Sulfasalazine, by an unknown mechanism, can irreversibly reduce the amount of tears produced. So the use of these drugs in cats must also be closely monitored. Sulfasalazine or related compounds are generally administered at high doses and the dose is maintained 3-4 weeks after improvement is noted. The cat is started at a relatively high dose which is then reduced after the condition has improved. Some cats need to be maintained on low doses of prednisone for the rest of their lives.
Cats can tolerate corticosteroids quite well, with few side effects.
Corticosteroids are used in dogs when dietary management and sulfasalazine do not adequately improve the condition. These drugs are immunosuppressive agents and are generally used only if other treatments have failed or in combination with corticosteroids to allow a lower dose of the steroid to be used. Metronidazole can be used alone or in combination with sulfasalazine or corticosteroids. It is an antibiotic and also inhibits the immune system. Antispasmodic drugs have also been used in some cases.