For as long as I can remember my 5 year old cat has intermittent rapid breathing. She doesn't seem bothered by this and she doesn't have any other symptoms when she is breathing quickly. I always forget to ask about this when she is at the vet and her breathing is always normal there. When her breathing is fast it's around 70 75 breaths per minute and normal is around 32. The intermittent fast breathing last maybe a few minutes and then goes back to normal.
My cat, Halia, is breathing heavily. However, she has mammary tumours which had reoccurred after prior removal of earlier tumours. On her second visit for the new tumours, it was found that the growth has spread to her lungs. The vets told me that any course of treatment at this stage will not be advisable or productive given that her tumours returned after only 2 months, and they are spreading very aggressively.

Because they are easily startled, it’s best to keep equipment and devices that make loud noises, i.e., vacuum cleaners, blenders and such tucked away in a storage or a corner spot in the house. When this happens, scoop up your cat, place them in a quiet, safe spot and reassure him. Allocate a quiet space for your cat as sort of “sanctuary” so they can retreat as needed.
So from your question it seems like the abscess was treated successfully but now you’re noticing at the respiratory rate is increased; there are many different causes for an increased respiratory rate which may include pain, heart disease, stress among other causes. Without examining Kitty I cannot (legally) diagnose a particular condition or offer treatment; you should return to your Veterinarian for another examination especially since there are many possible causes which it could be. Regards Dr Callum Turner DVM
Blood work will identify the presence of any infections and will involve a quick needle stick procedure, done in your veterinarian’s office. Depending on the results from a preliminary physical exam, review of symptoms, and blood work, your veterinarian may wish to order imaging of your cat’s chest area. Images such as x-rays or an ultrasound will help identify any fluid buildup, foreign objects, or potential tumors, masses or foreign objects that may be causing the heavy breathing. Depending on your cat, your vet may order a mild sedative be given to your cat to potential limit movement. Your cat remaining calm and still will have a large impact on the clarity of the images.
My fiance said the he saw her eat this afternoon, so that is a relief. Her gums are pink (that's one of the first things I looked at on her and I should've told you that...but... this is my BABY CAT and she has me a little panicked!.. not like dealing with humans on the ambulance... she's innocent!) I do have access to oxygen... so we can make her an oxygen tent if it's necessary. Right now, she is getting up every couple of minutes and repositioning or pacing.. her respiration rate is around 50 right now... her belly almost looks like it's spasming and her heart rate is running between 80 and 90 everytime we take it... which is low... what do you suggest??????