The biggest problem is that any site which attempts what you're aiming for would need to offer me more than my current approach, which is just to Google "[food] safe for dogs", which returns me:
A. Multiple sources of information to cross-reference the results, increasing my confidence in the answer. This site only gives me a YES/NO result with no(!) indication of where the information is coming from. You should definitely add a list of sources for the information below the results. For instance, my second search was for blueberries, which all the results on the first page of Google say are safe for dogs, but your website declares TOXIC. Mistakes like that will instantly kill my desire to trust your single source of information.
B. An indication of what level foods might be toxic to dogs at. As other commenters have mentioned, it's not a binary result. A note below the result quoting one or two of what your sources say about levels of toxicity would be really helpful.
Also, just from a usability perspective, when I start typing a food into the search bar and the list of autosuggestions appear, I was expecting to be able to hit the down arrow to start going down the list and hit enter to select the result I want. Making me go back to the mouse to select the answer I want was an (admittedly small) point of frustration).