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Objective

To determine whether a commercially available water hardness test kit could be used to measure total serum calcium concentration and diagnose hypocalcemia in dairy cows.

Design

Prospective study.

Animals

30 dairy cows from 19 commercial herds.

Procedure

Serum calcium concentration was determined using a water hardness test kit and a standard, laboratory-based method. Simple linear regression was used to determine whether there was a linear relationship between results of the 2 methods, and Spearman's rank correlation was used to calculate correlation between measurements. Sensitivity, specificity, and predictive values of using test kit-derived values for diagnosis of hypocalcemia (laboratory value < 8 mg/dl) were calculated.

Results

There was a high correlation and significant linear relationship between results of the 2 methods. Sensitivity, specificity, predictive value of a positive test result, and predictive value of a negative test result were 100, 73, 86, and 100%, respectively. Accuracy was improved by using a test kit-derived calcium concentration of 7 mg/dl as the cut-off for determining hypocalcemia.

Clinical Implications

Results indicate that a commercially available water hardness test kit can be used as a rapid, inexpensive method of estimating serum calcium concentrations and diagnosing hypocalcemia in dairy cattle. However, the test is not practical for cow-side use, because blood samples must be centrifuged to obtain serum for use in the test kit. (J Am Vet Med Assoc 1999;214:826–828)

Free access
in Journal of the American Veterinary Medical Association

Objectives

To evaluate effects of tilmicosin when used in fever-based and metaphylactic treatment programs to attenuate acute undifferentiated bovine respiratory disease (BRD) in cattle that recently arrived at feedlots, and to evaluate the effects of tilmicosin for the treatment of BRD.

Design

Randomized-block controlled study.

Animals

1,639 calves from livestock auctions.

Procedures

Cattle were assigned to 3 groups. Cattle in the nonmedicated (control) group were not given antibiotics during processing. Cattle in the fever-based treatment group were given tilmicosin (10 mg/kg [4.5 mg/lb] of body weight, SC) during processing when their rectal temperature was ≥ 40 C (104 F). All cattle in the metaphylactic treatment group were given tilmicosin (10 mg/kg, SC) during processing. Calves with BRD were treated with tilmicosin (10 mg/kg, SC).

Results

Morbidity rates in the metaphylactic (30.4%) and fever-based (44.7%) treatment groups were less than that for the nonmedicated group (54.8%). Mortality rate for the metaphylactic group during the first 28 days (1.1%) and during the entire study (1.7%) was less than that for the nonmedicated group (3.3 and 4.6%, respectively). Differences were not observed in therapeutic response rates among calves with BRD that were treated.

Clinical Implications

Fever-based and metaphylactic treatment programs that used tilmicosin decreased the prevalence of BRD and improved growth of calves. Metaphylactic treatment decreased the number of fatalities caused by BRD in high-risk calves. Fever-based treatment was less effective than metaphylactic treatment for decreasing the prevalence of BRD in newly arrived cattle. (J Am Vet Med Assoc 1998,212:1919–1924)

Free access
in Journal of the American Veterinary Medical Association

Objective

To describe the incidence of respiratory tract disease in dairy calves and to compare antibody titers and microbial isolates from transtracheal wash samples between calves with and without respiratory tract disease (cases and controls, respectively).

Design

Prospective observational cohort study, with matched case-control substudy.

Animals

410 dairy heifers; in substudy, 105 cases and 59 controls from the same population.

Procedure

Calves were examined weekly by a veterinarian during the first 3 months of life. Blood samples were collected for serologic testing at the first visit for each calf and during acute and convalescent periods for cases. Transtracheal wash samples also were obtained during the acute period from cases and controls.

Results

Incidence and case-fatality risk for clinician-diagnosed pneumonia were 25.6 and 2.2%, respectively. Mycoplasma sp and Pasteurella multocida together were isolated from 29% of cases and 11% of controls, and Mycoplasma sp alone from 7% of cases and 30% of controls (both P ≤ 0.05). From postcolostral to acute-phase serum samples, Mycoplasma dispar titers increased 1.3-fold among cases, compared with 0.7-fold among controls; from acute- to convalescent-phase samples, Μ dispar titers increased 2.4-fold among cases, compared with 5.6-fold among controls (both P ≤ 0.005).

Clinical Implications

Results of this study suggested a synergistic effect between Mycoplasma sp and P multocida and a possible initiative role of Μ dispar in the development of respiratory tract disease. Postcolostral total IgG values and antibody titers were not significantly different between cases and controls, implying that other factors have an important role in the development of respiratory tract disease. (J Am Vet Med Assoc 1996;208:2035-2042)

Free access
in Journal of the American Veterinary Medical Association

Objective

To describe causes of death, mortality, and morbidity from nonrespiratory diseases in dairy calves.

Design

Prospective observational cohort study.

Animals

Convenience sample of 410 dairy heifers born between January and December 1990 in 18 southwestern New York herds.

Procedure

Heifers were examined weekly by a veterinary clinician during the first 3 months of life and all disease conditions were recorded.

Results

Crude risks for diarrhea, umbilical infection, and umbilical hernia were 28.8, 14.2, and 15.1%, and the median ages at first diagnoses were 2, 1, and 3 weeks, respectively. Mean durations of umbilical infection and umbilical hernia were 3.7 and 6.7 weeks, respectively. Crude mortality was 5.6%. Case-fatality risks were 12.8% for diarrhea during the first week of life, 5.1% for diarrhea after the first week of life, and 0% for umbilical infection and umbilical hernia. Diarrhea was diagnosed by the caretaker or the clinician; umbilical conditions were diagnosed by the clinician. The primary cause of death was diarrhea in 43%, pneumonia in 24%, septicemia in 10%, and other single causes in the rest of the 21 necropsied calves.

Clinical Implications

The high incidence and somewhat long duration of umbilical infection, the finding that diarrhea was the primary cause of death, and the high case-fatality risk for diarrhea during the first week of life suggested that calf caretakers need training in the prevention and treatment of these conditions. (J Am Vet Med Assoc 1996:208:2043-2046)

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine associations between in vitro minimum inhibitory concentrations (MICs) of tilmicosin against Mannheimia haemolytica and Pasteurella multocida and in vivo tilmicosin treatment outcome among calves with clinical signs of bovine respiratory disease (BRD).

Design—Observational, retrospective, cohort study.

Animals—976 feeder calves with clinical signs of BRD enrolled in 16 randomized clinical trials.

Procedures—Records of clinical trials from October 26, 1996, to November 15, 2004, were searched to identify calves with BRD from which a single isolate of M haemolytica or P multocida was identified via culture of deep nasal swab samples prior to treatment with tilmicosin (10 mg/kg [4.5 mg/lb], SC) and for which MICs of tilmicosin against the isolate were determined. The MICs of tilmicosin against recovered isolates and response to tilmicosin treatment were evaluated.

Results—Tilmicosin resistance among M haemolytica and P multocida isolates was uncommon (6/745 [0.8%] and 16/231 [6.9%], respectively). Treatment outcome, defined as success or failure after tilmicosin treatment, did not vary with the MIC of tilmicosin against recovered isolates. The proportion of treatment failures attributed to M haemolytica isolates categorized as resistant (MIC of tilmicosin, ≥ 32 μg/mL) or not susceptible (MIC of tilmicosin, ≥ 16 μg/mL), was 0.2% and 0.5%, respectively.

Conclusions and Clinical Relevance—Recovery of tilmicosin-resistant M haemolytica or P multocida isolates was rare, and no association was detected between MIC of tilmicosin and treatment response.

Full access
in Journal of the American Veterinary Medical Association