Can dogs detect cows in heat by smelling their saliva?

They can, say German researchers with the Clinic for Animal Reproduction in Berlin, but not with complete accuracy.

During the study, the researchers trained 13 dogs of various breeds (both male and female) to detect estrus-specific smells in the saliva of dairy cows. Five dogs had no experience in scent detection, but eight had been previously trained to detect narcotics or cancer.

“We demonstrated that dogs could discriminate between saliva samples from cows in estrus and in diestrus but that overall accuracy was insufficient,” say the researchers in an interpretive summary of the research, published in the February 2013 Journal of Dairy Science.

The dogs' overall accuracy was 57.6 percent, or 175 out of 304 samples, with a range of 40 to 75 percent.

Read an abstract of the research here.

Source: Journal of Dairy Science, Volume 96, Issue 2, Pages 1081-1084, February 2013, C. Fischer-Tenhagen, B.-A. Tenhagen, W. Heuwieser.