Let's keep the tone positive, and regarding how to do it right. If this thread goes negative, it too will simply get closed. No one benefits from closed threads.
I wonder, in the area that this happened, was there an Animal Control officer? If yes, was he or she available?
Another point that I would make is that while some weapons are more or less effective, if it is the only weapon that you have at the second the crisis happens, it is likely what one will use.
Ergo, we come back to foresight and planning. Should LEOs carry shotshells for their pistols, or say #8 shot for their shotguns? And if so, what other unforeseen situation might next arise requiring yet other ammo or weapons?
After-thought. I don't believe that anyone has yet contributed a thought of...what if the LEO had a snake phobia? It is possible.
Edit to add:
XavierBreath:
I agree, it is wrong to expect LEOs to function as animal control. It is an entire separate profession, and requires fully different tools, weapons and tactics. Thank-you for supporting that position.