My advice is to always, ALWAYS press to know what could be causing ANY change in breathing, even if your cat's breathing rate is normal for them, they're not in distress, and you're told it's not concerning. ALWAYS worry about cancer and/or fluid in the chest, and push for further investigation such as imaging. If your cat's health is such that this would be risky at your local vets, ask for a referral to a larger hospital where they can more safely put your cat under anesthetic.
I'm making this video available because when my beloved cat Sparky had heavier breathing than normal, I wasn't sure what it meant. I checked online, googling for information and watching every video I could find, but every resource talked about cats with heavy breathing plus rapid breathing and/or distress. As you can see in the video, Sparky was relaxed (sleeping) and his breathing rate was his usual, which made me hesitate in worrying about this.
Worse, when I took Sparky to our local vets, they told me they were "not too concerned" provided that his breathing rate was normal and he wasn't in distress. They followed up by saying I should monitor his breathing and suggesting a blood test to check his hyperthyroidism. No followup imaging was suggested, nor were any potentially dangerous issues mentioned. I was so relieved to hear this which backed up my own research that, to my now great regret, I didn't ask what could be causing the change in his breathing.
Very sadly, and after two further vet visits, Sparky passed away just over a month after this video was taken, after suddenly having trouble breathing. The vets did an emergency xray (without anesthesia, which had been a concern due to his age [20] and issues including hyperthyroidism and CKD) and found that there was lots of fluid in his lungs and very strong indications of a mass high up in his chest. They told me that his prognosis was very poor (this has also been confirmed since by an expert), so I made the hugely difficult decision to say goodbye to my furry soulmate.
A few weeks later, struggling to come to terms with what had happened and my failures, I showed this and similar videos to an expert from a top veterinary college in the US. They told me that if they saw a cat with this type of breathing issue (which my other research tells me may be called "paradoxical breathing" in which the abdomen goes in when the thorax goes out, in a reverse of the usual) they would suspect issues ranging from asthma to fluid in the chest to tumors blocking passages. I was never told this by my local vets, and I will always regret not seeking more expert advice earlier, when it still might have been possible to treat Sparky's likely cancer either via surgery or with chemotherapy.
Sparky was something of a miracle cat already, having bounced back completely after the removal of a meningioma (tumor pressing on his brain) by a veterinary referral hospital 2 1/2 years previously. I hate to think that my inaction and the vet's lack of concern prevented us from perhaps carrying off another miracle that would have given us more months or even years together.
I am therefore sharing this video, even though it is painful to do so, in case anyone else finds themselves in a similar position of seeing a change in their cat's breathing and not knowing what it means.
Again, my advice is to always, ALWAYS press to know what could be causing ANY change in breathing, even if your cat's breathing rate is normal for them, they're not in distress, and you're told it's not concerning. ALWAYS worry about cancer and/or fluid in the chest, and push for further investigation such as imaging. If your cat's health is such that this would be risky at your local vets, ask for a referral to a larger hospital where they can more safely put your cat under anesthetic.
I am honestly scared to make this video open for comments, as I fear that people will pillory me for not having taking more action and I'm already struggling to deal with my guilt. However, I feel that I must do so in case anyone has questions for me, or advice that others may find beneficial.