Pet keeping has appeared in the historical record many times. Over 2,000 years ago people of Greece, Rome, and other regions of the classical world kept pets; some prized pets received special burials with tombstones, called stele.

Animals receiving the status of pet depended upon local cultural attitudes and beliefs. For example, before European contact, Mexican cultures kept pet birds; the small dogs that appear so often in their pottery, however, were mainly used as a food source and for spiritual purposes.

In the mid-19th century rabbits and squirrels were considered to be good pets for children. Hamsters and gerbils, two of the most common pets for children, were not introduced until the mid 1900s. The hamster arrived in this country as a laboratory animal before being taken up as a pet.

As in the past, dogs are one of the most popular pets. However, in the 19th century they also worked for a living as guards, pulling small wagons and carts, and powering some small machines by running on tread mills.

European colonists carried the habit of keeping cage birds with them. Trapped wild birds were some of the most common pets. Canaries arrived in America in the 1820s and by 1870 they were the most common pet bird.

First bred in Asia, goldfish arrived in America in the early 1800s. Until the 1880s they were very expensive and most families only kept one as a parlor ornament. By the 1910s they were common enough to be offered as dime store pets and carnival prizes.

By the 1860s, Americans began to experiment with what was called the “balanced aquarium,” where a small number of water creatures lived in balance with living plants. By the early 1900s, a few wealthy Americans began to collect tropical fish. These fish needed warm water and lots of oxygen to survive; hence the aquarium heater and the electric aquarium pump were invented.

Cats remained household workers long after family dogs were no longer expected to work for their keep. The invention of “cat litter” in the 1940s made it easier to keep cats indoors. By 1970, Americans claimed more cats as pets than dogs.

In the 1800s the majority of veterinarians were dedicated to the care of livestock and large animals. In 1884, the University of Pennsylvania veterinary school opened the first clinic for dogs in this country. By 2001, there were over 28,000 small animal veterinarians in the United States.