Penn Veterinary Medicine | University of Pennsylvania

Feline Renal Transplant Program

 

The Feline Renal Transplantation Program at Penn Vet was successfully initiated in February 1998 by Dr. Lillian R Aronson, Associate Professor of Small Animal Surgery. After completing veterinary school and an internship at the University of Pennsylvania, Dr. Aronson completed a small animal surgical residency at the University of California, Davis. From 1994 to 1996 she was the coordinator of the renal transplant program for animals at the University of California at Davis. Following her residency, she joined the faculty at the University of Pennsylvania and started Penn’s renal transplant program.

Renal transplantation is a treatment option for renal failure in cats. It is important to recognize that renal transplantation is a treatment for renal failure, and not a cure. The goal of renal transplantation is to provide a good quality of life for a cat that would otherwise be unable to survive; however, “normal” life expectancy is not yet achievable by today’s technology.

Recipient selection

Typically, renal transplantation is performed on cats that are in either acute or chronic renal failure, and are losing weight and/or becoming anemic in the face of regular medical management. Transplantation is generally not recommended in animals that are able to maintain body weight and hematocrit despite their renal insufficiency. Also, transplantation is not typically performed as an emergency or “last ditch” effort. Unfortunately, often when a transplant has been performed on an inappropriate candidate, a poor outcome has resulted.

Although, there is not an absolute age restriction for transplantation, the oldest cat that has been transplanted was 18 years of age. The degree of azotemia, anemia and urine specific gravity, do not determine, in themselves, a suitable patient for transplantation. Candidates should be free of other disease conditions including significant heart disease, recurrent urinary tract infections, and cancer. Fractious cats are also not good candidates for the procedure. Many cats in renal failure have a heart murmur. This murmur may be a physiologic murmur secondary to the anemia. This does not, in itself, disqualify a candidate for the procedure. The concern would be if the cat had significant underlying heart disease, for example, hypertrophic cardiomyopathy. Cats with recurrent urinary tract infections are also not good candidates, since infection can potentiate rejection. If the cat currently has a negative urine culture, a cyclosporine challenge is recommended prior to transplantation to determine if the cat will “break” with an infection.

 

 

Preoperative testing for the recipient

If possible, the following tests can be performed by your referring veterinarian prior to contacting the University of Pennsylvania to set up an appointment. The results of all tests can be faxed to us for immediate assessment.

1. Complete blood count
2. Serum chemistry profile
3. Urinalysis
4. Urine culture
5. Urine protein:Cr ratio
6. Echocardiogram
7. Abdominal ultrasound
8. Thoracic and abdominal radiographs
9. FeLV/FIV/FIP
10. Thyroid (T4) level
11. Blood typing
12. Toxoplasmosis titer
13. Intestinal biopsies IF history is suggestive of inflammatory bowel disease

Test results and exam findings that may preclude renal transplantation include:

1. Significant cardiac disease
2. FeLV positive status
3. Recurrent urinary tract infections
4. Pyelonephritis
5. Inflammatory bowel disease
6. Uncontrolled hyperthyroidism
7. Neoplasia
8. Fractious nature that prevents intensive nursing care and lifetime oral medication treatment

 

Donor selection

The renal donors are healthy, young adult cats free of any underlying disease. Donor selection for a specific recipient is based on blood cross-match compatibility which involves a simple blood test. The owner of the recipient is required to adopt the donor cat since no cat is ever euthanized for the program. If the owner would like to use one of the cats in their household, that is not a problem as long as the cat is found to be free of infectious or organic disease and is compatible to the recipient.

Preoperative care

Upon admission to the transplant facility, the recipient is typically placed on intravenous fluid therapy of a balanced electrolyte solution at 1.5 to two times the daily maintenance requirements. This rate may vary in cases of severe dehydration or in cats with underlying cardiac disease. Additionally, if the cat is hypertensive, the drug amlodipine (Norvasc) may be indicated before surgery. Anemia is typically corrected at the time of surgery with cross-match compatible whole blood or packed red cell transfusions. If the patient is unstable with respect to the anemia, blood products can be given at the time of admission to the transplant facility. If a delay in the transplant procedure is expected, erythropoietin (Epogen, 100IU/kg three times per week for the first one to two weeks and then tapered accordingly) can be administered. Phosphate binders and gastrointestinal protectants are given if deemed necessary and if the cat is anorectic, a feeding tube may be placed to administer nutritional support prior to surgery.

A combination of Cyclosporine and prednisolone are currently used for immunosuppression at our facility. Cyclosporine administration is begun 72 to 96 hours prior to transplantation at a dose of 1-4mg/kg PO q12h depending on the cat’s appetite. It has been the author’s experience that cats that are anorexic or eating a minimal amount have a much lower drug requirement to obtain appropriate drug levels prior to surgery. A 12-hour whole-blood trough concentration is obtained the day before surgery so that the dose can be adjusted prior to surgery if necessary. Using the technique of high-pressure liquid chromatography (HPLC), the goal is to obtain a trough concentration of 300 to 500ng/ml for surgery. This level is maintained for approximately one to three months following surgery and is then tapered to approximately 250ng/ml for maintenance therapy. There seems to be very little correlation between the oral dose of Cyclosporine and the blood level that will be achieved in a particular patient. Two 4kg cats can be given the same oral dosage and their blood levels may be entirely different. Because of interpatient and intrapatient variability in the absorption of oral Cyclosporine and its metabolism, blood levels should be monitored regularly to maintain therapeutic concentrations and minimize toxic side effects. Prednisolone is administered beginning the morning of surgery. At our facility, prednisolone is started at a dose range of 0.5-1mg/kg q12h orally for the first three months and then tapered to q24h.

If renal function starts to deteriorate in the first weeks to months following transplantation, Azathioprine (0.3mg/kg/72 hours) may be added to the immunosuppressive protocol. Cats receiving Azathioprine should have their white blood cell count monitored regularly.

Surgery

Kidney transplantation in the cat is a technically challenging procedure that requires a coordinated team of surgeons, anesthesiologists, and nursing staff. At Penn Vet, the donor and the recipient surgeries are performed simultaneously.

Renal transplantation is performed by veterinarians familiar with vascular surgery. At our facility, the donor and recipient surgeries are performed simultaneously. The blood vessels of the donor kidney are carefully sutured to the abdominal aorta and vena cava of the recipient using an operating microscope. Once the vascular connections are complete, the ureter of the donor kidney is attached to the bladder of the recipient. Prior to closure, the allograft is attached to the abdominal wall to prevent torsion and a biopsy of one of the native kidneys is taken. Additionally, an esophagostomy tube can be placed if necessary to aid in nutritional support. The native kidneys are usually left in situ to act as a reserve if graft function is delayed. The native kidneys can be removed at a later time if warranted.

From start to finish, the procedure takes approximately four to six hours. 

Long-term management

The recipient cat can be discharged from the hospital when graft function is determined to be satisfactory and trough whole blood levels of cyclosporine are stable. Most recipients are in the hospital for 10 to14 days as they recover from surgery and are stabilized on immunosuppressive drugs. Initially, your cat should be examined once a week until the cyclosporine blood levels have stabilized. During each exam, bloodwork is performed including packed cell volume, total protein, plasma creatinine, blood urea nitrogen, a cyclosporine level and a urinalysis if a free-catch urine sample is available. The intervals between veterinary visits are increased once the cat stabilizes. It is recommended that a complete blood count and serum chemistry panel be performed every three to four months and an echocardiography performed every six to 12 months in cats with any underlying cardiac disease.

Cats that have undergone renal transplantation should not be boarded in crowded facilities, and any contact with animals from outside the owners’ home should be minimal. The major complications that arise after transplantation are usually related to either rejection of the transplanted kidney or complications associated with long-term immunosupression including infection, diabetes and cancer. Rejection requires rapid and aggressive emergency treatment to prevent loss of the new kidney.

Cost

The cost for renal transplantation in cats (barring major complications) is approximately $12,500, which includes a complete work-up, the cost of surgery, general anesthesia and post-operative care of both recipient and donor cats. The cost of immunosuppressive drugs (cyclosporine and prednisolone) typically ranges from $30 to $60 per month; however some cats require more medication. Currently, routine cyclosporine assays cost $55 per assay (initially required weekly for the first four to six weeks, and thereafter less frequently). The current protocol for administering the immunosuppressive therapy requires the medication to be given orally, twice a day, for the rest of their lives. A once-a-day protocol can also be performed when necessary.

Success rate of feline kidney transplantation at Penn Vet

Presently, 90 to 95 percent of cats receiving kidney transplants recover sufficiently and will go home following renal transplantation and approximately 60 to 70 percent of transplanted cats are alive and continuing to do well at one year after transplant. Our longest survivor to date (5/5/2006) lived for eight years following his transplant.

A waiting list of two to four weeks is typical for renal transplantation. Surgeons at Penn Vet reserve the right to refuse any cat for renal transplantation at any point in the evaluation process. Renal transplantation can place considerable financial, emotional and physical burden on the owners of the transplant recipient, and requires a commitment and devotion to care for both recipient and donor that cannot be underestimated.