Renal transplantation (renal allograft transplantation) is a radical, life-saving procedure used in primarily young and middle-aged dogs with existing terminal renal disease that is non-neoplastic, non-infectious and an alternative to continuous renal dialysis.
This procedure is less successfully employed than in feline transplantation.
First described as a canine procedure in 1902, the techniques have not significantly improved until Drs Clare Gregory and Gary Gourley pioneered new techniques in the late 1980s that made this technique clinically feasible.
This procedure is highly technically advanced, expensive and is usually reserved for younger canine candidates. Also complicating the use of this procedure is the underlying ethical considerations of donor dogs and the cost-benefit ratio in middle-aged and older dogs versus euthanasia.
In dogs with azotemia and creatinine levels > 30mg/dL that are non-responsive to hemodialysis may be considered candidates if a specialty referral centre is avaialable to perform the procedure.
Indications for renal transplantation include:
- Trauma - bilateral renal trauma
- Ethylene glycol nephrotoxicity
- Renal agenesis
- Renal dysplasia
- Renal amyloidosis
Suitable donors are then tissue-typed with the recipient using microsatellite markers within DLA class I and class II regions.
The procedure involves use of a donor kidney which is usually implanted in the caudal abdomen and stabilized using a transverse abdominis muscle flap, which is raised from the abdominal wall and sutured to the renal capsule.
Blood supply to the donor kidney is established through surgical anastomosis of the donor artery and vein to the recipients vasculature (caudal abdominal aorta and vena cava) in an end-to-side anastomosis.
Urine drainage is established by implantation of the ureter into the urinary bladder.
With few exceptions, the native kidneys are not removed in order to allow residual renal function should the allograft die or become dysfunctional due to ischemia/reperfusion injury.
Dogs appear to have a high incidence of intussusception following transplantation, which is obviated by enteroplication of the adjacent intestines and use of intraoperative opioid administration.
Post-operative complications include ureteral stenosis, thromboembolism, glomerulonephritis and allograft rejection. Allograft rejection can be monitored by surveillance biopsies or by abnormal laboratory and/or hemodynamic data.
Long-term chemotherapy combinations of cyclosporine, azathioprine, capecitabine and prednisolone are required to prevent organ rejection. The use of ascorbic acid have been shown to reduce the risk of post-operative renal ischemia and should be considered.
An experimental protocol has been devised using immunological tolerance involving myoablative (whole body) irradiation followed by concurrent donor bone marrow and renal allograft transplantation. Immunosuppressive drugs are then administered initially after transplantation and eventually tapered.
In donor dogs, long-term renal complications are uncommon as they are usually thoroughly tested prior to renal donation.
Current canine renal transplantation in clinical patients is associated with a high morbidity and mortality (approximately 50% within the first 2 months).
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