Hi Berndiggitydog - welcome to the forum !
Has he "choked" - coughed - at any time during these syringe feedings?
Originally Posted by Berndiggitydog
...The vet...provided me with a large syringe for a food slurry with which I have been feeding him baby food...
My new concern is that he seems weak in the chest. When i pick him up predominately by his chest, he squeaks! His breathing is audible,,,
Today he seems just as lethargic...
There's always a danger of this happening when assist-feeding cats....there's usually some resistance to the procedure, and it's very easy for the cat to "aspirate" - breathe in - the liquid food.
IF THAT HAS HAPPENED I'd urge you to get him back to the Vet ASAP.
Cats who aspirate like this are in danger of developing a usually fatal type of pneumonia - "Aspiration Pneumonia". Some cats recover, but, unfortunately, many do not.
When "assist-feeding" with a syringe, NEVER, EVER squirt the food straight down the cat's throat
! (nor, should any kind of liquid ever be given like that). Use the syringe to insert just a few small drops of food into the SIDE POCKET of the cat's mouth, allow the cat to swallow, then repeat at slow intervals.