[header] How to scratch a dog's belly [title] Look for signs that your dog wants a belly rub. [step] Most dogs want their stomachs scratched or rubbed and it's generally fine to do so. However, some dogs are not comfortable with this and you will have to look for the signs that your dog is happy to have its belly rubbed before doing so. 
[substeps] A dog will lie down, presenting its stomach and wagging its tail to show it's comfortable with you. Your dog should look relaxed and will lay down without tension in its body.