Hemodialysis has become available at several referral centers and teaching institutions across the U.S.

Acute renal failure   Hemodialysis is used to manage anuria or oliguria progressing to anuria that is unresponsive to medical management; when there is life-threatening volume overload or acid/base or electrolyte disturbances (hyperkalemia). Medical management for oliguria/anuria should be attempted initially as follows:

Fluid Therapy - to restore circulating volume.

Mannitol - 0.5 g/kg bolus followed by infusion rate at 1-2 mg/kg/min. It works in 12-24 hours if it is going to work.

Common causes of acute renal failure

Dogs

• toxicosis with ethylene glycol, aminoglycosides, sulfonamides
• ischemia
• glomerulonephropathy
• pyelonephritis

Cats

• toxicosis with ethylene glycol
• uroliths causing bilateral ureteral obstruction. These cats often have pre-existing renal disease.

Chronic renal failure  Hemodialysis may be indicated in preparation for renal allografting or less commonly, as part of long term management. Advised only if the pet has suitable temperament and is of appropriate size.

Patient size  Can dialyze patients as small as 2 1/2 kg, as the smallest extra corporeal circuit has a volume of 63 mL. The circuit is usually primed with 3% dextran, but for very small patients priming with fresh homologous or autologous whole blood is usually done. Patients smaller than 5 kg need to have PCV > 20% before starting dialysis.

Cost  Cost for dialysis is ~ $3,500-$4,500 for the first 3 days, plus hospitalization which can vary from $500-$1200. Thereafter, patients usually need 3 treatments/week for maintenance at a cost of ~ $1,500 per week.

Diagnosis  Can often detect ethylene glycol metabolites in serum for as long as 6-7 days subsequent to exposure, as they cannot be excreted due to oligoanuria. Use of mannitol will cause false positives on the colorimetric test.

Therapy  Timing is critically important to c hances of recovery: Within 8-10 h of ingestion, a single dialysis treatment will typically eliminate the toxin and pets do well. 8 h - 3 d post exposure, requires several dialysis treatments but these patients often regain renal function in ~ 3-4 weeks. These patients may still be at risk for chronic renal failure as the ethylene glycol crystals remain in their renal interstitium for life. If more than 3 d post exposure, the odds of renal function recovery is virtually zero, and so owner must consider chronic dialysis or renal transplantation. [Contributed by Dr. Julie Fischer]