Juge Aiden E, Hall Nathaniel J, Richeson John T, Daigle Courtney L
Department of Animal Science, Texas A&M University, College Station, TX, United States.
Department of Animal Science, Texas Tech University, Lubbock, TX, United States.
Front Vet Sci. 2022 Jul 1;9:902151. doi: 10.3389/fvets.2022.902151. eCollection 2022.
Bovine respiratory disease (BRD) is the leading cause of morbidity and mortality in feedlot cattle and is a major welfare and economic concern. Identification of BRD-affected cattle using clinical illness scores is problematic, and speed and cost constraints limit the feasibility of many diagnostic approaches. Dogs can rapidly identify humans and animals affected by a variety of diseases based on scent. Canines' olfactory systems can distinguish between patterns of volatile organic compounds produced by diseased and healthy tissue. In this pilot study, two dogs ("Runnels" and "Cheaps") were trained for 7 months to discriminate between nasal swabs from cattle that developed signs of BRD within 20 days of feedlot arrival and swabs from cattle that did not develop BRD signs within 3 months at the feedlot. Nasal swabs were collected during cattle processing upon arrival to the feedlot and were stored at -80°C. Dogs were presented with sets of one positive and two negative samples and were trained using positive reinforcement to hold their noses over the positive sample. The dogs performed moderately well in the final stage of training, with accuracy for Runnels of 0.817 and Cheaps of 0.647, both greater than the 0.333 expected by chance. During a double-blind detection test, dogs evaluated 123 unique and unfamiliar samples that were presented as 41 sets (3 samples per set), with both the dog handler and data recorder blinded to the positive sample location. Each dog was tested twice on each set of samples. Detection test accuracy was slightly better than chance for Cheaps at 0.451 (95% CI: 0.344-0.559) and was no better than chance for Runnels at 0.390 (95% CI: 0.285-0.496. Overall accuracy was 0.421 (95% CI: 0.345-0.496). When dogs' consensus response on each sample set was considered, accuracy was 0.537 (95% CI: 0.384-0.689). Detection accuracy also varied by sample lot. While dogs showed some ability to discriminate between BRD-affected and healthy cattle using nasal swabs, the complexity of this task suggests that more testing is needed before determining whether dogs could be effective as a screening method for BRD.
牛呼吸道疾病（BRD）是饲养场肉牛发病和死亡的主要原因，也是一个重大的福利和经济问题。使用临床疾病评分来识别受BRD影响的牛存在问题，而且速度和成本限制也制约了许多诊断方法的可行性。狗可以基于气味快速识别受多种疾病影响的人类和动物。犬类的嗅觉系统能够区分患病组织和健康组织产生的挥发性有机化合物模式。在这项初步研究中，两只狗（“Runnels”和“Cheaps”）接受了7个月的训练，以区分饲养场到达后20天内出现BRD症状的牛的鼻拭子和在饲养场3个月内未出现BRD症状的牛的鼻拭子。在牛进入饲养场时进行处理期间采集鼻拭子，并储存在-80°C。给狗呈现一组一个阳性样本和两个阴性样本，并使用正强化训练它们将鼻子放在阳性样本上方。在训练的最后阶段，狗的表现中等，Runnels的准确率为0.817，Cheaps的准确率为0.647，两者均高于随机预期的0.333。在双盲检测试验中，狗评估了123个独特且不熟悉的样本，这些样本以41组（每组3个样本）的形式呈现，狗的训练者和数据记录者都不知道阳性样本的位置。每组样本对每只狗进行两次测试。Cheaps的检测试验准确率略高于随机水平，为0.451（95%置信区间：0.344-0.559），而Runnels则不高于随机水平，为0.390（95%置信区间：0.285-0.496）。总体准确率为0.421（95%置信区间：0.345-0.496）。当考虑狗对每组样本的一致反应时，准确率为0.537（95%置信区间：0.384-0.689）。检测准确率也因样本批次而异。虽然狗在使用鼻拭子区分受BRD影响的牛和健康牛方面表现出一定能力，但这项任务的复杂性表明，在确定狗是否能作为BRD的筛查方法之前，还需要进行更多测试。
