In veterinary medicine, prednisolone is often recommended as an alternative to prednisone where the former provides superior bioavailability. While some products are labeled for use in some animals with certain conditions, prednisolone’s use in cats, dogs, horses, small mammals, birds, and reptiles to treat inflammation, immune-mediated disease, Addison’s disease, and neoplasia is “off label” or “extra label”. Prednisolone is most commonly prescribed to help relieve inflammation and joint pain, and to decrease the swelling, redness, and itching often associated with allergic reactions. 

Recurrent Airway Obstruction (RAO) in the Horse 

Prednisolone is indicated for the treatment of Recurrent Airway Obstruction (RAO) in the horse. This condition was previously called heaves, chronic obstructive pulmonary disease or COPD. RAO is a disease of the bronchioles in the lungs and is caused by an allergy to small dust particles and spores that are inhaled by the horse.1 The allergic reaction results in the production of fluid and thickening of the walls of the small airways of the lungs, causing increasing obstruction. 

RAO is reversible in its early stages, but the damage may become permanent if management changes are not made, since affected horses must make increasing efforts to breathe. Although RAO cannot be cured as such, its progress can be halted.

The early signs of RAO are often only a slight nasal discharge or dry cough; unfortunately, these often go unnoticed. Later, the discharge and cough will become evident. As the disease progresses, the horse will cough with only slight exercise, and in severe cases it will have difficulty breathing even at rest.2 Symptoms may be mild for years, but in some horses, acute attacks of respiratory distress can come about after exposure to dust or pollens.1 

Two different forms of RAO are recognized in the horse: the barn-associated type seen in stalled horses that are fed hay, and summer pasture-associated obstructive pulmonary disease which is more commonly seen in horses living on pasture in the Southeastern United States.3,4 

Prednisolone for RAO in Horses

Prednisolone is a glucocorticoid that is used to treat a variety of conditions across numerous species, most notably horses, dogs and cats. Although prednisone and prednisolone are different drugs, they are often considered bioequivalent, as most species rapidly convert prednisone to prednisolone in the liver. Horses, cats, and animals with compromised hepatic function may not efficiently absorb or convert prednisone to prednisolone, however.1 Since prednisone does not appear to be absorbed well after oral administration in horses, prednisolone is often preferred where prednisone is indicated.

Systemic glucocorticoids such as prednisone and prednisolone can suppress adrenal function. Animals that have received these drugs chronically should be tapered off slowly, as endogenous ACTH release and corticosteroid function may return slowly. Additional glucocorticoids should be administered if the animal undergoes a stressor (e.g., surgery, trauma, illness) during the tapering process or until normal adrenal and pituitary functions resume.1 

Prednisolone should not be used in animals that are allergic to it, or with systemic fungal infections (unless it is used to treat Addison’s disease), viral infections, ulcers, tuberculosis, or Cushing’s disease. It should be used cautiously in animals with diabetes, heart or vascular disease, other types of infections, osteoporosis, cataracts, high blood pressure, or kidney disease. Caution should be used when using prednisolone in pregnant or lactating pets or in pets receiving medications that can cause ulcers. Adverse effects have been more widely reported in dogs and cats than in horses.

Where to buy Prednisolone 

Prednisolone is available in the U.S. through pharmaceutical manufacturers and through veterinary custom compounding companies. PREDNISOLONE 5 MG/ML by NexGen Pharmaceuticals is indicated for the treatment of Recurrent Airway Obstruction (RAO) in the horse, as well as certain immunomediated conditions in other species.

This product carries numerous potential drug interactions. Please consult your veterinarian prior to beginning any treatment regimen.

FOR RX ONLY: A valid prescription from a licensed veterinarian is required for dispensing this medication.

1Plumb’s Veterinary Drugs.

2vcahospitals.com.

3Merck Veterinary Manual.

4aaep.org.