AU develops new canine kidney transplant protocol

AUBURN, ALA. -Auburn University’s College of Veterinary Medicine has developed a canine kidney transplant protocol that promotes increased tolerance of transplanted organs between unrelated dogs. It also offers the possibility that the transplant recipients may not be required to take high-doses of immunosuppressive drugs for the rest of their lives.

Drs. Clint Lothrop, internal medicine professor at Auburn's Scott-Ritchey Research Center, and Michael Tillson, associate professor of surgery in the Department of Clinical Sciences, have been heading a team of researchers and clinicians that has shown that if simultaneous bone marrow and kidney transplants are performed, the dog receiving the new organ is much less likely to reject it.

"The big obstacle has always been that the recipient's immune system rejects the transplanted organ unless powerful immunosuppressive drugs are given for the rest of the dog's life says Tillson.

"Our first research dog is still doing well more than five years after receiving the transplanted kidney, and it is no longer on immunosuppressive medications. Based on our overall results, we have started offering the option of a kidney transplant to clients whose dogs have end-stage kidney disease. We have performed several of the procedures in the last two months," Tillson says.

Tammy Hanson holds Talitha, her 6-year-old dog that underwent simultaneous bone marrow and kidney transplants at Auburn University.

The research team developed the protocol from Lothrop's investigation into nonmyeloablative bone marrow transplantation for the treatment of a red blood cell disorder, pyruvate kinase deficiency. He showed that after the bone marrow transplantation corrected the enzyme deficiency, the dogs would also accept a skin graft from the donor dog.

"We reasoned that if a skin graft could be accepted after a bone marrow transplant, then maybe another organ, such as a kidney might be less likely to be rejected when combined with a bone marrow transplant," Lothrop says.

"After starting with genetically matched siblings, we have moved to unrelated dogs and found we can still decrease the requirement for chronic immunosuppression," he adds.

Lothrop says he believes the reason for this is that the protocol reduces tolerance. The immunosuppressive drug dosage is decreased around 60 days after the transplant surgery, he adds.

Kidney failure had been considered a death sentence for dogs because of organ rejection and limited availability of hemodialysis. While kidney transplants have been previously performed, the dogs had to be on anti-rejection medications for life. This made the dogs more susceptible to illness and represented a significant financial commitment since it could cost more than $30 per day, or almost $11,000 per year, for large dogs.

"Increasing tolerance is the key, without it, something as simple as kennel cough could cause significant illness or even lead to the death of a dog on immunosuppressive drugs," adds Lothrop. This process should be less expensive for dog owners in the long run, making a kidney transplant a more affordable option.

The first client animal to have the transplant was Talitha, a 6-year-old dog belonging to William and Tammy Hanson of Mountain Home, Ark. "She was initially given a less than 1 percent chance of survival," says Tammy Hanson. Hanson says Talitha suffered kidney failure due to antifreeze poisoning at an entrance gate leading to the Hanson's sanctuary for abused and chronically ill dogs. The transplant protocol requires recipients' owners provide loving homes for the dogs that served as kidney donors.

Just like humans who donate a kidney, the donor dogs can live healthy lives with a single kidney, Tillson says.

The kidney transplant program at Auburn is one of two centers, but Auburn is the only program using the protocol that offers the chance of reducing or eliminating the requirement for long-term immunosuppressive drug therapy.