Amyloidosis

Amyloidosis is a condition that occurs when amyloid protein is deposited in various organs in the body. It is a progressive disease that often leads to chronic kidney failure and is mostly seen in dogs, but rare in cats. Amyloidosis can be classified as systemic or localized, which is more common. Almost any tissue or organ in the body can be affected but kidneys, liver, spleen, and adrenal gland are at the highest risk.

There are two major forms of systemic amyloidosis. The most common form in domestic animals is reactive (secondary) amyloidosis due to chronic inflammatory disease. In reactive amyloidosis, the deposited amyloid protein is AA type is derived from serum (blood) amyloid A synthesized in the liver. The other form of systemic amyloidosis is light-chain (AL) amyloidosis, which is the most common type in human beings but very rare in domestic animals. One of the common underlying causes of human AL amyloidosis is multiple myeloma, which accounts for 12% to 15% of the cases.

Some types of amyloidosis are hereditary in dogs, others occur as a result of diseases such as heartworm infection, various cancers, or inflammatory or immune-related conditions. The inflammation in case of familial canine dermatomyositis may predispose to the development of amyloidosis. The disease can become fatal if amyloid is deposted into the tissue of critical organs, such as kidneys, liver, or heart.

Renal Amyloidosis

Renal amyloidosis is one of the most common hereditary disorders in cats and dogs which include renal dysplasia, polycystic kidneys, basement membrane disorders, and tubular dysfunction (Fanconi syndrome). Signs of renal amyloidosis in dogs usually include: vomiting, loss of appetite, lethargy, increased thirst and urination, weight loss, and dehydration. Some dogs may have intermittent fever and joint swelling. Laboratory findings are compatible with kidney failure. Both puppies and adult dogs may be affected.

Chinese shar pei
Renal amyloidosis is inherited in Chinese Shar Pei dogs

Recent studies showed that renal amyloidosis (RA) is inherited in Chinese Shar Pei dogs and that they develop RA at a younger age than other dog breeds, and that the acquisition of this trait is compatible with autosomal recessive inheritance. Familial renal amyloidosis also occurs in the Abyssinian cat, young Siamese and Oriental Shorthaired cats.



Diagnosiss & Treatment

Because of its wide distribution and stealthy onset, amyloidosis is difficult to diagnose. However, your veterinarian may suspect amyloidosis if your dog has a chronic infection or inflammation and develops kidney or liver failure. Renal biopsies are needed to differentiate renal amyloidosis from immune complex-mediated glomerulonephritis(ICGN). There is no proven specific treatment for amyloidosis. Treatment of the underlying disease may result in regression of amyloid and associated signs. The prognosis is usually poor. Some dogs can be managed up to 1 year. Some Abyssinian cats may have no signs of the disease.

References

  1. Thorough Investigation of a Canine Autoinflammatory Disease (AID) Confirms One Main Risk Locus and Suggests a Modifier Locus for Amyloidosis
  2. A Concise Review of Amyloidosis in Animals




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