The fiber type, fiber size, and capillary geometric features were determined from the center of the proximal half of the left and right semitendinosus muscles in 5 mixed-breed dogs, 5 hound-type dogs, and 5 Beagles. There were no significant differences between the left and right muscles of each dog. Comparisons among the 3 groups of dogs revealed that the hound-type dogs had the largest fibers (type I and type II); however, the 3 groups were similar in their fiber-type percentages and their capillary geometric features.

Analysis of hematologic and biochemical values in pigs is an important basis for biomedical research and veterinary clinical diagnosis. Reference values for specific-pathogen-free (SPF) 1-month-old Yorkshire (Y) pigs and Yorkshire-Landrace crossbred (YL) pigs are limited. The present research aimed to describe and compare the reference values for hematologic and biochemical parameters in such pigs. Blood samples were obtained from 90 Y pigs (52 males and 38 females) and 88 YL pigs (55 males and 33 females), all 1 month old and bred in an SPF environment. Among the 16 hematologic and 15 serum biochemical parameters tested, no significant differences between the Y and YL pigs were found except in the concentration of triglyceride (P < 0.05), and heterosis was not observed. Thus, the values determined in this study can be used as basic reference values for 1-month-old Y and YL pigs and will contribute to the use of SPF pigs in biomedical research.

OBJECTIVE To determine whether infrared thermographic images obtained the morning after overnight heat abatement could be used as the basis for diagnostic algorithms to predict subsequent heat stress events in feedlot cattle exposed to high ambient temperatures. ANIMALS 60 crossbred beef heifers (mean ± SD body weight, 385.8 ± 20.3 kg). PROCEDURES Calves were housed in groups of 20 in 3 pens without any shade. During the 6 am and 3 pm hours on each of 10 days during a 14-day period when the daily ambient temperature was forecasted to be > 29.4°C, an investigator walked outside each pen and obtained profile digital thermal images of and assigned panting scores to calves near the periphery of the pen. Relationships between infrared thermographic data and panting scores were evaluated with artificial learning models. RESULTS Afternoon panting score was positively associated with morning but not afternoon thermographic data (body surface temperature). Evaluation of multiple artificial learning models indicated that morning body surface temperature was not an accurate predictor of an afternoon heat stress event, and thermographic data were of little predictive benefit, compared with morning and forecasted weather conditions. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated infrared thermography was an objective method to monitor beef calves for heat stress in research settings. However, thermographic data obtained in the morning did not accurately predict which calves would develop heat stress later in the day. The use of infrared thermography as a diagnostic tool for monitoring heat stress in feedlot cattle requires further investigation.

Objective-To determine the response of cortical bone to a multicomponent and nanostructural polymeric matrix as a drug delivery system for enhancing bone healing. Animals-20 healthy adult crossbred goats. Procedures-A 3.5-mm-diameter unicortical defect was created in each tibia (day 0), and goats (4 goats/group) were treated as follows: not treated (control group), grafted with the matrix, grafted with antimicrobial (tigecycline and tobramycin)-impregnated matrix, grafted with recombinant human bone morphogenetic protein type 2 (rhBMP-2)-impregnated matrix, or grafted with antimicrobial- and rhBMP-2-impregnated matrix. Elution kinetics of antimicrobials was monitored through plasma concentrations. Bone response was assessed with radiographic scoring (days 1 and 30) and dual-energy x-ray absorptiometry (days 1, 14, and 30). Goats were euthanized on day 30, and histomorphologic analysis was performed. Categorical variables were analyzed with a generalized linear model, and continuous variables were analyzed with an ANOVA. Results-Plasma antimicrobial concentrations indicated continued release throughout the study. Radiography and dual-energy x-ray absorptiometry did not reveal significant differences among treatments on day 30. Periosteal reactions were significantly greater surrounding bone defects grafted with rhBMP-2–impregnated matrix than those not treated or grafted with matrix or with antimicrobial-impregnated matrix; periosteal reactions were similar in bone defects grafted with rhBMP-2–impregnated matrix and antimicrobial- and rhBMP-2-impregnated matrix. Conclusions and Clinical Relevance-The matrix served as an antimicrobial delivery system and stimulated bone proliferation when rhBMP-2 was present. Antimicrobial and rhBMP-2 can be used concurrently, but the presence of antimicrobials may affect the performance of rhBMP-2.

Objective-To compare the efficacy of gamithromycin with that of tulathromycin for the treatment of undifferentiated bovine respiratory disease complex (BRDC) in feedlot calves. Animals-1,049 weaned crossbred beef calves. Procedures-At each of 6 feedlots, newly arrived calves with BRDC were administered a single dose of gamithromycin (6.0 mg/kg, SC; n = 523) or tulathromycin (2.5 mg/kg, SC; 526). Case-fatality and BRDC retreatment rates during the first 120 days after treatment, final body weight, and average daily gain (ADG), were compared between treatments. At 2 feedlots, calves were assigned clinical scores for 10 days after treatment to determine recovery rates for each treatment. Bioequivalence limits for gamithromycin and tulathromycin were calculated for outcomes for which there was no significant difference between treatments. Results-Mean BRDC retreatment rate (17.7%) for calves administered gamithromycin was greater than that (9.0%) for calves administered tulathromycin. Mean case-fatality rate, final body weight, ADG, and clinical score 10 days after treatment did not differ significantly between treatments. Limits for mean differences within which gamithromycin was bioequivalent to tulathromycin were +/- 2.4% for case-fatality rate, +/- 13 kg for final body weight, and +/- 0.1 kg/d for ADG. Conclusions and Clinical Relevance-Calves administered gamithromycin had a higher BRDC retreatment rate than did calves administered tulathromycin; otherwise, the clinical efficacy did not differ between the 2 treatments for the treatment of BRDC in feedlot calves.

Objective-To measure effects of Escherichia coli O149:F4-induced diarrhea on water consumption and pharmacokinetics of amoxicillin after administration in drinking water. Animals-24 recently weaned 24- to 28-day-old crossbred pigs. Procedure-10 pigs were inoculated with E coli O149:F4; all 10 pigs subsequently developed diarrhea. Pigs were medicated by administration of amoxicillin in the drinking water (0.75 mg/mL) for a 4-hour period on 2 consecutive days. Fourteen age-matched noninfected healthy pigs (control group) were medicated in a similar manner. Blood samples were obtained from both groups daily, and plasma concentrations of amoxicillin were analyzed by use of high-performance liquid chromatography. Results-Diarrhea reduced the area under the plasma concentration-versus-time curve (AUC) and maximum plasma concentration (C(max)) of amoxicillin on the first day of medication by 56% and 63%, respectively. The AUC of amoxicillin on the second day of medication for diarrheic pigs did not differ significantly from that of control pigs on the first day of medication. Conclusions and Clinical Relevance-E coli-induced diarrhea reduced the AUC of amoxicillin and time that plasma concentration of amoxicillin was > 0.025 microgram/mL and, hence, less likely to have a therapeutic effect on the first day of administration in drinking water. On the assumption that plasma concentrations may indirectly reflect concentrations at the site of infection, analysis of our results suggests that higher doses of amoxicillin may be appropriate for administration in drinking water during a 4-hour period on the first day that pigs have diarrhea attributable to E coli O149:F4.

Objective-To determine whether alterations in myoplasmic calcium regulation can be identified in muscle cell cultures (myotubes) and intact muscle fiber bundles derived from Thoroughbreds affected with recurrent exertional rhabdomyolysis (RER). Animals-6 related Thoroughbreds with RER and 8 clinically normal (control) Thoroughbred or crossbred horses. Procedures-Myotube cell cultures were grown from satellite cells obtained from muscle biopsy specimens of RER-affected and control horses. Fura-2 fluorescence was used to measure resting myoplasmic calcium concentration as well as caffeine- and 4-chloro-m-cresol (4-CMC)-induced increases in myoplasmic calcium. In addition, intact intercostal muscle fiber bundles were prepared from both types of horses, and their sensitivities to caffeine- and 4-CMC-induced contractures were determined. Results-Myotubes of RER-affected and control horses had identical resting myoplasmic calcium concentrations. Myotubes from RER-affected horses had significantly higher myoplasmic calcium concentrations than myotubes from control horses following the addition of ≥ 2mM caffeine; however, there was no difference in their response to 4-CMC (greater than 1mM). Caffeine contracture thresholds for RER and control intact muscle cell bundles (2 vs 10mM, respectively) were significantly different, but 4-CMC contracture thresholds of muscle bundles from RER-affected and control horses (500µM) did not differ. Conclusions and Clinical Relevance-An increase in caffeine sensitivity of muscle cells derived from a family of related RER-affected horses was detected in vitro by use of cell culture with calcium imaging and by use of fiber bundle contractility techniques. An alteration in muscle cell calcium regulation is a primary factor in the cause of this heritable myopathy.

A technique for measuring upper airway resistance was developed in awake untrained dolichocephalic and mesaticephalic dogs. Twenty healthy dogs, 10 Collies (group dolichocehalic) and 10 mixed-breed dogs (group B-mesaticephalic), were studied. All dogs tolerated the procedure well and adverse effects were not observed. Mean (+/- SEM) value for upper airway resistance was 7.1 +/- 0.50 cm of H2O/L/s. There was a trend toward lower upper airway resistance (Ruaw) values in group-A dogs, compared with those in group-B dogs. Values of Ruaw were reproducible for an individual dog. The mean individual dog coefficient of variation for Ruaw was 7.5%. The overall Ruaw coefficient of variation for all 20 dogs was 31.4%. This technique for measuring upper airway resistance in dogs is clinically applicable for objectively assessing response to treatment of obstructive upper airway disorders.