What's going on with my Teddy's non-curly hair?

There are several reasons why a Teddy's hair doesn't curl.

Shaving: Dogs have sensitive skin, and frequently shaving their hair stimulates the hair follicles, causing the growing hair to grow slowly, become coarser, and lose its curl.
Skin diseases: When a dog has a skin disease, new hair growth not only changes in color but also becomes non-curly.
Nutrition: Insufficient protein intake makes the dog's hair dull and straight.
Breed reasons: If the parents are not purebred Teddies or have unstable bloodlines, it is possible to have non-curly Teddy hair.

Poodles are a breed of curly-haired dogs, so they rarely shed hair except during the annual shedding season. However, as the puppy grows older, its hair should become more curly.

If you feel that your Teddy's hair isn't as curly as you expected, you might wonder if your dog is mixed breed or if there's anything you can do to make its hair curl.

Poodle puppies have sparse, soft wavy hair that doesn't become the standard thick, curly adult hair until around 9 months old. You can trim 1/3 of the hair at 6 months old to let the hair grow slowly and naturally become curlier with age.
Use curl-enhancing shampoos. Many shampoos on the market have functional ingredients. If the shampoo you use makes the hair fluffy or smooth, it is detrimental to the curl of Poodle hair. It is recommended to use Poodle-specific or curl-specific shampoos.
Blow dry after bathing and brush the hair frequently. To keep your Poodle's hair curly, continue to brush, bathe, and blow dry your dog.
High-quality protein intake makes the dog's hair soft, shiny, and curly. High-quality food also increases the curl of Poodle hair, and shampoos containing keratin and silk protein have the same effect.
Mixed bloodlines: Some Mini or Toy Poodles are possibly hybridized with Standard Poodles and Maltese or Havanese, which could explain why their hair doesn't curl throughout their lives.