Amyloidosis Flashcards
What is amyloidosis
Amyloidosis is a group of diseases characterized by the extracellular deposition of proteins (e.g., amyloid A and apolipoprotein E (ApoE)) that form beta-pleated sheets within organs
The proteins affect the function of the various organs in which they are deposited
What is the origin of amyloid A protein
The amyloid A protein is derived from an acute-phase protein that is released in chronic inflammatory, infectious or neoplastic conditions or as a familal trait (e.g. Abyssinian cats)
What is the importance of apolipoprotein E in the development of amyloidosis
ApoE was found in all types of amyloid, suggesting the involvement of ApoE in the development of feline amyloidosis
How can systemic amyloidosis present clinically
Systemic amyloidosis may present as:
- a nephropathy (most commoonly seen in affected Abyssinians) or
- hepatopathy (the most common manifestation of which is spontaneous hepatic rupture and hemoabdomen)
What characterizes renal amyloidosis and what are the consequences for clinical presentation
Renal amyloidosis is characterized by deposition in the interstitial spaces, affecting tubular function (unlike Shar Pei dogs where the primary site of deposition are glomeruli)
Cats will present with signs and clinicopathological evidence of chronic renal insufficiency
What are the clinical and clinicopathological consequences of amyloid deposition in the liver
Amyloid deposition in the liver causes increases in liver enzymes
The striking feature of the disease is sudden, often fatal, intra-abdominal hemorrhage caused by hepatic rupture
What breeds of cats are predisposed to liver amyloidosis
Siamese and Oriental cats seem predisposed, however the condition has been described in DSH and Devon Rex cats
How can you make a diagnosis of hepatic amyloidosis
The diagnosis of hepatic amyloidosis can be challenging, as signs may be subtle if the cat experiences small episodes of hemorrhage
A pattern-recognition approach may be useful in these cases:
- young Siamese or Oriental cat presenting for acute episodes of collapse and pallor, combined with a regenerative anemia, elevations of liver enzymes and often, hepatomegaly
Explain why is it difficult to obtain a definitive diagnosis
A definitive diagnosis is made by demonstrating amyloid deposition by cytology or histopathology
Sampling organs with amyloidosis is not without significant risk of hemorrhage
What is the treatment for hepatic amyloidosis
There is no specific treatment that will dissolve deposited amyloid
- the only therapeutic intervention available is supportive treatment via cage rest, transfusion
Some authors suggest that supplementation of vitamin K1 should form part of the therapy
The prognosis is grave
