When adult dogs suddenly lose fur, muscle mass, and appetite and seem to stop playing and participating, it may be the onset of Addisons Disease. This imbalance of the adrenal glands is very treatable. Nonetheless, owners often make the mistake of thinking the new behavior is early aging or simple laziness.
The disease is far more common in female dogs, so if your girl suddenly declines in energy and appearance, request that your vet does an ACTH Challenge Test. A correct diagnosis and a prescription for hormone pills will put her back on the right track fast!