Diseases of Poultry
By Ivan Dinev, DVM, PhD
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ERYTHROBLASTOSIS
![337](https://cdn.globalagmedia.com/poultry/legacy/publications/images/image_Page_063_Image_0003.jpg)
![338](https://cdn.globalagmedia.com/poultry/legacy/publications/images/image_Page_063_Image_0004.jpg)
337.338.Erythroblastosis (ER) is characterized by intravascular proliferations of immature precursors of erythrocytes. ER has a leukaemic character and is manifested with signs of severe anaemia. The liver and the kidneys are moderately enlarged with a characteristic dark red to mahogany colour, sometimes with haemorrhages.
![339](https://cdn.globalagmedia.com/poultry/legacy/publications/images/image_Page_063_Image_0005.jpg)
339.ER is caused by the avian eryhtroblastosis virus (AEV); the most frequently encountered strains are E-26, ES4, R etc. The spleen is unusually enlarged or atrophied in cases of severe anaemia.
![340](https://cdn.globalagmedia.com/poultry/legacy/publications/images/image_Page_063_Image_0006.jpg)
340.Histologically, accumulation of erythroblasts in blood sinusoids and capillaries is seen. The diagnosis is based on visceral histological lesions, typical for ER and peripheral blood haematological and morpho-logical analysis.
![341](https://cdn.globalagmedia.com/poultry/legacy/publications/images/image_Page_064_Image_0001.jpg)
![342](https://cdn.globalagmedia.com/poultry/legacy/publications/images/image_Page_064_Image_0002.jpg)
341.342.Osteopetrosis is a neoplastic disease, aetiologically related to the L/S group of viruses. It is characterized by a significant thickening of bone periosteum. The diaphyses of the tibia and/or tarsometatarsal bones are most commonly affected. Often, osteopetrosis is seen simultaneously with LL in the same bird.