Also known as dirofilariasis, heartworm disease (HW) is a serious parasitic infection caused by the nematode Dirofilaria immitis which lives in the pulmonary arteries, lungs, and hearts of cats. Heartworms are a type of roundworm, with adult heartworms reaching a length of 12 to 30 cm. Microfilaria (baby heartworms) are present in the blood of an infected animal (in most cases, a dog), when a female mosquito feeds on the blood, microfilaria are also ingested, once, inside the gut of the mosquito, they undergo further development before migrating to the labium (a part of the mouth) of the mosquito. When the infected mosquito feeds on another host (in this case, your cat), the larvae move from the mouthpart and onto the skin of the cat (or dog), from there, they enter the bloodstream via the bite wound left behind by the mosquito.
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.
There is no approved adulticide (medications to kill adult heartworms) treatments for cats. Adulticides are themselves dangerous. A single dead worm can be fatal in cats as it can break away and cause a blockage of the pulmonary artery (pulmonary embolism). Heartworms in cats have a shorter lifespan than those in dogs; therefore it is preferable to manage symptoms and use a wait and see approach.

There is no approved adulticide (medications to kill adult heartworms) treatments for cats. Adulticides are themselves dangerous. A single dead worm can be fatal in cats as it can break away and cause a blockage of the pulmonary artery (pulmonary embolism). Heartworms in cats have a shorter lifespan than those in dogs; therefore it is preferable to manage symptoms and use a wait and see approach.


Thank you for your email, I'm sorry that Cracker is having these problems. Without examining him, it is hard for me to advise you on whether he is suffering, and that is probably a question to ask the most recent veterinarian that you took him to. If he has a fungal or bacterial infection, he should be improving on those medications. If he has cancer, he may not improve, and it is important to assess his quality of life. If he starts breathing with his mouth open or stretching his neck to breathe, that is serious respiratory distress and is an emergency. IF he is eating and drinking and generally happy, he may be breathing heavier but not suffering. It would be best to have a recheck with the most recent veterinarian, as it has been a week on medications, and see if they feel he is improving - they may want to take x-rays and compare them with the previous x-rays to look for signs of improvement. They will be able to give you a better idea as to whether he may be suffering, or if he seems comfortable. I hope that all goes well with him.
Rapid breathing may be caused by a variety of different issues which may include traumatic injury and pain; however if there has been a puncture wound to the chest or neck which is compromising the respiratory tract, it should be treated as a medical emergency. You should keep Grace calm for now but visit a Veterinarian as soon as one is open if she’s having difficulty breathing. Regards Dr Callum Turner DVM
There are various different causes for rapid breathing which may include infections, pain, heart disorders, dehydration among other causes; a cat’s respiration should be below 30 breaths per minute when at rest but if it is significantly above this rate at rest I would suggest visiting your Veterinarian for an examination to determine a cause. Regards Dr Callum Turner DVM
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