NAVLE Urinary

Canine Glomerular Disease Study Guide

📅 March 28, 2026 ⏱ 25 min read

Amyloidosis is a progressive and often fatal disease characterized by the extracellular deposition of insoluble fibrillar proteins (amyloid) in various organs.

Overview and Clinical Importance

Amyloidosis is a progressive and often fatal disease characterized by the extracellular deposition of insoluble fibrillar proteins (amyloid) in various organs. In dogs, the kidneys are the most commonly affected organ, with glomerular amyloidosis representing approximately 15% of all canine glomerular diseases. The condition results from misfolding of serum amyloid A (SAA) protein during chronic inflammatory states, leading to the accumulation of AA-type amyloid fibrils.

Understanding amyloidosis is critical for the NAVLE because it represents a distinct pathophysiological mechanism of protein-losing nephropathy that requires specific diagnostic approaches and has important breed predispositions. Unlike immune-complex glomerulonephritis, amyloidosis has no effective treatment to reverse protein deposition, making early recognition and supportive management essential.

High-YieldOn the NAVLE, when you see a Chinese Shar-Pei with recurrent fevers, swollen hocks, and proteinuria, think amyloidosis first. This breed has a unique hereditary form of the disease associated with Shar-Pei Autoinflammatory Disease (SPAID).

Category	Examples
Chronic Bacterial Infections	Pyometra, osteomyelitis, bronchopneumonia, bacterial endocarditis, prostatitis
Systemic Fungal Infections	Blastomycosis, coccidioidomycosis, histoplasmosis
Parasitic Diseases	Heartworm disease, leishmaniasis
Neoplasia	Various malignancies (especially plasma cell tumors)
Immune-Mediated Disease	Systemic lupus erythematosus, polyarthritis
Other Inflammatory Conditions	Chronic pancreatitis, inflammatory bowel disease, chronic skin disease

Etiology and Pathophysiology

Types of Amyloidosis in Dogs

AA Amyloidosis (Reactive/Secondary): The most common form in dogs, arising from chronic inflammatory conditions. During persistent inflammation, hepatocytes produce serum amyloid A (SAA) as an acute phase protein. When inflammation is prolonged, SAA undergoes abnormal proteolytic processing and misfolds into insoluble beta-pleated sheet fibrils that deposit in tissues.

Familial Amyloidosis: Hereditary forms occur in specific breeds due to genetic predisposition to amyloid formation. The most well-characterized is in Chinese Shar-Peis, associated with a copy number variant (CNV) mutation upstream of the HAS2 gene that causes overproduction of hyaluronic acid and dysregulated inflammation.

Conditions Associated with Reactive Amyloidosis

Mechanism of Amyloid Deposition

The pathogenesis of AA amyloidosis involves a cascade of events. Chronic inflammation triggers sustained hepatic production of SAA. This acute phase protein normally functions in lipid metabolism and immune modulation. However, with prolonged elevation, SAA undergoes incomplete proteolytic cleavage, producing fragments that misfold into characteristic beta-pleated sheet configurations. These misfolded proteins aggregate into insoluble fibrils that deposit extracellularly in various tissues.

In the kidney, amyloid preferentially deposits in the glomerular mesangium and capillary walls in most dog breeds. This disrupts the glomerular filtration barrier, leading to massive protein loss (primarily albumin) into the urine. As amyloid accumulates, it physically compresses and effaces glomerular capillaries, eventually causing nephron loss and chronic kidney disease.

NAVLE TipIn Shar-Peis, amyloid deposits predominantly in the renal MEDULLARY interstitium (100% of cases) rather than glomeruli, leading to earlier azotemia with milder proteinuria compared to other breeds. This is a distinguishing feature!

Breed	Type	Key Features
Chinese Shar-Pei	Familial	Most common breed affected; 23% prevalence; median age 4.8 years; medullary deposition predominates; associated with SPAID/Shar-Pei Fever
Beagle	Familial	Glomerular deposition pattern; older age at presentation
English Foxhound	Familial	Glomerular deposition; middle-aged presentation
Walker Hound	Familial	Similar presentation to English Foxhound
Collie	Possible familial	Increased risk reported; glomerular pattern
English Bulldog	Possible familial	At-risk breed; glomerular deposition

Breed Predispositions and Epidemiology

At-Risk Breeds

Age and Sex Distribution

Non-Shar-Pei dogs: Median age 9 years (range 2.4-11.1 years); typically middle-aged to older dogs

Chinese Shar-Peis: Significantly younger at presentation; median age 4.8 years (range 3.6-17 years); average age at death 4-6 years

Sex predisposition: Females appear slightly more affected than males

Exam Focus: Markedly proteinuric dogs less than 2 years old are UNLIKELY to have amyloidosis. Consider immune-complex glomerulonephritis or hereditary nephropathy instead in young dogs with severe proteinuria.

System/Finding	Clinical Manifestation
Non-specific signs	Lethargy, anorexia, weight loss (often progressive muscle wasting)
Renal signs	Polyuria/polydipsia (PU/PD), vomiting, uremic breath
Hypoalbuminemia signs	Peripheral edema (limbs, ventral abdomen), ascites, pleural effusion
Thromboembolism	Acute dyspnea (pulmonary TE), rear limb weakness/paralysis (aortic/iliac TE)
Hepatic involvement (Shar-Pei)	Jaundice, hepatomegaly, spontaneous liver rupture (rare), abdominal pain

Shar-Pei Autoinflammatory Disease (SPAID)

Shar-Pei Fever (also called Familial Shar-Pei Fever or SPAID) is a hereditary autoinflammatory syndrome analogous to Familial Mediterranean Fever (FMF) in humans. It is characterized by recurrent episodes of fever and inflammation that predispose affected dogs to systemic AA amyloidosis.

Clinical Features of Shar-Pei Fever

Recurrent high fevers: 103-107°F (39.4-41.7°C) lasting 12-36 hours
Swollen hock syndrome: Characteristic tibiotarsal joint swelling (feels like a flaccid water balloon)
Muzzle swelling: Facial edema during episodes
Abdominal pain, vomiting, diarrhea
Onset typically before 18 months of age

High-YieldThe number and frequency of fever episodes does NOT correlate with the severity of amyloidosis. A dog with a single fever episode is just as likely to develop amyloidosis as one with frequent episodes. ANY fever typical of Shar-Pei Fever should be considered a marker of high risk for amyloidosis.

Test	Expected Findings	Clinical Significance
UPC Ratio	Typically greater than 2.0 (often greater than 6-10)	Hallmark finding; among the highest UPC values of any glomerular disease
Serum Albumin	Hypoalbuminemia (often less than 2.0 g/dL)	More common in non-Shar-Pei breeds; risk factor for thromboembolism
Serum Creatinine	Often elevated at presentation (median 5.5 mg/dL)	Shar-Peis present with 3x higher creatinine than other breeds
Cholesterol	Hypercholesterolemia	Component of nephrotic syndrome
Antithrombin (AT)	Decreased (less than 70% indicates risk)	70% of dogs hypoantithrombinemic; correlates with albumin less than 2 g/dL
CBC	Non-regenerative anemia, leukocytosis, thrombocytosis	Anemia of chronic disease; inflammatory response
USG	Often isosthenuric (1.008-1.012)	Dogs with amyloidosis less likely to retain concentrating ability vs other glomerular diseases

Clinical Signs and Presentation

Common Clinical Findings

NAVLE TipUp to 40% of dogs with renal amyloidosis develop thromboembolism. The PULMONARY arteries are the most common site. Acute onset dyspnea with minimal radiographic changes should raise suspicion for pulmonary thromboembolism in any proteinuric dog.

Medication	Dosage	Purpose/Notes
Enalapril or Benazepril (ACE-I)	0.5-2.0 mg/kg PO q12-24h	Reduces proteinuria by decreasing intraglomerular pressure; standard of care
Telmisartan (ARB)	1-3 mg/kg PO q24h	Alternative to ACE-I; may achieve greater UPC reduction
Low-dose Aspirin	0.5-5 mg/kg PO q12-24h	Antithrombotic prophylaxis; indicated when albumin less than 2 g/dL
Clopidogrel	1-4 mg/kg PO q24h	Antiplatelet therapy; alternative or adjunct to aspirin
Omega-3 Fatty Acids	0.25-0.5 g/kg/day	Anti-inflammatory; may reduce intraglomerular pressure
Renal Diet	Prescription diet	Restricted protein, reduced sodium, omega-3 supplemented

Diagnostic Approach

Laboratory Findings

Nephrotic Syndrome

Nephrotic syndrome is characterized by the tetrad of: (1) Marked proteinuria, (2) Hypoalbuminemia, (3) Hypercholesterolemia, and (4) Edema/effusions. It occurs in approximately 10% of non-Shar-Pei dogs with amyloidosis but is uncommon in Shar-Peis (due to their predominantly medullary pattern of deposition).

Definitive Diagnosis: Renal Biopsy

Renal biopsy with Congo red staining is required for definitive diagnosis. The key histopathologic findings include:

Congo red staining: Amyloid appears orange to peach/red on light microscopy
Polarized light: Pathognomonic apple-green birefringence under polarized light
H and E stain: Amorphous, eosinophilic, acellular material in glomeruli
PAS stain: Pale pink, waxy appearance
JMS (Silver) stain: Amyloid does NOT take up silver (negative staining)

High-YieldCongo red staining with apple-green birefringence under polarized light is the GOLD STANDARD for amyloid identification. This distinguishes amyloidosis from glomerulosclerosis (which takes up silver with JMS stain) and immune-complex GN (which shows immunofluorescence).

"APPLE a day keeps misdiagnosis away"

A - Amyloid deposits | P - Pink/Peach with Congo red | P - Polarized light needed | L - Look for birefringence | E - Emerald/Apple-GREEN color confirms diagnosis

Diagnostic Imaging

Radiography: Kidney size is variable and non-specific. Kidneys may appear normal, small (chronic disease), or enlarged (early disease, amyloid accumulation).

Ultrasonography: May show increased cortical echogenicity and loss of corticomedullary distinction. Hepatomegaly may be present in Shar-Peis with liver involvement. These findings are not specific for amyloidosis.

Treatment and Management

There is NO specific treatment that can reverse amyloid deposition or dissolve existing amyloid fibrils. Management focuses on supportive care, reducing proteinuria, preventing complications, and addressing underlying inflammatory conditions when identified.

Standard Therapy Protocol

Shar-Pei Specific Treatment: Colchicine

Colchicine is the drug of choice for Shar-Peis with SPAID/Shar-Pei Fever. Based on success in treating Familial Mediterranean Fever in humans, colchicine may prevent further amyloid deposition (but does NOT reverse existing deposits).

Dosage: 0.025-0.03 mg/kg PO q24-48h (start q48h for 1 week, then increase to q24h)

Mechanism: Inhibits neutrophil migration and chemotaxis; blocks microtubule function preventing SAA secretion from hepatocytes; may inhibit amyloid-enhancing factor production

Side effects: GI upset (vomiting, diarrhea) - dose-related and reversible

Drug interactions: Avoid concurrent use with azole antifungals, macrolides, calcium channel blockers, and cyclosporine (increased colchicine toxicity)

NAVLE TipColchicine should be started EARLY in Shar-Peis - ideally after just 2 fever episodes. Continue lifelong regardless of whether fever episodes persist. The drug prevents NEW amyloid deposition but will NOT reverse existing kidney damage.

Prognosis and Monitoring

Survival Times

Prognosis for canine renal amyloidosis is guarded to poor. Most dogs are already in advanced kidney failure at the time of diagnosis.

Overall survival: Median 5 days (range 0-443 days) in one large study
Shar-Peis: Median survival only 2 days (present with more advanced disease)
Other breeds: 3-20 months reported; better prognosis if underlying cause identified and treated
Key prognostic factor: Serum creatinine at presentation negatively correlates with survival

Monitoring Protocol

Regular monitoring is essential to assess treatment response and detect complications early:

UPC ratio, urinalysis: Every 1-2 weeks initially, then monthly
Serum creatinine, BUN, albumin, potassium: Every 1-2 weeks initially
Blood pressure: At each recheck (hypertension common)
Antithrombin activity: If albumin less than 2.5 g/dL
Target: Greater than 50% reduction in UPC or UPC less than 0.5

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