Chronic renal disease
Chronic renal disease (CRD) is a common disease of the kidney characterized by progressive renal insufficiency due to glomerular loss. In most patients, chronic intermittent acute renal injury is an underlying inciting cause.
Although less frequently observed compared with cats, CRD is relatively common in older dogs and progress over months and years to the point of renal failure.
Chronic renal disease can also occur due to pre-renal causes (e.g. hypertension, thromboembolism, DIC, sepsis) or post-renal causes (e.g. urinary obstruction due to urolithiasis, cystitis, prostate diseases, hydronephrosis or transitional cell carcinoma).
Chronic renal disease is equated with progressive nephron loss due to glomerulonephritis or interstitial nephritis, affecting the glomeruli, tubules, interstitial tissue or renal vasculature Irreversible damage to any portion of the nephron renders the entire nephron nonfunctional.
This insidious loss of nephrons has many underlying causes including:
- - Amyloidosis
- - Ectopic kidney
- - Ureteral disease - ectopic ureter, ureteral stenosis, circumcaval ureter associated with portosystemic shunt, ureteral atresia, ureteral duplication, ectopic ureter
- - Fanconi's syndrome
- - Polycystic kidney disease
- - Renal agenesis
- - Renal cysts
- - Renal cystadenoma or cystadenocarcinoma - associated with dermatofibrosis in German Shepherds
- - Renal dysplasia
- - Renal hypoplasia (Ask-Upmark kidney)
- - X-linked hereditary nephropathy - Cocker Spaniel
- - Familial juvenile glomerulonephropathy (autosomal-recessive) - French Mastiff, Bull Terrier
- - Glomerulonephritis
- - Uroliths, ureteroliths, nephroliths
- - Ureteral trauma during ovariohysterectomy
- - Renal transplantation
- - Renal cystadenocarcinoma
- - Angiomyxoma
- - Renal lymphoma
- - Oncocytoma
- - Urinary bladder transitional cell carcinoma
- - Ureteral transitional cell carcinoma
- Secondary renal disease
- - Psychogenic polydipsia
- - Diabetes insipidus
- - Diabetes mellitus
- - Hyperadrenocorticism
- - Hypoadrenocorticism
- - Nephrotic syndrome
- - Prostatic disease
Disruption of the intrarenal renin-angiotensin system is correlated with the severity of kidney disease.
Diagnosis can be established based on blood testing, which usually shows varying degrees of nonregenerative anemia (due to myelosuppression), uremia and elevated creatinine as well as radiographs which may reveal small, nodular kidneys and secondary pulmonary mineralization lesions.
Definitive diagnosis requires excretory urography and renal biopsy, with histological changes equating to primary diseases is often similar since the healing of irreversibly damaged nephrons occurs by replacement fibrosis (glomerulosclerosis).
Staging of renal function is usually based on the International Renal Interest Society (IRIS) categories'
|Stage||Creatinine level||Blood pressure||Clinical signs|
|Stage 1||≤ 140 μmol/L||≤ 160 mm Hg||Asymptomatic|
|Stage 2||140 - 200 μmol/L||~160 mm Hg||Asymptomatic|
|Stage 3||180 - 440 μmol/L||≥160 mm Hg||Uremic breath, dehydration, vomiting, dehydration|
|Stage 4||≥ 440 μmol/L||≥160 mm Hg||Uremic breath, dehydration, vomiting, dehydration, moribund|
Management of chronic renal disease in dogs is a multifactorial process. Although the disease is irreversible, the use of dietary and antihypertensive drugs such as benazepril and amlodipine can decrease the progressive nature of canine CRD by reducing intrarenal hypertension and glomerular hyperfiltration.
Dietary modification has been shown to increase survival and quality of life and involves more than protein restriction as diets modified for use with CRD are lower in phosphorous and sodium, potassium and B-vitamin replete, and alkalinizing, and they contain n3-fatty acids.
The addition of chitosan, calcium carbonate and potassium citrate have also been shown to improve azotemia in these patients and reduce the risk of hyperphosphatemia and thus minimize the risk of secondary hyperparathyroidism.
The long-term prognosis for dogs with chronic renal disease is generally guarded in patients with stages 3 - 4, based on the International Renal Interest Society staging.
- Jeong WI et al (2006) Canine renal failure syndrome in three dogs. J Vet Sci 7(3):299-301
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