When the relative visual acuity of domestic animals is compared, the ranking is pig, sheep, cattle, dogs and horses. All the domestic animals have some ability to discriminate colors and most have superior night vision to humans. Again there are differing ranges of hearing, as well as different acuities. Sheep and dogs can discriminate higher frequencies than humans. Cats range of hearing is similar to humans.
Dogs probably have the greatest olfactory ability of the domestic species.
Odors and pheremones are very important triggers for domestic animal behavior. Horses, cats and dogs also have many sounds but those of cattle and sheep have been little studied. The categories of calls include greeting, distress, separation, excitement, aggression, fear, pain and so on. Visual - In the horse, for example, the ear position can tell a lot about the animals disposition. Ears pointed back generally denote aggression and the flatter the ears to the head the greater the aggression.