Our bitch had just one puppy and he’s now 6 days old and hasn’t gained even one ounce. What do you think?

I ran across your website and have learned a TON. We have a situation w/ an English Bulldog puppy maybe you could help me out with. Here's the situation:

Our bitch had just one puppy. The first two days he fed very energetically. He would stay on the same nipple for up to twenty minutes and was a great little eater. We were thrilled, but a little concerned because after two days he stilled weighed the same as he did at birth (6.5 oz). In the past our puppies started gaining almost immediately.

Then after two days he would nuzzle a lot on our females teets, but wouldn't latch on well or for very long. We started him on the bottle, but it was the same result. He got progressively worse at feeding and wouldn't suckle. He acted hungry, but wouldn't latch on. I ran across your website, made the puppy formula, and we started tube feeding him every three hours. That has been going on for a few days now with good results. He's eating, urinating, his feces looks like it should, and he's hydrated (no tenting of the skin, etc.), and he looks pretty chubby. He seems strong, moves around his little box, holds his head up, and even stands on his feet for short periods of time. He sleeps well and doesn't whine much now that we've got his food situation under control.

The problem is he is now six days old and is still at his same birth weight (6.5 oz). We've been weighing him regularly and he's never lost or gained an ounce. Have you seen a puppy like this that seems healthy in every other way, but won't gain weight? We're continuing on w/ the formula from the website and hoping he'll start gaining, but I wanted to pick your brain and see what you thought.

Thanks so much for all you do.

Chuck