OBJECTIVE To investigate regional differences of relative metabolite concentrations in the brain of healthy dogs with short echo time, single voxel proton magnetic resonance spectroscopy (1H MRS) at 3.0 T. ANIMALS 10 Beagles. PROCEDURES Short echo time, single voxel 1H MRS was performed at the level of the right and left basal ganglia, right and left thalamus, right and left parietal lobes, occipital lobe, and cerebellum. Data were analyzed with an automated fitting method (linear combination model). Metabolite concentrations relative to water content were obtained, including N-acetyl aspartate, total choline, creatine, myoinositol, the sum of glutamine and glutamate (glutamine-glutamate complex), and glutathione. Metabolite ratios with creatine as the reference metabolite were calculated. Concentration differences between right and left hemispheres and sexes were evaluated with a Wilcoxon signed rank test and among various regions of the brain with an independent t test and 1-way ANOVA. RESULTS No significant differences were detected between sexes and right and left hemispheres. All metabolites, except the glutamine-glutamate complex and glutathione, had regional concentrations that differed significantly. The creatine concentration was highest in the basal ganglia and cerebellum and lowest in the parietal lobes. The N-acetyl aspartate concentration was highest in the parietal lobes and lowest in the cerebellum. Total choline concentration was highest in the basal ganglia and lowest in the occipital lobe. CONCLUSIONS AND CLINICAL RELEVANCE Metabolite concentrations differed among brain parenchymal regions in healthy dogs. This study may provide reference values for clinical and research studies involving 1H MRS performed at 3.0 T.

OBJECTIVE To evaluate the potency of vecuronium and duration of vecuronium-induced neuromuscular blockade in dogs with centronuclear myopathy (CNM). ANIMALS 6 Labrador Retrievers with autosomal-recessive CNM and 5 age- and weight-matched control dogs. PROCEDURES Dogs were anesthetized on 2 occasions (1-week interval) with propofol, dexmedetomidine, and isoflurane. Neuromuscular function was monitored with acceleromyography and train-of-four (TOF) stimulation. In an initial experiment, potency of vecuronium was evaluated by a cumulative-dose method, where 2 submaximal doses of vecuronium (10 μg/kg each) were administered IV sequentially. For the TOF's first twitch (T1), baseline twitch amplitude and maximal posttreatment depression of twitch amplitude were measured. In the second experiment, dogs received vecuronium (50 μg/kg, IV) and the time of spontaneous recovery to a TOF ratio (ie, amplitude of TOF's fourth twitch divided by amplitude of T1) ≥ 0.9 and recovery index (interval between return of T1 amplitude to 25% and 75% of baseline) were measured. RESULTS Depression of T1 after each submaximal dose of vecuronium was not different between groups. Median time to a TOF ratio ≥ 0.9 was 76.7 minutes (interquartile range [IQR; 25th to 75th percentile], 66.7 to 99.4 minutes) for dogs with CNM and 75.0 minutes (IQR, 47.8 to 96.5 minutes) for controls. Median recovery index was 18.0 minutes (IQR, 9.7 to 23.5 minutes) for dogs with CNM and 20.2 minutes (IQR, 8 to 25.1 minutes) for controls. CONCLUSIONS AND CLINICAL RELEVANCE For the study dogs, neither potency nor duration of vecuronium-induced neuromuscular blockade was altered by CNM. Vecuronium can be used to induce neuromuscular blockade in dogs with autosomal-recessive CNM.

OBJECTIVE To determine the anabolic and lipolytic effects of a low dosage of clenbuterol administered orally in working and nonworking equids. ANIMALS 8 nonworking horses and 47 polo ponies in active training. PROCEDURES Each polo pony continued training and received either clenbuterol (0.8 μg/kg) or an equal volume of corn syrup (placebo) orally twice daily for 21 days, and then was evaluated for another 21-day period. Nonworking horses received clenbuterol or placebo at the same dosage for 21 days in a crossover trial (2 treatments/horse). For working and nonworking horses, percentage body fat (PBF) was estimated before treatment and then 2 and 3 times/wk, respectively. Body weight was measured at intervals. RESULTS Full data sets were not available for 8 working horses. For working horses, a significant treatment effect of clenbuterol was detected by day 3 and continued through the last day of treatment; at day 21, the mean change in PBF from baseline following clenbuterol or placebo treatment was −0.80% (representing a 12% decrease in PBF) and −0.32%, respectively. By day 32 through 42 (without treatment), PBF change did not differ between groups. When treated with clenbuterol, the nonworking horses had a similar mean change in PBF from baseline from day 6 onward, which peaked at −0.75% on day 18 (an 8% decrease in PBF). Time and treatment had no significant effect on body weight in either experiment. CONCLUSIONS AND CLINICAL RELEVANCE Among the study equids, long-term low-dose clenbuterol administration resulted in significant decreases in body fat with no loss in body weight.

OBJECTIVE To compare stability of hemostatic proteins in canine fresh-frozen plasma (FFP) thawed with a modified commercial microwave warmer (MCM) or warm water bath (37°C; WWB) or at room temperature (22°C). SAMPLE Fresh-frozen plasma obtained from 8 canine donors of a commercial blood bank. PROCEDURES A commercial microwave warmer was modified with a thermocouple to measure surface temperature of bags containing plasma. The MCM and a WWB were each used to concurrently thaw a 60-mL bag of plasma obtained from the same donor. Two 3-mL control aliquots of FFP from each donor were thawed to room temperature without use of a heating device. Concentrations of hemostatic proteins, albumin, and D-dimers; prothrombin time (PT); and activated partial thromboplastin time (aPTT) were determined for all samples. RESULTS Significant decreases in concentrations of factors II, IX, X, XI, fibrinogen, von Willebrand factor, antithrombin, protein C, and albumin and significant increases in PT and aPTT were detected for plasma thawed with the MCM, compared with results for samples thawed with the WWB. Concentrations of factors VII, VIII, and XII were not significantly different between plasma thawed with the MCM and WWB. Concentrations of D-dimers were above the reference range for all thawed samples regardless of thawing method. No significant differences in factor concentrations were detected between control and WWB-thawed samples. CONCLUSIONS AND CLINICAL RELEVANCE Significant differences in hemostatic protein concentrations and coagulation times were detected for plasma thawed with an MCM but not between control and WWB-thawed samples. Clinical importance of these changes should be investigated.

OBJECTIVE To evaluate the pharmacokinetics of hydrocodone (delivered in combination with acetaminophen) and tramadol in dogs undergoing tibial plateau leveling osteotomy (TPLO). ANIMALS 50 client-owned dogs. PROCEDURES Dogs were randomly assigned to receive tramadol hydrochloride (5 to 7 mg/kg, PO, q 8 h; tramadol group) or hydrocodone bitartrate–acetaminophen (0.5 to 0.6 mg of hydrocodone/kg, PO, q 8 h; hydrocodone group) following TPLO with standard anesthetic and surgical protocols. Blood samples were collected for pharmacokinetic analysis of study drugs and their metabolites over an 8-hour period beginning after the second dose of the study medication. RESULTS The terminal half-life, maximum serum concentration, and time to maximum serum concentration for tramadol following naïve pooled modeling were 1.56 hours, 155.6 ng/mL, and 3.90 hours, respectively. Serum concentrations of the tramadol metabolite O-desmethyltramadol (M1) were low. For hydrocodone, maximum serum concentration determined by naïve pooled modeling was 7.90 ng/mL, and time to maximum serum concentration was 3.47 hours. The terminal half-life for hydrocodone was 15.85 hours, but was likely influenced by delayed drug absorption in some dogs and may not have been a robust estimate. Serum concentrations of hydromorphone were low. CONCLUSIONS AND CLINICAL RELEVANCE The pharmacokinetics of tramadol and metabolites were similar to those in previous studies. Serum tramadol concentrations varied widely, and concentrations of the active M1 metabolite were low. Metabolism of hydrocodone to hydromorphone in dogs was poor. Further study is warranted to assess variables that affect metabolism and efficacy of these drugs in dogs.

OBJECTIVE To quantify concentrations of cartilage oligomeric matrix protein (COMP) and fibromodulin in synovial fluid from the tarsocrural joints (TCJs) of horses with osteochondritis dissecans (OCD) of the distal intermediate ridge of the tibia and determine whether concentrations would change following arthroscopic removal of osteochondral fragments. ANIMALS 115 client-owned horses with OCD of the TCJ and 29 control horses euthanized for unrelated reasons. PROCEDURES COMP and fibromodulin concentrations were measured in synovial fluid from the TCJs of the affected horses before and after osteochondral fragments were removed arthroscopically and in synovial fluid from the TCJs of the control horses after euthanasia. Synovial biopsy specimens from the TCJs of affected and control horses were examined histologically for evidence of inflammation. RESULTS Synovial fluid COMP and fibromodulin concentrations prior to surgery in horses with OCD were not significantly different from concentrations in control horses. Fibromodulin, but not COMP, concentration in horses with OCD was significantly decreased after surgery, compared with the concentration before surgery. Fibromodulin concentration was significantly correlated with joint effusion score but not with lameness score or results of a flexion test and was correlated with histologic score for number of synoviocytes on the surface of the synovium but not with score for degree of infiltration of inflammatory cells in the synovium. Synovial fluid COMP concentration was not significantly correlated with clinical or histologic findings. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that fibromodulin, but not COMP, could potentially be a biomarker of joint inflammation in horses with OCD of the TCJ.

OBJECTIVE To compare intraluminal pressure at initial leakage (leakage pressure), leakage location, and maximum intraluminal pressure (MIP) for various staple line offset configurations of functional end-to-end stapled anastomosis (FEESA). SAMPLE Grossly normal jejunal segments from 4 canine cadavers. PROCEDURES 52 jejunal segments (4 control and 24 anastomosis constructs [2 segments/standard FEESA construct]) were prepared for testing. Segments were assigned to three 8-segment gastrointestinal anastomosis staple line offset groups: complete offset (CSO group), partial gastrointestinal anastomosis offset (PSO group), and no gastrointestinal anastomosis offset (NSO group). Results for leakage pressure, leakage location, and MIP were compared. RESULTS Mean ± SD leakage pressure differed significantly among all groups and was highest for the PSO group (34.4 ± 3.7 mm Hg), followed by the CSO group (25.9 ± 4.1 mm Hg) and the NSO group (18.8 ± 1.5 mm Hg). Leakage location did not differ significantly among groups but was most commonly associated with the thoracoabdominal staple line. The MIP did not differ significantly among groups (PSO, 83.1 ± 9.4 mm Hg; CSO, 81.7 ± 6.7 mm Hg; and NSO, 58.5 ± 7.7 mm Hg). CONCLUSIONS AND CLINICAL RELEVANCE In this study, partial staple line offset leaked at a significantly higher pressure, which represented the greatest leakage protection of tested constructs. The thoracoabdominal staple line was more susceptible to leakage than was the gastrointestinal anastomosis staple line. Results suggested that surgeons should avoid FEESA with no staple line offset, strive for partial offset of the gastrointestinal anastomosis staples, and provide precise placement of the thoracoabdominal staple line.

OBJECTIVE To determine whether feeding a direct-fed microbial (DFM) to dairy calves would reduce total and antimicrobial-resistant coliform counts in feces and affect average daily gain (ADG). ANIMALS 21 preweaned Holstein heifer calves. PROCEDURES The study had a randomized complete block design. Within each block, 3 consecutively born calves were randomly assigned to 1 of 3 treatment groups within 24 hours after birth (day 0). Calves were fed the DFM at 1.0 g (DFM1; n = 7) or 0.5 g (DFM2; 7) twice daily or no DFM (control; 7) from days 0 through 29. A fecal sample was collected from each calf daily on days 0 through 3 and then every other day through day 29. Fecal samples were cultured, and mean numbers of total coliforms and coliforms resistant to ampicillin, ceftiofur, and tetracycline were compared among the 3 treatment groups. Calves were weighed on days 0 and 29 to calculate ADG. RESULTS Mean total fecal coliform counts did not differ significantly among the 3 treatment groups. Mean ceftiofur-resistant and tetracycline-resistant coliform counts for the control group were significantly lower, compared with those for the DFM1 and DFM2 groups. Mean ADG did not differ significantly between the DFM1 and DFM2 groups; however, the mean ADG for all calves fed the DFM was 0.15 kg less than that for control calves. CONCLUSION AND CLINICAL RELEVANCE Results suggested that the DFM fed to the preweaned calves of this study did not reduce total or antimicrobial-resistant coliform counts in feces.

OBJECTIVE To culture Lactobacillus spp from veterinary probiotics and measure their in vitro oxalate-degrading capacity. SAMPLE 2 commercial veterinary probiotics containing Lactobacillus spp. PROCEDURES Lactobacillus spp were cultured anaerobically on selective deMan, Rogosa, Sharpe agar medium and subcultured for speciation by 16S rDNA gene sequencing. Isolates were inoculated into broth containing sodium oxalate (5 mg/L) and incubated anaerobically for 72 hours. An oxalate-degrading isolate of Lactobacillus acidophilus (American Type Culture Collection [ATCC] 53544) was the positive control sample; sterile broth containing a known quantity of sodium oxalate was the negative control sample. Oxalate concentrations were detected with ion chromatography. Oxalate degradation was assessed with Dunnett tests to detect differences in mean oxalate concentration for each isolate, compared with results for the negative control. RESULTS Lactobacillus acidophilus, Lactobacillus plantarum, and Lactobacillus casei or Lactobacillus zeae (too closely related to differentiate) were isolated from probiotic 1, and L plantarum was isolated from probiotic 2. Sequencing of the 16S rDNA gene confirmed 100% homology to type species. Lactobacillus acidophilus (ATCC 53544) and L acidophilus from probiotic 1 significantly decreased oxalate concentrations by 85.3 and 161.9 mg/L, respectively. Lactobacillus plantarum from probiotics 1 and 2 significantly increased oxalate concentrations by 56.1 and 36.1 mg/L, respectively. Lactobacillus casei did not alter oxalate concentrations. CONCLUSIONS AND CLINICAL RELEVANCE Lactobacillus acidophilus isolates significantly reduced oxalate concentrations. In vivo studies are needed to determine whether probiotics containing L acidophilus decrease urine oxalate concentrations and reduce risk of urolith recurrence in dogs with a history of calcium oxalate urolithiasis.

OBJECTIVE To evaluate the impact of gentamicin, silver, or both additives in polymethylmethacrylate (PMMA) beads on methicillin-resistant Staphylococcus pseudintermedius (MRSP) biofilm formation in vitro. SAMPLE 4 preparations of PMMA beads (formed with no additive [control], gentamicin, silver, and gentamicin and silver). PROCEDURES Beads from each group were exposed to 10 MRSP isolates known to be strong biofilm formers. Following incubation, the beads were rinsed to remove planktonic bacteria, then sonicated to dislodge biofilm-associated bacteria. Resulting suspensions were serially diluted, plated on blood agar, and incubated overnight; CFUs were counted. Variance of mean CFU counts following log10 transformation was analyzed among PMMA groups. RESULTS None of the PMMA additives tested completely inhibited MRSP biofilm formation. There was a significant effect of gentamicin and gentamicin plus silver on this variable, compared with controls, but not of silver alone. There was no difference between gentamicin and gentamicin plus silver. When only isolates not susceptible to gentamicin were evaluated, there were no significant differences among PMMA additive groups. Within gentamicin-susceptible isolates, there was an impact of gentamicin and gentamicin plus silver, but no impact of silver alone and no difference between gentamicin and gentamicin plus silver. CONCLUSIONS AND CLINICAL RELEVANCE Gentamicin-impregnated PMMA was effective at reducing biofilm formation of gentamicin-susceptible MRSP isolates but had no effect on isolates not susceptible to gentamicin. Silver-impregnated PMMA had no effect on MRSP biofilm formation. Results suggested that gentamicin-impregnated PMMA may not be effective in vivo against MRSP isolates not susceptible to gentamicin. Antibacterial efficacy of silver should not be assumed without proper testing of the target bacteria and specific silver compound.