Need help! Dog problems: lethargy, hostility

[Lurker meow]

Помогите пожалуиста советом. Внизу описана проблема с собакой (человеком, плохо говоряшим по-русски - я посоветовала сюда обратиться). Я не стала переводить потому чтo неловко все звучит по-русски. Человек очень волнуется, хотя мне кажется особого повода нет. Но я не эксперт.

Got a little problem here. The dog (a five-year-old) mutt has recently had some behavior changes. Starting about four months ago the we first noticed that the dog was becoming lethargic. Although he was still fairly active around the house (although notably less enthusiastic about his toys) he began to refuse to walk for any longer than fifteen minutes and on any path that was uphill. At times this goes away and he can be made to walk for a long time, but most of the time he wants to return home immediately. The dog is slightly overweight and has never been a fan of physical activity, but it seems that he has had these problems far longer than this new behavior. At the same time we noticed an increase in hostility and a tendancy to pick fights. Are the problems related? Are they just signs of aging and maturing? Is the dog just used to inactivity and has become convinced that he can get away with only tiny walks every day? Or is this something to consult the vet about? Any help is appreciated.

[Koza]

К вету, к вету, к вету.