Although bovine respiratory disease complex (BRDC) is common in post-weaning cattle, BRDC prediction models are seldom analyzed. The objectives of this study were to assess the ability to predict cumulative cohort-level BRDC morbidity using on-arrival risk factors and to evaluate whether or not adding BRDC risk classification and daily BRDC morbidity and mortality data to the models enhanced their predictive ability. Retrospective cohort-level and individual animal health data were used to create mixed negative binomial regression (MNBR) models for predicting cumulative risk of BRDC morbidity. Logistic regression models were used to illustrate that the percentage of correctly (within |5%| of actual) classified cohorts increased across days, but the effect of day was modified by arrival weight, arrival month, and feedlot. Cattle arriving in April had the highest (77%) number of lots correctly classified at arrival and cattle arriving in December had the lowest (28%). Classification accuracy at arrival varied according to initial weight, ranging from 17% (< 182 kg) to 91% (> 409 kg). Predictive accuracy of the models improved from 64% at arrival to 74% at 8 days on feed (DOF) when risk code was known compared to 56% accuracy at arrival and 69% at 8 DOF when risk classification was not known. The results of this study demonstrate how the predictive ability of models can be improved by utilizing more refined data on the prior history of cohorts, thus making these models more useful to operators of commercial feedlots.

Objective-To compare the efficacy of gamithromycin with that of tulathromycin for control of undifferentiated bovine respiratory disease complex (BRDC) in feedlot calves. Animals-2,529 weaned crossbred beef calves. Procedures-At each of 2 feedlots, calves at risk of developing BRDC were administered a single dose of gamithromycin (6.0 mg/kg, SC; n = 1,263) or tulathromycin (2.5 mg/kg, SC; 1,266) metaphylactically. Health (BRDC morbidity, mortality, case-fatality, and retreatment rates) and performance (average daily gain, dry matter intake, and feed-to-gain ratio) outcomes were compared between treatments via classical hypothesis testing. Bioequivalence limits for gamithromycin and tulathromycin were established for outcomes for which no significant difference between treatments was detected. Results-Mean BRDC morbidity rate (31.0%) for calves administered gamithromycin was greater than that (22.9%) for calves administered tulathromycin; otherwise, health and performance did not differ between treatments. Limits for mean differences within which gamithromycin was considered bioequivalent to tulathromycin were +/- 10% for BRDC retreatment rate, +/- 3.5% for BRDC mortality rate, ± 16% for case-fatality rate, +/- 37 kg for final body weight, +/- 0.1 kg/d for average daily gain, +/- 0.3 kg/d for dry matter intake, and +/- 0.7 for feed-to-gain ratio. Conclusions and Clinical Relevance-The efficacy of gamithromycin did not differ from that of tulathromycin for all outcomes except morbidity rate; calves administered gamithromycin had a higher BRDC morbidity rate than did calves administered tulathromycin. On the basis of the bioequivalence limits established for this dataset, gamithromycin was considered equivalent to tulathromycin for the control of BRDC.

Objective—To evaluate the effect of ovariectomy on insulin sensitivity in horses and determine whether the effects of suppression of the hypothalamo-pituitary-adrenal axis differ before and after ovariectomy. Animals—6 healthy mares. Procedures—The horses underwent an IV glucose tolerance test (IVGTT), an insulin sensitivity test, and a dexamethasone suppression test before and 5 weeks after ovariectomy. Body weight, serum cortisol and plasma ACTH concentrations, serum insulin-to-blood glucose concentration ratios, and changes in blood glucose concentration with time after injection of glucose or insulin were compared before and after ovariectomy. Results—The dexamethasone injection resulted in a decrease in serum cortisol concentration before and after ovariectomy. In all horses, baseline plasma ACTH concentrations were within the reference range before and after ovariectomy. For each mare, results of an IVGTT before and after ovariectomy were considered normal. No significant differences in basal blood glucose concentration or time to reach baseline glucose concentration after an IVGTT were observed. Basal serum insulin concentration and serum insulin-to-blood glucose concentration ratios were not significantly different before or after ovariectomy, nor was the mean time to attain a 50% decrease in blood glucose concentration after insulin injection. Conclusions and Clinical Relevance—Results indicated that ovariectomy does not appear to modify dexamethasone response in horses and that it does not modify short-term measures of insulin sensitivity. Findings suggested that horses undergoing ovariectomy are not at higher risk of developing equine metabolic syndrome or hypothalamo-pituitary-adrenal axis dysfunction and associated morbidity.

This study established a disease model and protocol for bacterial challenge with Escherichia coli serogroup O2 strain EC317 in Japanese quail. Five groups of 10 birds each were injected subcutaneously in the breast with 200 μL of a brain–heart infusion (BHI) culture containing 1 × 10(8), 1 × 10(7), 1 × 10(6), 1 × 10(5), or 1 × 10(4) colony-forming units/mL of the test organism, which had been isolated from a turkey with cellulitis and septicemia. Birds in a 6th group were controls that received sterile BHI alone. Localized lesions of cellulitis developed in all of the birds that received E. coli. The morbidity and mortality rates were highest (100%) in the birds receiving the highest dose of E. coli and decreased linearly with decreasing dose (P < 0.05). Severity of disease, including lesions of pericarditis and perihepatitis, was also directly proportional to the dose of E. coli. These findings indicate that this disease challenge protocol can be used to study disease resistance and immunologic consequences of contaminant exposure or other stressors in birds.

We quantified the effect of passive immune status on pre- and postweaning health and growth performance of calves raised in a beef production environment. Blood samples were collected at postpartum hour 24 from 263 crossbred calves for determination of plasma protein (PP) and serum IgG concentrations. Serum IgG concentration was classified as adequate (> 1,600 mg/dl), marginal (800 to 1,600 mg/dl), or inadequate (< 800 mg/dl). Plasma protein concentration was classified as adequate (greater than or equal to 4.8 g/dl) or inadequate (< 4.8 g/dl). Morbidity and mortality events in the study population were monitored from birth to weaning, and after weaning throughout the feeding period. The lowest concentrations of serum IgG and PP were observed among calves that experienced morbidity or mortality prior to weaning. Calves that experienced morbidity in the feedlot had lower 24-hour PP values, but had IgG concentration similar to that in calves that were not observed to be ill during the feeding period. Calves classified as having inadequate IgG concentration were at greater risk of preweaning mortality (odds ratio [OR] = 5.4), neonatal morbidity (OR = 6.4), and preweaning morbidity (OR = 3.2), compared with calves classified as having adequate IgG concentration at 24 hours. Calves classified as having inadequate PP concentration at 24 hours had a greater risk of morbidity (OR = 3.0) and respiratory tract morbidity (OR = 3.1) while in the feedlot, compared with calves classified as having adequate PP concentration. The effects of 24-hour passive immune status on calf growth were indirect through effects on morbidity outcomes. Morbidity during the first 28 days of life was associated with a 16-kg lower expected weaning weight. Respiratory morbidity in the feedlot resulted in a 0.04-kg lower expected mean daily gain. Thus, passive immune status at postpartum hour 24 was an important determinant of health before and after weaning, and was indirectly associated with calf growth during the same periods.

Respiratory tract infections are prevalent in foals, yet the frequency with which the distal airways are affected in chemical episodes of respiratory tract disease has not been evaluated to our knowledge. The objective of the study was to determine the incidence of distal respiratory tract infection (DRTI) in foals on a sample of Thoroughbred breeding farms (n = 10) in Ontario. In a pilot study, clinical criteria commonly used to select foals for antimicrobial treatment (detection of abnormal lung sounds, plus nasal discharge, cough, fever, tachypnea, and/or lethargy) were found to segregate foals with and without endoscopically confirmed DRTI. Mucopurulent exudate and bronchial erythema were observed more frequently (P < 0.005), bronchial lavage total cell count and neutrophil concentration were significantly (P < 0.005) higher, and intracellular cocci were recovered significantly (P < 0.01) more often from bronchial lavage samples of affected foals (n = 8) than of controls (n = 8). These clinical criteria were used to identify cases in a cohort of Thoroughbred foals (n = 219) from May 1 to October 30, 1991. Case morbidity adjusted for clustering was 82 +/- 5% (95% confidence limits, 72 to 92%). Most (74%) episodes of clinical DRTI were detected in july and August, and equal numbers were detected before (53%) and after (47%) weaning of foals. Of 178 cases, 66 (48%) were selected at random for endoscopy and bronchial lavage. Grade-II pharyngeal lymphoid hyperplasia was observed commonly (60% of foals); auditory tube diverticulum (guttural pouch) discharge was observed in 18 of 86 (21%) foals, and guttural pouch infection was confirmed in 6 of 7 foals examined endoscopically. Endoscopically confirmed DRTI, defined as visual detection of bronchial exudate with microscopic detection of intracellular cocci and markedly high neutrophil count in bronchial lavage samples, was confirmed in 75 of 86 (87%) cases tested. These data indicate that DRTI might be reliably diagnosed by auscultation during a simple rebreathing exercise. The syndrome of DRTI was extremely common in Thoroughbred foals, characterized by marked inflammation of visible airways and cytologic evidence of bacterial infection. Risk factors for clinical (undifferentiated) DRTI were not identified in this study.

Ultrasound-guided brain biopsy of the cingulate gyrus and the head of the caudate nucleus was performed in clinically normal dogs. Dogs survived the surgery, and neurologic deficits were not detected in the 14-day postoperative period. Magnetic resonance imaging detected changes in the brain associated with biopsy in 9 dogs (90%) immediately after surgery and in 6 dogs (60%) 14 days after surgery. Fourteen days after surgery, sonography of the brain, performed through the skin overlying the burr hole, detected changes associated with biopsy in 9 dogs (90%). Histopathologic changes evident in the brain 14 days after surgery consisted of focal malacia and hemorrhage with associated subacute encephalomeningitis. Postmortem examination indicated that the biopsy specimen was accurately obtained from the desired site in 9 dogs (90%). Tissue specimens suitable for histologic examination were obtained from 10 dogs (100%). Accuracy and low morbidity of ultrasound-guided biopsy indicate that this may be a useful technique for diagnosis of focal brain disease in dogs.

Reference strains for Haemophilus parasuis serovars 1 to 7 were examined for virulence by inoculation of guinea pigs. Guinea pig response to intraperitoneal inoculation was similar for the 7 reference strains. However, apparent differences in virulence were detected after intratracheal inoculation. Cells of the reference strains for serovars 1 and 5 were most invasive, causing moribundity or death at higher doses and a persistent septicemia at lower doses. Haemophilus parasuis could be isolated from respiratory and systemic sites; purulent bronchopneumonia, pericarditis, and pleuritis were apparent in infected guinea pigs. Inoculation of cells of the reference strains for serovars 2 and 6 also resulted in bronchopneumonia and moribundity or death in some guinea pigs; however, reisolation of H parasuis and microscopic lesions at necropsy were less pronounced than those observed with serovars 1 and 5. Inoculation of cells of serovars 3, 4, and 7 induced only transient clinical signs and minimal evidence of H parasuis infection at necropsy. The data from intratracheal inoculation of guinea pigs are similar to data from other investigations in swine, indicating differences in the pathogenic potential of H parasuis strains. Thus, guinea pigs may be useful as a laboratory animal model for examining cellular factors associated with virulence and immunogenicity of H parasuis.

A circular (5.5 mm diameter) full-thickness cartilage defect was created on the medial ridge of the talus in 12 skeletally mature dogs. In 6 dogs, the articular surface of the lesion was repaired, using an osteochondral graft obtained from the ipsilateral manus. The graft (digit I, first phalanx, distal articular surface and diaphysis) was contoured to obtain a press fit in the drilled talar recipient site. In 6 dogs, the lesion was not treated and healed by fibrous tissue replacement. Functional assessment (lameness, hock range of motion, joint stability, joint crepitus, and mid-femoral muscle circumference) was completed before surgery and at postoperative weeks 2 through 20. Radiographic assessment (periarticular soft tissue width, joint space width, osteophyte formation, and graft incorporation) was completed before surgery and at postoperative weeks 0, 6, 12, and 20. To facilitate histologic assessment, tissues were stained with toluidine blue and H&E. Histologic assessment of the articular surface on the surgically treated talus, ipsilateral tibia, and contralateral talus was completed, using a modification of the Mankin grading system. Subchondral bone was examined to assess graft viability and incorporation. Analysis of the ordinal data was completed, using a Mann-Whitney rank sum test. All dogs were fully weight bearing by postoperative week 7. Dogs without grafts had significantly (P = 0.036) better clinical function at postoperative week 6. Significant difference in functional assessment was not evident at postoperative week 20. Immediate postoperative radiographic assessment revealed significant (P = 0.005) difference between nongrafted and grafted groups. Significant difference was not observed at postoperative week 6, 12, or 20. All grafts appeared radiographically incorporated by postoperative week 12. All grafts restored joint surface congruity, whereas 3 of 6 nongrafted lesions had poor articular congruity. Of 6 grafts, 4 partially retained normal hyaline cartilage, resulting in significantly (P = 0.014) lower Mankin grades. Significant histologic differences between groups were not apparent when the apposing tibia and control talus were examined. Talar reconstruction by use of a phalangeal osteochondral graft is a viable surgical procedure. These data indicate that normal articular and subchondral architecture are more closely approximated by osteochondral reconstruction than by fibrous tissue repair.

Serum IgA, IgG, and IgM concentrations were determined for Beagle sires and dams of 717 matings to assess the relationship of parental immunoglobulins with the morbidity and mortality of their pups. A significant relationship was not found between parental immunoglobulins and pup mortality. Pups born to dams with low serum IgA (P < 0.001) and IgM (P < 0.02) concentrations, however, were found to have an increased incidence of sneezing, coughing, nasal discharge, and conjunctivitis. Thirty-eight percent of pups born to dams with IgA less than or equal to 40 mg/dl developed these same conditions during the first 18 weeks of life, compared with 32% of pups of dams with IgA of 41 to 65 mg/dl and 27% of pups of dams with IgA > 65 mg/dl. Similarly, 41% of pups born to dams with low IgM (less than or equal to 135 mg/dl) developed abnormal respiratory tract signs, compared with 34% and 30% of pups born to dams with medium (136 to 175 mg/dl) and high (> 175 mg/dl) IgM, respectively. Serum IgA concentrations of the sires were also associated with abnormal respiratory tract signs in pups, but this influence was evident only at 10 to 18 weeks of age. To determine biologic variability of serum IgA, 60 Beagle dams were selected from 3 serum IgA categories, low (10 to 21 mg/dl), medium (60 to 80 mg/dl), and high (125 to 210 mg/dl). A second serum IgA was determined from a sample taken 2 years later. The intraclass correlation coefficient (rI) indicated considerable biologic variability in all 3 groups: rI = - 0.24, rI = 0.09, and rI = 0.46, for low, medium, and high IgA categories, respectively. In contrast, minimal variability was noticed between observers (rI = 0.98) and in the radial immunodiffusion test itself (rI = 0.96).