1. They are not educated on it and don't know better. Some vets have minimal nutrition training. They offer bad blanket advice like ''feed the dog chicken and rice'' (don't give your dog rice). In fact, if your dog has a severe condition like pancreatitis or allergies, they are likely to recommend something that will make the problem worse.
Their job is not to be nutritionists, but vets, so the nutrition part often falls behind.
2. They sell other products. They have agreements with the brands they recommend. Royal Canin, Purina and Hills are the big three. They all come under the illusion of ''prescription food''. In reality, these foods are very poor, irrespective of what they say on the front of the bag.
All you have to do is read the ingredients of these foods. Wheat, corn, rice, animal fats (not being specific), yeasts and parts thereof...These ingredients are best kept away from your beloved pet.
3. A lot of people do it incorrectly. People will only feed the dog tripe, or not feed them any bone, buy from an unregulated manufacturer with poor quality standards, or not know how to prepare it properly.
Raw food is best served following wholeprey ratios. Cartilage, offal, bone, fresh meat...but in the right proportions! If you haven't done your research, you are likely to do it incorrectly, and harm your dog's health as a result.
What questions do you have? Leave them below.