OBJECTIVE To compare the speed of onset and analgesic effect of mepivacaine deposited within or immediately outside the neurovascular bundle at the base of the proximal sesamoid bones in horses. ANIMALS 6 horses with naturally occurring forefoot-related lameness. PROCEDURES In a crossover study design, horses were randomly assigned to receive 1 of 2 treatments first, with the second treatment administered 3 to 7 days later. Trotting gait was analyzed with an inertial sensor–based motion analysis system immediately before treatment to determine degree of lameness. Afterward, ultrasound guidance was used to inject 2% mepivacaine hydrochloride around the palmar digital nerves of the affected forelimb at the level of the base of the proximal sesamoid bones either within the subcircumneural space or outside the circumneural sheath. After injection, gait was reevaluated at 5-minute intervals for 45 minutes. RESULTS Mepivacaine deposition outside the circumneural sheath did not resolve lameness in any horse; for 3 horses, the mean time to 70% reduction of initial vertical head movement was 13.3 minutes, and the remaining 3 horses had no such reduction at any point. Mepivacaine deposition within the subcircumneural space resulted in a mean time to 70% reduction of initial vertical head movement of 6.7 minutes and mean time to resolution of lameness of 21.7 minutes. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that when peripheral nerves of horses lie within a sheath, local anesthetic solution should be deposited within the sheath for an effective nerve block. If local anesthetic solution is deposited outside the sheath, the nerve block may yield erroneous results.

OBJECTIVE To determine the pharmacokinetics of hydromorphone hydrochloride after IV and IM administration in guinea pigs (Cavia porcellus). ANIMALS 8 healthy adult guinea pigs (4 sexually intact females and 4 sexually intact males). PROCEDURES In a crossover study, hydromorphone (0.3 mg/kg) was administered once IM (epaxial musculature) or IV (cephalic catheter) to each guinea pig at a 1-week interval (2 treatments/guinea pig). Blood samples were collected before and at predetermined intervals after drug administration via a vascular access port. Plasma hydromorphone concentrations were determined by liquid chromatography–tandem mass spectrometry. Noncompartmental analysis of data was used to calculate pharmacokinetic parameters. RESULTS Mean ± SD clearance and volume of distribution for hydromorphone administered IV were 52.8 ± 13.5 mL/min/kg and 2.39 ± 0.479 L/kg, respectively. Mean residence time determined for the IV and IM administration routes was 0.77 ± 0.14 hours and 0.99 ± 0.34 hours, respectively. The maximum observed plasma concentration following IM administration of hydromorphone was 171.9 ± 29.4 ng/mL. No sedative effects were observed after drug administration by either route. CONCLUSIONS AND CLINICAL RELEVANCE Pharmacokinetic data indicated that hydromorphone at a dose of 0.3 mg/kg may be administered IV every 2 to 3 hours or IM every 4 to 5 hours to maintain a target plasma concentration between 2 and 4 ng/mL in guinea pigs. Hydromorphone had high bioavailability after IM administration. Further research is necessary to evaluate the effects of other doses and administration routes and the analgesic effects of hydromorphone in guinea pigs.

OBJECTIVE To determine whether blood taurine concentrations in dogs with exocrine pancreatic insufficiency (EPI) were lower than the reference interval (200 to 350 nmol/mL) or the cutoff used to indicate taurine deficiency (< 150 nmol/mL). ANIMALS 18 dogs with clinical or presumptive subclinical EPI with residual blood samples available for taurine concentration analysis. PROCEDURES Dogs were classified as having clinical EPI if they had a serum trypsin-like immunoreactivity concentration of < 2.0 μg/L and presumptive subclinical EPI if they had a concentration of 2.0 to 5.0 μg/L. Archived, frozen blood samples stored in EDTA were submitted for measurement of taurine concentration with an automated high-performance liquid chromatography amino acid analyzer. Medical record data were examined for associations with blood taurine concentration. RESULTS None of the 18 dogs had a blood taurine concentration < 150 nmol/mL. Two dogs had a concentration < 200 nmol/mL. No clinical signs, physical examination findings, or serum biochemical abnormalities were associated with blood taurine concentration. Eleven of the 17 dogs for which diet histories were available were not receiving a diet that met recommendations of the World Small Animal Veterinary Association Global Nutrition Committee. CONCLUSIONS AND CLINICAL RELEVANCE A low blood taurine concentration was noted in a small subset of dogs with EPI. Additional research is needed to determine whether EPI was the primary cause of this low concentration. Findings suggested the importance of obtaining complete diet histories and ensuring dietary requirements are sufficiently met in dogs with EPI.

OBJECTIVE To evaluate holding security of 4 friction knots created with various monofilament and multifilament sutures in a vascular ligation model. SAMPLE 280 friction knot constructs. PROCEDURES 10 friction knots of 4 types (surgeon's throw, Miller knot, Ashley modification of the Miller knot, and strangle knot) created with 2-0 monofilament (polyglyconate, polydioxanone, poliglecaprone-25, and glycomer-631) and braided multifilament (silk, lactomer, and polyglactin-910) sutures were separately tied on a mock pedicle and pressure tested to the point of leakage. Linear regression analysis was performed to compare leakage pressures among suture materials (within friction knot type) and among knot types (within suture material). RESULTS Mean leakage pressure of surgeon's throws was significantly lower than that of all other knots tested, regardless of the suture material used. All the other knots had mean leakage pressures considered supraphysiological. Significant differences in mean leakage pressure were detected between various friction knots tied with the same type of suture and various suture types used to create a given knot. Variability in leakage pressure among knots other than the surgeon's throw was greatest for poliglecaprone-25 and lowest for polydioxanone. CONCLUSIONS AND CLINICAL RELEVANCE Most differences in knot security, although statistically significant, may not have been clinically relevant. However, results of these in vitro tests suggested the surgeon's throw should be avoided as a first throw for pedicle ligation and that poliglecaprone-25 may be more prone to friction knot slippage than the other suture materials evaluated.

OBJECTIVE To determine the effects of 2 augmentation techniques on the mechanical properties of titanium cannulated bone screws. SAMPLE 33 titanium cannulated bone screws (outer diameter, 6.5 mm; guide channel diameter, 3.6 mm). PROCEDURES 11 screws were allocated to each of 3 groups. The guide channel of each screw was filled with polymethyl methacrylate bone cement alone (OCS group) or in combination with a 3.2-mm-diameter orthopedic pin (PCS group) or remained unmodified (control group) before mechanical testing. Each screw underwent a single-cycle 3-point bending test to failure with a monotonic loading rate of 2.5 mm/min. Failure was defined as an acute decrease in resistance to load of ≥ 20% or a bending deformation of 15 mm. Mechanical properties were determined for each screw and compared among the 3 groups. RESULTS All screws in the control and OCS groups and 1 screw in the PCS group broke during testing; a 15-mm bending deformation was achieved for the remaining 10 screws in the PCS group. Maximum load and load at failure differed significantly among the 3 groups. Stiffness and load at yield for the PCS group were significantly greater than those for the control and OCS groups but did not differ between the control and OCS groups. CONCLUSIONS AND CLINICAL RELEVANCE Use of bone cement and an orthopedic pin to fill the guide channel of cannulated screws significantly increased the strength of the construct, but ex vivo and in vivo studies are necessary before this augmentation technique can be recommended for clinical patients.

In this study, we investigated whether β-glucan from Saccharomyces cerevisiae exerts beneficial effects on mucosal immunity in an ovine ruminal explant (ORE) model. Once the ORE model was established, viability was assessed through histological change, E-cadherin expression, CK-18 and Ki-67 distribution. Then, the OREs were co-cultured with β-glucan, following which, gene and protein expression levels of sheep β-defensin-1 (SBD-1), pro-inflammatory interleukin (IL)-6, and anti-inflammatory IL-10 were detected using quantitative real-time polymerase chain reaction (qPCR) and enzyme-linked immunosorbent assay (ELISA). Hematoxylin & eosin staining, qPCR, and immunohistochemistry showed that the overall ORE structure was intact after 96 hours in culture, but explants cultured for more than 24 hours showed epithelial degradation. Therefore, we performed the follow-up test within 24 hours. qPCR and ELISA revealed that the gene and protein expression levels of SBD-1, IL-6, and IL-10 in the OREs significantly increased (P < 0.05) after treatment with β-glucan compared with controls. This study identified the feasibility and optimal conditions of ORE culture and demonstrated that β-glucan activates SBD-1, IL-6, and IL-10 secretion in OREs to promote mucosal immunity.

Integrin alpha-v/beta3 (αvβ3) recognizes arginine-glycine-aspartic acid (RGD) sequences and has important functions in cell adhesion, signaling, and survival. However, the expression of integrin αvβ3 in the equine lungs and jejunum is not well understood. The objective of this study was to explore the hitherto unknown expression of integrin αvβ3 in the lungs and jejuna of the horse using light and electron immunocytochemistry. Immunohistochemistry showed integrin αvβ3 on the epithelium, the immune cells in Peyer's patches, the smooth muscle, and the endothelium of equine jejuna. In equine lungs, we recognized integrin αvβ3 on the endothelium of blood vessels, the alveolar septa, the bronchial lymph nodes, and the cartilages, although the expression of integrin αvβ3 was weak on the epithelium of bronchioles. In conclusion, these are the first data to show the expression of integrin αvβ3 in equine lungs and jejuna.

The objective of this study was to evaluate the efficacy of a modified-live virus (MLV) porcine reproductive and respiratory syndrome virus (PRRSV) vaccine against a heterologous PRRSV-2 challenge in late-term pregnancy gilts under experimental conditions. Eighteen gilts were randomly assigned to vaccinated-challenged, unvaccinated-challenged, and unvaccinated-unchallenged groups (n = 6 gilts per group). Pregnant gilts in the vaccinated-challenged and unvaccinated-unchallenged groups were able to carry their pregnancies to full term and farrowed after 114 to 115 days of gestation. In contrast, pregnant gilts in the unvaccinated-challenged group did not reach full term and farrowed early, after 104 to 108 days of gestation. Pregnant gilts vaccinated with the PRRSV-2 MLV vaccine exhibited a reduction in PRRSV-2 viremia. At the time of challenge with PRRSV-2, vaccinated gilts had relatively low levels of neutralizing antibody titers (≤ 1:16 titer), whereas the number of interferon-γ-secreting cells (IFN-γ-SC) was consistently at protective levels (IFN-γ-SC, ≥ 150 per million). Induction of cell-mediated immunity, as measured by PRRSV-2-specific IFN-γ-SC, correlated with a reduction in PRRSV-2 viremia. Duration of immunity was a minimum of 19 wk. Taken together, the results presented here suggest that vaccination of gilts with a PRRSV-2 MLV vaccine can protect against a heterologous PRRSV-2 challenge and improve the reproductive performance of late-term pregnancy gilts.

Concentrations of 64% to 70% nitrous oxide (N(2)O) provide intra-operative analgesia. Clinically, pulse oximeter estimation (SpO(2)) of oxygen (O(2)) hemoglobin saturation (SaO(2)) was observed to decrease with N2O. Absorption atelectasis from breathing O2 was thought to decrease arterial partial pressure of O2 (PaO(2)) below 70 mmHg and reduce SaO(2) and SpO(2) when N(2)O was used. Administering N(2)O from the beginning of the anesthesia might prevent atelectasis development and low PaO(2).The study was done in 2 parts (P, 0.05). In Part 1, isoflurane-anesthetized dogs undergoing ovariohysterectomy (n = 15 each group) breathed N(2)O from anesthesia start (N(2)O early) or 1 hour later (N2Olate). SpO(2), CO-oximetry values, and PaO(2) were compared to dogs breathing O(2) throughout anesthesia (control). Timing of N(2)O introduction did not affect PaO(2) (lowest = 94 mmHg), SaO(2), or SpO(2). With N(2)O, the lowest SpO(2) value was 91% and corresponded to a PaO2 of 151 mmHg. Carboxyhemoglobin increased (highest = 2.7%) and SaO(2) decreased with N2O (lowest = 96.7%). In Part 2, to replicate findings, 10 isoflurane-anesthetized dogs breathed N(2)O, then O(2). With N2O, SaO2 did not decrease, but carboxyhemoglobin increased and returned to baseline once N2O was discontinued. The dog with the highest carboxyhemoglobin (2%) had an SaO(2) of 96.8% (PaO(2) = 93 mmHg). Carboxyhemoglobin and SaO(2) changes were not clinically significant. Pulse oximetry did not reliably estimate SaO(2) but N(2)O was not always a factor.

There is evidence that perfusing the heart with a heart and lung machine is less injurious than cross-clamping the aorta and administering cardioplegia during cardiac surgery. Although mitral valve replacement has been carried out without aortic cross-clamping and cardioplegia, it has been stated that cross-clamping is necessary in order to maintain visualization and a motionless surgical field for mitral valve repair. The purpose of this study was to determine the surgical feasibility of mitral valve repair without cross-clamping the aorta and using cardioplegia. Our hypothesis was that a completely bloodless and motion-free field would not be necessary to carry out mitral valve repair with annuloplasty and synthetic chordae tendineae sutures. Papillary muscles, chordae tendineae, annulus, and mitral valve leaflets were all readily visualized. Chordae tendineae sutures were used and annuloplasty was conducted without visual obstruction or motion interference. Our results show that mitral valve repair is feasible without cross-clamping the aorta and using cardioplegia.