I am sitting here looking at our just turned 6 month old male as I type. So... Close in age. Comparatively, Striker's chest hair looks much thinner to me. As does his underarm and side/belly hair. If he does wear a harness frequently, as greenkouki asked, that could explain it. Also, I am used to my 6 yo, McCoy, who is actually pretty hairy with lots of cowlicks.
Why don't you ask his vet about it next time Striker has to visit?
Edit to say: BTW, his ears look like they are coming along nicely!
It is not uncommon for Dobes to go through some thinner hair in the neck area - usually due to some rubbing by collars, etc... I would ask your vet to look at it as it does seem pretty thin in a large area.
Hello guys the harness was just put on a few days ago that’s how he was since he was very small it does not bug me I love him any way I just wanted to know if it was normal I will ask the vet when I take him for the next ear taping
The last time I had a dobe who had hair that thin in that particular pattern he turned out to have a nice case of folliculatis which cleared up with just chlorhexadine shampoos on a schedule set by his vet for a couple of months. Then the hair filled in and looked like the rest of his coat.