strange sound

Our Cocoa started making this sound a couple of minutes ago. She's with treatment and we're kind of overprotective because of it, so I decided to ask. I can't upload the video of her from my cellphone but I found this on youtube, it's the same sound: Thanks! (I know I have been posting...

My two girls have been making a strange noise almost everyday for 5 months now, it starts like wheezing, or like hooting, and then it sounds like in the video below. I took them twice to the vet, and she doesn't find anything wrong with them, but i don't think it's normal at all. I can't even...