When writing an essay how do you make it sound upper grade. provide a couple of sentence's about how to take care of a sick pet? ?

I’m actually just learning this too. This may be different depending on the type of teacher. I would say to write a Thesis.

Try going off of the S.E.E essay style.

Your first paragraph could name off a few sicknesses or signs of a sick pet.
The second paragraph/body could explain what treats those sicknesses or common vet visits due to one of the sicknesses listed from the first paragraph. This is where you should include some kind of quote.

Example Being:
Veterinarian (name) has seen a few of these cases. He/she say “(insert quote here)”

The body should be long, but not too long. You should just do some research on the common sicknesses for pets and how to take care of them.

When you get to the conclusion, restate some things you mentioned.

Hope this helps!