Salbutamol toxicosis in dogs

Salbutamol (also known as albuterol) is a selective beta₂adrenoceptor agonist used as a bronchodilator and, in human medicine, in the management of premature labour. Salbutamol is available in various forms; powders and aerosols are administered by inhalation, and solutions (1 mg/ml) are used in respirators. Nebulisers including metered-dose inhalers (which are usually 100 or 200 mcg/dose and shown in Figure 1) are commonly available. Tablets (2 mg or 4 mg) and syrups (2 mg/5 ml) for oral administration are declining in use and nebulised beta₂-adrenoceptor agonists are more commonly used.

Salbutamol products, particularly inhalers (Figure 2), may be left unattended around the home and are readily accessible to pets and easily pierced by them. Salbutamol exposure in dogs can cause pronounced and rapid onset clinical signs, often requiring veterinary intervention and monitoring.

At therapeutic concentrations, salbutamol is selective for beta₂adrenergic receptors, primarily causing relaxation of bronchial, vascular and uterine smooth muscle which is thought to be mediated via the adenylyl cyclase-cyclic adenosine monophosphate (cAMP) system (Sutherland and Rall, 1960). At higher doses, however, beta₂ selectivity of salbutamol is reduced, with activation of beta₁-adrenergic receptors resulting in cardiovascular stimulation (Stiles and Plumb, 1993; Libretto, 1994). Increases in heart rate include a reflex response to systemic hypotension resulting from salbutamol-induced peripheral and coronary vasodilation (Nayler and McInnes, 1972; Petruska et al, 1997).