Common types of UC include: 1  proctosigmoiditis, which affects the rectum and lower portion of the colon. 2  left-sided colitis, which affects the left side of the colon beginning at the rectum.  total colitis, which affects the entire large intestine.
Vasovagal syncope. Vasovagal syncope is a sudden loss of consciousness mediated by the vagus nerve. It occurs when the vagus nerve is overreactive to certain triggers, such as the sight of blood or extreme emotional distress, and causes a sudden drop in blood pressure.
Diagnosing Vasovagal Syncope. To determine why your dog faints, your veterinarian will put him through a battery of tests, including chest X-rays, cardiac ultrasound and an electrocardiogram, and will conduct blood tests and a urinalysis. It's likely your dog will wear a Holter monitor for 24 to 48 hours.