If the kidneys are hit by a disease that causes many of its filters to be destroyed, the kidneys will fail to clean the blood. This is called renal or kidney failure.
Careful screening of the renal failure patient is essential to determine candidacy for renal transplantation.
Kidney donors have no greater incidence of kidney failure than the normal feline population.
Kidney transplantation usually will give the patient afflicted by renal failure a new lease on life. These patients typically feel awesome, like a normal cats should.
What is Renal failure?
A kidney is made of millions of filters that remove toxins from the blood. If the kidneys are hit by a disease that causes many of these filters to be destroyed, the kidneys will fail to clean the blood. This is called renal or kidney failure. Roughly 75% of the filters need to be destroyed before evidence of renal failure can be detected with routine blood testing. This shows us the phenomenal functional reserve of the kidneys. For this reason, it is safe for healthy humans and animals to donate a kidney for purposes of transplantation.
Common abnormalities that are associated with kidney failure include
azotemia - elevated blood urea nitrogen (BUN) and creatinine levels
acidosis - build up of acid products in the blood
hypokalemia - loss of potassium through the failing kidneys
hyperphosphatemia - retention of phosphates in the blood which may result in mineralization of internal organs and blood vessels
secondary hyperparathyroidism - the parathyroid glands are stimulated to produce excessive amounts of parathyroid hormone which may increase the calcium levels in the blood
nonregenerative anemia - the kidneys produce a hormone, erythropoietin, which stimulates the bone marrow to produce red blood cells. The failing kidney will not produce adequate amounts of erythropoietin, thus the patient gradually becomes anemic. In addition, vitamin B is lost through the failing kidney which also may contribute to the anemia.
systemic hypertension - high blood pressure results from an imbalance of the aldosterone/angiotensin enzyme system in the kidneys. This imbalance causes retention of sodium in the body and constriction of arteries.
heart failure - secondary to high blood pressure the muscle of the heart may become progressively thicker and thicker which results in poor function of the heart.
Many cats that have renal failure can be managed with conservative medical treatments; however, indications to pursue kidney transplantation include
Creatinine level greater than 4 mg/dl
Progressive weight loss - if transplantation is a feasible treatment option (based on finances and commitment to the pet) for the pet owner, do not wait until the patient is emaciated, as these patients will then become very poor candidates for anesthesia and surgery
Progressive anemia
Warning: patients that have mild azotemia and are clinically ill (vomiting, lethargy etc) likely have another disease unrelated to renal failure (inflammatory bowel disease, cancer etc)
Candidates for transplantation must be
Free of infections such as chronic recurrent upper respiratory viral infection, Feline Leukemia virus infection, Feline Immunodeficiency Virus infection, Hemobartonella, Toxoplasma, and urinary tract infection.
Free of inflammatory bowel disease
Free of cancer
Free of renal amyloidosis and glomerulonephritis
Free of significant heart disease and high blood pressure
Free of diabetes
Preferably free of thyroid disease (hyperthyroidism)
Type A blood
Kidney recipient patient preoperative evaluation
Complete physical examination
Eye examination
Doppler blood pressure
Blood typing
Major and minor blood cross match with kidney donor
Complete blood count
Urinalysis and urine culture (collected by cystocentesis - cat must not be receiving antibiotics)
Thyroid levels
Feline leukemia and Feline immunodeficiency virus testing
Note: all blood testing must be done by a reputable laboratory
Kidney donor preoperative evaluation
Donors must be preferably large (greater than 10 pounds lean weight) frame cat, males and 1 to 5 years old
If you do not have a donor, we will provide one, but this cat must then be adopted into a good home
Blood typing
Major and minor blood cross match with kidney donor
Complete blood count
Urinalysis and urine culture (collected by cystocentesis - cat must not be receiving antibiotics)
Feline leukemia and Feline immunodeficiency virus testing - donor must not be exposed to other cats that have unknown FeLV and FIV for at least 2 months prior to blood testing
Kidney recipient patient preparation prior to surgery
Establish a good plane of nutrition - a stomach (or esophagostomy) feeding tube may be placed weeks prior to surgery if needed, otherwise it will be placed at the time of transplantation
Correct dehydration - all transplant patients should receive intravenous fluid therapy starting at least one day prior to surgery; respiratory rate and serial body weights are used to monitor the patient for fluid overload
Normalize blood abnormalities as much as possible. This may include:
phosphate binders
potassium supplementation
anemia - supplement vitamin B, administer blood transfusion(s) one to two days prior to surgery; we usually do not use human recombinant erythropoietin, as 50% of patients of patients develop antibodies against this hormone and thus have worsening of the anemia
correct acidosis - bicarbonate
correct severe azotemia (high BUN and creatinine) with fluid therapy
Surgery
The donor cat is taken to surgery first and the kidney is dissected out of its bed, leaving the blood vessels and ureter intact; if the kidney has two renal arteries, it cannot be used and the transplantation must be aborted.
Mannitol is administered to the kidney donor to improve blood supply and to help prevent free radical damage while the kidney is not perfused
After the kidney is removed, cold preservation solution is flushed through the kidney to minimize free radical damage. The kidney is also stored in ice cold preservation solution until it is implanted into the recipient patient.
The kidney recipient patient is anesthetized and the renal artery and vein of the harvested kidney are surgically connected to the abdominal aorta and abdominal vena cava, respectively. The native kidneys are not removed.
Mannitol is administered to the kidney recipient patient
After surgery
the kidney donor is hospitalized for at least an additional 24 hours; at home, oral buprenorphine is used to control pain; kidney values are tested after surgery (while in hospital and 2 weeks later)
the kidney recipient patient is hospitalized for 3 to 7 days (if the patient is not local to the Southeastern Michigan we usually recommend a 7 day stay in our hospital). The patient will receive intravenous fluid therapy, nutritional support via the feeding tube, antibiotics, prednisolone and cyclosporine.
Below is a narrated slide show that will take you through a kidney transplantation procedure in a cat. If you do not have a strong stomach, do not start the slide show, as actual surgical photographs will be seen.
Care of the transplant patient at home
The transplant patient must remain indoors to minimize exposure to infectious diseases
Provide a stress free environment for the recipient patient
Antibiotics are administered for 2 weeks after surgery
Exercise is restricted for 3 weeks after surgery
Cyclosporine is administered twice daily for the entire life of the recipient patient; cyclosporine must be put in gelatin capsules, as it is very bitter
Prednisolone is administered for at least 1 month after surgery
Nutritional support is continued until the patient is eating well; most patients are eating well within 7 days after surgery
The feeding tube can be removed 3 weeks after surgery; if cyclosporine cannot be administered orally to the patient (noncompliant patient), the feeding tube will be left in place so that the medication can be administered via this route
Postoperative evaluation of the patient
Weekly evaluations are done by a veterinarian (preferably an internist) and the following testing is recommended:
CBC, chemistry profile, urinalysis (urine should be free catch or collected by ultrasound-guided cystocentesis to ensure that the implanted ureter is not penetrated with the needle)
Trough cyclosporine level (12 hours after the last dose was administered)
Weekly evaluations are done during the first 8 to 10 weeks, or until the cyclosporine level has stabilized
Ultrasonography of the urinary tract is done to ensure that the kidney is not showing signs of rejection and to ensure that the implanted ureter is not becoming obstructed with scar tissue; the frequency of this test is determined by the internist
After the first 3 months, an evaluation by an internist is performed every third month for the life of the patient
Prognosis
Kidney transplantation usually will give the patient afflicted by renal failure a new lease on life. These patients typically feel awesome, like a normal cat.
A successful kidney transplantation will allow patients to live for at least two years after surgery
Eventual rejection of a donated kidney is expected over time and will result recurrence of kidney failure
MVS Surgery Team
Click on a name below to read a biography of a team member:
