I noticed that Bao is a little food lover, and always wants to have snacks and staple foods.

Living together for some time, I've realized he has a sensitive stomach.

Once he eates too much, he will vomit.

Firstly, I threw away all of his staple foods and snacks and gave him stapledog food (Acana) only.

staple foods are stuff like wheat, rice etc. Simple stuff that's usually shelf stable. I don't think you can apply it to brands of dog food. The plural form "foods" is not usually used except in the concept of staple foods, but then it's more normal to use the plural form here because otherwise it makes it sound like you're only feeding him one specific variety. One staple food is like "wheat", while a variety of food from that list would count as "staple foods".

Then, I switched from free-feedly eating to eating food at fixed times and with fixed portions.

Only staple foods, no snacks!

Finally, I made up my mind that he was only allowed to have staple food!

Now, he hardly vomits, not even once a week.

Bao gained some weight compared to whenhow he was back then and I feel more relieved.

My Cat (6)-2

I don't understand what "(6)-2" means here.

I noticed that Bao is a little food lover, and always wants to have snacks andin addition to his staple food.

OnceIf he eates too much, he will vomit'll throw up.

"Vomit" would be ok here too, but it's more formal.

DAfter discovering these issues, I decided to change his diet.

Firstly, I threw away all of his stapleorignal food and snacks and gave him staple food (Acana) onlynow only give him Acana brand dry food/cat chow/kibble.

"Staple food" is very formal and sounds out-of-place. It's also not very specific. It's ok to use once, but I would use a more standard word throughout the rest of the essay.

Then, I switched from free-feeding to eating foodfeeding at fixed times and with fixed portions.

Only stapledry food, no snacks!

Finally, I made up my mind: he was only allowed to have stapledry food!

Now, he hardly vomits even once a week.

Bao has gained some weight compared to when he wasfirst came back and I feel more relieved.

I noticed that Bao is a little food -lover, and always wants to have snacks and (staple food).

I'm not quite sure what you mean by "staple food" Do you mean his usual cat kibble?

LivingNow that we've lived together for some time, I realize he has a sensitive stomach.

While the second part of your sentence is not incorrect, the standard phase here would be "Now that....I've come to realise that he has..."

Once he has eaten too much, he will vomit.

DNow that I have discoveringed these issues, I have decided to change his diet.

Firstly, I threw away all of his staple food and snacks and gave him staple food (Acana) only.

Again as I'm not fully sure what you mean by staple food, I can suggest the following "Firstly, I threw away all of his current cat food and snacks and fed him Acana brand cat food instead.

Then, I switched from free-feeding to eatgiving foodhim meals at fixed times and portions.

Only stapleregular cat food, no snacks!

Sometimes, Bao kept pesterings me to give him snacks.

Finally, I made up my mind that he was only allowed to have (staple food) perhaps you mean cat kibble?!

Now, he hrardely vomits eve- less than once a week.

Bao gained some weight compared to when he wasfirst came back and I feel more relieved.