Avian Diseases

False layer syndrome is a condition in which the reproductive tract of chicks is infected with infectious bronchitis virus (IBV) strains that cause permanent damage to the oviduct. These chickens subsequently develop cystic oviducts and do not lay eggs, and affected flocks fail to reach expected egg production peaks. The California Animal Health and Food Safety laboratory, Turlock Branch, received four separate case submissions from a 25-to-28-wk-old commercial ISA Brown layer flock. Birds were submitted for diagnostic evaluation due to suboptimal egg production and vent pecking...

A cerebral tumor was identified in an adult female domestic chicken ( Gallus domesticus ). On gross examination, the cut surface of the cerebrum revealed a poorly circumscribed, pale tan soft mass within the thalamus and midbrain. On histologic examination, there was an unencapsulated, multilobulated neoplasm composed of spindle cells on a loose fibrovascular stroma. Neoplastic cells had variably distinct cell borders, abundant fibrillar eosinophilic cytoplasm, oval nuclei with finely stippled chromatin, and 1-2 distinct nucleoli...

Campylobacter hepaticus ( C. hepaticus ) was recently discovered as the causative agent of Spotty Liver Disease (SLD). SLD affects laying hens and causes significant economic losses in egg production in several countries throughout the world. Field observations reveal that cases of SLD appear with a high risk of reoccurrence, specifically in free-range and organic brown-feathered layer lines. Possible factors contributing to the development of SLD still have to be elucidated. In this field study, one free range (Flock 1) and one organic flock (Flock 2) of brown laying hens kept on farms with a history of clinical SLD were monitored for C...

The carcass of a 4-mo-old, female, mixed-breed backyard chicken was submitted for postmortem evaluation and diagnostic workup. The bird was previously presented to a veterinary clinic because of chronic weight loss and loose stool, and was euthanized before submission to the California Animal Health and Food Safety, Turlock lab. On gross examination, the proventriculus, gizzard, and duodenum were markedly distended and impacted with a mixture of fibrous plant material, cereal grain, and litter material. The koilin layer of the gizzard was eroded...

Host cellular responses against Clostridium perfringens (CP), the causative agent of necrotic enteritis (NE) in chickens, are poorly understood. In the present study, we first tested the NE-producing ability of seven netB + CP strains (CP5, CP18, CP26, CP64, CP67, CP68, and NCNE-1), using an experimental infection model of broiler chickens. Evaluation of intestinal gross lesions showed that all the strains, except CP5, were able to produce NE, while CP26 and CP64 strains produced relatively more severe lesions when compared with other groups...

Focal duodenal necrosis (FDN) is a common intestinal disease of table egg layers. In this research we aimed to identify the bacteria commonly found in FDN lesions as seen with histopathological analysis. Fifty-nine ethanol-fixed duodenum samples were collected from egg layers on eight FDN-affected farms, and 42 samples had typical FDN lesions. Excision of bacteria-containing lesions using laser capture microdissection was performed, followed by 16S rRNA gene sequencing of extracted DNA for bacterial identification...

The objective of the trial was to evaluate three vaccination schemes against Clostridium perfringens (CP) alpha-toxoid through drinking water to determine if they can protect against clinical signs of necrotic enteritis and coccidiosis in broiler chickens. Three hundred 1-day-old Cobb 500 male chicks were used in 4 treatments with 10 repetitions. Each group received 1 of the following treatments over the course of 29 days: T1, no vaccination; T2, vaccination on Day 1; T3, vaccination on Day 7; and T4, vaccination on Days 7 and 17...

Mass vaccination against infectious laryngotracheitis virus (ILTV) in drinking water can result in variable initial vaccine take. Partial initial vaccine coverage of 20% with an Australian ILT vaccine (A20) previously resulted in significant protection against virulent ILTV challenge. This follow-up study used the international Serva ILT vaccine strain in a factorial design testing four levels of vaccination coverage (0%, 10%, 20%, or 100% of chicks eye-drop vaccinated with the live vaccine at 7 days of age) and three levels of ILTV challenge (no challenge or challenge at 7 or 21 days postvaccination [DPV])...

Avibacterium paragallinarum is an important respiratory pathogen of domestic chickens. Avibacterium paragallinarum has been subtyped into three serogroups and nine serovars according to the Page and revised Kume schemes. The major hemagglutinin antigen of A. paragallinarum is HMTp210, which is a large protein of about 2000 amino acids (aa), including a 70-aa signal peptide at its N-terminal end. However, the regions important for the hemagglutination (HA) activity and serotypes of HMTp210 remain unclear. In this study we constructed a series of A...

Infectious laryngotracheitis (ILT) is a respiratory disease that causes significant economic losses to the poultry industry. Control of the disease is achieved by vaccination and implementation of biosecurity measures. The use of bivalent and trivalent recombinant herpesvirus of turkey (rHVT) vaccines expressing infectious laryngotracheitis virus (ILTV) genes has increased worldwide. In the United States, vaccination programs of long-lived birds (broiler breeders and commercial layers) against ILT include immunizations with either HVT recombinant vector vaccines, in ovo or at hatch, or live attenuated vaccines administered via drinking water (chicken embryo origin [CEO]) or eye drop (tissue culture origin [TCO])...

Enterococcus cecorum has been associated mainly with osteomyelitis of the free thoracic vertebra in chickens. However, there are reports of E. cecorum producing septicemic lesions and having tropism for cartilages, resulting in the presentation of femoral head necrosis and synovitis. This paper discusses the presentation of E. cecorum as it relates to an outbreak in one vertical integrator where the main lesions were related to septicemia. Using a convenience sampling method, 100 broiler chicken cases received at the Poultry Research and Diagnostic Laboratory of Mississippi State University from April to December of 2021 were analyzed...

A flock of 50,000 28-day-old broiler breeder chickens experienced an elevated mortality event. Chickens from that flock, five pullets and six cockerels, were submitted for diagnostic investigation. Necropsy revealed bacterial septicemia with fibrinous polyserositis in the majority of the birds while two cockerels had coccidial typhlitis. Because sulfadimethoxine was not available at the time, sulfaquinoxaline (SQ) was prescribed at label dosage with water treatment for 2 days, followed by 3 days of no medication, followed by 2 days of medication...

Intestinal health plays a major role in profitable and efficient turkey production. Blackhead disease (histomoniasis) is caused by Histomonas meleagridis , an anaerobic protozoan parasite. Histomonas meleagridis disrupts intestinal integrity and may cause systemic infection. Some field outbreaks of blackhead disease are associated with low morbidity and mortality, while in some instances, it may cause severe morbidity and mortality. In the current study, a presumptive diagnosis of blackhead disease was made based on the characteristic gross lesions in the liver and ceca...

An unusual case of swollen head syndrome in a 55-wk-old broiler breeder flock was identified in north Georgia in the summer of 2019. The presenting complaint was elevated mortality and visibly swollen heads. Necropsy of affected birds on the farm primarily revealed signs of bacterial septicemia, with few large scab lesions near the vent area. Bacterial culture analysis identified multiple organisms, but the primary organism of interest was identified as Erysipelothrix rhusiopathiae , cultured from affected liver, lung, sinuses, and one swollen wattle of birds in the affected house...

A sudden drop in egg production in commercial poultry flocks can be economically devastating, and rapid identification of the cause often requires a combined effort between the producer, veterinarian, and pathologist. In September 2019, a 35-wk-old commercial Pekin breeder duck flock in Indiana suffered a drop in egg production from 1700 to 1000 eggs daily (41.2% drop). Again, in September 2021, three Pekin breeder duck flocks aged 32, 58, and 62 wk from the same company suffered a similar drop in egg production, with a mild increase in weekly mortality of 1...

The present study was conducted to determine the serotype diversity of Salmonella among poultry in northern India. A total of 101 poultry droppings from 30 farms in the Jammu and Kashmir union territory were analyzed. Nineteen isolates of Salmonella were obtained, and these belonged to four serotypes: Salmonella enterica enterica serotype Kentucky ( n = 3), Salmonella enterica enterica serotype Infantis ( n = 5), Salmonella enterica enterica serotype Agona ( n = 4), and Salmonella enterica enterica serotype Typhimurium ( n = 7)...

The U.S. Department of Agriculture Avian Disease and Oncology Laboratory currently relies on live birds of specific genetic backgrounds for producing chicken-embryo fibroblasts that are used for the diagnosis and subtyping of field isolates associated with avian leukosis virus (ALV) outbreaks. As an alternative to maintaining live animals for this purpose, we are currently developing cell lines capable of achieving the same result by ablation of the entry receptors utilized by ALV strains. We used CRISPR-Cas9 on the cell fibroblast-derived cell line DF-1 to disrupt the tva gene, which encodes the receptor required for binding and entry of ALV-A into cells...

Despite the essential role of innate immunity in defining the outcome of viral infections, the roles played by different components of the avian innate immune system are poorly delineated. Here, we investigated the potential implication of avian toll-like receptor (TLR) 3 (TLR3) and melanoma differentiation-associated (MDA) gene 5 (MDA5) receptors of double-stranded RNA (dsRNA) in induction of the interferon pathway and avian orthoavulavirus 1 (AOAV-1) replication in chicken-origin DF-1 fibroblast cells. TLR3 and MDA5 knockout (KO) DF-1 cells were generated using our avian-specific CRISPR/Cas9 system and stimulated with a synthetic dsRNA ligand polyinosinic:polycytidylic acid [poly(I:C)] or infected with AOAV-1 (previously known as Newcastle disease virus)...

Poultry producers in Costa Rica have informally reported a spotty liver disease-like syndrome for more than 20 yr. However, despite many attempts, the infectious agent responsible for this syndrome had not been identified. Therefore, following current knowledge of spotty liver disease diagnosis, we invited veterinarians and poultry producers to submit samples to the diagnostic laboratories of the Veterinary Medicine School, Universidad Nacional, to identify the infectious agent of this syndrome. Veterinarians and poultry producers were instructed to collect gallbladders and livers aseptically and send them for pathology examinations and bacterial cultures in less than 24 hr after collection...

Clostridial dermatitis (CD), caused by Clostridium septicum and Clostridium perfringens , is an economically important emerging disease of turkeys characterized by sudden deaths and necrotic dermatitis. Immune responses in CD-affected commercial turkeys are poorly understood. In the present study, C. septicum was isolated from CD-affected commercial turkeys during a recent outbreak, and the tissues (skin, muscle, and spleen) were collected and analyzed for immune gene expression, along with samples from clinically healthy birds...