Fowl adenovirus serotype 1 (FAdV-1) as a putative trigger of clostridial ventriculitis in laying hens

Although often overlooked, the gizzard can be a major target for avian disease, producing a negative impact on poultry production. Most commonly referred to as gizzard erosion-ulceration syndrome (GEU), erosions and ulcers in the gizzard can be caused by multiple environmental conditions, dietary factors, toxins, or infectious agents. Fowl adenovirus serotype-1 (FAdV-1) is a common pathogen of the chicken gizzard, causing adenoviral gizzard erosion (AGE), which is largely subclinical but has a negative impact on poultry production. On the other hand, C. perfringens rarely causes disease in the gizzard without predisposing factors, but may have much more severe consequences, as it causes much higher mortality rates. In this study, we report the first detection of coinfection of FAdV-1 and C. perfringens, causing high mortality rates in hens older than previously reported. Affected hens displayed severe ulcerative ventriculitis, which featured characteristic histologic features for both agents, such as intranuclear inclusion bodies (for FAdV-1) and necrotic and vascular lesions with intralesional Gram-positive bacilli (for C. perfringens). This case further evidences the potential impact of FAdV-1 on poultry production, not only by its direct effect but also because it might trigger the appearance of clostridial ventriculitis.