Dirty Mouth

Picture of board:

Abstract:

Do Cats or Dogs Have a Dirtier Mouth?

Everyone has heard and has an opinion about the rivalry between cats and dogs. I’m deciding to settle the score on which species has the cleaner mouth! As a hypothesis, I took an educated guess and thought that a cat’s mouth would be dirtier because a cat cleans itself every day, and who knows where it’s fur has been. Let’s take a look, does a cat or a dog have a dirtier mouth?

To find out my question, I swabbed cotton swabs with my dog’s on agar plates to started growing the bacteria in an incubator. This was on a Friday, so when I came in the next Monday, the bacteria had grown. As an average, each plate took about three days to show some good results. A few weeks later, I had tested both the two cats I tested twice, and the two dogs I tested twice.

Continually, the results were in. As the pictures show, the dogs had a dirtier mouth by far. I counted how many small bacteria blobs there were as a unit of measurement. The dog’s bacteria agar plates had on average 6.5mm, and in total 26mm of bacteria The cat’s bacteria agar plates had on average 3.85mm, and in total 15.5mm. This is really surprising, because I thought for sure cat’s mouths would be dirtier due to them cleaning themselves. I bet it is because the dogs might have eaten strange things.

My hypothesis was wrong. I assumed that cats would have the dirtier mouth, but in fact, I was wrong. From my results, it shows me that a dog’s mouth is almost twice as dirty than a cat’s mouth. I judged this by seeing how much bacteria there was on each plate. I should think more carefully when I let my dogs lick me from now on. Although my results looked pretty clear, what could have happened was that my cats didn’t fully coat the cotton swab with their spit, so the results were less prominent. It could have also been that outside bacteria infected the plate. Although these options aren’t likely, it could have happened. I feel like my test was accurate, though. This experiment could have been improved by having a cleaner environment to test, rather than just a classroom that many children use every day. Overall, this experiment was highly interesting, and I would recommend repeating it.

Data Tables:

Graph:

Question:

Which animal has a dirtier mouth, a cat or a dog?

Hypothesis:

I think that the cat will have a dirtier mouth because a cat cleans itself with its own tongue every day.

Procedure:

First, I swabbed the mouths of cats/dogs to get a bacteria sample. Then, I rubbed the swabs onto agar plates and let them grow under a heat lamp in a lab for three days, being careful not to touch the bacteria before or after they grew. Finally, I measured the square mm of bacteria.

Conclusion:

Overall, I conclude from my results that dogs have a dirtier mouth. I discovered this by observing the grown bacteria plates, and saw that there was a higher percentage of bacteria in the dog’s agar plates.