There are some commonly cited reasons, which are mostly not true or not fully true:
Cutting the hair will cause it to grow back differently or not grow back. This is not true because hair is dead and has no sensory ability, so the hair follicle has no way to know if a hair has been cut or not. Thus, the follicle cannot change based on a hair being cut. (If ...
I will provide a comparison dog - human, along with explanations.
For a human, there are 2 ways for cooling:
lowering the temperature of the environment; possible indoors with air conditioning, not possible under the full sun;
perspiration + evaporation; the effect is amplified by applying ventilation, even without any active cooling. It works, because the ...
I agree 100% with Elmy
Sometimes when groomers are trained, they may not be told or may not absorb the true reason for doing certain tasks in certain ways. They may simply be told, "Don't do this".
There are plenty of folk-tales circulating in the dog world that have little or no scientific basis.
A groomer will know that it is a bad idea to trim ...
The main question is this: Is your dog
Single coated with hairs that grow endlessly at a constant speed?
Or double coated with hairs that grow to a predefined length and are shed?
Single coated breeds are often "fashion" or "toy" breeds like Poodles and Shih Tzu. They actually do need regular hair cuts because their hairs don't stop ...