Hi Jeannine-
Osteosarcoma can have a genetic link and pediatric spay and neuter can also increase the risk of Osteosarcoma. It’s unlikely that food played any role in the diagnosis.
When your vet suggested “an allergy” could be the cause of the pink ears, did she make mention of what kind of allergy it could be? Food allergies are not common, especially not in a dog so young.
As much as I like Fromm I do hear an overwhelming amount of complaints about loose stool on it. I would choose a food for a growing large breed puppy based on the guidelines of WSAVA. http://www.wsava.org/sites/default/files/Recommendations%20on%20Selecting%20Pet%20Foods.pdf
Most diets from companies that meet these standards will have an appropriate large breed puppy food.
