There are a few things to consider when trying to identify a track.

The length of stride is probably the most important, soil condition is an equal or close second. Why it was doing what it was doing when it made the track is the next thing.

Both dogs and cats have four protrusions or "nubs" in it's tracks. They both show claw marks and a "wide" spread when running in soft dirt or mud.

Your picture does not show the surrounding tracks, or give much of an indication about surrounding conditions, but I would surmise that where that particular track was...was wet, or dried mud, or "set" snow.

It's a very clear track, of a very particular animal, in a very particular soil condition...The thing is, there are several animals that fit that particular foot patern.

Without seeing additional tracks and knowing the soil conditions around it, I would guess;

That particular track, in my opinion shows a dog running in soft soil and bearing to the right.

I say that because all four pads are very distinct, and the claws are shown, which indicates nothing except that the soil was soft or soft and wet.

The pad in the middle has a high arch, which makes me think it was a dog...a cats arch. or center pad has a more "round" shape to it. (A dog AND a cat have center pads that look kind of like a "club" in a deck of cards, but a dogs often has a little more of a point on top)

You mention that it was about the size of a tennis ball...That enforces my thinking that it was a dog and not a cat.

I would even make a further guess and say that this track was found along a trail that is close to water.

I'm gonna finish my guessing with this prediction:

It was a rather big dog...A setter or retriever, that was out for a walk with it's owner, and this was a track it made in wet soil while it was running.