Illnesses and death losses in baby calves are significant problems for producers raising calves in beef or dairy operations. Several of these issues, especially sudden deaths and certain enteric (intestinal) conditions, are potential effects of infections due to Clostridium perfringens. Clostridium perfringens are Gram-positive, spore-forming, anaerobic bacteria that are very commonly found in many environments, including soil, water, poorly preserved feeds, contaminated or improperly thawed colostrum or milk, calf-housing environments, and the normal bovine intestinal tract. In small amounts, these bacteria are generally harmless in the intestine, but under the right conditions they may grow and proliferate, resulting in enterotoxemia, a condition in which specific toxins produced by the bacteria in the small intestine result in both local damage and systemic (whole body) effects.
Pathogenesis: How C. perfringens causes disease Because of the widespread nature of the organism, calves are readily exposed to C. perfringens in their environment and commonly ingest the bacteria in various quantities, after which it enters the stomach and intestine. Sometimes bacteria are ingested in sufficient quantities to cause disease, but oftentimes small quantities are ingested, followed by rapid proliferation in the intestine.
Enterotoxemia due to C. perfringens is more likely to affect baby calves (within the first two months of age) than mature cattle because the calves lack a fully functioning rumen. C. perfringens feeds on starches and sugars in the small intestine. In mature cattle, these starches and sugars are predominantly digested in the rumen, so they are not available to the C. perfringens microbes for use. However, in baby calves, nearly all feed bypasses the rumen and is digested in the abomasums (true stomach) and the small intestine, so the starches are available for the microbes to feed on. This, coupled with a normal intestinal flora that has not yet developed, provides a suitable environment for the C. perfringens to proliferate. Several factors can contribute to this rapid proliferation. Primary among these are abrupt changes in feeding patterns (see “Prevention” below), physical or environmental stress, nutritional deficiencies, and conditions that impair movement of the intestine (such as diarrhea due to other causes).
As C. perfringens proliferates in the gut, the bacteria secrete toxins that have profound effects not only on the local intestinal environment (causing damage to the intestinal lining), but throughout the body as well. Death occurs when high levels of these bacterial toxins enter the bloodstream, leading to inflammation, shock, and cardiac arrest. C. perfringens is not spread from calf to calf, but it is not uncommon for several calves in a group to be affected at the same time, due to similar exposure and management practices.