Dr. Universe: Do all animals pass gas? Do cats fart?

Hasandi, 11, Jeddah; Harrison, 10, Albany, Ore.

Dear Hasandi and Harrison,

If you’ve ever been near a cat or dog when they tooted, the smell might have sent you running right out of the room. A lot of animals pass gas. But believe it or not, some animals do not.

First, let’s talk about the gassy ones. When us cats and humans eat food, we are also swallowing air, or gas. It’s made up of elements like nitrogen and oxygen. The gas travels down into our digestive system and can take up space in our stomach and intestines. In our digestive systems, we also find tiny living things called bacteria.

You might blame the dog for your farts, but the real credit goes to your bacteria. Not all bacteria are bad. In fact, a lot of bacteria are helpful. Some of them help break down your food into its simplest form, like proteins and sugars that you can use for energy and growing. Some get rid of waste. But as they do their different jobs, they produce a bit of gas.

That’s what I found out from my friend Kristen Johnson. She’s a researcher at Washington State University who has tackled some big questions about how cow gas impacts the environment. She explained that while each bacterium makes a small amount of gas, there are millions of them doing it. It really adds up.

This gas needs to leave your body somehow, so you can release it either as a burp, a fart or by breathing. But if you were a clam or other mollusk, you wouldn’t toot. If you were a sea anemone, you wouldn’t fart, but you could probably burp.

Last year, a bunch of researchers listed which animals they studied farted. According to their list, it appears that some worms don’t pass gas either. Then there are some animals that scientists aren’t sure about, like spiders and parakeets. One researcher even found that some millipedes have hard valves on their rear ends that silence their toots. It would be nice if some other animals I know had those.

Birds have the equipment to fart but apparently don’t. Some scientists have found that a lot of them don’t usually carry the same kinds of gas-forming bacteria in their guts that humans and other mammals do.

As it is, humans toot around 20 times a day, producing enough gas to fill up about half a two-liter bottle of soda. A lot of the time these farts don’t smell. But sometimes your bacteria release sulfur and other things that can get pretty stinky. It might not always be pleasant, but it’s totally normal. Silent or deadly, a fart is usually a sign that our bodies are healthy.

Sincerely,
Dr. Universe