Objective—To determine the usefulness of physiologic, behavioral, and pathological changes as objective indicators of early respiratory disease in calves with Mannheimia haemolytica pneumonia.
Animals—14 crossbred beef steers.
Procedures—Disease was experimentally induced in healthy calves through endoscopic pulmonary inoculation of M haemolytica. Calves were necropsied on days 1, 2, 3, 5, 7, and 9 after inoculation. Physical examination variables (rectal temperature, heart rate, and respiration characteristics), clinical illness score, and degree of activity were assessed 3 times daily beginning 4 days prior to inoculation and continuing throughout the study. Twice before inoculation and on days 1, 2, 3, 5, 7, and 9, arterial blood gas measurements, serum biochemical analyses, and CBCs were performed. Pedometers and accelerometers were used to monitor cattle behavior and activity throughout the trial.
Results—All calves became clinically ill after inoculation and had gross and histopathologic signs of bronchopneumonia. No variable was a reliable indicator of disease progression as judged by percentage of pulmonary involvement. However, activity as measured by total steps taken in a 24-hour period was lower after versus before disease induction.
Conclusions and Clinical Relevance—This single-pathogen challenge model successfully yielded clinical signs and pathological effects consistent with naturally acquired respiratory disease. Routine laboratory variables and subjective measures were not reliable indicators of lung involvement or the progression of pneumonia. However, activity, objectively measured with pedometers and accelerometers, appeared to be a promising indicator for early recognition of bovine respiratory disease.
Objective—To determine the precision of a clinical illness score (CIS) system for identification of clinical signs in calves with experimentally induced Mycoplasma bovis pneumonia and to evaluate the accuracy of CISs in relation to pulmonary consolidation scores assigned at necropsy.
Animals—178 Holstein bull calves that were 52 to 91 days of age at the time of pneumonia induction.
Procedures—5 trials involved calves challenged with M bovis and scheduled for euthanasia and necropsy 12 to 24 days afterward. Nine veterinarian observers with various degrees of experience simultaneously assigned CISs to calves within 48 hours before necropsy. The precision of the CIS system among observers was evaluated via the Cohen κ statistic. The accuracy of each observer's CISs relative to 6 cutoffs (≥ 5%, ≥ 10%, ≥ 15%, ≥ 20%, ≥ 25%, and ≥ 30%) of percentage pulmonary consolidation was determined by comparing prenecropsy CISs with the gross pulmonary consolidation scores assigned at necropsy. Estimates for sensitivity and specificity were calculated relative to the 6 pulmonary consolidation cutoffs.
Results—A slight level of agreement was evident among observers (κ range, 0.10 to 0.21 for the individual trials) and overall (κ = 0.16; 95% confidence interval, 0.10 to 0.24). Median sensitivity and specificity changed with pulmonary consolidation score cutoff. Median sensitivity for all observers ranged from 81.7% to 98.9%, and median specificity ranged from 80.8% to 94.9% over all cutoff values.
Conclusions and Clinical Relevance—Agreement among observers assigning CISs to calves was low; the accuracy of the CIS system in relation to that of pulmonary consolidation scoring varied with the severity of consolidation considered to represent bovine respiratory disease.
Objective—To determine correlation between results
of computed tomography (CT) versus pathologic
examination for determining the volume percentage
of affected lung in mice experimentally infected with
Animals—30 adult mice.
Procedure—After helical CT scans on day 0, mice
were inoculated intranasally with P pneumotropica.
Repeat CT scans were performed on days 1, 2, 3, 4,
6, 8, 10, and 13. Regions of interest (affected areas)
were manually drawn on the CT images, and percentage
volume of normal lung was calculated by use
of 3 methods: first-day volume, largest volume, and
last-day volume. Three mice were euthanatized for
pathologic evaluation after each scan day. The lungs
were examined with a dissection microscope, and
lesion scores were assigned on the basis of percentage
volume of pneumonia. Correlation coefficients
comparing results of the 3 CT methods with results
of gross examination were calculated.
Results—Lung abnormalities were detected via dissection
microscopy by postinfection day 2 and via CT
by days 2 or 3. Correlation coefficients for the 3 CT
methods of analysis, compared with pathologic findings,
were 0.7 via first-day lung volume, 0.8 via
largest lung volume, and 0.8 via last-day lung volume.
Conclusions and Clinical Relevance—Results of CT
correlated well with results of dissection microscopy
for estimating percentage volume of lung affected by
pneumonia in mice experimentally infected with
P pneumotropica. This method may be useful for longitudinal
studies of pneumonia in mice. (Am J Vet Res
Objective—To compare anamnestic antibody responses of dogs and cats with current versus out-of-date vaccination status.
Animals—74 dogs and 33 cats.
Procedures—Serum samples were obtained from dogs and cats that had been exposed to rabies and brought to a veterinarian for proactive serologic monitoring or that had been brought to a veterinarian for booster rabies vaccination. Blood samples were collected on the day of initial evaluation (day 0) and then again 5 to 15 days later. On day 0, a rabies vaccine was administered according to label recommendations. Paired serum samples were analyzed for antirabies antibodies by means of a rapid fluorescent focus inhibition test.
Results—All animals had an antirabies antibody titer ≥ 0.5 IU/mL 5 to 15 days after booster vaccination. Dogs with an out-of-date vaccination status had a higher median increase in titer, higher median fold increase in titer, and higher median titer following booster vaccination, compared with dogs with current vaccination status. Most (26/33) cats, regardless of rabies vaccination status, had a titer ≥ 12 IU/mL 5 to 15 days after booster vaccination.
Conclusions and Clinical Relevance—Results indicated that dogs with out-of-date vaccination status were not inferior in their antibody response following booster rabies vaccination, compared with dogs with current vaccination status. Findings supported immediate booster vaccination followed by observation for 45 days of dogs and cats with an out-of-date vaccination status that are exposed to rabies, as is the current practice for dogs and cats with current vaccination status.
Objective—To describe the character and frequency of causes of death and associated lesions in long-distance racing sled dogs.
Design—Retrospective case series.
Procedures—Medical records of dogs that died during or soon after competition in the Iditarod Trail sled dog races (1994 through 2006) were examined for findings of gross necropsy and histologic evaluation of tissue samples. From the data, descriptive and comparative statistics were obtained.
Results—Recognized causes of death included aspiration of gastric contents (n = 4), aspiration pneumonia (4), acute blood loss secondary to gastric ulceration (3), and sled dog myopathy (2). A cause of death was not established for 7 dogs. Prevalent lesions among the study population included rhabdomyolysis (n = 15), enteritis (10), gastritis (10), aspiration pneumonia (8), and gastric ulceration (8). All dogs with aspiration pneumonia had concurrent gastric mucosal lesions. Subjective biventricular cardiac hypertrophy was evident in most dogs; other lesions detected frequently included centrilobular hepatic fibrosis, gastric dilatation, and mild cardiac myodegeneration and necrosis.
Conclusions and Clinical Relevance—Unexpected death is a rare event among conditioned sled dogs during competition in endurance races. Potentially life-threatening conditions of dogs that are associated with periods of long-distance physical exertion include aspiration pneumonia, gastric mucosal lesions, and severe rhabdomyolysis. Dogs that develop clinical signs suggestive of these conditions should be excluded from strenuous activities. Epidemiologic investigations are required to clarify the risk for death associated with these lesions in dogs competing in endurance races.
Objective—To determine the effect of transportation during periods of high ambient temperature on physiologic and behavioral indices of beef heifers.
Animals—20 heifers (mean body weight, 217.8 kg).
Procedures—Ten heifers were transported 518 km when the maximum ambient temperature was ≥ 32.2°C while the other 10 heifers served as untransported controls. Blood samples were collected from transported heifers at predetermined intervals during the transportation period. For all heifers, body weights, nasal and rectal temperatures, and behavioral indices were measured at predetermined intervals for 3 days after transportation. A week later, the entire process was repeated such that each group was transported twice and served as the control twice.
Results—Transported heifers spent more time near the hay feeder on the day of transportation, had lower nasal and rectal temperatures for 24 hours after transportation, and spent more time lying down for 2 days after transportation, compared with those indices for control heifers. Eight hours after transportation, the weight of transported heifers decreased 6%, whereas that of control heifers increased 0.6%. At 48 hours after initiation of transportation, weight, rectal temperature, and time spent at various pen locations did not differ between transported and control heifers. Cortisol concentrations were higher 4 hours after initiation of transportation, compared with those determined just prior to transportation.
Conclusions and Clinical Relevance—Results indicated transportation during periods of high ambient temperatures caused transient changes in physiologic and behavioral indices of beef heifers.
Objective—To optimize methods for the use of computed tomography (CT) to assess pathologic changes in the lungs of calves and to determine the effect of treatment on lung consolidation.
Animals—10 male Holstein calves.
Procedures—Calves were anesthetized to facilitate CT imaging of the thorax. After initial images were obtained, pneumonia was induced in the calves by inoculation through a bronchoscope. Two calves were used in a preliminary study to refine the inoculation dose and optimize CT images. Four calves were administered florfenicol and 4 calves were untreated control animals. Serial images were obtained 24, 48, and 72 hours after inoculation. After final images were obtained, calves were euthanized, and lung consolidation was estimated by use of lung surface area scoring and water displacement. These estimates were compared with estimated lung consolidation obtained by use of CT.
Results—Calves had rapid disease progression. Percentage of lung consolidation was not significantly different between treatment groups for any of the estimation methods. Results of an ANOVA of the 3 assessment methods indicated significant differences among methods. Estimates of the percentage of lung consolidation obtained by use of surface area scoring and CT correlated well, whereas water displacement estimates correlated poorly with other methods of consolidation estimation.
Conclusions and Clinical Relevance—Because of the correlation with other methods for estimation of lung consolidation, CT has the potential to be used to monitor disease progression in calves with experimentally induced respiratory tract disease.
Objective—To determine associations of blood analysis variables and orbit and nasal planum surface temperatures with the onset and severity of Mycoplasma bovis pneumonia in calves.
Animals—28 healthy calves.
Procedures—Calves were challenged with M bovis (n = 24) on day 0 or not challenged (4). Blood samples were obtained for cardiac troponin I, CBC, and serum biochemical analyses on various days. Orbit and nasal planum surface temperatures were determined with infrared thermography on various days. Calves were euthanized, gross necropsies were performed, heart and lung samples were collected for histologic evaluation, and microbial cultures of lung samples were performed on day 14. Pneumonia severity was categorized as mild (< 10% lung consolidation) or moderate (≥ 10% lung consolidation). Associations between measured variables and severity of pneumonia or sample collection day were determined.
Results—Plasma cardiac troponin I concentration for the 28 calves was significantly higher on day 14 than it was on day 0 or 7 (least squares mean, 0.02, 0, and 0 ng/mL, respectively). No other variables changed significantly during the study. No substantial gross or histologic abnormalities were identified in cardiac muscle samples. Day 14 plasma fibrinogen concentration was significantly different between calves with mild pneumonia and those with moderate pneumonia (mean, 0.44 and 0.74 g/dL, respectively). Calves with moderate pneumonia had significantly lower least squares mean surface temperature of the dorsal aspect of the nasal planum (18.7°C) versus calves with mild pneumonia (22.9°C).
Conclusions and Clinical Relevance—Results indicated the evaluated variables had low value for assessment of bovine respiratory disease complex in calves.
Objective—To characterize clinical and behavioral changes in calves following inoculation with Mycoplasma bovis and evaluate relationships between those changes and pulmonary disease.
Animals—22 healthy Holstein steers.
Procedures—20 calves were inoculated intranasally with < 108 CFU or > 109 CFU of M bovis. Calves were assigned a clinical illness score (CIS) on a scale of 1 through 4 twice daily on the basis of severity of cough, labored breathing, and lethargy. For each calf, distance traveled and time spent near the waterer, feed bunk, or shelter were determined via a remote location monitoring device. Calves were euthanized and necropsied 22 days after inoculation.
Results—13 calves became clinically ill after challenge inoculation; 3 calves were euthanized within 20 days. Among all calves, consolidation was evident in 0% to 79.9% of the lungs; extent of lung consolidation did not differ between the challenge dose groups. Distance traveled and percentages of time spent in proximity to the feed bunk and shelter were associated with CIS; calves with more severe disease traveled less distance and spent less time at the feed bunk and more time in the shelter. Distance traveled by calves was negatively associated with extent of lung consolidation (< or ≥ 10% of lungs affected); this effect was modified by trial day.
Conclusions and Clinical Relevance—Following inoculation with M bovis, calf behavior patterns were associated with both CIS and severity of pulmonary disease. Use of behavior monitoring systems may aid in recognition of respiratory tract disease in calves.