Emerging clostridial disease targets calves
Type A continues to garner researchers’ attention as a potential emerging patho gen. It’s often associated with severe calf disease, such as abomasitis, with fatality rates varying from 5 percent to 50 percent.
“There are as many ques tions about this disease syn drome as there are an swers,” says David Van Metre, DVM, College of Vet erinary Sciences, Colorado State University (CSU). “It’s a multifactorial disease. No one has found the complete set of factors that cause it.” C. perfringens Type A is the most commonly isolated in fectious agent in abomasitis cases, according to Van Me tre, who presented to at tendees during a sympo sium at the Western Veteri nary Conference in Las Ve gas, NV. Abomasitis occurs with an acute onset of gas accu mulation in the abomasum.
It typically occurs in calves less than two weeks of age. Clinical signs can include rapid progressive bloat and shock, colic, hypersalivation and a distended abdomen.
Treatments may include penicillin, antitoxin serum, fluid support, oral adsor bents and oral antibiotics.
“Unfortunately, most calves die acutely,” says Doug Scholz, director of vet erinary services for Novar tis Animal Health. “Most times, the calf appears fine in the morning. When you come back that evening, you find a dead bloated calf.” Van Metre recommends focusing prevention mea sures on enhancing immu nity and using feeding practices that inhibit pro liferation of C. perfringens in the gut. He recommends using good colostrum and milk/ milk replacer hygiene; keep ing consistent feeding schedules for dairy calves and maintaining consisten cy in milk/milk replacer composition and tempera ture; and avoiding feeding long-stem forage too early.
Whenever possible during severe weather, encourage calves and dams to stand up to limit milk engorgement by the calf after the weather passes. Make sure animals have adequate copper and selenium status.
If you are experiencing significant calf losses, vac cination may be an option to consider. Van Metre shared results of a trial he conducted with Clostridi um Perfringens Type A Toxoid in a commercial dairy herd. The CSU researchers randomly assigned cows and pregnant heifers to a control or vaccinate group.
Vaccinates received two doses of Clostridium Per fringens Type A Toxoid in late pregnancy. The study goal was to measure C. perfringens Type A alpha toxin titers in vaccinated dams and the calves fed that colostrum.
“The cows and heifers re ceiving two doses of the vac cine generated significantly higher antibody titers to alpha toxin one week after the second immunization than did controls,” says Van Metre. “Additionally, the calves ingesting colostrum from vaccinated dams had significantly higher serum neutralizing antibody titers to alpha toxin than calves born to controls.”
Scholz adds that vacci nation with Clostridium Perfringens Type A Toxoid is anticipated to work best when you vaccinate the dam and get antibody into the calf through the cow’s colostrum.
“If you are experiencing an outbreak and have sig nificant death loss, you may also want to vaccinate the calf,” advises Scholz.
“The important thing is to involve your veterinarian and call as soon as you suspect a problem. If you aren’t tuned in to watch for clinical cases, you will likely be calling for a necropsy rather than a treatment.” — WLJ