My cat has excessive thick mucous and drooling..?

The fact that he has got rotten teeth and red gums could be he has an infection in the gums due to the bad teeth may be even an abscess, so its a good thing you are taking him to the vet tomorrow,

and the weight loss could be connected as he cant eat very well as its uncomfortable and maybe pain full for him, so he feels weak and lethargic due to not being able to eat properly and fighting a possible infection,

Edit:As his chest is rattling he has most likely got a bad chest infection and is drooling is caused by trying to breath with the phlem ,but still mention his teeth and gums to the vet.

It sounds like a VERY serious respiratory infection.

I've seen many cats in the animal shelter come in with these and unfortunately become so sick that they have to be put down. They will cough, wheeze, chest rattling, and have thick green mucus coming out of their noses. Sometimes the whole ward could become infected from one sick cat passing through (even if it was in the isolation ward).

A gum infection could cause excessive drooling, but it sounds more likely caused by a respiratory infection. I'm not sure about the cat's BMs - but sometimes if the odor changes, it does mean there is something wrong/different about the cats health.

I hope my opinions/ideas help.

Good luck with your cat and I hope he will be better soon.

My cat got into something and the vet said a 1/2 a child strength benedril would be ok if it was an allergic reaction. Did you call the vet and ask them? They will usually be able to give you a home remedy until you can come in. I've had to do it alot with 2 cats and a dog. There's so many plants and foods that are very very bad for cats. Like Asprin will kill a cat (but not a dog). Also ferns are very toxic to cats. There's tons of lists you can look up on line. I got rid of all the plants in my house.. they dig in them anyway. And that is why I am a huge advocate for keeping your cat inside ALL the time. There's just too much out there for them to get into. (get cat insurance if you let him outside) They are just fat, clean, and happy cats! :)

Could be Distemper, or Severe upper respiratory infection probably due to infected teeth. I hope your vet can save your cat.