It differs between each one. Some stand up at around 5 weeks, and some take a couple months.
Generally between 4 and 6 months
The procedure is usually done with Doberman Pinschers, Boxers, Boston Terriers, or Great Danes. Generally, ear cropping is performed when dogs are between 9 and 12 weeks old. After this, the chances of success drop, as Fido’s ears may already be drooping.
All dogs will, do, and need to chew. However, if you train your dog at an early age not to chew, they will not.
For a small breed like a boston it would be about 10 months. You can switch it to adult food.
German Shepherds' ears typically stand up on their own as they grow, usually by 6 months of age. If your puppy's ears haven't stood up by this age, you can try posting or taping them to help them stand. If the ears still haven't stood up by around 8-9 months, it's less likely they will naturally stand on their own.
Puppies' ears typically start to stand erect around 3 to 4 months of age. However, it can vary depending on the breed and individual dog. If the ears have not stood up by 6 months, it is advisable to consult a veterinarian.
Boston Terriers typically experience a separation of their skull plates, known as "head splitting," around 3 to 6 months of age. This process is part of their normal growth and development. However, it’s important to consult a veterinarian if there are any concerns about your puppy's head shape or overall health. Regular veterinary check-ups can help ensure their development is on track.
Ear mutilation is usually done around 9 to 11 weeks of age. Any later and the ears may not want to stand. You are trying to find that time when the puppy is old enough to handle the butchery and anesthesia well, but young enough that the cartilage is not set in their ears yet.
When a chihuahua is young, the cartilage in its ears hasn't become strong yet. Depending on the day and the dogs behavior, the ears may or may not stand up. When the dog has reached a certain age (sometimes 6 months or more), its ears should permanentely stand up. Also if it has adopted a trait from one of its relatives, the ears might never stand up. So sometimes it's just genetics.
They will eventually stand up on their own, although the exact age is different with every puppy. I have seen a few that had one ear stand up completely and the other ear stand up only part way. If you see this starting to happen you can massage the ear in an upright postition and it will help strengthen the ear and help it stand.
All dogs are different. Some will grow whiskers when they are a few months old. Others will start when they are two years old! All dogs are different!
Ear cropping is generally done when a dog is between 7 and 12 weeks old. After this period, the ears become more mature and it can be more painful and less effective. It is recommended to consult with a veterinarian for the best timing for the procedure based on the breed and individual dog.