
It sounds like the breeder has been honest about it which is great BUT...
Having owned one dog with immunity problems I would steer clear of this puppy even if it might not be a problem later, but it might!
Our story(very shortened version)
She was itchy all her puppyhood...Not very itchy but would definately scratch lot more than our other dog.
we tried different foods as we thought she might be allergic to something.
No difference and allergy tests only showed allergy to Fish.
So we were told she just has a dry skin so that might cause her to itch(and new coat coming in etc) Basically we were told not to worry about it.
We had her on breeding terms and she had a litter as we were assured she has not got a problem.
About 6 months later she developed skin problems lost most of her coat on her back and was gnawing her skin and developing scabs and being very itchy indeed! We were in and out of vets but nothing was found. About 4 months later this just cleared we still do not know what it was that caused it or cleared it.
She was still more scratchy than our other dog but seemed ok.
She also had very dirty ears all her life, this did not cause any problems as such as there was no infection but her ears would have to be cleaned much more often than any of our dogs.
Quite a lot of money was spend at Vets, by now we had definately took our vet on a holiday few times :)!
Then when she was 4 years old that is when it really started, the spending I mean!
She developed Anal Furunkolosis (disease linked to immune system)... Loads of vet visits followed and it took a while to find a treatment.
She had this disease for the rest of her life and was on a medication for it which kept it away...
Due the medication every 6 months she would have to go and get her bloods checked even if everything was ok.
Do you want to hear the cost of this...
Luckily my parents could afford it(I could not so would have had to put her to sleep) and were ready to pay for the medication as she lived a happy 6 years and died of old age.
Oh yeah and they stopped counting when the medication bill was nearing £10 000, and this was few years before she died so after all the total cost of her "weak immune system" must have been nearing £20 000+.