Renal amyloidosis Flashcards
How common is renal amyloidosis in cats
Renal amyloidosis is an uncommon disease in cats
Are there any breed predisposed to renal amyloidosis
Renal amyloidosis is a manifestation of systemic amyloidosis in the cat
It is seen most commonly in Abyssinian and Siamese/Oriental cats where there is an inherited predisposition
- however, the condition can be seen as an acquired disease in any breed of cat
Is feline renal amyloidosis similar to canine renal amyloidosis
Feline renal amyloidosis is pathophysiologically distinct from the condition in dogs
- in cats, it is predominantly an interstitial disease (primarily medullary amyloid deposits)
- in dogs, it is predominantly a glomerular disease and an imporatnt cause of protein-losing nephropathy
Explain the pathomechanism of amyloidosis
Amyloidosis is potentially the result of a variety of disease processes that lead to the deposition of extracellular (intercellular) fibrillar protein material (amyloid)
- there are several types of amyloid but with a similar physical conformation
Systemic amyloidosis can affect many organs, but progressive accumulation in the kidneys leading to renal failure is one of the common presentations
Renal amyloidosis predominantly involves medullary deposition in cats, which results in defective urine concentrating ability, renal papillary necrosis if the blood supply to the papilla is disrupted, and eventually severe interstitial nephrosis and fibrosis
The beta-pleated sheet configuration of amyloid is responsible for the insolubility of the fibrils, and its resistance to proteolysis
- although inert, the deposition of amyloid within organs can result in progressive interference with normal function and blood flow and may result in necrosis and fibrosis
How many forms of systemic amyloidosis are recognized
Immunoglobulin-related amyloidosis
- the amyloid precursor is a degradation product of the light-chain from an immunoglobulin
- it has been reported in association with multiple myeloma and paraproteinemia
- it is rare in cats
Reactive amyloidosis
- the amyloid precursor is an acute phase protein known as serum amyloid-A related protein (SAA)
- in most cases, the underlying cause is unknown
Familial amyloidosis in Abyssinian/Somalis and Siamese/Orientals
Explain the specific clinical condition of amyloidosis in Abyssinian/Somalis
- the amyloid is formed from SAA
- clinical signs are related to renal disease
- average age of onset of signs is 3 years
- there is a great variation between individuals in the progression of the disease
- high SAA concentrations are clearly necessary for amyloidosis but are also clearly not the only factor
Explain the specific clinical form of amyloidosis in Siamese/orientals
In many of these cats, the liver is more severely affected
The etiology for these cases is controversial and maybe they have both hereditary and reactive disease
In the liver, progressive amyloidosis results in hepatomegaly and fragility causing spontaneous rupture and hepatic bleeding
- recurrent episodes of acute anemia may sometimes precede a catastrophic bleed leading to death
What are the clinical signs of systemic amyloidosis in cats
Although signs of CRF predominate in many cats, if there is an infectious or inflammatory disease underlying the amyloidosis, clinical signs attributable to this primary disease may predominate
In affected cats, kidneys may be shrunken
- earlier in the disease, mild renomegaly may be found and serum protein electrophoresis may reveal mild elevations in alpha-globulins (which is a non-specific finding)
how is a diagnosis of renal amyloidosis made
Diagnosis can only be made by renal biopsy
What is the prognosis for renal amyloidosis
There are no specific treatment today so the prognosis for cats with renal amyloidosis remains grave, and therapy is aimed at controlling the CRF present
What is the origin of proteinuria in cats with CKD
Feline CKD is characterized as tubulointerstitial inflammation and fibrosis which is different from dogs
In the setting of CKD, proteinuria is typically secondary to tubular dysfunction and glomerulosclerosis, which increase in prevalence with disease sevirity
