     

The Effects of Plaster of Paris and Autogenous Cancellous Bone on the Healing of Cortical Defects in the Femurs of Dogs

Four one quarter inch evenly spaced circular defects were created bilaterally in the lateral femoral diaphysis of 12 clinically normal adult dogs. The defects were left unfilled (control), or were filled with one of the following: (1) plaster of Paris, (2) an equal-volume mixture of plaster of Paris and autogenous cancellous bone, and (3) autogenous cancellous bone. The degree of bone healing was evaluated radiographically and histologically at 2, 4, 6, 8, 10, and 12 weeks. Radiographically, no objective conclusions could be drawn due to the small size of the defects and limited amount of plaster of Paris implanted. Histologically, there was no inflammatory reaction to the plaster of Paris. No differences were determined in the degree of bone healing between autogenous cancellous bone, plaster of Paris, and a mixture of plaster of Paris and autogenous cancellous bone. All implants were superior to the control defect in degree of bone healing.     

Evaluation of Fibular Head Transposition for Repair of Experimental Cranial Cruciate Ligament Injury in Dogs

Unilateral cranial cruciate ligament excision and fibular head transposition (FHT) were performed on 30 adult dogs. Vertical ground reaction forces were determined using force plate data before and after surgery. Cranial drawer motion, tibial rotation, and varus-valgus motion were measured at monthly intervals. Radiographic, gross, and histological examinations of the stifle joints that had been operated on were performed 3 weeks, 4 months, and 10 months after surgery. A scoring system was used to evaluate lameness, osteophyte formation, and meniscal damage. Rank correlation coefficients were calculated between variables tested in pairs. Cranial drawer motion and abnormal tibial rotation were present in all of the joints that had been operated on. Peak vertical force and associated impulse were not restored during the study time period. Meniscal damage was noted in 25% of the dogs at month 4 and in 50% of the dogs at month 10. Progressive gross and histological deterioration of the articular cartilage was observed in all joints. Positive correlations were noted between the degree of stifle joint instability and meniscal injury or radiographic changes. FHT did not control cranial drawer motion and rotational instability, was not successful in restoring limb function, and did not prevent joint degeneration, especially meniscal damage.     

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.     

Repair of a Mandibular Defect With a Free Vascularized Coccygeal Vertebra Transfer in a Dog

Bilateral mandibular defects in a male mongrel dog were repaired. On the left side, a free vascularized coccygeal bone graft that included the median caudal artery and caudal vein was used to correct the defect. On the right side, the defect was bridged with a bone plate and screws. For further immobilization, the muzzle was temporarily taped for 3 weeks and a pharyngostomy tube was used for nutritional support. The dog was able to eat dry commercial food satisfactorily within 2 months of surgery despite mild malocclusion. Radiographs taken 2 months and 18 months postoperatively showed bony union with graft hypertrophy in the left mandible, whereas the right mandibular defect showed protracted nonunion. The results indicate that vascularized coccygeal vertebra transfer provides an alternative for the management of canine mandibular defects.     

The Effects of Surgical Isolation and Application of Polypropylene Spiral Prostheses on Tracheal Blood Flow

Tracheal blood flow before and after division of the segmental tracheal blood supply with and without application of a polypropylene spiral prosthesis was measured in dogs by radiolabeled microsphere injection. Ischemia of the central part of the trachea, from the mid-cervical to mid-thoracic regions, was observed immediately after division of the segmental tracheal blood supply with and without polypropylene spiral prosthesis application. On day 3, tracheal blood flow was significantly decreased in the central part of the trachea with and without polypropylene spiral prosthesis application. On day 7, tracheal blood flow was significantly increased throughout the trachea, with no significant differences between animals with and without prosthesis application. There was no evidence of a collateral source of blood supply to the trachea. Surgical division of the segmental tracheal blood supply of the trachea. Surgical division of the segmental tracheal blood supply of the entire trachea is not recommended.