Objective--To test the hypotheses that preparation method, exposure to shear force, and exposure to collagen affect the release of growth factors from equine platelet-rich plasma (PRP). Sample Population--PRP obtained from 6 horses. Procedures--PRP was prepared via 2 preparation methods (tube and automated) and subjected to 6 treatment conditions (resting, detergent, exposure to shear via 21- and 25-gauge needles, and exposure to collagen [10 and 20 μg/mL]). Concentrations of platelet-derived growth factor, isoform BB (PDGF-BB); transforming growth factor β, isoform 1 (TGFβ1); and insulin-like growth factor, isoform 1 (IGF-1) were quantified by use of ELISAs. Statistical analysis was conducted via repeated-measures ANOVA. Results--Platelet numbers were significantly higher in tube-prepared PRP than in automated-prepared PRP Growth factor concentrations did not differ significantly between preparation methods. Mean PDGF-BB concentration ranged from 134 to 7,157 pg/mL, mean TGFβ1 concentration ranged from 1,153 to 22,677 pg/mL, and mean IGF-1 concentration ranged from 150 to 280 ng/mL. Shear force did not affect growth factor concentrations. Dose-dependent increases in PDGF-BB and TGFβ1 were detected in response to collagen, but equalled only 10% of the estimated total platelet content. Concentrations of IGF-1 were not significantly different among treatments and negative or positive control treatments. Serum concentrations of PDGF-BB and TGFβ1 exceeded concentrations in PRP for most treatment conditions. Conclusions and Clinical Relevance--Release of growth factors from equine PRP was negligible as a result of the injection process alone. Investigation of platelet-activation protocols is warranted to potentially enhance PRP treatment efficacy in horses.

Objective—To compare the toxic effects of a Delphinium occidentale chemotype containing -(methylsuccinimido) anthranoyllycoctonine (MSAL)—type alkaloids and a D occidentale chemotype lacking MSAL-type alkaloids in mice and cattle. Animals—225 male Swiss Webster mice and 11 Black Angus steers. Procedures—4 collections of larkspur containing MSAL-type alkaloids and 4 collections of larkspur lacking MSAL-type alkaloids were used. From each collection, total alkaloid extracts (0.05 to 0.20 mL) were administered via tail-vein injection in 27 to 29 mice. Dried, finely ground plant material from 1 collection with and 1 collection without MSAL-type alkaloids (doses equivalent to 37.6 mg of total alkaloids/kg) were each administered to 8 cattle via oral gavage in a crossover experiment; 3 cattle received a single dose equivalent to 150.4 mg of total alkaloids/kg (no MSAL-type alkaloids). In mice, clinical effects were monitored; in cattle, heart rate was monitored before (baseline) and 24 hours after treatment. At the 24-hour time point, cattle were exercised as a measure of muscle weakness. Results—In mice, mean LD50 associated with alkaloid extracts prepared from plants that did or did not contain MSAL-type alkaloids was 2.3 and 54.2 mg/kg, respectively. In cattle at 24 hours after treatment, plant material containing MSAL-type alkaloids significantly increased heart rate from baseline and was associated with exercise-induced collapse; plant material lacking MSAL-type alkaloids had no similar effects. Conclusions and Clinical Relevance—Taxonomic classification of D occidentale alone was not a good indicator of the toxic risk to grazing cattle.

Objective—To determine the effects of syringomyelia on electromyography (EMG) findings, somatosensory-evoked potentials (SEPs), and transcranial magnetic motor-evoked potentials (TMMEPs) in Cavalier King Charles Spaniels (CKCSs). Animals—27 client-owned CKCSs that underwent prebreeding magnetic resonance imaging screening or investigation of clinical signs consistent with syringomyelia. Procedures—In dogs with (n = 11) and without (16) magnetic resonance imaging-confirmed syringomyelia, the median nerve in each thoracic limb was stimulated and SEPs were recorded over the C1 vertebra; onset latency and latency and amplitude of the largest negative (N1) and positive (P1) peaks were measured. The TMMEPs were recorded bilaterally from the extensor carpi radialis and tibialis cranialis muscles; onset latencies in all 4 limbs were measured. Bilateral systematic needle EMG examination was performed on the cervical epaxial musculature, and the number of sites with spontaneous activity was recorded. Results—In dogs with syringomyelia, amplitudes of N1 and P1 and the amplitude difference between P1 and N1 were significantly smaller than those recorded for dogs without syringomyelia (approx 2-fold difference). No difference in SEP latencies, TMMEP latencies, or the proportion of dogs with > 2 sites of spontaneous activity detected during EMG examination was detected between groups. Conclusions and Clinical Relevance—Results indicated that SEP amplitude at the C1 vertebra was a more sensitive measure of spinal cord function in CKCSs with syringomyelia, compared with results of EMG or TMMEP assessment. Measurement of SEP amplitude may have use as an objective assessment of the evolution and treatment of this disease.

Objective—To evaluate and compare circulating concentrations of islet amyloid polypeptide (IAPP), insulin, and glucose in nondiabetic cats classified by body condition score (BCS) and in cats with naturally occurring diabetes mellitus. Animals—109 (82 nondiabetic, 21 nonketoacidotic diabetic, and 6 ketoacidotic diabetic) cats. rocedures—Cats were examined and BCSs were assessed on a scale of 1 to 9. After food was withheld for 12 hours, blood was collected and plasma concentrations of IAPP and serum concentrations of insulin and glucose were measured. Differences in these values were evaluated among nondiabetic cats grouped according to BCS and in diabetic cats grouped as ketoacidotic or nonketoacidotic on the basis of clinicopathologic findings. Correlations were determined among variables. Results—In nondiabetic cats, BCS was significantly and positively correlated with circulating IAPP and insulin concentrations. Mean plasma IAPP concentrations were significantly different between cats with BCSs of 5 and 7, and mean serum insulin concentrations were significantly different between cats with BCSs of 5 and 8. Serum glucose concentrations were not significantly different among nondiabetic cats. Mean IAPP concentrations were similar between nonketoacidotic diabetic cats and nondiabetic cats with BCSs of 8 or 9. Mean IAPP concentrations were significantly reduced in ketoacidotic diabetic cats, compared with those of nondiabetic cats with BCSs of 6 through 8 and of nonketoacidotic diabetic cats. Conclusions and Clinical Relevance—Results indicated that increased BCS (a measure of obesity) is associated with increased circulating concentrations of IAPP and insulin in nondiabetic cats.

Objective—To compare in vitro axial compression, abaxial compression, and torsional stiffnesses of intact and plated radii from small- and large-breed dogs. Sample—Radii from 18 small-breed and 9 large-breed skeletally mature dogs. Procedures—3 groups were tested: large-breed dog radii plated with 3.5-mm limited-contact dynamic compression plates (LCDCPs), small-breed dog radii plated with 2.0-mm dynamic compression plates (DCPs), and small-breed dog radii plated with 2.0/2.7-mm cut-to-length plates (CTLPs). The axial compression, abaxial compression, and torsional stiffnesses of each intact radius were determined under loading with a material testing machine. An osteotomy was performed, radii were plated, and testing was repeated. The stiffness values of the plated radii were expressed as absolute and normalized values; the latter was calculated as a percentage of the stiffness of the intact bone. Absolute and normalized stiffness values were compared among groups. Results—The absolute stiffnesses of plated radii in axial and abaxial compression were 52% to 83% of the intact stiffnesses in all fixation groups. No difference was found in torsion. There was no difference in normalized stiffnesses between small-breed radii stabilized with CTLPs and large-breed radii stabilized with LCDCPs; however, small-breed radii stabilized with DCPs were less stiff than were any other group. Conclusions and Clinical Relevance—Plated radii of small-breed dogs had normalized stiffnesses equal to or less than plated radii of large-breed dogs. The complications typically associated with plating of radial fractures in small-breed dogs cannot be ascribed to an overly stiff bone-plate construct.

Objective—To determine selected cardiopulmonary values and baroreceptor response in conscious green iguanas (Iguana iguana) and to evaluate the use of blood gas analysis and pulse oximetry in this species. Animals—15 healthy juvenile green iguanas. Procedures—Baseline cardiopulmonary values were determined in 15 conscious iguanas breathing room air. Effects of 100% O2 inspiration were also measured (n = 6), and the baroreceptor reflex was characterized by exponential sigmoidal curve fitting analysis. Results—Conscious iguanas had a mean ± SD resting heart rate of 52 ± 8 beats/min, respiratory rate of 28 ± 6 breaths/min, and systolic, mean, and diastolic arterial blood pressures of 69 ± 10 mm Hg, 62 ± 12 mm Hg, and 56 ± 13 mm Hg, respectively. Mean arterial pH at 37°C was 7.29 ± 0.11, Pao2 was 81 ± 10 mm Hg, and Paco2 was 42 ± 9 mm Hg; corrected for a body temperature of 30°C, mean arterial pH at 37°C was 7.382 ±0.12, Pao2 was 54 ± 15 mm Hg, and Paco2 was 32 ± 7 mm Hg. Inspiration of 100% O2 did not change heart and respiratory rates but increased Pao2 to 486 ± 105 mm Hg (corrected value, 437 ± 96 mm Hg). A baroreceptor reflex was evident, with mean heart rates ranging from 30 ± 3 beats/min to 63 ± 5 beats/min and mean arterial blood pressures ranging from 42 ± 3 mm Hg to 58 ± 3 mm Hg. Conclusions and Clinical Relevance—This study provided needed information on cardiopulmonary values in healthy green iguanas, the application and limitation of arterial and venous blood gas analysis, and the accuracy of pulse oximetry.

Objective-To determine plasma concentrations and behavioral, antinociceptive, and physiologic effects of methadone administered via IV and oral transmucosal (OTM) routes in cats. Animals-8 healthy adult cats. Procedures-Methadone was administered via IV (0.3 mg/kg) and OTM (0.6 mg/kg) routes to each cat in a balanced crossover design. On the days of drug administration, jugular catheters were placed in all cats under anesthesia; a cephalic catheter was also placed in cats that received methadone IV. Baseline measurements were obtained greater than 90 minutes after extubation, and methadone was administered via the predetermined route. Heart and respiratory rates were measured; sedation, behavior, and antinociception were evaluated, and blood samples were collected for methadone concentration analysis at predetermined intervals for 24 hours after methadone administration. Data were summarized and evaluated statistically. Results-Plasma concentrations of methadone were detected rapidly after administration via either route. Peak concentration was detected 2 hours after OTM administration and 10 minutes after IV administration. Mean +/- SD peak concentration was lower after OTM administration (81.2 +/- 14.5 ng/mL) than after IV administration (112.9 +/- 28.5 ng/mL). Sedation was greater and lasted longer after OTM administration. Antinociceptive effects were detected 10 minutes after administration in both groups; these persisted greater than 2 hours after IV administration and greater than 4 hours after OTM administration. Conclusions and Clinical Relevance-Despite lower mean peak plasma concentrations, duration of antinociceptive effects of methadone was longer after OTM administration than after IV administration. Methadone administered via either route may be useful for perioperative pain management in cats.

Objective-To assess the accuracy of isoflurane, halothane, and sevoflurane vaporizers during high oxygen flow and at maximum dial settings at room temperature and to test sevoflurane vaporizers similarly during heating and at low-fill states. Sample-5 isoflurane, 5 halothane, and 5 sevoflurane vaporizers. Procedures-Vaporizers were tested at an oxygen flow of 10 L/min and maximum dial settings for 15 minutes under various conditions. All 3 vaporizer types were filled and tested at room temperature (21 degrees to 23 degrees C). Filled sevoflurane vaporizers were wrapped with circulating hot water (42 degrees C) blankets for 2 hours and tested similarly, and near-empty sevoflurane vaporizers were tested similarly at room temperature. During each 15-minute test period, anesthetic agent concentration was measured at the common gas outlet with a portable refractometer and temperature of the vaporizer wall was measured with a thermistor. Results-For each vaporizer type, anesthetic agent concentrations and vaporizer wall temperatures decreased during the 15-minute test period. Accuracy of isoflurane and halothane vaporizers remained within the recommended 20% (plus or minus) deviation from dial settings. Heated and room-temperature sevoflurane vaporizers were accurate to within 23% and 11.7% (plus or minus) of dial settings, respectively. Sevoflurane vaporizers at low-fill states performed similarly to vaporizers at full-fill states. Conclusions and Clinical Relevance-Under these study conditions, the isoflurane and halothane vaporizer models tested were accurate but the sevoflurane vaporizers were not. Sevoflurane vaporizer accuracy was not affected by fill state but may be improved with vaporizer heating; measurements of inspired anesthetic agent concentrations should be obtained during the use of heated vaporizers.

Objective—To determine the effect of differences in structural and mechanical tendon properties on functionality of the passive stay apparatus in horses. Sample—5 forelimbs each from nondwarf Friesians, dwarf Friesians, and ponies. Procedures—Harvested forelimbs were loaded to test the passive stay apparatus. Tendons that stabilize the distal portion of the limb (superficial digital flexor tendon, deep digital flexor tendon, and tendo interosseus [suspensory ligament]) were isolated, and force-elongation data were obtained. Bone lengths, initial tendon lengths, and initial tendon cross-sectional areas were measured, and Young moduli were calculated. A model was used to determine whether joint angles could be explained by these 4 factors only. Results—Dwarf limbs were unable to stand passively under loading because tendons that prevent overextension of the distal limb joints were too long and compliant to prevent over-extension. Tendon properties of limbs of nondwarf Friesians appeared to be intermediate between those of ponies and dwarf Friesians. Conclusions and Clinical Relevance—Dysfunction of the passive stay apparatus in dwarf Friesians could be related to differences in structural and material properties of the tendons that result in hyperextension of the joints under loading. Nondwarf Friesians had intermediate tendon properties, which might be a breed-specific variation. Results indicated that certain tendon properties were associated with load failure of the stay apparatus and provided additional information about the functionality and requirements of the passive stay apparatus.

The interaction of Bordetella bronchiseptica, toxigenic Pasteurella multocida serotype D, and the mycotoxin fumonisin B1 (FB1) was studied. On day 0 of the experiment, 28 artificially reared 3-day-old piglets were divided into 4 groups (n = 7 each): a control group (A), a group fed FB1 toxin (B), a group infected with the 2 pathogens (C), and a group infected with the 2 pathogens and fed FB1 toxin (D). The B. bronchiseptica infection [with 106 colony-forming units (CFU)/mL] was performed on day 4 and the P. multocida infection (with 108 CFU/mL) on day 16. From day 16 a Fusarium verticillioides fungal culture (dietary FB1 toxin content 10 mg/kg) was mixed into the feed of groups B and D. In groups C and D, clinical signs including mild serous nasal discharge, sneezing, panting, and hoarseness appeared from day 4, and then from day 16 some piglets had coughing and dyspnea as well. Computed tomography (CT) performed on day 16 demonstrated lung lesions attributable to colonization by B. bronchiseptica in the infected groups. By day 25 the number of piglets exhibiting lesions had increased, and the lesions appeared as well-circumscribed, focal changes characterized by a strong density increase in the affected areas of the lungs. The gross pathological findings confirmed the results obtained by CT. These results indicate that, when combined with dual infection by B. bronchiseptica and P. multocida, dietary exposure of pigs to FB1 toxin raises the risk of pneumonia and increases the extent and severity of the pathological changes.