Feline Kidney Transplants

The Kidney Recipient

Qualification

Patients who have been diagnosed in the earlier stages of renal failure are the best candidates. The surgery is a considerable risk and the patient's chances are enhanced by being in generally good health, aside from the kidney failure itself. Although physical condition is more important than age, a transplant may not be the right choice for a patient whose life expectancy might be just as long with aggressive supportive care. It should also be recognized that an older cat is more likely to develop other life-threatening, age-related problems which could shorten his post-transplant survival time. A transplant does not make the patient invincible from other diseases or problems and, in fact, could make those conditions more serious because of the required immune suppression. A transplant should be viewed not as a cure, but as one of several options for the treatment of feline CRF.

To qualify for a transplant, a thorough screening must be done to rule out medical conditions or diseases that would threaten the life of the patient during or after surgery. Cancer, heart disease, diabetes, inflammatory bowel disease, infections, FeLV, FIV, and kidney or bladder stones are some of the major conditions that would be disqualifying. A series of tests will have to be done prior to the surgery and any negative findings will disqualify a potential candidate. Some or all of the following tests will be required and additional ones may be necessary depending on the patient's history and the surgeon's opinion:

• Kidney biopsy if it is suspected that renal failure is the result of a disease that might also spread to the transplanted organ or other areas of the body
• Intestinal biopsies if history is suggestive of Inflammatory Bowel Disease (IBD)

Once the transplant is done, the patient will be on antirejection drugs which compromise the immune system. It is, therefore, critical to screen for any problems that may take advantage of the patient's somewhat reduced resistance to diseases, infections, etc.

Preoperative Treatment

The primary objective of preoperative preparation and care is to get the CRF patient in the best condition possible to undergo the surgery. A key issue here is determining when the time is right. Since the very early signs of renal failure are subtle and cats hide their illnesses so well, most of us do not recognize the problem until the more dramatic symptoms appear. At that point, the patient has probably lost a considerable amount of weight, is dehydrated and anemic, and has seriously elevated BUN and creatinine levels. To stabilize the patient for surgery, these conditions must and can be significantly improved with treatment (fluids, medications, etc.). Supportive care can be so successful that the patient feels good and appears healthy again, making the decision to proceed with the surgery more difficult. The decision of how long to wait should be made in conjunction with your local veterinarian and the transplant surgeon.

The patient will need to be in the hospital several days before the surgery but the amount of time depends somewhat on the recipient's condition. The patient will be started on antirejection drugs prior to the transplant and IV fluids 24 to 48 hours before the surgery. Since some blood will be lost during the surgery, the patient's hematocrit must be well within the normal range. (It is recommended that the patient's PCV be greater than 30%). Transfusions are possible and one school of thought has suggested that this might even be helpful in minimizing rejection. Although Epogen can be used to raise the PCV, there is a risk of antibody formation which can be avoided with transfusions.

Unless you live in close proximity to the transplant facility, it is likely that the surgeon will see the patient for the first time just prior to the operation. This examination represents a final screening and the potential for a last minute disqualification.

Postoperative Treatment

After the surgery, the recipient will remain under intensive care for one to three weeks. While in the hospital, the recipient is typically kept on IV fluids, antibiotics and oral antirejection drugs (prednisolone and cyclosporine). An ultrasound may be done to verify blood flow through the new kidney and blood samples are taken frequently to monitor cyclosporine level and kidney function.

Total rejection of the new kidney is not common but rejection episodes are, and they are more likely to occur early than later on as the body "gets used to" the presence of the foreign kidney. A rejection episode is essentially the body's immune system attacking what it perceives as an invasion by the new kidney. When this occurs, the patient feels sick and may vomit, stop eating, run a fever and/or become depressed. An immediate response is essential so that the antirejection medication can be increased to suppress this immune system activity.

Every case is different, but it is typical for the new kidney to show some signs of function three to ten days after the surgery. Generally, the three major kidney functions return at different rates, with the production of erythropoietin often being the last to return. The surgeon will determine when the patient is stabilized enough to go home. There is no set formula nor test numbers that must be reached before the patient is discharged. BUN and creatinine levels may or may not have fallen into the normal ranges by the time the patient leaves the hospital.

Homecoming

When discharged, the patient will be stable and active but still in a recuperation period. For the first month, the transplant cat must be restrained from any excessive movements, such as jumping. During this time it is also advisable to kennel the recipient when he is not being closely monitored. These precautions are to allow sufficient time for the new kidney to become firmly set in the transplant cat's body and for the surrounding tissue to solidly heal around the new organ.

The surgeon will provide detailed instructions for administering medications, for recognizing rejection episodes and for scheduling follow-up visits and tests. You may also be required to have a scale to monitor the patient's weight and, initially, it might be necessary to give the patient sub-Q fluids and/or Epogen shots to support the new kidney. You may be given a vial of IV cyclosporine to keep with the patient at all times so that any vet can treat a rejection episode.

Follow-up Visits with the Surgeon

If the surgeon is in a distant city, he will eventually turn over the follow-up visits to your local veterinarian but maintain telephone contact with you for some elements of continuing care. Be sure you have made the necessary arrangements for you or your local vet to be able to contact the surgeon in case of an emergency.

Follow-up Veterinarian Visits

Be sure that any vets that you will be seeing have a copy of the instructions you were given, particularly those explaining the protocol for dealing with rejection. At first the follow-up visits will be frequent but the length of time between visits will gradually become longer as the patient further stabilizes. Visits are generally every two weeks for the first several months, then monthly for the next four to five months. The frequency after the first six months will depend somewhat on how the patient is doing and how consistent the cyclosporine level checks become. The equipment needed to assay cyclosporine is very specialized and generally found only at hospitals that perform human transplants or at veterinary schools that perform feline transplants.

The primary purpose of these maintenance visits is to check the patient's condition and draw blood to monitor BUN, creatinine, PCV, Total Protein and cyclosporine levels. Urine samples are also required periodically to check the specific gravity as an indication of how well the new kidney is functioning. It is best to free-catch a urine sample since the new kidney's proximity to the bladder makes cystocentesis more difficult (ultrasound guidance is recommended).

Although hundreds of transplants have been performed, it is highly unlikely that your local general practice veterinarian will have any experience with post-transplant care and the possible complications. It is advisable to locate and contact a board-certified internist or kidney specialist in your area in case more than routine follow-up care is ever required.

Home Care

The patient generally is given a course of antibiotics for the first few weeks. Cyclosporine and prednisolone will be required for life. In some cats, prednisolone may inhibit fur growth, slowing the replacement of fur that was shaved for the surgery. Cyclosporine is used to suppress the immune system (T cells) and is the very potent drug that has made human and animal transplants possible. It is an oily liquid that must be measured and put into a gel cap. This is a simple procedure that you can do yourself or you can arrange to have the capsules made by a pharmacist. (Since the dosage will frequently change, it is not helpful to make up too many capsules ahead of time.) The patient must take cyclosporine for the rest of his life and generally these pills must be given every 12 hours. Some transplant surgeons combine cyclosporine with ketoconazole and the medication protocol will differ slightly. The patient may also need Epogen shots for some period of time and should be weighed every few days. Weight maintenance is essential and if the patient is not eating enough, the stomach tube can be utilized.

Other Treatments

Unless the patient develops a problem unrelated to the transplant, no other treatments or tests are required and there are no special dietary requirements. At the point when it is felt that the patient is eating and drinking sufficiently, the stomach tube can be removed (without anesthesia). The recipient is at a somewhat greater risk of disease or infection but there is no reason for isolation, assuming that other cats in the household are healthy. The recipient can continue to get yearly vaccinations since the cyclosporine should not interfere with the body's ability to process immunization shots. In general, your cat will return to a normal, active life with virtually no restrictions.