Emaciation and Sporadic Mortality in Older Laying Hens Caused by Intussusception of the Proventriculus.

Laying hens (n = 2267) ranging in age from 2 to 4 yr in a study evaluating ovarian cancer prevention were necropsied. Those that died or were culled during the 2-yr study (n = 1591) were necropsied weekly to determine the most probable cause of death or culling and cancer status. Hens surviving until the end of the study (n = 676) were euthanized and necropsied. Hens necropsied before and after a hen with proventricular intussusception served as cohorts (n = 38). Nineteen hens (13 dead, 6 culled) had intussusceptions of the proventriculus into the ventriculus. Mean age of affected hens was 154 wk (range 110-204 wk). None of the hens in the study had an intestinal intussusception, and none of the hens euthanized at the end of the study had a proventricular intussusception. Hens with proventricular intussusceptions were severely emaciated; mean body weights were 1040 and 1736 g for affected and cohort hens, respectively. Necropsy findings included prominent keel, marked muscle atrophy, generalized serous atrophy of fat, no visible proventriculus, esophagus directly entering the ventriculus, and an enlarged, spherical, firm ventriculus, which contained an invaginated, swollen, diffusely ulcerated proventriculus. Eighteen affected hens were anovulatory (94.7%) compared to 27 cohorts (71.1%). Severe, diffuse necrosis and ulceration of the proventricular mucosa was confirmed microscopically, but no etiologic agent was identified. In conclusion, proventricular intussusception of undetermined etiology was identified as a cause of sporadic emaciation, culling, and mortality in older laying hens.

Reporte de caso- Emaciación y mortalidad esporádica causadas por intususcepción del proventrículo en gallinas de postura maduras. Se realizaron necropsias de gallinas ponedoras (n=2267) de dos a cuatro años de edad en un estudio que evaluó la prevención del cáncer de ovario. Las aves que fueron eliminadas semanalmente durante el estudio de dos años (n=1591) se sometieron a la necropsia para determinar la causa más probable de muerte o de desecho y el estado de cáncer. Las gallinas que sobrevivieron hasta el final del estudio (n=676) se sacrificaron y se les realizó la necropsia. Las gallinas a las que se les practicó la necropsia antes y después de la intususcepción proventricular sirvieron como cohortes (n=38). Diecinueve gallinas (13 muertas y seis sacrificadas) tuvieron intususcepciones del proventrículo dentro de la molleja. La edad media de las gallinas afectadas fue de 154 semanas (con un rango de 110 a 204 semanas). Ninguna de las gallinas en el estudio mostró una intususcepción intestinal y ninguna de las gallinas sometidas a eutanasia al final del estudio tuvo una intususcepción proventricular. Las gallinas con intususcepciones proventriculares estaban severamente emaciadas; los pesos corporales medios fueron 1040 g y 1736 g para las gallinas afectadas y para las gallinas cohorte, respectivamente. Los hallazgos de la necropsia incluyeron la quilla de la pechuga prominente, atrofia muscular marcada, atrofia serosa de la grasa generalizada, no proventrículo visible, esófago entrando directamente en la molleja y una molleja esférica y firme, que contenía un proventrículo, invaginado, abultado y difusamente ulcerado. Dieciocho gallinas afectadas fueron anovulatorias (94.7%) en comparación con 27 cohortes (71.1%). La necrosis y la ulceración severas y generalizadas de la mucosa proventricular se confirmaron microscópicamente, pero no se identificó ningún agente etiológico. En conclusión, la intususcepción proventricular de etiología indeterminada se identificó como una causa de emaciación esporádica, sacrificio y mortalidad en gallinas ponedoras maduras.

Avian Encephalomyelitis in Layer Pullets Associated with Vaccination.

Avian encephalomyelitis (AE) was diagnosed in three flocks of leghorn layer pullets following AE vaccination. Ages of the birds were 11, 12, and 14 wk. The submissions came from three different companies located in two geographic areas of the Central Valley of California. The clinical signs included birds down on their legs, unilateral recumbency or sitting on their hocks, lethargy, reluctance to move, dehydration, unevenness in size, low weight, tremors of the head in a few birds, and mildly to moderately elevated mortality. The flocks had been vaccinated against fowl pox and AE with a combined product in the wing-web 2 wk prior to the onset of AE clinical signs. Histopathologic examination revealed lesions consistent with AE, including lymphocytic perivascular infiltration and neuronal central chromatolysis in the brain and spinal cord, as well as gliosis in the cerebellar molecular layer. The AE virus was detected by reverse-transcriptase PCR in the brain homogenate from three cases and peripheral nerves in one case. Additionally, the AE virus was isolated in specific-pathogen-free (SPF) embryonated eggs from brain tissue pool samples. Other avian viral infections capable of causing encephalitis, including avian paramyxoviruses, avian influenza virus (AIV), West Nile virus (WNV), eastern equine encephalitis virus (EEEV), and western equine encephalitis virus (WEEV), were ruled out by attempting virus isolation and molecular procedures.

A persistent outbreak of ulcerative enteritis in bobwhite quail (Colinus virginianus).

Ulcerative enteritis is a disease that typically responds well to medication. An outbreak of ulcerative enteritis that was persistent and unresponsive to treatment is described. The outbreak started in semimature birds and progressively spread to younger birds. Confounding factors leading to this persistence were a significant coccidosis problem, a feed mixing error, and suspected antibiotic resistance. Although Clostridium colinum was never isolated, a bacitracin-resistant Clostridium perfringens was cultured from affected birds. Only the combined treatment of the flocks with an anticoccidial and tylosin was effective in controlling clinical disease. Numerous other management and treatment strategies were unsuccessful in lowering the severe mortality.

Strain persistence and fluctuation of multiple-antibiotic resistant Campylobacter coli colonizing turkeys over successive production cycles.

The dynamics of colonization of turkeys by thermophilic campylobacters that are resistant to multiple antibiotics is poorly understood. In this study, we monitored cecal colonization of turkeys by Campylobacter over three successive production cycles at the same farm. Campylobacter isolated from the ceca was predominantly C. coli in all three flocks. Isolates with two distinct fla types that represented a single clonal group based on pulsed-field gel electrophoresis and that were resistant to multiple antibiotics (tetracycline, streptomycin, ampicillin, erythromycin, kanamycin, nalidixic acid, and ciprofloxacin) predominated throughout the three production cycles. The relative prevalence of each fla type, however, varied significantly from one flock to the next. The repeated isolation of these multiresistant C. coli from successive flocks likely reflected persistence of the organisms in currently unknown reservoirs in the production environment or, alternatively, repeated introduction events followed by establishment of these bacteria in each successive flock.

Campylobacter colonization of sibling turkey flocks reared under different management conditions.

Uncertainty exists concerning the key factors contributing to Campylobacter colonization of poultry, especially the possible role of vertical transmission from breeder hens to young birds. A longitudinal study of Campylobacter colonization was performed in two sibling pairs of turkey flocks (four flocks total). Each pair of sibling flocks shared breeder hen populations and was obtained from the same hatchery. One flock of each pair was grown on a commercial farm, and the other was grown in an instructional demonstration unit (Teaching Animal Unit [TAU]). Flocks were located within a 60-mi (96.8-km) radius. The time of placement, feed formulations, stocking density, and general husbandry were the same for both flocks, and each flock was processed at a commercial processing plant following standard feed withdrawal and transport protocols. Both flocks grown on the commercial farms became colonized with Campylobacter between weeks 2 and 3 and remained colonized until processing. Between 80 and 90% of isolates were Campylobacter coli, and the remainder were Campylobacter jejuni. In contrast, neither C. coli nor C. jejuni were isolated from either of the TAU flocks at any time during the production cycle. None of the fla types of Campylobacter from the breeders that provided poults to one of the commercial flocks matched those from the progeny. These results failed to provide evidence for vertical transmission and indicate that this type of transmission either did not occur or was not sufficient to render the TAU turkey flocks Campylobacter positive. Management practices such as proper litter maintenance, controlled traffic between the TAU farm and other turkey flocks, and other less well-defined aspects of turkey production were likely responsible for the absence of Campylobacter in the TAU flocks before harvest.