Ears pointed back generally denote aggression and the flatter the ears to the head the greater the aggression. Another visual expression in male horses and ruminants is the Flehmen response . This is a curl of the lip when the urine of a female in estrus is smelled. In the cat, a high tail is a greeting or sign of being curious. Pigs and horses show grooming behavior, as do many of the monkeys and primates.
Subordinate pigs groom dominant ones.
Horses tend to groom horses of comparable rank. Subordinate cattle will lick dominant cattle. Olfactory - Olfactory clues and scent serve to mark territory , show the way home, and distinguish individuals. Urine and feces are powerful means of olfactory communication. Cats and dogs also have anal sacs which are additional scent organs.