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You've described shar pei fever/swollen hock syndrome which is a symptom of familial amyloidosis in this breed. Abnormal proteins (amyloid) are deposited in soft tissue causing that swelling. Here's a thorough review of this disorder. It's taken from Clinical Veterinary Advisor, 3rd ed., Cote', 2015 and is designed for vets and so you're likely to have many questions after perusing it. Please return to our conversation with further questions or concerns if you wish.
Amyloidosis is the pathologic deposition of polymerized proteins in a beta-pleated sheet conformation, particularly the kidneys. It is a common cause of glomerular disease in dogs. (The glomeruli are the filtering organs in the kidneys.)
In Chinese shar-peis: swollen hock syndrome, familial shar-pei fever
Species, Age, Sex
Uncommon in dogs; rare in cats. Middle-aged to older dogs (median age at diagnosis, 9.0 years) and cats; Chinese shar-peis present at a younger age (median age at diagnosis, 4.5 years).
Genetics and Breed Predisposition
Dogs: Chinese shar-peis (renal and hepatic amyloidosis), English foxhounds; any breed may be affected by reactive/secondary form.
Cats: Abyssinians (renal amyloidosis), Siamese/oriental cats (systemic amyloidosis)
Chronic inflammatory/infectious/neoplastic diseases may predispose to reactive amyloidosis.
Protein-losing nephropathy (PLN)
Chronic kidney disease and renal failure
Other organ dysfunction depends on sites of amyloid deposition.
Reactive amyloidosis occurs secondary to chronic inflammatory diseases (e.g., hepatozoonosis); most amyloidosis in non-predisposed breeds is reactive.
Reactive amyloid deposition causes protein-losing nephropathy (PLN) and variable progression to renal failure
Amyloidosis in Chinese shar-peis: variable proteinuria; renal failure possible without PLN
History may include intermittent fever and inflammatory, nonerosive polyarthritis.
Hepatic amyloidosis with or without renal amyloidosis may also occur.
Cats: amyloid deposition rare; often occurs without clinical signs
Abyssinians: glomerular and/or medullary amyloid deposition with variable severity of proteinuria; renal failure may develop without PLN
Siamese/oriental cats: systemic amyloid deposition with clinical signs dependent on organs affected
History, Chief Complaint
Clinical signs frequently absent until late in disease course.
Chinese shar-peis may be intermittently febrile and/or lame.
Siamese or oriental cats may present with life-threatening intra-abdominal hemorrhage due to liver lobe fracture secondary to massive hepatic deposition of amyloid.
Clinical signs of uremia (see p. 188) are common.
Clinical signs of nephrotic syndrome (e.g., edema/ascites and/or concurrent hypercoagulability (e.g., pulmonary thromboembolism) may be noted.
For reactive amyloidosis, clinical signs may be attributable to an underlying inflammatory process.
Physical Exam Findings
Often unremarkable; mild enlargement of involved organs is possible.
For reactive amyloidosis, abnormalities depend on underlying inflammatory process.
For Chinese shar-peis, may have fever, joint effusion, and arthralgia (especially distal joints)
If nephrotic syndrome is present ascites, edema, or effusion (fluid collection in the abdomen or chest) may be seen.
Variable kidney size
Evidence of thromboembolism (blood clots)
Evidence of hypertension (e.g., retinal changes, central nervous system signs)
Very rarely, cats with systemic amyloidosis develop hepatic rupture and acute hemoabdomen.
Etiology and Pathophysiology
Proteins with beta-pleated sheet conformation accumulate within extracellular spaces, leading to organ dysfunction.
Glomeruli are the most common site of accumulation in dogs, leading to proteinuria.
Deposition within the renal medulla, liver, and other organs may occur with or without glomerular involvement.
Reactive amyloidosis is most common.
Deposited protein is amyloid protein A, a fragment of serum amyloid A (SAA).
SAA increases with systemic inflammation.
Evidence suggests a dysregulated inflammatory response leads to amyloid deposition.
Immunoglobulin light chain-associated amyloidosis rare
Associated with multiple myeloma, some lymphomas, and plasma cell tumors
Definitive diagnosis of amyloidosis requires biopsy of an affected organ (usually kidney). Presumptive diagnosis is appropriate for Chinese shar-peis with fever and/or joint pain.
Initial database should include:
CBC: unremarkable or reflective of underlying inflammatory process
Chemistry profile: unremarkable or reflective of underlying disease until amyloidosis is advanced. Most dogs with renal amyloidosis eventually develop hypoalbuminemia and may develop findings typical of nephrotic syndrome and/or chronic kidney disease. Azotemia may occur without proteinuria in Chinese shar-pei dogs and cats. Chinese shar-pei dogs are less likely to develop nephrotic syndrome than dogs with reactive amyloidosis, and are more likely to be azotemic at time of diagnosis.
Urinalysis: proteinuria secondary to glomerular amyloid deposition. Ability to concentrate urine is compromised as kidney damage progresses.
Arterial blood pressure: systemic hypertension is common.
Urine protein/creatinine (UPC) ratio: often dramatically increased in non-Chinese shar-pei dogs; variably increased in Chinese shar-peis and cats
Imaging: often unremarkable; kidneys and liver may be mildly enlarged and hyperechoic on ultrasonographic examination. Rarely, hemoabdomen and hepatic fracture identified in Oriental cats with hepatic amyloid deposition.
Advanced or Confirmatory Testing
Biopsy is required for definitive diagnosis. Histologic findings:
Hematoxylin and eosin stain: homogeneous eosinophilic material within affected organs, particularly the glomerular mesangium
Congo red stain: apple-green birefringence when viewed under polarized light
Amyloid deposition in Chinese shar-peis and Abyssinian cats may be limited to the renal medulla, so biopsy may not be diagnostic (renal biopsies should only contain cortex).
As other organs can be affected, biopsy can confirm amyloid outside of the kidney. Hepatic biopsy may be preferred when there is clinicopathologic evidence of liver dysfunction.
Additional testing may be indicated to identify underlying inflammatory/infectious/neoplastic disease.
Prognosis is guarded to poor unless an underlying disease is identified and corrected. Nonspecific therapies include reduction of proteinuria and treatment of renal failure and its consequences. Efficacy of specific treatments for amyloidosis is unknown.
Acute General Treatment
Stabilization and treatment of uremic crisis if present
Treatment of complications if present
Management/resolution of any concurrent inflammatory diseases
Continued management of PLN and chronic kidney disease
Dimethyl sulfoxide may slow or prevent progression of amyloidosis: 300 mg/kg PO q24h, or dilute 90% solution 1 : 4 in sterile water and administer 20-80 mg/kg SQ 3 times/week. Owners should wear gloves when administering. SQ injections may cause local irritation. Treatment should likely be lifelong.
Colchicine should administered to Chinese shar-peis at earliest diagnosis, regardless of disease severity or presence of proteinuria: 0.01-0.03 mg/kg PO q 24h. If vomiting/diarrhea develop, decrease dose temporarily. Treatment should likely be lifelong.
Prednisone and other antiinflammatory medications are of no known benefit.
Renal diets are appropriate for affected animals
UPC ratio, urinalysis, serum albumin and creatinine, blood pressure, body weight, and body condition score should be monitored weekly to monthly initially. Once patients are stable, recheck every 3-6 months unless therapy or condition changes.
Prognosis & Outcome
Guarded to poor despite treatment. Median survival of dogs with renal amyloidosis is 5 days from time of diagnosis, with only 20% of dogs surviving ≥ 30 days.
Survival is negatively associated with serum creatinine concentration. Azotemic dogs often rapidly progress to uremic crisis.
Prognosis may be improved (with occasional reported resolution) if concurrent diseases are identified and successfully treated.
Early colchicine therapy (before onset of renal failure) for Chinese shar-pei dogs may greatly improve prognosis.
Pearls & Considerations
Differentiation of amyloidosis from other causes of PLN requires biopsy. Histologic diagnosis allows tailored therapy and prognosis.
Amyloidosis is primarily a renal cortical disease in dogs other than Chinese shar-peis.
Chinese shar-peis with consistent clinical signs (recurrent lameness and fever with or without proteinuria and azotemia) can be presumptively diagnosed with amyloidosis even without biopsy.
Substantial amyloid deposition may be present despite normal blood urea nitrogen, creatinine, and urine specific gravity values.
Affected animals should not be bred.