Best Answer: The pupil size limits the the amount of light that enters the eye. There are also day-time photoreceptors, the cones, which occur with three kinds of photo-sensitive pigments, for red, yellow-green, and blue.
Those âdevotedâ dogs lying on their mastersâ graves? Theyâre depressed. âMany dogs are simply depressed for their whole lives because theyâre deprived of the normal amount of attention, exercise, and stimulation they need from day one. These humans wonât know they have a problem and wonât want the dog any livelier as that wouldnât fit in with their lifestyle,â says Tamara.
Symptom 3: Lack of Appetite. 1  Less Serious Causes: A dog may eat less because of stress, recent vaccinations, pickiness, or because they are getting older. 2  More Serious Causes: A decreased appetite can also be a sign of illness, especially if your dog is exhibiting other symptoms as well. More serious causes of appetite loss include but are not limited to: liver problems, kidney failure, cancer, infection, dental disease, and pain.