My pet is breathing fast with his mouth open and won't lie down — what do I do?

Go to an emergency vet now — put the phone down and drive. Breathing trouble is the one emergency where minutes genuinely count, and if this is a cat it is even more urgent: cats do not pant, so a cat breathing with an open mouth is critical until proven otherwise.

What you are describing has a name, respiratory distress: the belly and the chest heaving as two separate efforts, elbows held out from the body, neck stretched and head held low, refusing to lie down or even to sit, gums that look blue, grey or purple, and a quiet gurgling or wheezing. Any one of those on its own is a reason to leave immediately.

Do not stress him on the way, because stress is what kills breathing patients. That means no washing him, no examining him, no forcing him into a carrier he is fighting — take the top off the carrier and lower it over him, or use an open box. Keep the car cool and quiet, do not crowd him, and phone ahead so the door is open and they can take him straight to oxygen. Do not put your fingers into his mouth unless you can see an object and he is choking.

One number is worth bringing with you: count his breaths for 30 seconds and double it. A dog or cat who is resting or asleep and breathing more than about 40 breaths a minute is abnormal, and a real count tells the triage nurse far more than he is breathing funny. Whatever the cause — fluid around the lungs, heart failure, asthma, trauma, an obstruction — it gets diagnosed after he can breathe, not before. That order is not negotiable, and the call belongs to the vet who has him in front of them.