Effect has a lot of subtle meanings as a noun, but to me the meaning a result seems to be at the core of all the definitions. For example, you can say, The effect was eye-popping, or The sound effects were amazing, or The rain had no effect on Amy's hairdo..
There are some side effects to using hydroxyzine for your dog. Many dogs that take hydroxyzine suffer from a loss of appetite. Others will experience dehydration, vomiting, diarrhea or general lethargy as well. These side effects are relatively uncommon and generally mild.
Hydroxyzine blocks the effects of histamine in the body. Hydroxyzine also depresses activity of the central nervous system and is also used to treat anxiety disorders and tension in stressful situations. Cautions: It should not be used in pregnant or nursing animals. Hydroxzyzine may cause drowsiness.