Effect of oestrous-cycle stage on the response of mares in a novel object test and isolation test.

This research investigates whether the stage of a horse’s oestrous cycle affects its response to new objects and isolation, and whether horses assumed to suffer from oestrous-related behavioural issues respond differently to these tests than controls.

Overview of the Research

• The study focuses on examining how oestrous-cycle stages affect the behavior of mares in response to a novel object and isolation tests. The research also looks at whether mares, speculated to undergo oestrous-related behavioral issues, react differently to these tests as compared to mares not flagged for such issues.
• The subjects of the study included twelve mares that were tested twice, once in oestrus and once in dioestrus, following a crossover design. For the tests, seven behavioral and two heart rate variables were recorded for the novel object test and two heart rate variables for the isolation test.

Findings of the Research

• The study found that the oestrous-cycle stage and the speculated behavioral problem classification did not affect the mare’s response to the tests. However, the study did identify that the order of test (i.e., whether the mare was tested in the oestrus or dioestrus stage first) significantly impacted its reaction to the novel object.
• Significant differences were noted between the first and the second test occasions in three behavioral variables and one heart rate variable in the novel object test. Mares were found to explore novel objects more frequently and exhibit a higher mean heart rate during the first test.
• The increase in exploration of novel objects was largely accredited to mares tested in their dioestrus stage first, suggesting that mares in their oestrus phase may have been less receptive to the presence of a new object.
• The study hypothesizes that the differences in behavior between the test occasions could be due to learning or habituation.