Although newer therapies are being developed in humans that allow a certain targeting specificity, immunosuppressive therapy in dogs and cats is largely based on the use chemotherapeutic drugs. Liver and hematological toxicity are major limiting factors that often can be reduced with the use of appropriate drug combinations. Therapeutic protocols are largely empirical and further pharmacokinetic, efficacy and safety information are required to better use these drugs in cats. This review focuses on current safety and efficacy data of common and newer immunosuppressive agents in feline patients.

Objectives Of The Presentation

     1. To evaluate currently available agents and treatment protocols for immunosuppressive therapy in small animals, with particular emphasis on cats.

     1. The use of immunosuppressive drugs is often chronic and toxicity is the major limiting factor of therapy.
     2. With the exception of glucocorticoids and cyclosporine, there are no formulations approved for animals. Human formulations are often expensive, although some (e.g. leflunomide) are becoming available in generic forms.
     3. Combination therapy is often more effective and less toxic given the differences in mechanism of action among drugs and the fact that they are effective at different stages of the cell cycle.
     4. Immunosuppressive therapy in cats is mostly reliant on the use of glucocorticoids or cyclosporine-glucocorticoid combinations. The adrenal and immune-related complications associated with long-term use of glucocorticoids propitiate the search for steroid-sparing treatment protocols.
     5. Newer drugs are available that may bridge this gap but need to be further explored before safe and effective protocols can be consistently implemented in cats.
     6. Standard methods to assess immunosuppressive effects in vitro are being explored¹ that may help to optimize dosage regimens.