Breeding a Small Poodle-Yorkie Mix Who Had a Fast Heart Rate as a Puppy

Puppies normally have faster heart rates than adults, and a small, nervous puppy at a vet visit can easily have a racing heart, so that finding alone isn't worrying. It's good that your vet hears nothing abnormal now.

Your vet's suggestion of an echocardiogram before breeding is sensible: it's the best way to check for a heart defect, such as a patent ductus arteriosus (PDA), which is more common in these breeds and could stress her during pregnancy or be passed on. Small breeds such as Poodles and Yorkies are also prone to inherited problems such as kneecap (patella) issues, so ask your vet about other health screening too. Very small females can also have trouble giving birth, which is worth discussing before you decide.

See heart disease in dogs for breeds prone to heart disease.

This is general information, not a diagnosis. Please follow your own vet's advice.