When I was in veterinary school we spent 100s of hours studying courses like anatomy, physiology, surgery and all the essential skills needed to practice medicine. But often my friends are most interested in things we didn’t spend much time discussing, like:

§         How do cats purr?

§         Do dogs dream?

§         Why do cats always land on their feet when they fall?

§         Why does my dog howl when he hears fire engines and police cars?

§         Why does my cat make a really weird face when he smells other cats?

Purring is caused by the vibration of muscles in your cat’s larynx (voice box). Cats that don’t roar, such as domestic kitties, pumas and mountain lions, can purr. The sound is produced when air passes over the voice box as they breathe in and out, when they’re happy and relaxed, but also sometimes when they are sick or in pain. Some researchers believe that the frequency range of the vibrating purring sound may actually have positive healing benefits for animals and people, and some practitioners of holistic human medicine believe that listening to a purring sound may have positive healing properties.

Yes, dogs most likely do dream. Humans dream during the period of deep sleep called the REM (rapid eye movement) phase, when our bodies relax and our brain gets to process and make sense of our thoughts and experiences. Dogs also go into REM sleep.  So if you’ve ever noticed your dog paddling his feet or making little barking noises while sleeping, it’s likely he is dreaming -- perhaps about his next big adventure at the dog park.

Unfortunately cats do not always land on their feet when they fall, but they have a better chance of it than most animals due to a combination of things in their favor. Cats have a very good sense of balance allowing them to easily detect which direction is up, even when they are moving. They have a very flexible spine and no collarbone so they are able to twist and rotate their body, particularly their front legs, while falling. This allows them to quickly position all four feet underneath them and, hopefully, land on their feet.

There a few theories as to why some dogs howl when they hear sirens. Some say it is because the noise hurts their ears, but I believe it has more to do with their ancestral roots. Wolves howl to communicate with the pack, to say: “Here I am” and “Where are you?” The sound of a siren howling in the distance may be similar enough in pitch and quality to evoke our dogs to feel their “inner wolf,” throw their heads back and communicate with the pack.

What is up with the weird open mouth face that cats sometimes make when they smell other animals? My cat usually makes it when he stiffs my clothes or coat after I’ve visited friends with pets. Many animals have an area in the roof of their mouth called the vomeronasal organ, or Jacobson’s gland. It is the same part of the body that helps snakes to ‘smell’ their prey. It is especially sensitive for detecting the pheromone scents given off by other animals. When cats open their mouths in this manner they are most likely allowing the vomeronasal organ to detect the scent secreted by other animals, especially cats, so that they can determine if this cat might be a friend or foe.

Dr. Vega received her veterinary medicine degree in North Carolina and a small animal surgery externship at the Animal Medical Center in New York City. For questions or comments, please email ThePetVet@aol.com.