The intelligence of the dog is among the highest of all the animals, maybe higher than we give him credit for. Although his brain is proportionately only half as large as ours, he is certainly the most intelligent of domestic animals.
As with humans, individual intelligence varies greatly according to inherited genes. While no one breed can be said to be more intelligent that another, some breeds that have been selectively bred for work ability are often brighter and more receptive than those bred primarily for purely physical attributes.
Whether a dog is a mixed breed for purebred, studies have shown that neither is much more intelligent than the other. However, dogs that have been exposed to a more varied lifestyle, both indoors and out, and with both human and animal interaction, does show more intelligent behavior.
Simply put, giving your dog an opportunity to investigate and manipulate all sorts of objects, to explore all sorts of places, to share all sorts of experiences with you will stimulate his or her intelligence. Aside from getting a lot more out of life, your dog will be eager to learn more and he will learn with increasing ease and rapidity. Nothing is sadder and more wasteful than an intelligent dog that is confined in a kennel and deprived of mental stimulation.
Despite opinions to the contrary, dogs are endowed with an elementary reasoning power. Anyone who has ever owned a dog has often seen him size up a situation and then taken some logical action. Guide dogs for the blind, as well as working and hunting dogs of many breeds constantly have to use their judgment and make decisions.
Memory is an important component of intelligence. The dog's memory for scents is extraordinary. His visual memory is only fair, but his memory for sounds is very good, since he can remember and identify familiar voices even after an absence of many years. While he builds up a large store of identifiable sounds without the slightest effort, remembering different words requires more concentration.
The dog's capacity for learning is more a matter of memory than of true understanding. He will remember the sequence of cause and effect in his actions, but he is unable to draw broad conclusions from his experience. The greater the variety of experiences and contact with others they have, the quicker they learn, and the more they retain.
Dogs are bound by nature to remain intellectually inferior to man, but we owe them a chance to develop their native intelligence by training, teaching, and working with them as much and as often as we can.