Renal transplantation

From Cat

Typically, renal transplantation is performed on cats that are in chronic renal failure and are losing weight and/or becoming anaemic in spite of medical management (low protein diet, subcutaneous fluids, epogen, etc.). Transplantation is generally not recommended for animals that are able to maintain body weight and hematocrit despite their renal insufficiency. Transplantation is never performed on an emergency basis or as a last ditch effort. Cats that are in acute or oliguric/anuric renal failure usually require a period of intravenous fluid diuresis or dialysis to stabilize them prior to transplantation. Due to all the inherent risks with transplantation it is not considered a prophylactic procedure and those cats that are doing well with medical management are not considered candidates for transplantation. It is important that all potential candidates be stable and in good body condition. There is no age restriction for transplantation as long as the cat is in good condition and all other criteria discussed below are met[1].

Feline renal allotransplantation has become an accepted means of treating cats with chronic renal failure that is unresponsive to medical therapy. When successful, a renal allograft may offer the recipient an improved quality of life and extended lifespan. Mean and median survival times of 12 and 15 mo in cats following renal transplantation are reported, with long-term survival times as long as 8 y. Presently, the success rate is approximately 75-80%. This means that approximately 20-25% of cats may die in the first year following transplantation. Typically, death is due to one of 4 major problems following transplantation:

  • Rejection
  • Infections
  • Cancer (due to the effects of chronic cyclosporin administration
  • Diabetes

Cats surviving the first year may go on to live for many years. Our current longest survivor is still doing well 15 years after transplantation.

Costs

The cost, barring major complications, for renal transplantation ranges from $A12-15,000. If a cat requires dialysis prior to transplantation this could potentially add $A3,000-$4,000 dollars to the estimate. Routine cyclosporine assays, initially required weekly and then decreasing to once every 3 months, cost $60 per assay.

Protocol

Renal transplant patients are typically in the hospital for 10-14 days from the time of admission. Owners of a transplant recipient are required to adopt the donor cat and provide a life-long home. The donor cat is chosen from colony cats on a blood cross-match. The donor can typically go home 2 days after surgery. Owners of transplant recipients will be asked to sign an authorization/consent form prior to transplantation. It is imperative, if you are considering transplantation for your cat, that you have access to 24-hour emergency veterinary care and a referring veterinarian who is willing and able to help with the process following transplantation. This will mean weekly visits initially, blood tests, submitting cyclosporine assay blood samples and being able to hospitalize and treat your cat in the event of an emergency. You must be able to administer pills to your cat as they will require twice-daily medications the rest of their lives in pill form only. Immunosuppression is begun 48 hours prior to surgery.

Risks/Complications

A major complication that can arise after transplantation is acute rejection, which requires rapid and aggressive emergency treatment to prevent loss of the new kidney. Many times rejection episodes occur in the first few months following transplantation and can be linked to difficulties with owner compliance in giving the medications appropriately and/or failing to have cyclosporine assays performed on a regular basis. Another potential complication that can occur is infection. Transplant cats are immunosuppressed and therefore are always at slightly higher risk for any kind of infection. Cats that have undergone renal transplantation must not be boarded in crowded boarding facilities and any contact with animals from outside the owner's home should be minimal. Cats that have undergone transplantation are at a slightly higher risk (9.5%) for developing cancer than the average population. About 10% of cats may develop diabetes post-transplantation that requires insulin administration. It typically occurs months to years after transplantation.

Pre-Transplant Diagnostics

There are certain criteria that potential transplant recipients must fulfil before being considered as acceptable candidates. In general, although each case will be given individual consideration, all candidates must be free of any systemic disease other than renal failure. Cats that have clinical histories that are suggestive of urinary tract infections or a positive urine culture must first be treated with appropriate antibiotics and then undergo a cyclosporine challenge prior to consideration for transplantation. Cats that have any history of inflammatory bowel disease require intestinal biopsies (endoscopic or surgical) prior to consideration for transplantation. Also, it is very important that cats are not fractious. With the amount of intensive care and handling required for renal transplantation, a cat that is fractious and unable to be handled easily will not be considered for transplantation.

The following tests must be performed with your referring veterinarian:

Optional tests include:

  • kidney biopsy
  • intestinal biopsies

Some test results or physical exam findings that would preclude transplantation include:

References

  1. de Cock, HE, et al (2004) Histopathologic Findings and Classification of Feline Renal Transplants. Vet Pathol '41:244-256