my cats health

Question
my cat is three i recently started putting him outside.today just know actually he started spitting up white saliva foam . Do you now what it could be?

Answer
Well, there could be many reasons.  
1.) Since he since he's an outdoor cat he could have contracted rabies.  But since that is kind of extreme and many other things could cause it you can rule this one out for now.

2.) He could have eaten plants or flowers that had pesticide on it, the pesticide would have gotten him sick and cause the white saliva.

3.) It could be that he has hairballs... try getting him on cat food that helps prevent hairballs.

4.) There might be something (like part of a toy) lodged in his throat and he may be trying to get it up.

5.) Also it might be a bacterial infection.  When cats use a litter box they bury waste (feces and urine).  But by burying their waste they get some on their paws.  Try washing the paws with a wet wash rag with no soap or chemicals on it once in a while.

6.) He could have gotten into any chemicals you happen to have in your house or ingested some medicine you put on him (i.e. frontline or other flea medicines)

I'm sorry if you don't understand it the way I put my answer.  I just figured it would be easier to read in this way.  Good luck with him... and if you don't believe it is any of the things I listed then I insist that you should go to a vet.