Can one pup in a litter have a food allergy and not the rest? Got one buyer who keeps switching foods because thinks pup has food allergy. Pup has loose stool whenever he is not on diet prescribed from vets.

How old is the pup? We had one that started with loose stools around 6 months old, a bit of mucous at the end of the stool too.
Vet had us to a bland diet for two weeks, she was fiine on the bland diet. Soon as I started introducing her regular kibble, when we got to the point that the ration was mostly kibble, it started again. Then we did the food elimination trial, different dog foods, etc. ... same thing, soon as she was on all kibble it started again.
Back on a bland diet, she was fine. Vet said to face it, we might have to just home cook for her. Talked to the breeder that my lines came from, she said there were no food allergies in this line and said to try a long course of Tylan.
That did the trick. When it was time for her yearly check up, vet asked how she was doing with the stools. Told him we got it all taken care of. He asked if we found a food that agreed with her. Told him she was back on her regular kibble after being on a course of Tylan.
He said, "Oh yes, we used to use that at the very first practice I worked for. Will have to get some on hand."

Pup is 4 months old. Thanks for info.

I have to think back because this was quite a few years ago. I believe we put her on the bland diet for about a week when we first started the Tylan, then gradually started introducing her regular kibble. When I say long course, it was close to a month. I believe the last week the dosage was cut so that she was weaned off it.
I should mention that we did numerous fecals for Coccidia and Giardia when this all started and every time was negative. Also Flagyl was given and it didn't help. So I think it's good to rule these other things out.
With stools, at anytime a owner ever sees blood or blood tinged, they need to let their vet know.

I don't know what it is with the Tylan that works sometimes where all else has failed, I don't think it's the antibiotic properties so much, there something supposedly with Tylan that sooth the mucousa lining of the intestines, so maybe it's that it allows things to settle and heal?

Is Tylan an anti-biotic?

http://www.marvistavet.com/html/body_tylosin.html

Tylosin is the same thing.

Tylosin (Tylan®)

Brand name: Tylan®

Available in Oral Powder or Injectable

Background

Tylosin is an antibiotic of the macrolide class (same class as erythromycin). It is made naturally by the bacterium Streptomyces fradiae and acts to inhibit bacterial protein synthesis by inhibiting the 50S ribosome, a cellular structure only certain bacteria have and use to make internal proteins.

How This Medication Is Used

Tylosin is licensed for use as a broad spectrum antibiotic for injectable or oral use in treatment of infection in livestock. In small animals, tylosin is used for its anti-inflammatory properties in the large intestine rather than for its ability to fight infection. While few formal studies have been performed to examine this non-antibacterial property of tylosin, this has not stopped tylosin from being widely used in the treatment of colitis in pets.


Tylosin can also be used in ferrets, rabbits, and pocket pets.

Side Effects

While there is definite side effect potential in large animal species, dogs can tolerate very high doses of tylosin with no adverse effects. The biggest problem with small animal use seems to be the especially foul taste of tylosin which necessitates formulation into capsules, which is usually done by a compounding pharmacy.

Tylosin may falsely elevate certain liver blood tests (ALT and AST).

Just because one pup from a litter has allergies doesn't mean the entire litter will. My first puppy has had allergies since the day I brought him home at 8 weeks old. It took me almost a year to figure out the cause of his chronic diarrhea. But he is the only one from his litter to be affected, or so his breeder tells me. I know 2 people that got littermates of his so I know for a fact that they're fine, no issues. What kinds of foods are these people trying and how often are they switching? Constant switching before a pup adjusts to a new food can also cause loose stools, so make sure they're aware of that. They may not be giving the pup enough time to adjust to a particular food. Are there any other symptoms in addition to the loose stool?

What would the doage be of Tylan for this?

I know the dosage I used, but I really hesitate to recommend a specific dosage since it's not my dog or one of my puppies and not knowing that they have ruled out other things.
Find out of your vet is familiar with Tylan and it's usage for such things as IBD, colitis, etc. and if he has any objection to giving it a try.