Evaluation of a cattle rapid test for early pregnancy diagnosis in sheep

Tropical Animal Health and Production - The early pregnancy diagnosis allows optimizing production and timely management correction, with a greater reproductive output of livestock. The Idexx Rapid...     

Real-time ultrasonic scanning in the diagnosis of pregnancy and the estimation of gestational age in cattle

Diagnoses of pregnancy were made on 110 Hereford cross Friesian and 69 blue grey (white shorthorn cross Galloway) cows between 92 and 202 days after last service using a real-time ultrasonic scanning instrument with a 3.5 MHz rectal transducer. Of the 174 cows which subsequently calved, one was wrongly diagnosed as non-pregnant. Of the five cows which did not subsequently calve two were diagnosed as pregnant and may in fact have been pregnant at the time of scanning. The overall level of accuracy of pregnancy diagnosis was 98.3 per cent. In further trials with 16 Hereford cross Friesian and 16 blue grey cows scanned at regular intervals between 20 and 140 days of gestation, pregnancy was diagnosed with confidence from 30 days, and relationships were established whereby gestational age could be estimated from measurements of certain uterine and fetal dimensions. Crown-rump length provided the most precise estimate of gestational age (residual sd +/- 4.5 days) and uterine diameter the least (+/- 12.6 days) with head length and the diameters of trunk, head and nose being intermediate (+/- 6.9 to 8.7 days).     

Whole milk progesterone analysis used for pregnancy diagnosis in beef cattle

In Finland the routinely used method to determine milk progesterone level is based on whole milk analysis (Progesterone RIA-kit for Veterinary Diagnostic use, Farmos Group ltd.). The method is standardised for milk samples which are taken from the udder just after the cow has been milked. This kind of aftermilk sample contains a high percentage of fat and–as progesterone is lipidofil–also large, sexual-cycle correlated, variability in milk progesterone.     

Evaluation of conventional and radiometric fecal culture and a commercial DNA probe for diagnosis of Mycobacterium paratuberculosis infections in cattle.

Radiometric (RCM) and conventional fecal culture (HEY) and a commercial polymerase chain reaction/DNA probe were evaluated as diagnostic tests for subclinical paratuberculosis in dairy cattle using fecal specimens from a repository of paratuberculosis specimens. The case definition of subclinical bovine paratuberculosis was isolation of Mycobacterium paratuberculosis, by conventional or radiometric culture, from fecal samples or internal organs of dairy cattle without diarrhea or chronic weight loss. Animals designated as free of the disease originated exclusively from certified paratuberculosis-free herds in Wisconsin. Among 182 infected cattle, RCM and HEY fecal culture and the DNA probe had test sensitivities of 54.4%, 45.1% and 33.5%, respectively. Fecal samples from only 111 of the M. paratuberculosis-infected cows tested positive by at least one of the three tests and these cows were designated as fecal shedders; the remaining 71 were considered to have prepatent infections. Among the 111 M. paratuberculosis fecal shedders, RCM, HEY and the probe detected the organism in 89.2%, 73.8% and 55.0% of the fecal specimens, respectively. Herd prevalence significantly affected the sensitivity of all three diagnostic tests (p less than 0.05) but only affected the fecal shedder detection efficiency of the DNA probe (p less than 0.01). No positive DNA probe results were found on 100 randomly selected fecal samples from cows in four certified paratuberculosis-free herds, thus the DNA probe was 100% specific. Probe analyses could be performed in 24 h or less. Time to complete the culture-based tests was 12 wk for HEY and 7 wk for RCM.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of a commercial ELISA for diagnosis of paratuberculosis in cattle

OBJECTIVE: To evaluate sensitivity and specificity of a new ELISA for antibodies against Mycobacterium avium subsp paratuberculosis. DESIGN: Cross-sectional observational survey. SAMPLE POPULATION: Serum samples from 590 cattle that were infected with M avium subsp paratuberculosis and 723 cattle that were not infected. PROCEDURE: Serum samples were tested by use of an ELISA for antibodies against M avium subsp paratuberculosis. RESULTS: Sensitivity of the test varied from 15.4 to 88.1%, depending on the clinical stage and bacterial shedding status of the cattle. CONCLUSIONS AND CLINICAL RELEVANCE: Results obtained with use of the new ELISA agreed favorably with those of a previous ELISA. Practitioners must be aware of variability in the sensitivity of the test, which depends on the clinical and shedding status of the cattle, because this may affect interpretation of test results.     

Evaluation of the DG29 test for early detection of pregnancy in cattle

The objective of this study was to evaluate a commercial blood test (DG29) for pregnancy in cattle. Compared with ultrasound, the sensitivity of the assay for detecting pregnancy around day 30 post-insemination was 99.4% [95% confidence interval (CI): 96.1–100]. The specificity was 100% (95% CI: 84.7–100) in noninseminated cattle, and 66.7%; (95% CI: 49.7–80.4) in inseminated nonpregnant cattle. Positive and negative predictive values were 92.6% and 96.3%, respectively, in a sample of inseminated cattle in which 80% were pregnant.     

Evaluation of an ELISA for the diagnosis of experimentally induced and naturally occurring Leptospira hardjo infections in cattle

An enzyme-linked immunosorbent assay (ELISA) for the diagnosis of Leptospira interrogans serovar hardjo (hardjo) infection in cattle was compared with the microscopic agglutination test (MAT). Glutardialdehyde was used in the ELISA to couple sonicated hardjo antigen to the microtiter plate. Mouse monoclonal anti-bovine IgG1 coupled to peroxidase was used as conjugate. Sera from calves experimentally inoculated with hardjo reacted positively in the MAT as early as 10 days after inoculation; these sera did not react positively in the ELISA until 25 days after the first inoculation. Positive and negative field sera from 704 adult cattle on 90 farms were examined by the MAT and the ELISA; a 90% correlation between the two tests was demonstrated. Eighty-six sera from calves inoculated with four Leptospira serogroups other than hardjo and 227 field sera from adult cattle with naturally occurring leptospirosis other than hardjo were examined by the ELISA. Fewer than 1% of these heterologous sera reacted with hardjo antigen in the ELISA. We concluded that the ELISA described in this report is an advantageous alternative to the MAT for diagnosing leptospirosis.     

Evaluation of an antigen capture ELISA for the early diagnosis of Hypoderma lineatum in cattle under field conditions

An antigen capture or sandwich ELISA (sELISA) was evaluated for the diagnosis of Hypoderma lineatum in cattle under field conditions in northwestern Spain. The kinetics of circulating hypodermin C (HyC) and specific antibodies during the course of natural infestation were determined in a group of 10 Frisian calves. In addition, oesophagi and blood samples were taken from 105 cows at a slaughterhouse in order to compare three methods for the diagnosis of H. lineatum: sandwich ELISA for the detection of the antigen HyC (sELISA), indirect ELISA for the detection of antibodies anti-HyC (iELISA) and the detection of first instars (L1) in the oesophagus. In naturally infested cattle, HyC was present in circulation at low levels during the early and late phases of the infestation. However, in the middle phase, coinciding with the presence of L1 in the oesophagus, two peaks of increased HyC concentration were observed. Specific antibodies increased progressively until the first appearance of larvae in warbles on the back. There was no correlation between antigen or antibody levels and the number of grubs in the back. Prevalence of first instars in the oesophagi of slaughtered cows was 21.9% (23/105). The percentage of cattle that were positive for circulating antigen was slightly higher (24.8%), suggesting the recent destruction of migrating larvae in some animals. However, there was no correlation between the number of L1 and HyC levels. With the iELISA, 79% of the animals were positive to Hypoderma, which means that a high percentage of those animals have been exposed to the parasite but they had no apparent current infestation. The sELISA is a good tool to follow larval development within the host; however, the episodic elevation of HyC levels limits the usefulness of this test for the early diagnosis of Hypoderma under field conditions.     

Cloprostenol for termination of pregnancy in cattle

One hundred and eight cows and 65 maiden heifers which were pregnant from 32 to 250 days were treated with 500 meg cloprostenol. Abortions occurred in 53 (49%) cows and 47 (72%) heifers, with 62% of aborted foetuses being expelled within 5 days of treatment. Of 96 pregnancies treated before 150 days, 86 (89.5%) were terminated. Luteolysis, followed by oestrus and ovulation occurred in both those which aborted and those which did not, although serum progesterone levels and ovarian palpations suggest that luteolysis was not complete in those animals which maintained pregnancy. Abortions occurred in only 2 of 51 cows at 151 – 250 days pregnancy, while 12 of 26 similar pregnancies were terminated in heifers. Reasons for this difference are discussed, as are possible methods for improving the success rate in aborting pregnancies between 151 – 250 days.     

Evaluation of an antibody-ELISA using five crude antigen preparations for the diagnosis of Trypanosoma evansi infection in cattle.

Attempts were made to improve the accuracy of an antibody-detection ELISA for the detection of Trypanosoma evansi infection in cattle by improving the method of preparation of the crude antigen used. An IgG-ELISA was performed with five different antigen preparations: crude soluble antigen, soluble and insoluble fractions of crude antigen treated with 0.1% formalin and whole formalin-fixed trypanosomes treated with either trypsin or 2-mercaptoethanol. An IgM-ELISA using crude soluble antigen was also performed. Each ELISA was evaluated using serum from 44 Indonesian cattle infected with T. evansi and 262 uninfected cattle from Australia. There was no significant difference between the sensitivity or specificity of the IgG-ELISA using each of the five antigens. The IgM-ELISA using a crude untreated lysate was significantly less sensitive (p<0.05) than the IgG-ELISA using the same antigen, trypsin-treated antigen or the 0.1% formalin-treated soluble antigen (68, 64 and 64%, respectively). These results show that these modifications to the method of producing crude antigens for the Ab-ELISA does not improve the accuracy of diagnosis of T. evansi infection in cattle.     

Evaluation of oscillometric and Doppler ultrasonic devices for blood pressure measurements in anesthetized and conscious dogs

Two non-invasive blood pressure (NIBP) devices (oscillometry and Doppler) were compared to invasive blood pressure using a Bland–Altman analysis, in anesthetized and conscious dogs. When considering the systolic arterial pressure only during general anesthesia, both NIBP devices slightly underestimated the systolic arterial blood pressure however the precision and the limits of agreement for the Doppler were of a greater magnitude. This indicates a worse clinical performance by the Doppler. The performance of both NIBP devices deteriorated as measured in conscious animals. In general, for the oscillometric device, determination of invasive diastolic and mean arterial pressures was better than the invasive systolic arterial pressure. Overall, the oscillometric device satisfied more of the criteria set by the American College of Veterinary Internal Medicine consensus statement. Based upon these results, the oscillometric device is more reliable than the Doppler in the determination of blood pressure in healthy medium to large breed dogs.