A Domestic Rat Can be the Ideal Pet by Frank Utchen, DVM

When you tell someone that you, as a supposedly mature, sane adult, have two rats as pets, you'll generally get one of two responses: revulsion, followed by a questioning of said supposed sanity, or delight, from those who once had rats as pets (usually when they were young) and still remember how much fun they are.

In my life I’ve adopted 4 rats and have experienced both responses countless times, the former far more than the latter.

The reaction of disgust is unfortunate, for rats can be entertaining, affectionate and clever pets. They're excellent first pets for children, great sole pets for adults who might prefer a dog but are in "no pets" housing, and easy-care pets for those who aren't home much or don't have the desire to clean up after a dog, cat or bird.
 
Still not convinced? Let go of everything you've ever thought about rats and consider the benefits with an open mind:

Rats are social animals. Many small pets don't like being handled, but rats get used to careful socialization easily, and come to enjoy riding in pockets and on shoulders. They like people!  They generally love to be petted. One of my rats used to like to sleep in the hood of my sweatshirt while I studied in veterinary school.

Because rats are so social, if you're going to get one, you should consider getting two so they can keep each other company. 

Rats are obsessively clean, spending most of their waking hours grooming themselves.

Rats are smart. Rats respond quickly to food-based training and seem to love to perform. With little effort, I've trained rats to perform a few of simple tricks. In fact, they are so trainable that they will pick up on the subtle cues that let them know mealtime is here faster than any dog I've ever known. 

Rats are agile and sturdy. Try to get a guinea pig to run a maze or climb a ladder, and you'll appreciate the fleet-footedness of a rat. Unlike mice, rats can stand up to the handling -- and occasionally, the unintentional mishandling -- of well-meaning children.

Rats are cute. Really. Think sleek, shiny fur, dark, glossy eyes and cute little ears. You say it's the tail that gets to you? Give a rat a break. If he just had a fluffy tail he'd be a squirrel, and people would give him nuts in the park.  

Did you know that rats come in oodles of colors and coat patterns? Colors like silver mink, platinum, blue and chocolate, and markings like hooded (the head a different color than the body) or masked or patched. 

Rats are easy to keep. Get a cage sized for a larger pet, such as a chinchilla or guinea pig, and your rat will be content. Add bedding, a place for your rat to hide and sleep, a food dish, water bottle and some toys. These can be freebies, such as the leftover core of a paper-towel roll, or small untreated blocks of wood.

Your rat will happily eat the food manufactured for them and available at pet supply stores, and will love it if you add fruit, nuts, vegetables and other "people food."
 
The downside of rats? The only thing that comes to mind is they don't live all that long -- two to three years -- and they're prone to tumors. And, as with all small pets, cage changes must be frequent, otherwise the smell will become unpleasant--to both you and your rats.