Glucocorticoid Pharmacology and Clinical Applications in Veterinary Medicine

Species-Specific Dosing and Management

Feline Considerations

Cats present unique challenges due to their metabolism and physiological sensitivities. When managing chronic conditions like feline lower airway disease, clinicians must balance efficacy with the risk of side effects.

For chronic management of feline asthma, prednisolone is often used at doses of $0.5-1 \text{ mg/kg}$ PO every 12 hours for the first 7–14 days, followed by a gradual taper over 2–3 months.

Equine Considerations

In horses, the choice of administration route can significantly impact the side-effect profile. For example, systemic administration carries a higher risk of inducing laminitis, particularly in older horses with Pituitary Pars Intermedia Dysfunction (PPID).

Inhaled Steroids and Lower Airway Disease

For respiratory conditions like asthma in both cats and horses, inhaled steroids offer a way to deliver medication directly to the site of inflammation, providing local effects with reduced systemic exposure.

In cats, fluticasone is a common inhaled option ($110 \text{ mcg}$ every 12 hours). For acute dyspnea, rapid-acting glucocorticoids like dexamethasone ($0.15–1 \text{ mg/kg}$ IM or IV) may be required.

Intrasynovial Corticosteroids for Horses

In equine medicine, corticosteroids are frequently administered directly into joints (intrasynovial) to treat osteoarthritis (OA) and other inflammatory joint diseases. The choice of drug depends on the desired duration of action and the type of joint being treated.

• High-motion joints: Triamcinolone acetonide (TA) is often preferred due to its medium duration of action.
• Low-motion joints: Methylprednisolone acetate (MPA) is used for its long-acting properties.

Adverse Effects of Glucocorticoids

While highly effective, glucocorticoids can cause significant systemic issues, especially with prolonged or high-dose use.

Common Adverse Effects:

• Metabolic: Hyperlipidemia, glucose intolerance (risk of diabetes), obesity, and hepatomegaly.
• Endocrine: Adrenal atrophy and iatrogenic hyperadrenocorticism.
• Musculoskeletal: Osteoporosis and myopathy (muscle weakness).
• Gastrointestinal: Gastric or colonic ulceration and hemorrhage.
• Ocular: Glaucoma and cataracts.
• Immune: General immunosuppression, increasing the risk of infection.

Clinical Caution: Avoid glucocorticoid use in patients with known infections, diabetes, kidney disease, heart disease, or during pregnancy unless absolutely necessary.

When discontinuing therapy, especially for immunosuppressive purposes, it is vital to taper the dose gradually to prevent acute adrenal crisis.