Hi There! There are definitely things you need to keep track of for taxes. Rover would go on a schedule C. You would put your 1099 income there. So the goal would be to write off most of the income if you can. This would of course reduce your tax liability. You don't want to write off all of it because for the IRS to recognize it as a business, it has to show a profit at least 1 time in a span of 3 years, or else its considered a hobby. So anything that you buy for your rover business should be eligible. You just want to make sure you keep your personal stuff separate from the stuff for your business, especially if you have a dog(s) of your own.
For example, if I buy treats to give to the dogs I watch, including mine, then I would write that off. However, if I buy special treats or a supplement for my dog, I wouldn't write that off. So I would say as long as its available for use by your business (dogs you watch).
You can write off quite a few things.. such as, bowls, foods, treats, leashes, pet gates, crates, business cards, mileage, etc. You can also input your health insurance premiums. Just make sure, once again, these items are for your business purposes and not personal. I would definitely recommend keeping receipts and such for purchases.
If you only have 1099 income, I would also recommend setting up some quarterly estimated tax payments.
But remember, you want to show some profit!
Hope that helps!