Focus on the messaging of your ad.
Consider creating customer avatars to get to understand how people that want your product will think and feek. What language do they use? What hobbies do they have? etc
Then you want to make sure the ad copy relates to them and so does the creative.
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This is much more important than interest targeting.
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But you can also search Dogs and then use the suggested button to look for similar interests.
Dog food brands, vet centres etc.