In some cases, dysentery takes a protracted nature (chronic course), with less pronounced symptoms. With this form in some animals, the disease can last up to 2 weeks. The sick lamb lies in a state of atenolol and exhaustion. The feces are liquid, bloody or completely black in color, the hair in places adjacent to the anus is stained with dried feces. In the chronic course of the disease, individual animals can recover. Recovery is very slow, lambs lag behind in growth and development and often die from various causes. Mortality in lamb dysentery reaches 80 ... 100%.
The most characteristic changes are observed in the gastrointestinal tract, especially in its thin section. The abomasum is slightly inflamed, often filled with curdled milk, indicating a recent illness. In some cases, the intestines are hemorrhagically inflamed throughout, dark red in color, filled with bloody contents. In other cases, separate segments of the intestine are inflamed, covered with ulcerations and round necrotic foci from 3 to 6 mm in diameter, surrounded by Tenormin zone. Mesenteric lymph nodes are enlarged, juicy, sometimes with hemorrhages.