Pharmacokinetics and pharmacodynamics of intramammary cefquinome in lactating goats with and without experimentally induced Staphylococcus aureus mastitis.

Values for pharmacokinetic variables are usually obtained in healthy animals, whereas drugs are frequently administered to diseased animals. This study investigated cefquinome pharmacokinetics in healthy goats and goats with experimentally induced mastitis. Five adult lactating goats received 75 mg of cefquinome intramammary infusion using a commercially available product into one udder half in healthy goats and goats with clinical mastitis that was induced by intracisternal infusion of 100 cfu of Staphylococcus aureus ATCC 29213 suspended in 5 ml of sterile culture broth. Cefquinome concentrations were determined in plasma and skimmed milk samples using high-performance liquid chromatography (HPLC). Pharmacodynamics was investigated using the California Mastitis Test and pH of milk. Experimentally induced mastitis significantly increased the California Mastitis Test score and pH, and decreased the maximal cefquinome concentration and shortened the half-life in milk when compared to healthy goats. In conclusion, mastitis facilitated the absorption of cefquinome from the mammary gland of lactating goats and induced marked changes in milk pH, emphasizing the importance of performing pharmacokinetic studies of antimicrobial agents in infected animals.

Plasma calcium concentrations are decreased at least 9 hours before parturition in multiparous Holstein-Friesian cattle in a herd fed an acidogenic diet during late gestation.

Calcium homeostatic mechanisms are challenged in periparturient multiparous dairy cattle due to the rapid transport of large amounts of calcium into the mammary gland associated with colostrogenesis, resulting in decreased plasma total calcium concentration ([Ca]). An unresolved issue is the timing of the decrease in plasma [Ca] relative to the time of parturition, with the consensus view being that plasma [Ca] does not decrease until after parturition. The objective of this study, therefore, was to characterize the change in plasma [Ca] over time in periparturient dairy cattle. Plasma and mid-stream urine samples were collected daily starting 3 d before calving from 104 periparturient Holstein-Friesian dairy cows in a herd fed an acidogenic total mixed ration during the late dry period. Mixed-models ANOVA and linear and multivariable regression analyses were conducted. Plasma [Ca] decreased in periparturient multiparous cattle (n = 70) but not in primiparous cattle (n = 34). Compared with mean values approximately 72 h before parturition ([Ca] = 2.32 mmol/L), mean plasma [Ca] in multiparous cattle first decreased at 9 h before parturition (2.13 mmol/L) and remained decreased for up to 48 h after parturition, with the lowest mean value (1.87 mmol/L) occurring at 28 h after parturition. Mean 24-h urine Ca excretion was calculated to decrease by 3.5 to 3.8 g in periparturient multiparous cattle. Regression analysis indicated that plasma [Ca] in the 12-h period before and 24-h period after parturition was strongly and negatively associated with age but was also negatively associated with milk production indices. We conclude that plasma [Ca] was decreased at least 9 h before parturition in multiparous dairy cattle fed an acidogenic diet in late gestation, and that calcium homeostasis was disrupted for 2 to 3 d around parturition.

Radiographic evaluation of femoral torsion and correlation with computed tomographic techniques in labrador retrievers with and without cranial cruciate ligament disease.

OBJECTIVES: To (1) develop a technique to determine the anteversion angle (AA) of the femur on a single radiograph; (2) determine the correlation between this technique and other published radiographic and computed tomographic (CT) methods; and (3) compare the diagnostic outcome of these methods in determining the level at which femoral torsion occurred in Labrador Retrievers with cranial cruciate ligament (CCL) deficiency. STUDY DESIGN: Cross-sectional clinical study. ANIMALS: Mature pure-bred Labrador Retrievers (n = 30). METHODS: Pelvic limbs (n = 28) of 14 dogs without CCL deficiency were classified as control, whereas limbs of 16 dogs (18 limbs) with CCL deficiency were considered as diseased. Femoral torsion was evaluated using radiography and CT and variables were compared among limb groups by use of a mixed-model ANOVA, with P < .05 considered significant. RESULTS: There was a significant association between biplanar and lateral plane AAs but neither correlated with CT assessment of femoral torsion. On CT, a significant correlation was identified between overall AA and each of the distal, proximal, and femoral head trochanteric angles. Biplanar and lateral plane AAs did not differ between normal and CCL deficient limbs. On CT, overall and distal AAs were increased in CCL deficient limbs compared to control. CONCLUSION: Biplanar determination of femoral torsion can be estimated based on a single lateral radiograph but the results will be inaccurate as only CT identified and localized the site of femoral torsion.

Teaching veterinary anesthesia and surgery: the impact of instructor availability on anesthesia, operative, and recovery times in dogs undergoing ovariohysterectomy or castration.

Veterinary students learning to perform elective ovariohysterectomy (OVH) and castration procedures have traditionally been taught by a few instructors supervising many student groups simultaneously. This study, using a historical control group, explored the impacts of having a dedicated instructor with each student group for anesthetic induction and an entire surgical procedure. Our hypothesis was that preparation, surgical, and anesthesia times would be shorter and, consequently, post-operative recovery times would be shorter with a dedicated instructor compared to traditional methods. Anesthesia records of dogs undergoing elective surgery by third-year veterinary students were reviewed over 3 consecutive years. Traditional instruction was used in year 1 (Y1), and a dedicated instructor per student group was used in year 2 (Y2) and year 3 (Y3). Anesthesia time, surgical time, recovery time, and pre- and post-operative rectal temperature were analyzed, and a stepwise regression model was developed for factors influencing recovery time. Of 206 records reviewed (Y1, 33; Y2, 98; Y3, 75), there were 101 OVH procedures and 105 castration procedures. Preparation, surgery, and anesthesia times were longer in animals undergoing surgery in Y1, when the traditional instruction method was used. Recovery time was not influenced by instructor assignment. Using dedicated instructors to teach OVH and castration to third-year veterinary students decreased overall anesthesia time by 36 to 49 minutes for OVH and 29 to 32 minutes for castration. A teaching model of dedicated instructors requires excellent coordination between surgeons and anesthesiologists to ensure that a similar number of animals can undergo procedures in the time allotted for teaching.

Predictors of blood ionized calcium concentration in sick adult cattle.

BACKGROUND: Data on the factors affecting blood ionized calcium concentration (ciCa2+ ) and diagnostic performance of serum total calcium concentration (ctCa) measurements to detect abnormal blood iCa2+ status are lacking in sick adult cattle. OBJECTIVE: Assess the association of ciCa2+ with venous blood pH, plasma concentrations of chloride (cCl), sodium (cNa), and potassium (cK), and ctCa, and total protein, albumin, and globulin concentrations in sick adult cattle. ANIMALS: Two-hundred and sixty-five adult cattle (≥1-year-old) with different diseases. METHODS: Prospective study. Whole blood pH, ciCa2+ , cNa, cK, and cCl were measured using a blood gas and electrolyte analyzer, whereas ctCa, and total protein, and albumin concentrations were determined using an autoanalyzer. The relationship between ciCa2+ and venous blood pH, plasma cCl, cNa, cK, and ctCa, and total protein, albumin, and globulin concentrations was investigated. Sensitivity and specificity were calculated for ctCa for diagnosis of abnormal ciCa2+ . RESULTS: Sensitivity of ctCa measurements to detect abnormal ciCa2+ was 66.0% whereas specificity of ctCa measurements was 72.3%. Serum total calcium concentration measurements accounted for 42% of adjusted blood ionized calcium (iCa2+ 7.40 ) concentration variance. Plasma cCl, and cK had explanatory power of ciCa2+ 7.40 , accounting for an additional 21% and 9% of the variance, respectively. CONCLUSIONS AND CLINICAL IMPORTANCE: Serum tCa measurements failed to accurately predict blood iCa2+ status in ill adult cattle. Serum tCa concentrations and plasma cCl were the strongest predictors of ciCa2+ in sick adult cattle.

Effect of anisotropy and spatial compound imaging on renal cortical echogenicity in dogs.

The echogenicity of the renal cortex is an important parameter to consider in dogs that are suspected to have renal dysfunction. Focal increases in echogenicity have been attributed to neoplasia, infection, calcification, fibrosis, gas, and infarction. Anisotropic backscatter has been described as a source of focally increased renal cortical echogenicity in several species. The source of anisotropy appears to be the medullary rays, which are oriented perpendicular to the renal capsule. Spatial compound imaging (SCI) is an ultrasound setting that uses beam steering to acquire and average several overlapping scans of an object from different view angles, creating a compound image that is updated in real time. The impact of insonation angle and SCI on renal cortical echogenicity was evaluated ex vivo in eight kidneys from four dogs. Significant angle-dependent differences in cortical echogenicity were detected with both microconvex and linear transducers (P < 0.0001). Furthermore, the angle-dependent echogenicity differences persisted when SCI mode was used. Our finding that echogenicity was increased using a perpendicular insonation angle (90°) relative to the tubules, compared to a parallel insonation angle (0°) should assist in the interpretation of ultrasonographic images of the dog kidney.

Acid-base imbalances and the association of blood-gas variables, electrolytes, and biochemical analytes with outcome in hospitalized calves undergoing abdominal surgery.

BACKGROUND: Surgical abdominal emergencies in calves are associated with a guarded prognosis and have the potential for complex metabolic derangements including acid-base imbalances. OBJECTIVES: To perform a comprehensive analysis of acid-base status and to assess the prognostic relevance of preoperative clinicopathologic variables in calves undergoing abdominal surgery. ANIMALS: Hospital-based study samples of 535 (dataset 1; DS1) and 83 calves (dataset 2; DS2). METHODS: Retrospective (DS1) and prospective (DS2) case series. RESULTS: In DS1, acidemia (pH <7.33) was present in 49.9%, whereas alkalemia (pH >7.37) was present in 30.7% of calves. Plasma L-lactate, chloride, and serum inorganic phosphorus concentration accounted for 51.9%, 11.6% and 9.4% of the variation of venous blood pH, respectively. Classification tree analysis indicated that a negative outcome (death or euthanasia during hospitalization) was associated with venous pO2 ≤33.6 mm Hg, anion gap >18.3 and >22.9 mEq/L, serum albumin concentration ≤36.5 and ≤29.4 g/L, serum urea concentration >4.4 mmol/L, and plasma ionized calcium concentration ≤1.26 mmol/L. The area under the receiver operating characteristic curve of this model was 0.85 (95% CI: 0.82-0.89, P < .001) and the resulting sensitivity and specificity for the prediction of nonsurvival at the optimal probability cut-point of 0.5 was 89.8% and 65.7%, respectively. In DS2 the model had a similar sensitivity and specificity of 90.5% and 70%, respectively. CONCLUSIONS AND CLINICAL IMPORTANCE: Clinicopathologic imbalances and associated changes of acid-base status are common in calves with surgical abdominal emergencies and have clinical utility for the prediction of a negative postoperative outcome.

Evaluation of a point-of-care benchtop analyzer for quantitative measurement of C-reactive protein in canine serum and plasma.

BACKGROUND: Canine C-reactive protein (cCRP) is an acute-phase protein that increases dramatically with inflammation and has potential utility in monitoring disease progression and response to treatment. Rapid, automated point-of-care test (POCT) formats could enhance the clinical utility of cCRP measurement. OBJECTIVES: We aimed to evaluate the VetChroma canine-specific POCT assay for the quantitative measurement of cCRP in canine serum or plasma. METHODS: Serum and plasma from discarded canine diagnostic samples were used. Evaluation included intra- and inter-assay coefficients of variation and observed total error (TEobs ), linearity and spike recovery, the effect of interfering substances and sample matrices, and a method comparison study. RESULTS: Intra-assay variation ranged from 2.5%-6.1%, and inter-assay variation ranged from 2.1%-5.4%. The TEobs ranged from 15.1%-19.7%. The assay was linear over the manufacturer's analytical range with no evidence of constant or proportional bias. Recovery of purified cCRP from canine serum ranged from 116.2% to 138.4%. Hemolysis, icterus, and turbidity did not interfere with the assay. The comparison of paired plasma and serum samples revealed constant and proportional bias. Comparison of the VetChroma cCRP assay to a commercial cCRP ELISA revealed significantly different results. CONCLUSIONS: The VetChroma cCRP assay has acceptable test performance to measure serum cCRP concentration. The POCT protocol and test kit are valid for clinical use, although results obtained using other cCRP assays or plasma may not be directly compared.

Evaluation of an acute focal epidural mass model to characterize the intracranial pressure-volume relationship in healthy Beagles.

OBJECTIVE: To characterize the intracranial pressure-volume relationship (ICPVR) in dogs by use of an acute frontal-parietal mass lesion model. ANIMALS: 7 healthy adult female Beagles. PROCEDURES: Dogs were anesthetized with isoflurane to achieve a surgical plane of anesthesia. A fiberoptic intracranial pressure (ICP) monitor was inserted to a depth of 1 cm in the parenchyma of the right frontal-parietal region of the brain. A Foley balloon-tipped catheter was placed in the epidural space of the left frontal-parietal area through a separate 1-cm burr hole. Baseline measurements were obtained with the balloon deflated. The balloon was then inflated incrementally with 0.5 mL of 0.9% NaCl solution every 10 minutes until ICP exceeded mean arterial blood pressure. Nonlinear regression analysis with 2-factor and 3-factor exponential equations was used to characterize the ICPVR. RESULTS: The mean baseline ICP was 11 mm Hg, with a 95% confidence interval of 2 to 20 mm Hg. The ICPVR was well characterized by 2-factor or 3-factor exponential equations for all dogs (R² > 0.93). Balloon volumes of > 1. 2 mL were associated with ICP > 20 mm Hg. CONCLUSIONS AND CLINICAL RELEVANCE: Characterization of the ICPVR may provide clinically useful information regarding the safety of obtaining CSF from the atlanto-occipital space or implantation of brachytherapy catheters and for determining the need for decompressive craniectomy in dogs with acute intracranial disease. High ICP should be suspected in dogs that have an acute frontal-parietal mass lesion estimated to exceed 2% of the brain volume.

Evaluation of the learning curve for natural orifice transluminal endoscopic surgery: bilateral ovariectomy in dogs.

OBJECTIVE: Study the learning curve for canine Natural Orifice Transluminal Endoscopic Surgery (NOTES) ovariectomy by evaluating operative times and complications. STUDY DESIGN: Preclinical research study. ANIMALS: Adult female dogs (n=20). METHODS: NOTES ovariectomy procedures were performed as follows: Feasibility Group 1 (n=5), Feasibility Group 2 (n=5), and Early Clinical Group 3 (n=10). Six steps of the procedure were identified, timed separately, and the overall time was recorded from introduction to removal of the endoscope. Complications were recorded. Repeated measures analysis of variance using ranked data compared the effect of group (3 levels) on the time for each step. Nonlinear regression using an exponential model with nonzero asymptote was used to model the operative time-procedure number relationship. RESULTS: Overall median operative time was significantly longer for Group 1 (195 minutes; range, 160-265 minutes) than Group 2 (108 minutes; range, 81-148 minutes; P=.048) and Group 3 (77 minutes; range, 41-136 minutes; P=.0008). The estimated asymptotic operative time was 71 minutes (95% confidence interval, 41-100 minutes); this time was reached after 10 procedures. Gastric cleansing and removing the left ovary took significantly longer in Group 1 than in Group 2 or 3. Operative complications included incomplete ovarian excision, dropping an ovary during retrieval, and conversion to an open procedure. No intraoperative complications occurred in Group 3. CONCLUSION: NOTES procedures result in longer operative times in the early part of the learning curve and require considerable experience before reaching proficiency.

Comparison of transvaginal natural orifice transluminal endoscopic surgery (NOTES®) and laparoscopy for elective bilateral ovariectomy in standing mares.

OBJECTIVE: To compare surgical trauma, perioperative pain, surgical time, and complication rate in mares undergoing standing bilateral ovariectomy by natural orifice transluminal endoscopic surgery (NOTES) or laparoscopy. STUDY DESIGN: Experimental study. ANIMALS: Healthy mares (n = 12). METHODS: Ovariectomy was performed with a vessel-sealing device by transvaginal NOTES (n = 6) using a flexible endoscope and specialized instruments or by bilateral flank laparoscopy (n = 6). Preoperative and postoperative complete blood count (CBC), plasma fibrinogen concentration, serum amyloid A concentration, peritoneal nucleated cell count, and total protein concentration were compared using repeated measures ANOVA. Surgical times were compared using an unpaired t-test. Mares were monitored for 2 weeks postoperatively and necropsy was performed at 3 weeks (n = 6) or 3 months (n = 6) to assess short- and medium-term effects of each procedure. Complication rate, necropsy, and bacteriology findings were compared using a Fishers exact test. Significance was set at P < .05. RESULTS: All surgical procedures were performed successfully and all but one laparoscopy mare were bright, alert, and maintained a good appetite until euthanasia. Mean ± SD surgical time was similar between groups (NOTES: 100 ± 40 minutes; laparoscopy: 107 ± 47 minutes). There were no significant temporal differences in vital parameters, CBC, plasma fibrinogen concentration, serum amyloid A concentration, peritoneal nucleated cell count, and total protein concentration between groups. CONCLUSIONS: Bilateral ovariectomy by transvaginal NOTES or laparoscopy resulted in minimal inflammation and surgical trauma.

Dependence of the apparent bicarbonate space on initial plasma bicarbonate concentration and carbon dioxide tension in neonatal calves with diarrhea, acidemia, and metabolic acidosis.

BACKGROUND: Marked strong ion (metabolic) acidosis in neonatal diarrheic calves usually is corrected by IV administration of NaHCO3 . The distribution space for IV-administered bicarbonate, called the apparent bicarbonate space (ABS), appears to depend on initial plasma bicarbonate concentration (cHCO3 ) and varies considerably in calves. OBJECTIVE: To determine whether ABS was associated with initial plasma cHCO3 and other acid-base variables. ANIMALS: Twenty-five neonatal diarrheic calves with acidemia and metabolic acidosis. METHODS: Prospective observational study using a convenience sample. Calves received NaHCO3 (10 mmol/kg) and glucose (1.4 mmol/kg) IV in a crystalloid solution at 25 mL/kg over 60 minutes. The ABS (L/kg) was calculated at 4 time points over 2 hours after the end of the infusion. The relationship between ABS and initial acid-base variables was characterized using nonlinear, linear, and stepwise regression. RESULTS: The median value for ABS calculated from the initial plasma cHCO3 increased from 0.53 L/kg (range, 0.40-0.79) at the end of IV infusion to 0.96 L/kg (range, 0.54-1.23) 120 minutes later. Data obtained at the end of infusion provided the best fit to initial plasma cHCO3 and jugular venous blood Pco2 , such that: ABS = 0.41 + 1.06/cHCO3 and ABS = 0.87-0.0082 × Pco2 . CONCLUSIONS AND CLINICAL IMPORTANCE: The observed median value for ABS of 0.53 L/kg in our study was similar to the empirically used value of 0.6. However, ABS values varied widely and were increased in calves with severe metabolic acidosis. We therefore recommend calculating ABS using the initial plasma cHCO3 or venous blood Pco2 , if respective measurements are available.

Comparison of selected serum biochemistry measurements between the Nova Prime Plus VET, Nova pHOx Ultra, and Beckman Coulter AU680 analyzers in dogs.

BACKGROUND: Blood gas chemistry analyzers typically produce results faster and use smaller sample volumes than reference chemistry analyzers. However, results may not be comparable between blood gas chemistry analyzers and reference chemistry analyzers or between different models of blood gas chemistry analyzers. This could suggest the use of separate reference intervals and, thus, has implications when making clinical decisions. OBJECTIVE: We aimed to perform method comparison studies to evaluate selected canine serum biochemical values obtained using the Nova Stat Profile Prime Plus VET (Prime Plus VET), Stat Profile Nova pHOx Ultra (Ultra), and Beckman Coulter AU680 (Beckman) analyzers. We hypothesized that the three analyzers would be identical within inherent imprecision. METHODS: Jugular venous blood samples were collected from 103 endurance-trained sled dogs, and serum was harvested and stored for analysis. Results for serum chloride, potassium, sodium, creatinine, and urea nitrogen concentrations obtained from the Prime Plus VET and Ultra analyzers were compared with results from the Beckman analyzer, which was considered to be a reference method. Results for serum chloride, potassium, sodium, creatinine, urea nitrogen, and L-lactate concentrations obtained from the Prime Plus VET and Ultra analyzers were compared. Passing-Bablok regression and Bland-Altman plots were used for method comparison. RESULTS: Significant (P < 0.05) constant or proportional bias was found for many analytes for all three method comparison studies. CONCLUSIONS: Due to the presence of statistically significant differences between all three analyzers that may be clinically relevant, it is recommended that reference intervals be created for new blood gas analyzers, even when similar methodologies are used.

Effect of antepartum vitamin D3 (cholecalciferol) and postpartum oral calcium administration on serum total calcium concentration in Holstein cows fed an acidogenic diet in late gestation.

Several strategies are available to control periparturient hypocalcaemia in dairy cows. Three complementary strategies were applied in this study: feeding a low DCAD (acidogenic) ration during late gestation, oral vitamin D3 (cholecalciferol) administration in late gestation, and oral Ca administration immediately after parturition. Multiparous Holstein cows (n = 240) were fed an acidogenic ration in late gestation and randomly assigned to one of three treatment groups. Group A (n = 80) were fed the acidogenic diet without supplementary Ca or cholecalciferol. Group Ca + A (n = 80) received 50 g of Ca as an oral bolus at calving and 12 h later. Group D3 + Ca + A (n = 80) were administered 3 mg of cholecalciferol orally each day starting 3 to 5 days before the anticipated calving date and 50 g of Ca as an oral bolus at calving and 12 h later. Blood and urine samples were obtained periodically from a random subset of 20 cows in each group from day 5 antepartum to day 21 postpartum and selected analytes measured. Data was analyzed using mixed models analysis. Serum Ca concentrations in group D3 + Ca + A were higher 12 h before and at parturition, compared to the two other groups. Oral Ca administration transiently increased mean serum Ca concentrations at 6 h after treatment initiation in groups D3 + Ca + A and Ca + A. We conclude that daily oral administration of 3 mg of cholecalciferol for up to 5 days before calving, combined with feeding an acidogenic ration in late gestation and oral Ca immediately after parturition, provided the highest periparturient serum Ca concentrations.

Comparison of pain and postoperative stress in dogs undergoing natural orifice transluminal endoscopic surgery, laparoscopic, and open oophorectomy.

BACKGROUND: Few studies are available to compare the potential benefits of natural orifice transluminal endoscopic surgery (NOTES) approaches to traditional surgery. OBJECTIVE: To compare complications, surgical stress, and postoperative pain. DESIGN: Prospective study in dogs. SETTING: Research laboratory. SUBJECTS: Thirty dogs. INTERVENTIONS: Oophorectomy procedures were performed via NOTES and laparoscopic and traditional open surgery. MAIN OUTCOME MEASUREMENTS: Operative time, pain scores, systemic stress parameters (cortisol, glucose), surgical stress markers (interleukin 6, C-reactive protein), 3-day observation. RESULTS: Median operative times were 76, 44, and 35 minutes for the NOTES, laparoscopic, and open procedures, respectively, with the NOTES procedure being significantly longer than the other 2 procedures. All ovaries were completely excised, and all the animals survived without complications. The NOTES animals had greater increases in serum cortisol concentrations at 2 hours but no statistically significant differences in glucose concentrations compared with the other groups. Serum interleukin 6 and C-reactive protein concentrations were significantly increased at specific times compared with baseline in the NOTES group, but not in the open or laparoscopic surgery groups. Based on the cumulative pain score and nociceptive thresholds, the animals in the NOTES group demonstrated less evidence of pain. LIMITATIONS: Small sample size, limited follow-up. CONCLUSIONS: Although the NOTES oophorectomy procedures took approximately twice as long and there may be more evidence of tissue damage as judged by increases in serum cortisol and interleukin 6 concentrations, the dogs in the NOTES group had lower pain scores, especially when compared with animals undergoing open surgery.

Effect of colostral volume, interval between calving and first milking, and photoperiod on colostral IgG concentrations in dairy cows.

OBJECTIVE: To identify cow and management factors associated with colostral IgG concentration in dairy cows. DESIGN: Prospective observational study. ANIMALS: 81 multiparous Holstein-Friesian cows from a single herd. PROCEDURES: Serum was obtained at the start of the nonlactating period, and cows were assigned to 1 of 4 photoperiod groups: natural day length (n = 22 cows), long days (16 h of light/d [21]) or short days (8 h of light/d [20]) for the entire nonlactating period, or natural day length followed by short days for the last 21 days of the nonlactating period (18). Serum and colostrum were collected at the first milking after calving. Regression analysis was used to investigate associations between colostral IgG concentration and the interval between calving and first milking, colostral volume, photoperiod, length of the nonlactating period, and season of calving. RESULTS: Colostral IgG concentration decreased by 3.7% during each subsequent hour after calving because of postparturient secretion by the mammary glands. The interval between calving and first milking and the colostral volume were significantly and negatively associated with colostral IgG concentration, with the former effect predominating. Photoperiod had no effect on colostral IgG concentration or volume. Serum protein concentration at calving correlated poorly with colostral IgG concentration. CONCLUSIONS AND CLINICAL RELEVANCE: Dairy producers should harvest colostrum as soon as possible after calving to optimize transfer of passive immunity in neonatal calves. Photoperiod can be manipulated without adversely affecting colostral IgG concentration.

In vitro biomechanical evaluation and comparison of FiberWire, FiberTape, OrthoFiber, and nylon leader line for potential use during extraarticular stabilization of canine cruciate deficient stifles.

OBJECTIVE: To compare biomechanical properties of 3 new generation polyethylene sutures (FiberTape [FT], FiberWire [FW], and OrthoFiber [OF]) with nylon leader line (NL) for use during extraarticular fixation of cranial cruciate deficient stifles. STUDY DESIGN: In vitro biomechanical testing of suture loops under monotonic tensile and cyclical loading until failure. SAMPLE POPULATION: Constructs of FT, FW, OF, and NL. METHODS: Twenty loops of each of 12 combinations of fixation and suture had monotonic tensile and cyclical loading. Two knotting techniques (square knot [SQ], slip knot [SL]) and a crimp clamp (CR) system were evaluated. Elongation, stiffness, and strength of constructs was tested. The main effects of group, loop material, and their interaction were evaluated. RESULTS: Knotted FT, FW, and OF had less elongation than knotted NL under monotonic tensile and cyclical loading. Under monotonic tensile loading, knotted FT and OF were stiffer than knotted NL. CR FT, CR FW, and CR OF were stiffer than CR NL and CR FT, CR FW, and CR OF were stiffer than knotted FT, FW, and OF. FW and OF knotted loops were weaker than knotted NL. CR FT was stronger than CR NL. CR FT and CR OF were weaker than knotted FT and OF. CONCLUSIONS: Polyethylene sutures are stronger, stiffer and elongate less than nylon leader. Crimping suture alters the biomechanical properties of the loop. CLINICAL RELEVANCE: FW, FT, and OF may perform better in reconstructive procedures, where increased strength and stiffness are considered to be beneficial.

Morphometric characteristics of the pelvic limb musculature of Labrador Retrievers with and without cranial cruciate ligament deficiency.

OBJECTIVE: To identify morphometric characteristics of the pelvic limb musculature associated with the development of cranial cruciate ligament (CCL) deficiency in Labrador Retrievers. STUDY DESIGN: Cross-sectional clinical study. ANIMALS: Pure-bred female (n=18) and male (n=12) Labrador Retrievers with (n=16) and without (n=14) CCL deficiency. METHODS: Muscle conformation of pelvic limbs was evaluated by physical examination, radiography (widths of quadriceps, hamstring, and gastrocnemius were expressed relative to tibial length and to each other), and dual-energy X-ray absorptiometry (DEXA, lean contents of quadriceps, hamstring, and gastrocnemius were expressed relative to tibial length and to each other). Pelvic limbs of dogs without CCL deficiency were classified as normal (n=28 limbs), whereas those with CCL deficiency were considered diseased (n=18 limbs) or sound contralateral to CCL deficiency (n=10 limbs). Variables were compared between groups using mixed models analysis of variance, with P<.05 considered significant. RESULTS: The ratios of quadriceps width to tibial length (P=.008), hamstring width (P=.013), and gastrocnemius width (P=.005) on lateral radiographs were lower in diseased limbs than controls. The mass of hamstring muscles in CCL deficient limbs was similar to that of normal limbs. The ratio of the lean content of gastrocnemius to hamstring muscles was greater in diseased (P=.007) and sound contralateral (P=.013) limbs than in normal limbs. CONCLUSIONS: Atrophy associated with CCL deficiency may predominantly affect the quadriceps muscle. Dominance of the gastrocnemius muscle over active restraints to the cranial tibial thrust may be associated with predisposition to CCL deficiency in Labrador Retrievers. CLINICAL RELEVANCE: If confirmed, this dynamic imbalance between muscle groups of the rear limbs could serve as a basis for screening programs and preventive rehabilitation.

The effect of age and sex on selected hematologic and serum biochemical analytes in 4,804 elite endurance-trained sled dogs participating in the Iditarod Trail Sled Dog Race pre-race examination program.

Endurance-trained sled dogs provide a unique translational model to characterize changes in hematologic and serum biochemical analytes due to the aging process. The primary objective of this study was to determine the effect of age and sex on specific hematologic and serum biochemical parameters in the endurance trained sled dog. Longitudinal and cross-sectional data were analyzed from 9,746 blood and serum samples from 4,804 dogs collected over 7 years as part of the Iditarod Trail Sled Dog Race pre-race examination program. Mixed models analysis was used for statistical analysis and P < 0.01 was considered significant. Dogs ranged from 1-12 years of age and 39% were female. Serum total calcium and phosphorus concentrations and white blood cell count decreased nonlinearly to asymptotic values by 6.6, 3.1, and 6.9 years of age, respectively, equivalent to estimated physiologic ages in human years of 44, 27, and 46 years. Serum glucose concentrations reached their lowest value at 7.8 years of age, equivalent to an estimated human physiologic age of 50 years, after which time the concentration increased. Serum globulin concentrations increased with age, but nonlinearly for females and linearly for males. Most sex-related differences were <5%; however, females had lower serum urea nitrogen (14.7%) and creatinine (7.3%) concentrations, lower serum alanine aminotransferase activity (16.6%), and higher serum total bilirubin concentration (12.8%) and platelet count (6.0%). The endurance-trained sled dog provides an excellent model to separate the physiologic effects of age from those of a sedentary lifestyle on hematologic and serum biochemical analytes.

Intravenous and Oral Fluid Therapy in Neonatal Calves With Diarrhea or Sepsis and in Adult Cattle.

Optimal fluid therapy protocols in neonatal calves and adult cattle are based on consideration of signalment, history, and physical examination findings, and individually tailored whenever laboratory analysis is available. Measurement of the magnitude of eye recession, duration of skin tenting in the lateral neck region, and urine specific gravity by refractometry provide the best estimates of hydration status in calves and cattle. Intravenous and oral electrolyte solutions (OES) are frequently administered to critically ill calves and adult cattle. Application of physicochemical principles indicates that 0.9% NaCl, Ringer's solution, and 5% dextrose are equally acidifying, lactated Ringer's and acetated Ringer's solution are neutral to mildly acidifying, and 1.3-1.4% sodium bicarbonate solutions are strongly alkalinizing in cattle. Four different crystalloid solutions are recommended for intravenous fluid therapy in dehydrated or septic calves and dehydrated adult cattle: (1) lactated Ringer's solution and acetated Ringer's solution for dehydrated calves, although neither solution is optimized for administration to neonatal calves or adult cattle; (2) isotonic (1.3%) or hypertonic (5.0 or 8.4%) solutions of sodium bicarbonate for the treatment of calves with diarrhea and severe strong ion (metabolic) acidosis and hyponatremia, and adult cattle with acute ruminal acidosis; (3) Ringer's solution for the treatment of metabolic alkalosis in dehydrated adult cattle, particularly lactating dairy cattle; and (4) hypertonic NaCl solutions (7.2%) and an oral electrolyte solution or water load for the rapid resuscitation of dehydrated neonatal calves and adult cattle. Much progress has been made since the 1970's in identifying important attributes of an OES for diarrheic calves. Important components of an OES for neonatal calves are osmolality, sodium concentration, the effective SID that reflects the concentration of alkalinizing agents, and the energy content. The last three factors are intimately tied to the OES osmolality and the abomasal emptying rate, and therefore the rate of sodium delivery to the small intestine and ultimately the rate of resuscitation. An important need in fluid and electrolyte therapy for adult ruminants is formulation of a practical, effective, and inexpensive OES.