EQUINE | CPD Article
EQUINE | CPD Article
sistent feature of sleepy foal disease ( neonatal septicemia ), implicating an important and possible primary role of endotoxin in lesion induction .
Pathogenesis
Predisposing factors to the development of disease in foals includes failure of passive transfer of maternal antibodies , unsanitary conditions in the foaling area and concurrent immunosuppressive conditions . Infection in foals is acquired in utero , during parturition , or shortly after birth as an umbilical infection or less commonly from gastrointestinal ( ingestion ) or respiratory ( inhalation ) infections . Disease presentation is often peracute with death at birth or within the 1st few days due to fulminant septicemia . In foals that survive the initial infection and survive for several days , usually present with the classical microabscessation syndrome . These neonatal septicemic infections are considered to be primary infections in most instances .
During bacteraemia , septic emboli lodge in glomeruli and peritubular capillaries producing multifocal glomerulonephritis and interstitial nephritis . Abscesses are usually cortical but can be seen in the medulla ( Figure 1 and Figure 2 ).
Figure 2 : Foal kidney and adrenal gland - note the early and subtle embolic nephritis ( arrow ) with enlarged and hemorrhagic adrenal gland due to extensive bacterial emboli station of the adrenal with associated vasculitis and hemorrhage .
Another target organ besides the kidney is the adrenal ( Figure 3 ). Death may occur because of fulminating septicaemia . In foals that survive for several days , micro-abscesses are seen in the kidneys and other organs , and polyarthritis is present , most commonly involving the hock and stifle joints .
Figure 1 : Foal Kidney - multifocal embolic bacterial nephritis with microabscesses ( arrows ). Image courtesy of the University of Georgia .
Figure 3 : Foal adrenal gland – note the multifocal embolic adrenalitis with micro-abcessation ( arrows ) and extensive hemorrhage . The adrenal gland is a frequently overlooked target organ of Actinobacillus equuli .
20 • Equine Health Update •