A disease, previously known as cellulitis, has been renamed Clostridial Dermatitis (CD) and it has become a major cause of disease in turkeys in many parts of the U.S. A survey of U.S. turkey veterinarians reported in the U.S. Animal Health Association's Turkey Health Report for 2008 ranked CD as the third most significant health threat to turkeys ranking behind only "lack of approved drugs for use in turkeys" and "collibacilosis."
Survey of CD incidence
A regional survey of turkey flocks placed during 2007 was conducted by researchers at the Maryland/Virginia Veterinary Medical School led by Dr. Bill Pierson. This survey found that almost a third of the 167 turkey farms and over 11% of the 1,057 turkey flocks surveyed reported having CD at least once during the year. Results of the survey were presented by Megan Lighty, a D.V.M. and Ph.D. student at Virginia Tech, at the National Turkey Federation's (NTF) annual convention in Orlando, Florida.
The highest incidence rate was in heavy toms where almost 30% of the 58 survey flocks had CD. In this survey, the higher the average market weight of the heavy hen flock, the more likely it was to have CD. There was no significant relationship found between the market weight of light hen or heavy tom flocks and the likelihood of the flock having CD. Also, there were no relationships found between incidence of CD and prior health events in the flock, prior vaccination/medication of the flock, or of housing density (floor space per bird).
CD is not a new disease; there is reference to a CD-like condition in the scientific literature dating back to the 1930s, Lighty reported. The first recognition of the disease in the modern turkey industry came in 1993. NTF will be working with Pierson's research group to conduct a national CD incidence survey of NTF members' turkeys marketed in 2008.
An interactive event, sponsored by the Minnesota Turkey Research and Promotion Council (MTRPC), was held in Minnesota last December to bring together researchers, veterinarians and turkey growers to discuss CD. Over 100 individuals participated in the two day meeting to produce a comprehensive review of the disease and to identify and prioritize research needs.
Dr. Steven Clark, technical service veterinarian, Alpharma Animal Health, provided a summary of the Minnesota meeting's results at the NTF convention. He said that Clostridia species, particularly C. perfringens and C. septicum, play a role in the pathogenesis. The prevalence of CD is relatively low; however the disease can be devastating in the individual flocks affected.
What we know about CD
Clostridial diseases in both broilers and turkeys appears to be associated with rearing on built-up litter. In turkeys, CD appears as excess mortality in older birds, around 16 to 18 weeks of age, but it has been reported as early as seven weeks of age. In some cases, mortalities will have fluid filled blisters associated with broken feather follicles around the base of the tail. Other cases will have dead birds with a gelatinous accumulation of fluid under the skin, usually along the thighs and breast. Mortality from this condition can be severe and acute, dead birds decompose very quickly. It is common to have some houses on a farm that is affected and others not affected.
Control of clostridia is difficult, particularly during the spore forming stage, according to Clark. Clostridia are normally found in the environment and in the intestines of healthy animals, but when the organism is in concentrated numbers and produces a lot of toxins, it can become a problem. Basic principles of controlling CD involve reducing the number of organisms in the bird, reducing the number of organisms in the poultry house and improving bird immunity.
No silver bullet
Clark said that based on the information currently available, controlling CD will require a multifactor approach. "Unfortunately, no effective, long-term preventative programs have been indentified. Particularly frustrating is that some of the noted strategies have appeared successful, only for the same farm or house to break with the disease again after only one to three growing cycles. Control of CD will require constant consistent and urgent attention," Clark said.
The MTRPC is expected to publish proceedings from its December CD meeting soon.