Page 1123 - Veterinary Immunology, 10th Edition

bone marrow allograft from the donor animal or by treatment with
VetBooks.ir rabbit anti-dog thymocyte serum. In practice, median survival

times of 8 months can be achieved, with some animals surviving for
longer than 5 years. However, this varies greatly between

transplant centers, and much depends upon appropriate selection
of recipients. Dogs have significant perioperative mortality.
Thromboembolic complications are common and many experience
recurrent acute infections, especially respiratory tract infections

with Bordetella bronchiseptica as well as urinary tract infections.
Newer immunosuppressive agents such as leflunomide show
promise of improving the prognosis for canine renal allografting
(Chapter 41).

Cats that receive renal allografts without immunosuppression die
in 8 to 34 days. Immunosuppressive therapy involves the use of
prednisolone and cyclosporine possibly supplemented with
ketoconazole. (The ketoconazole suppresses cyclosporine

metabolism in the liver and prolongs its half-life.) The therapy can
begin 2 days before surgery so that cyclosporine levels are optimal
when the graft is introduced. Six-month survival of treated cats
ranges from 59% to 70%, whereas 3-year survival ranges from 40%

to 50%. The longest survival time reported for cats receiving renal
allografts is 8 years. These figures are gradually improving as
experience grows. Long-term complications include acute or
chronic rejection and opportunistic infections. (Infection is the

second most important cause of death or euthanasia after acute
rejection.) Acute rejection can occur at any time, especially if
cyclosporine levels fall below the therapeutic range. Chronic
allograft rejection (graft vascular disease) due to progressive arterial

arteriosclerosis may cause ischemic graft destruction. It is not
responsive to immunosuppressive therapy.
In some circumstances, such as when a dog has maintained
functioning renal allografts for several years, immunosuppressive

therapy may be reduced gradually and eventually discontinued as
graft acceptance becomes complete. It is probable that the
immunosuppressive drugs gradually eliminate antigen-sensitive
cells. Once their numbers are sufficiently low, the large mass of
grafted tissue may be sufficient to establish and maintain tolerance.

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