Most studies show that adverse effects from cyclosporine are rare in dogs and cats at the dosages used for most dermatologic
The most common side effects in dogs receiving cyclosporine at a therapeutic dosage of 5 mg/kg once daily or less are gastrointestinal
problems (diarrhea, nausea, vomiting, anorexia).1,3,4,6 These side effects may occur within the first few weeks of administration and are generally transient. By starting at a
lower dosage and gradually increasing to a therapeutic dosage or by administering the medication with food, the side effects
may be minimized. Metoclopramide may also be administered 30 to 60 minutes before cyclosporine to help reduce gastrointestinal
side effects in patients exhibiting nausea or vomiting.7 Diarrhea or soft stool is the most common side effect noted in cats receiving cyclosporine.4
Field study data from the manufacturer and a recent retrospective study on the long-term use (six to 30 months) of cyclosporine
in dogs showed that cyclosporine administration may cause abnormalities on routine blood work (e.g. elevated alkaline phosphatase and alanine aminotransferase activities, increased cholesterol concentrations, hypoalbuminemia).8,9 However, these changes were not associated with clinical signs of disease. In addition, urinary tract infections may occur.
Whether these infections are related to the medication is unknown. Some evidence suggests that atopic dogs are generally more
prone to urinary tract infections.8,10 In people, cyclosporine is considered to be nephrotoxic, hepatotoxic, and associated with hypertension. These effects have
not been observed in dogs or cats receiving therapeutic doses for dermatologic conditions.4
Table 1. Less Common and Rare Adverse Effects of Cyclosporine in Dogs and Cats
Other adverse effects and those noted at higher dosages of cyclosporine in dogs and cats are summarized in Table 1.
The safety and efficacy of cyclosporine in dogs < 6 months old or < 4 lb are unknown. The drug is contraindicated for use
in dogs with a history of malignant neoplasia and should not be given to breeding dogs and pregnant or lactating bitches.9 In addition, because of the drug's mechanism of action, the manufacturer recommends the use of killed vaccines in patients
receiving cyclosporine. In a small study, 16 dogs received either 20 mg/kg daily of cyclosporine or placebo for 56 days and
were vaccinated on day 27 with a killed rabies vaccine and a multivalent vaccine that included a modified live virus.9 Antibody titers measured on days 0, 27 (before vaccination), 42, and 56 revealed no antibody titer rise in any dog to any
of the components of the multivalent vaccine but appropriate antibody titer response in all dogs to the killed rabies vaccine
by day 42. Whether this response occurs at therapeutic dosing recommendations (5 mg/kg daily) is unknown. Studies have not
been conducted on what length of drug withdrawal is necessary before vaccination.
Studies on the safety of cyclosporine have been limited to 12 months. The long-term effects of this potent immunosuppressive
drug are unknown.