Parenteral medications. Steroids are the most effective treatment and are able to control clinical signs in most cases. Bronchodilators (terbutaline, sustained-release theophylline [TheoDur, Slo Bid]) may also be needed. Trade-named sustained-release theophylline products have recently been taken off the market. Generic sustained-release theophylline products can be substituted, but it is uncertain whether they will have the same clinical efficacy. Ciproheptadine has been reported to work at a suggested dose of 1-2 mg P O q 12 h, but no controlled clinical studies are available to date. Leukotriene receptor blockers have anecdotally been successful in cats (zafirlukast [Accolate]) at doses of 0.25-2.0 mg/kg P O q 12-24 h.

Inhaled medications. A good approach for feline asthma. Metered dose inhalers, used routinely in people, are now becoming popular in cats. They are used in combination with a face mask and a "spacer" (an enclosed cylinder), into which medication is dispersed before inhalation. The best mask for cats is a large feline anesthesia mask (use the lowest volume mask that the patient will tolerate), which needs to fit snugly around the cat's face. One end of the spacer attaches to the facemask. Medication is actuated (pumped) into the spacer and the mask is placed over the cat's face for about 10-15 sec (around 10 breaths). Fluticasone (Flovent) is an inhaled steroid having equivalent therapeutic effect without the side effects of systemic steroids. For moderate asthma, oral prednisone is given at 1 mg/kg twice daily for 5 days, then once daily for 5 days along with 2 puffs of 220 µg fluticasone twice daily. The drug is expensive (~$120/month).

Inhaled albuterol (Ventolin, Proventil) is used in cats with sporadic signs on an "as needed" basis, or as a rescue drug in severe attacks. For severe signs, a parenteral steroid such as dexamethasone is given with albuterol, using the same dosing scheme as fluticasone (2 puffs, 10-15 sec, around 10 breaths) every 30 min until clinical signs abate or until a total of 8 doses are given. Once stable, treatment resumes as for moderate cases along with albuterol four times daily, or as needed. Most cats tolerate inhaled medications very well.

Avoidance of inhaled irritants. Avoiding dusty cat litter, exposure to dusty environments, and aerosol sprays is thought to be an important component of therapy. For allergic cats, replacing dry cereal-based food with canned food may be an effective way to reduce exposure to storage mite or cockroach antigens.

Immunotherapy. While theoretically useful, one has to be able to identify the offending allergens. In humans, these are most often house dust mite and cockroach antigens. In one study, immuno- therapy subsequent to intradermal skin testing resulted in improvement in 6 of 7 cats with asthma. There is no evidence incriminating food allergy with asthma.

References: Smallwood, DVM Newsmagazine 32 (12): 1-25, 2001; Padrid, Vet Clin N Am Sm An Pract 30: 1279-1293, 2000; Padrid et al, AJVR 56: 109-115, 1995.