The only real competitor in this market, DogVacay, is focused primary on dog boarding.
I feel there might be a bigger market for just dog walking, but how can I go about quantifying that market? Is my only option to contact several hundred people with pets and see if they're interested?
Is there a better way?
There likely is a big market for just dog walking. I myself have had the need for one several times, especially when I'm consulting and have to go to a client's location for long hours.
Both Rover.com and DogVacay focus on dog sitting / boarding first and walking is featured more as a subset service. It's likely because the margins on boarding are a lot more (it costs way more to leave a dog with someone for a few days than to get your dog walked).
But dog walking would definitely have a lot more volume.
Do post your url here if you go forward with this service, I'll be down to using it!
Apart from the fact that you apparently haven't found Rover.com who recently raised 12million series c funding, why do you think there's a better way to understand a business than by asking the potential customers?
Of course *what* you ask them plays a huge part in what you learn from them. I suggest you read "The Mom Test" by Rob Fitzpatrick.