Accuracy of the “index finger test” to determine type of death of dairy cows at destruction plants

• Dead cows are routinely brought to destruction plants and monitoring the influx may be useful for early detection of emerging (infectious) diseases. A prerequisite is that it can be determined if the cow was euthanized or died unassisted, because a sudden increase in the latter may be indicative of an outbreak. The objective of this study was to evaluate the accuracy of visual inspection at the destruction plant as a means to distinguish between the two types of deaths. The two main destruction plants in Sweden were visited 3 times, 3 days each, in spring, summer and autumn during 2011. The identity, and whether the cow was shot in the forehead or not, was recorded for all dairy cows entering the destruction plants during these days. We phoned the owner of the cow within 3 weeks after the cow was examined and asked whether the cow died unassisted or was euthanized. A total of 468 cows examined, also had information from the farmers. The comparison demonstrated that there were discrepancies between the observations. According to the farmers (gold standard) the proportion of cows that died unassisted was 30%, while the visual inspection (test) found that the proportion was 40%. Three cows were euthanized by an overdose of an anesthetic, which explained some of the discrepancy. The sensitivity and the specificity of the visual examination were 93% and 83%, respectively. The positive predictive value was 70% and the negative predicted value was 97%. This study showed that visual inspection of dairy cows at destruction plants overestimate the proportion of cows that died unassisted. The accuracy of the method is however judged to be sufficient to monitor the proportion of unassisted death.

Ämnesord

LANTBRUKSVETENSKAPER  -- Veterinärmedicin -- Annan veterinärmedicin (hsv//swe)

AGRICULTURAL SCIENCES  -- Veterinary Science -- Other Veterinary Science (hsv//eng)

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