Western
Meeting of Poultry
Clinicians and Pathologists
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Clinicians and Pathologists
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"Hepatitis Splenomegaly" Syndrome in Commercial Egg Laying Hens Stewart J. Ritchie
A flock of 27,000 leghorn chickens experienced a reduced rate of lay and high mortality from 32 weeks of age. Lesions observed were at first attributed to fatty liver hemorrhagic syndrome (FLHS); however, necropsy revealed lesions not consistent with FLHS. The main purpose of this paper is to report preliminary observations made on this new condition. The prevalence of this problem is low. This disease had occurred on one other farm in the Fraser Valley of B.C. (H.D. McCausland, personal communication) and has been observed in Alberta (K. McMillan, personal communication) and Saskatchewan (C. Riddell, personal communication). The flock in B.C. was affected from 32 weeks of age at which time a sudden increase in mortality was noted with reduced egg production. Total mortality reached 1.30 percent per month. No abnormal clinical signs were noted. Affected birds were found dead, sometimes with heads extended into the feeding area. Birds sometimes died on the egg belt and blocked the movement of eggs. Gross lesions observed include an extremely pale to white comb with reddish edges. The comb was slightly to moderately shrunken. The birds were in poor to moderate body condition. Livers were swollen and friable and were mottled tan and red with multifocal miliary pale areas and hemorrhage. The spleens were enlarged two to three times. The oviducts were regressing and the ovaries were regressing with injected blood vessels. The abdomens were full of a red fluid with a consistency of water. There was recently ingested feed present in the crops and gizzards. Histological lesions in the liver consisted of large areas of hepatocellular coagulation necrosis and hemorrhage. This was amorphous eosinophilic mononuclear and heterophil infiltration. Special stains were negative for fungus and Campylobacter. The spleens had generalized lymphoid depletion and accumulation of amorphous eosinophilic material. No significant histological lesions were noted in the pancreas, intestines, lungs, sciatic nerve or kidneys.
No significant pathogens were cultured on routine bacteriology.
Discussion These lesions were not consistent with a diagnosis of FLHS. Birds dying of FLHS tend to be in full egg production, have yellow livers with a blood clot extending from a rupture of the liver capsule.
This disease problem poses a significant negative economic impact to affected flocks. Differential diagnosis at the time includes: 1) a lymphoproliferative disease, 2) bacterial infection, such as Campylobacter sp. or Clostridial sp., 3) feed toxin, such as rape seed or mycotoxins.
Further diagnostic and epidemiological studies are required.
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