Growth and functional assessment of pulmonary valves in pigs after replacement of sinuses of Valsalva.

Neopulmonary artery stenosis may occur after the arterial switching procedure to correct transposition of the great arteries. One technique to reduce this complication is to use a single rectangular piece of autogenous pericardium to reconstruct two adjacent sinuses of Valsalva and maintain pulmonary artery size. The long-term effect of this technique on pulmonary artery and valve growth and function is unknown. To assess this technique, Yorkshire-cross pigs (n = 5) weighing 29 +/- 1.7 kg (mean +/- SEM) were anesthetized, and during cardiopulmonary bypass, the pulmonary artery was transected distal to the pulmonary valve. Pulmonary artery diameter and commissure distances were measured. Two adjacent pulmonary artery sinuses of Valsalva were completely excised from the anulus to 4 mm distal to the commissures, leaving 2 mm of pulmonary artery tissue attached to the skeletonized commissure and on each side of the one remaining intact sinus of Valsalva. A single rectangular patch of fresh autologous pericardium was sutured to the anulus and remnant of the pulmonary artery along the commissure and edges of the one intact sinus of Valsalva. Pericardium composed two thirds of the circumference of the proximal pulmonary artery; this was anastomosed to the distal pulmonary artery. Weight gain occurred at a rate of 0.6 kg/day (median). The animals underwent right heart catheterization and cineangiography. They were killed 157.2 +/- 12.9 days post-operatively. The reconstructed pulmonary artery grew from 17.6 +/- 0.8 mm to 30.8 +/- 1.5 mm (p < 0.01), and the commissure distances grew from 17.0 +/- 1 mm to 27.2 +/- 1.6 mm (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of skin graft preparation and graft survival on the secondary contraction of full-thickness skin grafts in dogs.

The effects of 4 skin grafting techniques and graft survival on the secondary contraction of full-thickness skin grafts were evaluated. A total of 48 skin grafts were done on 12 dogs, with 2 skin grafts placed on both sides of the thorax of each dog. The grafting techniques included the sheet graft, sheet graft with continuous low-level suction provided by a butterfly catheter and evacuated glass tube, pie-crust graft, and nonexpanded mesh graft. Graft viability was assessed by visual inspection 10 days after surgical operation. Thirty skin grafts (64%) had a viability of 90% or greater. The final area of these grafts ranged from 73% to 119% of the original area. The secondary graft contraction followed a similar pattern for all graft types. During the first 10 days after surgical operation, the grafts contracted to 83% of their original area. Enlargement of the grafts began between 10 and 21 days after surgical operation. By 12 weeks, the grafts had attained a mean value of 96% of the original area. A significant difference in final area was not observed among graft types. Grafts with a high percentage of viability generally contracted less than those with larger areas of necrosis, but statistical relationship between viability and degree of contraction could not be proven. The results of the present study indicate that full-thickness skin grafts may be successfully done in dogs and that the grafts can be expected to undergo minimal postoperative contraction when graft survival is nearly complete.

Transcutaneous oxygen monitoring for predicting skin viability in dogs.

Transcutaneous oxygen (PO2-TC) monitoring is commonly used in human medicine for evaluating skin viability. The application of transcutaneous monitoring for evaluating skin viability in dogs was investigated. The changes in PO2-TC values were measured from 16 avascular skin flaps created along the lateral hemithoraces of 4 dogs. Transcutaneous oxygen values were serially recorded from the vascular base and avascular apex of each flap for 12 hours after surgery. A single transcutaneous measurement was obtained from each flap base and apex 24 hours after surgery. Serial arterial blood gas analyses were obtained to compare central oxygen values with PO2-TC values. Full-thickness skin biopsy specimens were harvested from the base and apex of each flap 24 hours after surgery. The flaps were observed for 4 days and then excised for histologic examination. A subjective grading scale was used to assess histologic changes. Throughout the 12-hour period and at 24 hours, a statistically significant difference was found between the PO2-TC values for apices and bases of the flaps. The mean PO2-TC for all bases was 90.9 mm of Hg +/- 3.3 SEM, and the mean PO2-TC for all apices was 21.2 mm of Hg +/- 1.8 SEM. The mean regional perfusion index (apex PO2-TC/base PO2-TC) was 0.23 +/- 0.02. The subjective numbers assigned to the biopsy specimens were statistically evaluated by using a paired Student's t test and a Wilcoxon signed-rank test. A significant difference was found between the numbers for the collective bases and apices with both tests.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of skin viability in dogs, using transcutaneous carbon dioxide and sensor current monitoring.

Transcutaneous oxygen monitoring is commonly used in human beings to assess skin viability. Little attention has been directed toward the use of transcutaneous carbon dioxide (PCO2-TC) monitoring for the same purpose. The application of PCO2-TC monitoring for evaluating skin viability in dogs was investigated. The changes in PCO2-TC and local power reference (LPR) values were measured from 16 skin flaps created along the lateral hemithoraces of 4 dogs. Transcutaneous PCO2 and LPR values were serially recorded from the base and apex of each flap for 12 hours. A single measurement was obtained from each flap base and apex 24 hours after surgery. Arterial blood gas analyses were obtained to compare central PCO2 values with peripheral skin PCO2 values. The flaps were observed for 4 days and then harvested for histologic examination. Full-thickness skin biopsy specimens were obtained 24 hours after surgery and when the flaps were harvested to evaluate the viability of the apex and base of the flaps. A subjective grade was assigned to all skin biopsy specimens during histologic examination. For all measurements, a significant difference was found between the PCO2-TC values for apices and bases of the flaps. The mean PCO2-TC for all bases was 52.66 mm of Hg +/- 2.24 (SEM), and the mean PCO2-TC for all apices was 106.4 mm of Hg +/- 2.44. The regional carbon dioxide index (apex PCO2-TC/base PCO2-TC) was 2.02. A significant difference was not found between the LPR values for bases and apices.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of three occlusive dressing materials on healing of full-thickness skin wounds in dogs.

The effects of 3 occlusive dressing materials and a standard, nonadherent dressing material on healing of full-thickness skin defects were evaluated in dogs. Two wounds measuring 2 x 2 cm were created bilaterally (4 wounds/dog) on the dorsolateral aspect of the trunk of 12 Beagles. Wound treatments were evenly distributed between 4 sites, using a Latin square design. Treatments evaluated were: equine amnion (group A), biosynthetic hydrogel dressing (group B), transparent polyethylene sheeting (group T), and a semi-occlusive rayon/polyethylene, nonadherent dressing (group C). Rates of contraction and epithelialization of group-A wounds were significantly greater than those of wounds of groups C, B, and T. On days 14, 21, and 28, mean percentage of wound contraction and mean percentage of total wound healed in group A exceeded those wounds in groups C, B, and T. On day 28, wounds in group A were significantly smaller than wounds in groups B and T, but were not significantly smaller than wounds in group C. All wounds in group A achieved 100% healing during the 28-day study period. Mean time for complete healing of group-A wounds was 21 days. The percentages of wounds completely healed by day 28 for groups B, C, and T were 25, 67, and 25%, respectively. Results indicate that use of equine amnion as an occlusive biological dressing on full-thickness wounds in dogs increases rate of healing.

Evoked potentials induced by transcranial stimulation in dogs.

Evoked potentials were induced by transcranial stimulation and recovered from the spinal cord, and the radial and sciatic nerves in six dogs. Stimulation was accomplished with an anode placed on the skin over the area of the motor cortex. Evoked potentials were recovered from the thoracic and lumbar spinal cord by electrodes placed transcutaneously in the ligamentum flavum. Evoked potentials were recovered from the radial and sciatic nerves by surgical exposure and electrodes placed in the perineurium. Signals from 100 repetitive stimuli were averaged and analyzed. Waveforms were analyzed for amplitude and latency. Conduction velocities were estimated from wave latencies and distance traveled. The technique allowed recovery of evoked potentials that had similar characteristics among all dogs. Conduction velocities of potentials recovered from the radial and sciatic nerves suggested stimulation of motor pathways; however, the exact origin and pathway of these waves is unknown.

Comparison of the degree of abdominal adhesion formation associated with chromic catgut and polypropylene suture materials.

OBJECTIVE: To evaluate the histologic pattern and biomechanical properties of adhesions caused by chromic catgut and polypropylene sutures, using an enteropexy model. DESIGN: Enteropexies were created in dogs, using chromic catgut and polypropylene suture. The adhesions associated with the enteropexies were examined histologically and mechanically. ANIMALS: 6 mixed-breed dogs weighing 16 to 20 kg. PROCEDURE: 72 enteropexies were created between the jejunum and abdominal wall. 36 sites were sutured with chromic catgut and 36 were sutured with polypropylene. 3 dogs were euthanatized after 1 week. The remaining dogs were euthanatized after 1 month. Samples of the enteropexy sites were obtained for histologic examination. The remaining sites were mechanically distracted until failure of the enteropexy site or adjacent tissue occurred. RESULTS: Histologic examination of the enteropexy sites did not reveal substantial differences in the degree of inflammation between the 2 suture types at 1 week or 1 month. The degree of inflammation decreased and the maturity of fibrous tissue formed at the enteropexy sites increased for all specimens over time. No statistically significant difference in breaking strength was observed between suture types at 1 week or 1 month. CONCLUSION: In dogs, the formation and strength of intentionally created abdominal adhesions are not increased by use of chromic catgut. CLINICAL RELEVANCE: Selection of chromic catgut suture for use in surgical procedures where adhesions are desired is unwarranted.

Regional anesthesia of the infraorbital and inferior alveolar nerves during noninvasive tooth pulp stimulation in halothane-anesthetized cats.

OBJECTIVE: To determine whether anesthesia of the infraorbital and inferior alveolar nerves abolishes reflex-evoked muscle action potentials (REMP) during tooth-pulp stimulation in halothane-anesthetized cats. ANIMALS: 8 healthy adult cats. PROCEDURE: In halothane-anesthetized cats, an anodal electrode was attached to the tooth to be stimulated and a platinum needle cathodal electrode was inserted in adjacent gingival mucosa. Cathodal and anodal electrodes were moved to the upper and lower canine, upper fourth premolar, and lower first molar teeth for stimulation; baseline REMP was recorded. A 25-gauge 1-cm needle was inserted 0.5 cm into the infraorbital canal. A 25-gauge 1-cm needle was inserted 1 cm rostral to the angular process of the ramus, and advanced 0.5 cm along the medial aspect. Chloroprocaine was injected at each site. Each tooth was stimulated every 10 minutes for 90 minutes. RESULTS: REMP was abolished within 10 minutes for all upper teeth, except for the upper canine tooth in 1 cat, and abolished within 10 minutes for lower teeth in 4 cats. In 1 cat, REMP was not abolished in the lower first molar tooth. In 3 cats, REMP was not abolished in the lower canine and first molar teeth. At 90 minutes, REMP was restored for all teeth except the lower canine tooth in 1 cat, for which REMP was restored at 120 minutes. CONCLUSIONS AND CLINICAL RELEVANCE: Regional anesthesia of the infraorbital and inferior alveolar nerves may provide dental analgesia in cats.

Androgen receptors in the pelvic diaphragm muscles of dogs with and without perineal hernia.

Levator ani and coccygeus muscle estrogen and androgen receptors were measured in 6, healthy, > or = 5-year-old, noncastrated, male Beagles (controls) and in 24 dogs with perineal hernia. Estrogen and androgen receptor analyses were performed on levator ani and coccygeus muscle specimens obtained from control dogs at the time of castration; contralateral levator ani and coccygeus muscle specimens were assayed 2 months after castration. During herniorrhaphy of dogs with perineal hernia, levator ani (non-castrated, n = 12; castrated, n = 7) and/or coccygeus (noncastrated, n = 5; castrated, n = 4) muscle biopsy specimens were obtained for estrogen and androgen receptor analyses. For estrogen and androgen receptor assays, each muscle biopsy specimen was homogenized in Tris-EDTA-glycerol buffer, and centrifuged at 30,000 x g; extracts were used for binding with ligands: [3H]methyltrienolone (3HR1881) for androgen receptors, and [3H]estradiol-17 beta for estrogen receptors. Extracts were incubated overnight at 0 to 4 C. Nonspecific binding was estimated, using 100-fold concentration of cold ligands. Bound and free hormones were separated, using hydroxylapatite batch assay. Receptor numbers for each tissue were calculated as femtomoles (fmol) per milligram of protein. Quantified data were compared between precastration and postcastration controls, using a paired t-test. One-way ANOVA and Bonferroni post-hoc test were used to compare values for precastration controls, postcastration controls, castrated dogs with perineal hernia, and noncastrated dogs with perineal hernia. Significance was set at P < 0.05.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical evaluation of a modified circumcostal gastropexy in dogs.

A modified circumcostal gastropexy was performed in 5 Greyhounds. A 3-cm-long tunnel was created between the seromuscular and submuscosal layers of the pyloric antrum. A 6- to 7-cm-long segment of the cartilaginous portion of the 10th or 11th rib was dissected free of surrounding tissues and transected; the proximal portion of the rib was inserted through the seromuscular tunnel. The transected ends of the rib were overlapped approximately 1.5 cm and sutured in apposition in a side-by-side manner. Mean time for completion of the gastropexy was 11.5 minutes. Persistence of the surgically created gastric adhesion was verified by laparoscopy and ultrasonography 6 and 18 months after surgery. Positive-contrast radiography confirmed normal anatomic position of the stomach. Important complications associated with the procedure were not detected. Results for these 5 dogs indicated that modified circumcostal gastropexy could be performed rapidly, was safe, and created long-lasting gastric fixation.

Perineal hernia in a cougar.

An 8-week-old female cougar with a history of acute perineal swelling was determined to have a perineal hernia. The hernia was repaired with the conventional suture technique. This case represents an unusual perineal hernia, which may have been congenital.

Intraosseous approach to the nasolacrimal duct for removal of a foreign body in a dog.

A Labrador retriever was evaluated because of chronic mucopurulent discharge from the left eye. A foreign body was identified in the nasolacrimal duct by use of dacryocystorhinography. Attempts to alleviate the inflammation by use of flushing and administration of antimicrobials were unsuccessful. At surgery, the infraorbital foramen was used as a landmark for a skin incision, because the nasolacrimal duct courses dorsal and parallel to the infraorbital canal. An air drill was used to remove the portion of the maxillary bone overlying the nasolacrimal duct, which exposed the intraosseous portion of the duct and allowed removal of a plant-material foreign body. The incision in the duct was allowed to heal by second intention, and the dog recovered without complications.

Paraesophageal hiatal hernia and pyloric obstruction in a dog.

Paraesophageal hiatal herniation and pyloric obstruction were diagnosed in a pup with a history of vomiting. Findings of contrast radiography included esophageal reflux, delayed gastric emptying time, and paraesophageal herniation. Exploratory celiotomy revealed increased firmness of the pylorus and a primary defect in the esophageal hiatus, which allowed gastric herniation. Nissen fundoplication was performed following reconstruction of the esophageal hiatus, and pyloroplasty was performed to relieve the gastric outlet obstruction. Pyloric biopsy findings were consistent with a diagnosis of chronic gastritis. Recovery from surgery was initially unremarkable; however, the dog died suddenly 3 weeks after surgery. Necropsy revealed a large diaphragmatic hernia adjacent to the esophageal hiatus; the hernia had resulted in incarceration of the abdominal organs. The hiatal hernia reconstruction remained intact and was not the cause of the diaphragmatic disruption.

Paraparesis caused by epidural granuloma in a cat.

Caudal paraparesis in a cat was determined to be caused by an epidural mass. Surgical decompression was performed, and the mass was determined to be a granuloma. Fusobacterium and Bacteroides spp were isolated from the granuloma. Epidural granulomas are seldom reported in dogs and cats. Decompression and administration of antibiotics led to recovery of this cat even though in human beings an unfavorable prognosis is given if neurologic deficits have developed.

Regional anesthesia of the infraorbital and inferior alveolar nerves during noninvasive tooth pulp stimulation in halothane-anesthetized dogs.

OBJECTIVE: To document that regional anesthesia of the infraorbital and inferior alveolar nerves would abolish reflex-evoked muscle action potentials (REMP) in the digastricus muscle during noninvasive stimulation of tooth pulp in halothane-anesthetized dogs. DESIGN: Prospective study. ANIMALS: 9 healthy female dogs between 2 and 6 years old. PROCEDURE: Dogs were anesthetized using halothane. An alligator clip anodal electrode was attached to the tooth to be stimulated, and a platinum needle cathodal electrode was inserted in adjacent gingival mucosa. The cathodal and anodal electrodes were moved to the left upper and lower canine, fourth premolar, and first molar teeth for sequential stimulation. Baseline recording of REMP was made for each tooth. Catheters were inserted percutaneously in the infraorbital and mandibular canals. Saline (0.9% NaCl) solution was injected at each catheterized site in 3 control dogs, and chloroprocaine hydrochloride was injected at each catheterized site in 6 test dogs. Each tooth was stimulated every 10 minutes for 90 minutes (test dogs) or every 10 minutes for 30 minutes and at 90 minutes (control dogs), and REMP was recorded. RESULTS: REMP was abolished within 10 minutes in all test dogs, except during stimulation of the lower first molar in 1 dog. In 4 dogs, duration of blockade was less than 90 minutes. The REMP was not restored within 90 minutes for the upper teeth in 1 dog and within 2 hours for all teeth in another dog. At 24 hours, REMP was restored for all teeth except the lower left canine in 1 dog. The REMP was restored for the lower left canine in that dog at 96 hours. The REMP was not abolished at any time in control dogs. CLINICAL IMPLICATIONS: Regional anesthesia of the infraorbital and inferior alveolar nerves may effectively provide analgesia for dental procedures in dogs.

Use of an ultrasonic Doppler flow detector for determining tissue viability in a dog.

An 8-month-old sexually intact female Boxer was examined because of an almost complete disarticulation of the right thoracic limb at the level of the proximal phalanges. Viability of the tissue distal to the injury was considered questionable. An ultrasonic Doppler flow detector was used to determine that circulation to the portion of the digits distal to the injury had been preserved on the palmar aspect of the foot. Orthopedic repair of the fractures of the third and fourth digits and primary skin closure of the wound was performed. Infection and instability at the fracture sites resulted in pseudoarthrosis and a valgus deformity of the digits distal to the injury. The ultrasonic Doppler flow detector provided a simple noninvasive method for determining tissue viability in the severely traumatized foot of this dog.

Bronchoesophageal fistula and transient megaesophagus in a dog.

Bronchoesophageal fistula and megaesophagus were diagnosed in a dog. Within 2 days after surgical correction of the bronchoesophageal fistula, peristalsis in the thoracic portion of the esophagus returned to normal and the esophagus resumed its normal size. The cause of the fistula was attributed to damage from a foreign body. The cause of the transient megaesophagus likely was related to the bronchoesophageal fistula.

Mesh skin grafting.

Mesh grafts are split-thickness or full-thickness skin grafts in which parallel rows of staggered slits have been cut. The mesh incisions allow the graft to be expanded to cover large defects, provide a route for drainage of blood or serum from under the graft, and increase the flexibility of the graft so that it can conform to uneven recipient beds. Meshing can be accomplished using a no. 11 scalpel blade or a special meshing machine. The use of unexpanded full-thickness mesh grafts is recommended because their cosmetic appearance equals that of sheet grafts, but the mesh incisions still allow drainage of blood and/or serum from under the graft. This technique has been very successful, with 90 to 100 per cent "take" when the grafts have been applied on healthy granulation beds.