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H. John Barnes, DVM, PhD


Poultry Health Management

Office: C-332, CVM Main Building
Phone: 919.513.6273
Fax: 919.513.6464

Course Involvement

Graduate Courses


Areas of Research/Study

Birds are highly specialized animals that have evolved flight as their primary means of survival. Weight and its distribution are important in maintaining the ability to fly. All of the cells, tissues, and systems of flying birds have evolved to provide maximum function with minimum weight. There is little or no reserve or backup defense mechanisms. When disease affects an individual or flock of birds, it often progresses differently than a similar disease would progress in mammals. Studying how birds respond to an injurious agent is the basis of avian pathology. The tissue and response differences between birds and other animals make avian pathology a distinct field of study within the broad area of veterinary pathology.

My work is primarily with poultry, although other birds, including free-living, captive, and companion birds, are occasionally studied. While disease control in poultry flocks has improved greatly over the past several decades, losses still amount to approximately 10% of all production. Much of the loss comes from production diseases that cannot be attributed to specific disease organisms. Rather, they result from poorly understood, complex interactions among a number of factors including  environment, genetics, nutrition, parasites, and infectious agents. Control of these diseases is based on management aimed at minimizing the impact of the various factors. In addition to known diseases and production diseases, new diseases due to new emerging or re-emerging causes arise with astonishing regularity. Identifying new diseases quickly and accurately is essential to their control. Food-borne illnesses continue to be a societal concern as is the increasing recognition of antimicrobial resistance. Minimizing the organisms that cause food-borne illnesses and judiciously using antimicrobials for specific purposes are goals challenging the poultry industry and poultry veterinarian.

I use avian pathology as a basis for diagnosing known and unknown diseases and to study the mechanisms and causes of diseases in birds, especially those affecting the reproductive, intestinal, and musculoskeletal systems. Emphasis is on studying naturally occurring disease. Experimental studies are sometimes done to confirm observations arising from clinical findings or to reproduce a natural disease for examination at specific times post-exposure. A long-range goal is to collect material and information on avian pathology for future reference and educational purposes.

Currently, I am involved in research projects investigating the pathogenesis of spondylitis in broiler chickens caused by Enterococcus cecorum and a muscle disease in the breasts of broiler chickens called “Wooden Breast” because of the texture of affected meat.  Previously, I have compared ovarian cancer in chickens and turkeys to that in women, determined the cause and pathogenesis of transmissible viral proventriculitis in broiler chickens and examined the causes of early lay mortality and male infertility in broiler breeders. Previously,  considerable effort was directed toward studying studied a severe form of Poult Enteritis Complex known as Poult Enteritis Mortality Syndrome.

Appointments and Honors

Selected Publications

Scientific Papers

Books/Book Chapters