Page 699 - Cote clinical veterinary advisor dogs and cats 4th

322 Fanconi Syndrome

Technician Tips • Owners should clean the lip commissures AUTHOR: Stephanie A. Thomovsky, DVM, MS,
Assess corneal appearance for signs of ulceration, after meals. DACVIM, CCRP
EDITOR: Karen R. Muñana, DVM, MS, DACVIM
VetBooks.ir affected eye(s). SUGGESTED READING
and liberally apply topical lubricant to the
Dewey CW, et al: Disorders of the peripheral nervous
Client Education
Dewey CW, et al, editors: Practical guide to canine
• Instruct owners to assess for blepharospasm or system: mononeuropathies and polyneuropathies. In
corneal opacities at home. If observed, owners and feline neurology, ed 3, Ames, IA, 2016, John
should seek veterinary care immediately. Wiley & Sons, pp 453-454.

Fanconi Syndrome Client Education
Sheet

BASIC INFORMATION ASSOCIATED DISORDERS Etiology and Pathophysiology
• Polyuria and polydipsia • Inherited disease: pathophysiology not fully
Definition • Metabolic acidosis elucidated
Uncommon constellation of renal tubular • Electrolyte abnormalities • Acquired disease has been associated with
reabsorptive defects (including glucose, ketones, • Renal tubular acidosis heavy metal intoxication (lead, copper,
amino acids, phosphates, bicarbonate, calcium, • Acute kidney injury (AKI) or chronic kidney mercury, organomercurials), copper storage
and potassium) accompanied by renal tubular disease (CKD) hepatopathy, maleic acid, Lysol, drugs (e.g.,
acidosis and isosthenuria or hyposthenuria • Urinary tract infection (UTI) tetracycline, gentamicin, cephalosporins, cis-
• Skeletal disease is uncommon in dogs platin, salicylate, zonisamide, chlorambucil),
Synonym (rickets common in children with Fanconi amyloidosis, hyperglobulinemia, hyperpara-
Proximal renal tubular impairment/acidosis syndrome). thyroidism, vitamin D deficiency, hypokale-
• Urolithiasis mia, interstitial nephritis, glomerulonephritis
Epidemiology • Gastrointestinal disturbances (with any cause associated with antibodies to glomerular
SPECIES, AGE, SEX of Fanconi syndrome but especially common basement membrane, leptospirosis, and renal
• Inherited and acquired forms in dogs; with jerky treat intoxication) transplantation.
anecdotal reports in cats • Systemic manifestations of leptospirosis • Starting in 2007, a form of acquired
• No sex predisposition Clinical Presentation Fanconi syndrome has been recognized
• Inherited forms: glucosuria, aminoaciduria, in dogs and putatively associated with
phosphaturia, and renal sodium loss are first DISEASE FORMS/SUBTYPES ingestion of jerky treats. This form of AKI
documented when dogs are adults. • Tubular reabsorptive defects can vary among varies in presentation (glucosuria not always
individual dogs. present) and can wax and wane in severity.
GENETICS, BREED PREDISPOSITION • Acquired: signs associated with primary Gastrointestinal signs may overshadow mani-
• Inherited in basenji dogs, affecting 10%-30% disease (e.g., copper hepatopathy, leptospi- festations of renal disease (e.g., polyuria or
of basenjis in the United States; mode of rosis) may dominate clinical presentation. uremia).
inheritance unknown • Hereditary: dogs typically appear well until • Defects: primarily proximal tubular resorptive
• Other breeds (not necessarily inherited): middle age or older. function
border terriers, Norwegian elkhounds ○ Fanconi syndrome may be discovered ○ Renal glucosuria: defective transport
• West Highland white terriers and single incidentally during routine health screens. mechanism allows glucosuria even when
cases among Clumber spaniel, Cardigan blood glucose concentration is below
Welsh corgi with hepatic copper storage HISTORY, CHIEF COMPLAINT transport maximum (≥180-220 mg/dL
disease can have a reversible Fanconi syn- Complaints may be absent; some or all may [10-12.2 mmol/L]).
drome, with or without copper accumula- be present: ○ Aminoaciduria: generalized or selective
tion in renal proximal tubular cells (similar • Polyuria, polydipsia (specific carrier molecules for acidic, basic,
to Wilson disease in humans). Anecdotally, • Weight loss, muscular weakness and neutral amino acids). Some dogs have
renal involvement can be seen in any breed • Poor haircoat cystinuria with minor defects in resorption
with copper storage disease (p. 458). • Gastrointestinal signs (vomiting, diarrhea, of methionine, glycine, and dibasic amino
anorexia) acids.
RISK FACTORS ○ Phosphate reabsorption defect (proximal
• Copper storage hepatopathy PHYSICAL EXAM FINDINGS tubule); if severe, can cause hypophospha-
• Ingestion of contaminated jerky treats Exam may be normal; some or all may be temia
• Renal tubular injury (e.g., Leptospira spp present plus those listed above: ○ Hyperchloremic metabolic acidosis
infection, nephrotoxic insult [see Etiology • Dehydration possible
below]). • Uremic halitosis ○ Hypokalemia possible (kaliuresis is exac-
• Hypoparathyroidism (causality unconfirmed) • Oral ulceration with severe azotemia erbated with primary bicarbonaturia or
• Chlorambucil (cats) • Poor body/muscle condition supplementation alkali)
• Mucous membrane pallor if anemic • Dogs with Fanconi syndrome are resistant
CONTAGION AND ZOONOSIS • Muscle weakness if hypokalemic/hypophos- to antidiuretic hormone, creating a form
Leptospira spp can cause Fanconi syndrome. phatemic of nephrogenic diabetes insipidus (DI).

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