If there is an audience behind your blog niche, then you can make it profitable. This is even if you can put products behind the blog or not. Because the niche has passionate readers, the more readers equal, the more traffic, and a highly trafficked site can always make money passively with ads.
What you should figure out is if the niche audience will connect with your writing. Plain and simple, the pet niche has a passionate audience behind it. People are NUTS over their pets and consider them a part of their family. That’s why there are pet toys, pet clothes, specialty pet foods, pet subscription boxes, and on and on.
However, considering the competition, your writing style, the amount of information you are bringing, how often you post, how you promote the content will make the difference if the audience will stick with your blog or not.