Hello, i'm sorry to hear about your kitty.Does he go out doors?Does he have any nasal or eye discharge? If yes what does it look like?
How long has this been going on?Is Sparky coughing at all?Do you have any other cats? If so how are they?
The most common reason for raspy breathing in cats is an upper respiratory infection.Cats can easily catch them by breathing in airborne infectious particles, either by going outdoors or having access to open doors or windows. These kitties tend to have a nasal or eye discharge and sneeze quite a bit for a week to 10 days but may have no further effects. As long as they eat and drink ok they should be fine and the virus should run its course in a week or two. Some of them will become chronic. These kitties will have symptoms on and off throughout their lives, triggered by stress.
Another reason for raspy breathing is feline asthma, diagnosed by a radiograph and treated with bronchodilators and steroids.Feline heartworm disease can also manifest as raspy breathing.Heart disease in cats can cause raspy breathing but those cats can become quite lethargic and very winded with little exercise. And they tend to have a decreased appetite as well.Feline Infectious Peritonitis can cause fluid accumulation in the lungs as well.
Even though your fella is feeling well otherwise if his raspy breathing persists beyond 10 days then I recommend an examination by his veterinarian. If he is coughing, has pale or bluish gum color, loses his appetite or is panting he should be seen as soon as possible.