Reasons for a kitten's hoarse voice:
1. If a kitten is physically normal and mentally normal, its hoarseness may be due to prolonged lack of vocal cord use.
2. If a kitten has a cold or bronchitis, it is important to keep it warm. Bronchitis can also cause hoarseness.
3. If a kitten's voice becomes hoarse, it may be due to meowing for too long. In this case, you can feed it some goat milk to soothe its throat and let it recover in a couple of days.
4. If a kitten gets a fever, its voice will become hoarse. Make sure to give it water or feed it some wet food. 
What to do if a kitten has a hoarse voice:
1. If a kitten has a severe cold, its voice may become hoarse. In this case, you should buy special pet cold medicine for the kitten and keep it warm so that it can have a better place to rest.
2. If the kitten's throat is inflamed and has become hoarse, you can give the kitten more warm water and give it pet anti-inflammatory medication containing bezoar. If there is no improvement, you should take it to the vet for treatment in time.
3. If the cat's hoarseness is caused by feeling insecure in a new environment, you should give the cat more water and patiently soothe its emotions. This should usually resolve the issue.
4. If the kitten's stomach upset is caused by a cold or indigestion, resulting in prolonged vomiting and hoarseness, you can add some probiotics to its diet to regulate its gastrointestinal tract and give it more warm water. It will gradually get better.
