Characterization and classification of psittacine atherosclerotic lesions by histopathology, digital image analysis, transmission and scanning electron microscopy

Abstract

Atherosclerosis is a degenerative and inflammatory vascular disease characterized in mammals and birds by the accumulation of inflammatory cells, lipids, calcium, and formation of large fibrofatty lesions within the intima of arteries resulting in the disorganization of the arterial wall and stenosis of the lumen. Despite the high incidence of atherosclerosis in parrots and the high number of case reports, there are few pathologic investigations and the ultrastructural study of the lesions has not been documented. Sixty-three major arteries were collected from 24 psittacine birds of 11 species during routine post-mortem examinations. Samples from the major arteries were fixed in 2% paraformaldehyde and 1.25% glutaraldehyde, and processed for transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Additional samples were fixed in 10% formalin and embedded in paraffin for histological examination. Additional histochemical stains for calcium, elastic fibres, and lipid were performed. Toluidine blue-stained 0.5 mm-thick resin sections were also obtained. Digital image analysis was performed to provide objective quantitative information on the different lesions. The histopathology and ultrastructure of psittacine atherosclerosis were found to be similar to other avian and mammalian species. Seven lesion types could be described, which were similar to the human classification system. Digital image analysis, TEM, and SEM helped to further describe the lesions and refine the classification system. TEM findings were similar to other avian and mammalian species with the notable presence of macrophage-derived and smooth muscle cellderived foam cells and extracellular lipid. SEM revealed various stages of endothelial surface defects and, occasionally, adherent blood cells.

Malignant Melanoma of the Syrinx and Liver in an African Grey Parrot (Psittacus erithacus erithacus)

“…The lumen of the aorta was mineralized and severely decreased in size, characteristic of type IV atherosclerosis. 2 …”

Cardiovascular Diseases

“…Atherosclerosis is a chronic inflammatory fibroproliferative vascular disease characterized by the buildup of atheromatous materials containing numerous compounds including inflammatory cells (mainly macrophages), lipid, calcium, and collagen in the luminal side of the arteries in response to multiple forms of endothelial injuries, which, in chickens, include Marek's disease (which also affects lipid metabolism) [30,33,58]. Risk factors have not been completely characterized in poultry but age, gender, specific breeds, inbreeding (some experimental lines of chickens and quails), and dietary factors may have a role in the pathogenesis.…”

Prevalence of and risk factors associated with atherosclerosis in psittacine birds

“…[4][5][6][7] However, scientific investigations are scarce and certainly not of a scale in proportion to the importance of the disease in this taxon. [4][5][6][7] However, scientific investigations are scarce and certainly not of a scale in proportion to the importance of the disease in this taxon.…”

“…5,6,12,13 Psittacine atherosclerotic lesions consist of the progressive accumulation of inflammatory cells, cholesterol, fat, and cellular debris in the intima and luminal side of the media. 5,6,12,13 Psittacine atherosclerotic lesions consist of the progressive accumulation of inflammatory cells, cholesterol, fat, and cellular debris in the intima and luminal side of the media.…”

“…13,14 Human postmortem and clinical imaging studies 13,15,16 reveal that humans with clinical signs of atherosclerosis have lesions of type IV or higher. [4][5][6] Knowing the prevalence of advanced and clinically important atherosclerosis is crucial to the development and interpretation of diagnostic tests (with regard to positive and negative predictive values) but also constitutes an invaluable aid in assessing and managing psittacine patients on the basis of their signalment and medical history. Few studies [17][18][19][20][21][22] have investigated the effect of dietary factors in psittacine birds.…”