My dog died suddenly, on Friday. He was a 13 year old Chihuahua, name Tank. He had his left eye taken out in 2020, he was diagnosed with a possible heart murmur, and possibly anal gland cancer in Nov of last year, but I couldn't afford testing to be sure. He was a little over weight but not by much, 10lbs was his weight. My question is, I found him dead after him seeming pretty normal that day. He'd eaten some that morning, but not a lot... He'd gone to the bathroom. He acted fine. I took him to get groomed and I do that every 6-8 weeks. He got in his carrier excited to go someplace as usual. He didn't seem sick. The groomer said he did fine as usual through the groom. She said she took him out and he peeed. But she did say she noticed him drooling a little this time, which was not ususl. I brought him home and I opened his carrier but he didn't come right out like normal. I went about my business, later I noticed he had came out the carrier and gone to his crate. I didn't see him walk so I don't know if he was okay as far as walking normal. I did notice his breathing was a little more rapid and labored, but I just attributed that too his stress of getting groomed, which he tolerated but never really liked getting it done. So I didn't think think anything was wrong out of the ordinary. I went to do my laundry came home and found him. He had gotten out of his crate and gone into my room. He was on the floor with his hind legs stretched out behind him, one front leg underneath him, and the other one sort of bent under him. His head slightly bent to the side, his mouth was opened and his tongue out and bluish and sort of swollen looking. His one eye was opened with no vomit just some salvia on the carpet. I'm assuming it was salvia because it was wet. He had did a small bowel movement but it wasn't runny. Oh and he had developed a cough some few months ago, not chronic just every now and then. He would also cough and gag after drinking water at times. He would also seemed he'd breath heavy when he walked, through his nose lately. He always made like a snorting sound. And he would sound like he was snoring when awake but just lying down. Could someone please tell me what do you think he died of. It's really bothering me that I don't know. And I'm wondering if he suffered or was it quick. I'm so sorry I didn't know his time was near and wasn't with him when he passed. Can someone help me with some possible answers. I'd really appreciate it. I miss him so much. He was an Applehead and had him since he was16 weeks old. I'm having remorse because I didn't check him to see if he was okay. I'm feeling guilty by thinking if I'd been here maybe I could've done something. If I'd just made him come out of his carrier. If I'd just held him. If I'd given him a treat before I left like I started to, maybe then I'd knew something was wrong with him because if he refused that, then something would've been out of the ordinary. Thanks all.