Feeling tired is a very common complaint. There are many causes of this, ranging for serious underlying conditions to minor causes. I would recommend you discuss this with your primary care doctor
. He or she can complete a quick evaluation -- both an exam and a laboratory evaluation -- to rule out serious problems causing your symptom.
Firstly, fatigue is a general symptom of any major illness. Infection, kidney problems, liver problems and any serious illness can cause fatigue. Talking with your doctor to see if you have any other signs or labs consistent with these conditions.
The common causes of fatigue include: (1) low thyroid hormone. Known as hypothyroidism this also causes constipation, feeling cold and hair changes. (2) Anemia
or low hematocrit level. Low red blood cells cause fatigue and can occur because of loss of blood or decreased production. (3) Depression
-- likely the most common cause of fatigue. There are many other causes that should be investigated.
Dog bites is often concerning for infection or rabies. Rabies rarely occurs in the US today and fatigue, while a possible symptom, is unlikely. Without other symptoms, this would be less of a concern.
Talk to you doctor. This is a concerning symptom that should be investigated. I would recommend that you see your primary care doctor at once. Good luck!