What can we infer from the passage?

Animals perform many useful and entertaining jobs. Dogs are particularly valuable in guiding the blind, protecting property, finding lost people, and hunting criminals. Horses are used in guarding herds, carrying men in lands when there are no roads and helping farmers work on their lands.
    Dogs are extremely useful as companions for blind people. When a dog has been properly trained, he will al ways lead its blind master in the right direction and keep him out of danger. For instance seeing-eye dogs learn never to cross a busy road when cars are coming, even if their masters command them to do so.
     Horses are also able to learn lots of things. Horses used for guards or police duty must learn never to be frightened of noises, traffic and other disturbances. Racing horses are able to learn much faster than other horses. Therefore it is necessary for those who train them to be very patient and understanding.
     Pigeons have a natural instinct to return home, even if they are far away and the trip is very hard and dangerous. Men utilize this instinct to send messages on small pieces of paper that are fastened to the pigeon’s back or legs. In wartime, pigeons have been known to fly as fast as 75 miles an hour and to cover distances of 500 to 600 miles.