Nonenteric Lesions of Necrotic Enteritis in Commercial Chickens in California: 25 Cases (2009-2018).

Necrotic enteritis (NE) is an important enteric disease affecting a wide variety of avian species, including poultry, caused by Clostridium perfringens type G and, rarely, type C. Significant economic losses can result from elevated mortality rates and poor performance, such as decreased weight gain associated with intestinal damage and impaired absorption of nutrients. Additional losses can result from elevated condemnation at the processing plant because of a high incidence of cholangiohepatitis. Nonenteric lesions associated with NE have been rarely reported. This paper describes uncommon presentations of NE in commercial chickens received by the California Animal Health and Food Safety Laboratory (Turlock and Tulare branches) between 2009 and 2018. Overall, extraintestinal lesions associated with C. perfringens were diagnosed in 25 cases of NE involving commercial broiler chickens. The extraintestinal sites most commonly affected included liver, followed by gizzard, bursa of Fabricius, gall bladder, and spleen. The etiology of these lesions, C. perfringens, was confirmed from a combination of gross, bacteriologic, microscopic, and immunohistochemical findings. The most common predisposing factors for NE identified were coccidiosis (56%, 14/25) and immunosuppressive disease agents, including infectious bursal disease virus (16%, 4/25) and fowl adenovirus group 1 (4%, 1/25). Additionally, four cases (16%) had microscopic lesions compatible with cystic enteritis, probably of viral etiology. This study describes the incidence of extraintestinal lesions of NE in chickens, underlying the role of enteric disorders and immunosuppression as major predisposing factors for the development of NE.

Liposarcoma in a Backyard Silkie and Retrospective Summary of Neoplasms Diagnosed in Backyard Chickens Submitted to the California Animal Health and Food Safety Laboratory System, 2008-2017.

Liposarcomas are a malignant neoplasm of adipocytes, and are rarely diagnosed in avian species. This case report describes the evidence supporting a diagnosis of metastatic liposarcoma in a backyard silkie chicken. On September 28, 2017, a dead 3-yr-old backyard silkie chicken, with a history of unknown skin lesions involving the entire body and severe weight loss, was submitted to California Animal Health and Food Safety Laboratory System-Turlock branch for necropsy. At necropsy, raised necrotic lesions involving the majority of the skin and multiple nodules in the liver, spleen, and bone marrow were noticed. Microscopically, stellate, spindle, and myxoid cells containing large vacuoles, which were confirmed as lipid droplets by Oil Red O, were observed infiltrating the dermis and underlying a necrotic epidermis, with metastasis to liver, spleen, bone marrow, and ovary being the most significant findings. PAS, Oil Red O, Ziehl-Neelsen, Congo red, Gram, and Von Kossa stains, along with immunohistochemistry for pan cytokeratin, vimentin, S100, CD3, pp38, and Meq were used to classify the lesions. Intensely positive vimentin immunohistochemistry, along with large quantities of Oil Red O-positive lipid droplets within the neoplastic cells, were supportive of our diagnosis of liposarcoma. The incidence of neoplastic diseases diagnosed in backyard flock submissions to CAHFS system wide from 2008 to 2017 was also reviewed.