Veterinarian’s Corner: Clostridium perfringens and Abomasal Bloat – Dr. Jenn Rowntree, Vita Plus

By Dr. Jenn Rowntree, Vita Plus calf and heifer specialist
Unfortunately, many producers have experienced that feeling of walking into the calf barn early in the morning and seeing a calf that appeared perfectly healthy the night before, now dead in its stall with a distended abdomen; or the experience of watching calves bloat and appear uncomfortable following a milk meal.

Sudden death in a healthy calf can be due to any number of causes, but Clostridium perfringens rises to the top of this long list when sudden death is accompanied by abomasal bloat.  More research needs to be done to understand when and why Clostridium perfringens strikes, but we are aware of several risk factors that make these bacteria much more likely to impact calf health.

Clostridium perfringens is an anaerobic bacterium, which means it requires environments devoid of oxygen to thrive.  It is part of the normal gastrointestinal microbiome and does not cause clinical disease until conditions are favorable to support rapid growth of the bacteria and subsequent toxin production.  These toxins damage local tissues and, if severe enough, result in illness and death once the toxins invade tissues and spread to the rest of the body via the bloodstream.

Although abomasal bloat is a complex syndrome, the rapid growth and toxin production by Clostridium perfringens is most likely due in part to delayed abomasal emptying.  Following a meal, milk is gradually metered out of the abomasum into the small intestine for further digestion and absorption of nutrients. The more milk present in the abomasum, the longer it takes to empty the abomasum, and the more likely an adequate amount of carbohydrates will be available to support rapid growth of Clostridium and subsequent toxin production.  In addition to large meal size (greater than 3 liters), other management and nutritional factors that can slow abomasal emptying and impact growth of Clostridium are listed below.

1. Consistency is key.  Meal times, meal sizes and milk temperatures should be consistent.  Inconsistencies can increase stress in the calf, which has been linked with enhanced growth of Clostridium bacteria.
2. Always use a scale to weigh and mix milk replacer powder.  A 1-percent change in total solids between meals can increase the risk for digestive issues.
3. Avoid total solids greater than 14 percent.  A cow’s milk is typically 12.5 percent total solids.  Increasing total solids will also increase osmolality.  Meals with high energy density and high glucose levels will slow abomasal emptying.
4. Beware of high-osmolality milk replacers (greater than 600 mOsm/L).  For comparison, whole milk is about 280 mOsm/L (isotonic).  It is not uncommon for some milk replacers to reach osmolality of 400 to 600 mOsm/L (hypertonic).  Ask your calf specialist for a product’s osmolality information.  Your veterinarian may also submit a sample to a laboratory for testing.
5. Make sure water is always available.  Mistakes happen, but when milk replacer mixing errors occur and water is not available, the calf is not able to consume water that may dilute high total solids and/or osmolality.

A definitive diagnosis of enterotoxemia (the spread of toxin through the body via blood) due to Clostridium perfringens is possible, but also difficult to obtain.  Calves with acute bloat due to Clostridium perfringens must be diagnosed early based on clinical signs to have the best chance of successful treatment.  Signs of bloat include abdominal distension, dehydration, depression and colic.  Severe cases of bloat require IV fluids and electrolytes, penicillin, antitoxin, and IV flunixin if calves are in shock.  Recovery is slow, often requiring supportive fluids and antibiotics for five to seven days.

Herds that have experienced issues with Clostridium perfringens may benefit from vaccinating dry cows and bred heifers to help ensure that newborn calves receive appropriate antibodies from colostrum.  Be aware that vaccination is not a replacement for proper maternity and hygiene practices.  If your herd struggles with bloat due to Clostridium perfringens in calves, work with your herd veterinarian and calf nutritionist to determine if management practices associated with delayed abomasal emptying are occurring.  Taking the time to evaluate the consistency of your feeding program and whether any of the above risk factors for delayed abomasal emptying are occurring may help save energy, and calves, in the future.