Collars are dangerous for our little Yorkies fragile trachea...Here is some info I just googled:
"PET NECK PROBLEMS DUE TO RESTRAINT
Studies have shown that many pets that have been restrained on a leash have experienced neck problems.
Many times the smaller breed dogs experience a condition called collapsed trachea. Trachea is another name for the windpipe which is the tube that connects the mouth, nose, and throat to the lungs. Some dogs with a collapsed trachea will experience an occasional cough that sounds similar to a honking noise. Pets with a collapsed trachea can experience gagging and difficulty with breathing
It has been noted that a collapsed trachea is more likely to occur when a pet is breathing faster than normal, or when there is added pressure around the outside of the trachea, such as when a pet is being restrained. Pet owners can help with this condition by switching from a collar to a harness that does not place pressure on the pet’s trachea.
A harness, instead of a collar, is recommended for restraining dogs susceptible to tracheal collapse so that pressure is not applied to the neck, forechest or airway area."
Hope that info was helpfull. I never use a collar...just a harness
