Effects of Carbon Dioxide Insufflation Combined With Changes in Body Position on Blood Gas and Acid-Base Status in Anesthetized Llamas (Llama glama)

Objective— To study the combined effects of intra-abdominal CO₂ insufflation with changes in body position during laparoscopy in xylazine-ketamine-halothane anesthetized llamas. Study Design— Prospective, controlled study. Animals— Nine castrated, male llamas weighing 114 ± 23 kg, 3 to 13 years old. Methods— Three llamas (preliminary study [PS] group) were used to study the effect of right lateral, dorsal, and left lateral recumbency on gas exchange and acid-base status. The other six (experimental study [ES] group) were used to study the combined effects of changes in body position and CO₂ insufflation to an intraabdominal pressure of 10 to 12 mm Hg. Heart rate, respiratory rate, and indirect arterial blood pressures (systolic [SAP], mean [MAP], and diastolic [DAP]) were recorded every 5 minutes during anesthesia. Arterial blood gases (PaO₂ and PaCO₂) and acid-base status (pHa and HCO₃) were measured immediately after induction of anesthesia and before each change of position. Results— In the PS group, significant decreases in SAP, MAP and PaCO₂ and increases in PaO₂ and pHa were observed when the llamas were turned from right lateral to dorsal recumbency. Values for HCO_-3 were lower than the postinduction values, but they remained unaffected by the changes in position. In the ES group, values for MAP were significantly lower when the llamas were placed in dorsal and left lateral recumbency than those observed during right lateral recumbency. Arterial O₂ tension during right lateral recumbency was lower but returned to preinsufflation values when the llamas were placed in the dorsal position. All llamas recovered uneventfully within 30 minutes after termination of anesthesia. Conclusions— Insufflation of CO₂ and changing body position induce minor and transient changes in cardiovascular and respiratory function. Clinical Relevance— Laparoscopy with mild intra-abdominal CO₂ insufflation (10 to 12 mm Hg) can be used safely in spontaneously breathing llamas anesthetized with xylazine, ketamine, and halothane.     

A Biomechanical Comparison of Headless Tapered Variable Pitch and AO Cortical Bone Screws for Fixation of a Simulated Lateral Condylar Fracture in Equine Third Metacarpal Bones

OBJECTIVE: To compare drilling, tapping, and screw-insertion torque, force, and time for the 4.5-mm AO and 6.5-mm Acutrak Plus (AP) bone screws, and to compare the mechanical shear strength and stiffness of a simulated complete lateral condylar fracture of the equine third metacarpal bone (MC3) stabilized with either an AO or AP screw. STUDY DESIGN: In vitro biomechanical assessment of screw-insertion variables, and shear failure tests of a bone-screw-stabilized simulated lateral condylar fracture. SAMPLE POPULATION: Eight pairs of cadaveric equine MC3s METHODS: Metacarpi were placed in a fixture and centered on a biaxial load cell in a materials-testing system to measure torque, compressive force, and time for drilling, tapping, and screw insertion. Standardized simulated lateral condylar fractures were stabilized by either an AO or AP screw and tested in shear until failure. A paired t test was used to assess differences between screws, with significance set at P < .05. RESULTS: Insertion and mechanical shear testing variables were comparable for AO and AP insertion equipment and screws. CONCLUSION: The 6.5-mm tapered AP screw can be inserted in equine third metacarpal condyles and is mechanically comparable with the 4.5-mm AO screw for fixation of a simulated lateral condylar fracture. CLINICAL RELEVANCE: Considering the comparable mechanical behavior, the potential for less-persistent soft-tissue irritation with the headless design, and the ability to achieve interfragmentary compression by inserting the screw in one hole drilled perpendicular to the fracture plane, the 6.5-mm tapered AP screw may be an attractive alternative for repair of incomplete lateral condylar fractures in horses.     

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.     

Complications and Long-term Results after Partial Laryngectomy for the Treatment of Idiopathic Laryngeal Paralysis in 45 Dogs

Forty-five dogs with severe respiratory signs caused by idiopathic, acquired laryngeal paralysis were treated by partial laryngectomy. The predominant postoperative complications were coughing in 28 dogs and pneumonia in 15 dogs. Eight dogs required a second operation to alleviate persistent or recurrent upper airway obstruction. Results of surgery were considered excellent in 11 dogs (25%), good in 18 dogs (40%), fair in 6 dogs (13%), and poor in 10 dogs (22%). Poorer results were obtained by surgical residents than by more experienced surgeons. Death in the immediate postoperative period was related to pneumonia (8 dogs) and laryngeal collapse (1 dog). Nine dogs died later of respiratory disease. Although partial laryngectomy is effective for the treatment of laryngeal paralysis, it is not recommended because of the high incidence of postoperative complications.     

The cardiopulmonary effects of romifidine in dogs with and without prior or concurrent administration of glycopyrrolate

Objective To determine the electrocardiographic and cardiopulmonary effects of romifidine with and without prior or concurrent administration of glycopyrrolate. Study design Randomized crossover experimental study. Animals Six (three male, three female) cross‐bred dogs weighing 23 ± 2.4 kg. Methods Baseline cardiopulmonary measurements were obtained in conscious dogs and one of five treatments was administered. Glycopyrrolate (G) 0.01 mg kg^?1, or saline (S) 0.5 mL, were administered IM as premedication (Gp or Sp), or G was administered concurrently (Gc) with romifidine (RO). Treatments were as follows T1, Sp + RO 40 µg kg^?1; T2, Gp + RO (40 µg kg^?1); T3, Sp + RO 120 µg kg^?1; T4, Gp + RO (120 µg kg^?1); T5, Sp + Gc + RO (120 µg kg^?1). Romifidine or RO + Gc was administered subcutaneously 20 minutes after premedication (time 0), and further measurements were taken 10, 20, 30, 60 and 90 minutes after RO. The main treatment effect was evaluated using two‐way anova for repeated measures, followed by one‐way anova and a post‐hoc least squares difference test with a modified Bonferroni correction (p < 0.02). A Student's t‐test was used to compare the effect of romifidine at 20 and 60 minutes versus baseline values (p < 0.05). Results Both low‐ and high‐dose RO (T1, T3) significantly decreased heart rate (HR), respiratory rate (RR), cardiac index (CI) and stroke volume index, and increased arterial blood pressure (SAP), systemic vascular resistance (SVR), pulmonary arterial occlusion pressure (PAOP) and central venous pressure. High‐dose RO produced greater increases in SVR and SAP measurements. Neither dose of RO produced an alteration in blood gas values or the alveolar to arterial oxygen gradient. Glycopyrrolate significantly increased HR and CI from 10 to 90 minutes between T1/T2 and T3/T4. Increases in SAP were dose related with significant differences between T1/T3 and T2/T4 at 90 and 10 minutes, respectively, and were highest in animals receiving Gp or Gc. High‐dose RO groups (T3, T4) had higher values for SVR than low‐dose RO groups (T1, T2), unrelated to G administration. There was an increase in PAOP in all treatments. The oxygen extraction ratio was increased with all treatments: larger increases were observed in T1, T3 and T4 compared with only minimal changes in T2. Concurrent G administration was associated with an increased frequency of high‐grade second‐degree atrioventricular heart block with variable conduction at 10 and 20 minutes. Conclusions Romifidine produced effects consistent with other selective α₂‐adrenoreceptor agonists. Glycopyrrolate offset the decrease in HR and partially offset the decrease in CI associated with RO administration. Glycopyrrolate premedication produced an initial tachycardia and added to the increase in SAP associated with RO. Concurrent G administration was associated with a higher frequency of dysrhythmias and is not recommended. Despite the decrease in RR, RO sedation did not alter blood gas values. Clinical relevance It appears likely that G administration prior to or concurrent with RO produces an increase in myocardial workload and oxygen demand suggesting that this combination should not be used in dogs with cardiomyopathy or heart failure. The improvement in oxygen extraction ratio with T2 suggests that G may be beneficial with lower doses of RO, nevertheless, the use of G and RO in cardiovascularly compromised patients is not advised.     

Diaphragmatic Hernia Repair in Three Young Horses

Objective- This clinical report describes surgical correction of diaphragmatic hernia in three young horses.
Study Design- Retrospective investigation of medical records and subsequent racing performance.
Animals- Three young horses with diaphragmatic hernia.
Results- Three young horses with signs of abdominal pain had diaphragmatic hernia causing small intestinal strangulation. The strangulated small intestine was resected and an end-to-end jejuno-jejunal (two horses) or a side-to-side jejuno-cecal anastomosis (one horse) was performed. Diaphragmatic hernias were closed with a continuous suture pattern. All horses recovered and raced. No difference in race records was found between the subject horses and their siblings. One subject horse died of colic at 5 years of age, but the cause of the colic was undetermined. The remaining two horses are in use as broodmares and have produced multiple foals without recurrence of signs of diaphragmatic hernia
Conclusions- Diaphragmatic hernias can be repaired in horses. These horses can achieve race records similar to their siblings and can produce foals without recurrence of signs of diaphragmatic hernia.     

Detection of Bacteria in Equine Synovial Fluid by Use of the Polymerase Chain Reaction

Equine synovial fluid aliquots were inoculated with Salmonella enteritidis, Escherichia coli, Actinobacillus equuli, Staphylococcus aureus , and Streptococcus zooepidemicus to obtain approximate concentrations of 1000, 100, 10, and 1 colony forming U/mL. Synovial fluid aliquots were also inoculated with an unquantitated inoculum of Bacteroides fragilis and Clostridium perfringens. Inoculated synovial fluid was incubated in trypticase-soy broth or Columbia broth for approximately 12 hours. Then aliquots were removed for DNA extraction and polymerase chain reaction (PCR) analysis for detection of a 531 base-pair segment of bacterial DNA corresponding to a region of the 16S ribosomal gene. Duplicate samples of inoculated synovial fluid were prepared for microbial culture. Bacteria were detected in all samples inoculated with bacteria but not in control synovial fluid samples. Under experimental conditions there was no difference between microbial culture and PCR analyses for detection of bacteria. Experimentally, PCR was able to detect bacteria in synovial fluid within 24 hours of inoculation.