Others mention issues with the difficulty, but I didn't have too big of an issue with that. I suspect they took on too many cats at a time and got overwhelmed, perhaps you could do something to avoid over-adoption. Like perhaps each cat could cost $10 to adopt, so if you tried getting too many you'd run out of money and need to wait before adopting more. Or maybe you could only have only a few cats in the street which gradually replenish. Another issue could be that they didn't know what clicking on the cats was doing. The game asks you to click on the cat again to confirm, but it's not clear what you're confirming. If you were clearer with this, then the risks of over adoption might have been more obvious. Perhaps after confirming, some text could've appeared to say "adopted", and maybe it could show you how many cats you already have.
Otherwise though, a cute little game. I like that there is an ending, though towards the end was a bit slow as I had just a few cats that were waiting for spca. What does that stand for by the way? Did you make some funny acronym for that or just a random substitute for rspca?