First, because cats have stress sequelae.
If the doctor sterilises the cat, the cat's temperament will change greatly, and even all the hatred will be vented on the doctor. A dog was sterilized by a doctor before, so the dog went to the doctor's office to pee and did a lot of damage, which also made people laugh and cry. In fact, these pets are also bitter. Cats are probably reluctant to eat honestly because of stress sequelae caused by surgery, and then they will become thinner and thinner.
Second, it may be that the diet is not very good.
If the Zen restaurant doesn't prepare some appetizing food for cats, I believe that these cats don't have much appetite after surgery, their bodies are developing, and the wounds will slowly heal. If they lack nutrition, they will become lighter and lighter. However, if the cat is not very thin, that is normal. When the cat recovers, it will eat more.
Three. Concluding remarks
A cat is also an independent individual. If the shovel officer takes the cat for sterilization, the cat may also bear a grudge against the shovel officer. After all, these things are a part of the cat's body, and being deprived suddenly will make the cat uncomfortable.