When most people think about inflammation, they typically picture a localized area of swelling on a limb or around a wound. But inflammation often occurs systemically (affecting the whole body). Equine researchers have been studying the concept of systemic inflammation because of its links to a variety of health problems, including equine metabolic syndrome, insulin resistance, laminitis, leaky gut syndrome and risks for musculoskeletal injury.1

Systemic inflammation occurs when the body’s protective responses intensify over time, turning what starts as a defense mechanism into a chronic condition. Normally, the immune system normally secretes pro-inflammatory cytokines; these are chemical messenger proteins such as interleukins (IL) and tumor necrosis factor (TNFα).2 These substances are important for initiating a physiological response to infections or injury and seeing to a successful recovery.

While inflammation may start in one tissue, excessive inflammation releases substances into the circulatory system which begin to act systemically on other tissues throughout the body. 

The Dynamics of Systemic Inflammation in Horses

One example of how systemic inflammation comes about is in the case of glucose metabolism.1 Horses obtain glucose from consuming carbohydrates, and this can negatively affect the horse’s endocrine system if it is not used or properly stored in body tissues, leading to systemic inflammation. 

When an animal is sick and off its feed, the preservation of glucose is necessary for tissues that require it. TNFα (for example) is important for initiating insulin resistance that is beneficial in the face of illness.2 Unfortunately, the body doesn’t differentiate between cytokines released to initiate the sickness response or cytokines released due to diet or obesity. Thus, insulin resistance develops when an animal consumes a diet that promotes inflammation, such as high-starch and high-sugar feeds, which is often the case with working and performance horses. Such feeding regimens can also lead to obesity, which further exacerbates the inflammatory response.

These factors and the association between inflammation and obesity depends on factors such as breed, exercise, diet, and aging. Older horses naturally have higher circulating concentrations of cytokines, namely IL-6 and TNFα.1,2

Flumethasone for Equines

Flumethasone is a glucocorticoid that is FDA-approved for use in horses. Branded under the name Flucort®, it is a chemical modification of prednisolone, which possesses greater anti-inflammatory and gluconeogenic properties than the parent compound when compared on an equivalent basis. Once used in small animal veterinary practices, it is no longer commonly used in small animals.3 Flumethasone is long-acting and 15 times more potent than hydrocortisone.

Flumethasone is recommended for various rheumatic, allergic, dermatologic and other disease states which are known to be responsive to the anti-inflammatory corticoids. It is recommended for parenteral administration using various routes depending on the animal species under treatment. The intravenous (IV) use of flumethasone may be indicated when a rapid method of administration is desired such as in toxemias or shock or shock-like states.

Injectable flumethasone is available commercially as a free steroid alcohol solution. While flumethasone does not work as rapidly as the corticosteroid phosphate and succinate esters (methylprednisolone sodium succinate, prednisolone sodium succinate, or dexamethasone sodium phosphate), it can be given either IM or IV and is useful for acute reactions such as insect bite hypersensitivity or vaccine reactions.4

Flumethasone is labeled in horses as indicated for: 1) Musculoskeletal conditions due to inflammation, where permanent structural changes do not exist, such as bursitis, carpitis, osselets, and myositis. Following therapy, an appropriate period of rest should be instituted to allow a more normal return to function of the affected part. 2) Allergic states such as urticaria (hives) and insect bites.3

In dogs, flumethasone injection (Flucort®) is labeled for: 1) musculoskeletal conditions due to inflammation of muscles or joints and accessory structures, where permanent structural changes do not exist, such as arthritis, osteoarthritis, intervertebral disc syndrome and myositis. In septic arthritis, appropriate antibacterial therapy should be concurrently administered. 2) Certain acute and chronic dermatoses of varying etiology to help control the pruritus, irritation, and inflammation associated with these conditions. The drug has proven useful in otitis externa in conjunction with topical medication for similar reasons. 3) Allergic states such as urticaria and insect bites.

Flumethasone Dosing for Horses

Dosages of flumethasone for horses are as follows (Adapted from label; Flucort®):

For musculoskeletal conditions due to inflammation, where permanent changes do not exist; and also for allergic states such as hives, urticaria and insect bites; 1.25 – 2.5 mg per horse daily by IV, IM, or intra-articular injection. If necessary, the dose may be repeated. Primary adverse effects of flumethasone in horses are Cushingoid in nature with sustained use, and there are numerous potential drug interactions.3

The Association of Racing Commissioners International Uniform Classification Guidelines for Foreign Substances has designated flumethasone a CLASS 4 DRUG.

Please consult your veterinarian prior to beginning any treatment regimen.

Where to buy Flumethasone

Flumethasone is available in the U.S. through several pharmaceutical manufacturers and through veterinary custom compounding companies. FLUMETHASONE 0.5 MG/ML by NexGen Pharmaceuticals is an excellent alternative to traditional corticosteroids for local or systemic inflammation in equines.

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

1thehorse.com.

2Knych HK, Arthur RM, McKemie DS, Baden R, Oldberg N, Kass PH. Pharmacokinetics of intravenous flumetasone and effects on plasma hydrocortisone concentrations and inflammatory mediators in the horse. Equine Vet J. 2019 Mar;51(2):238-245.

3Plumb’s Veterinary Drugs.

4Dowling, P. Corticosteroids: The wonderful, terrible drugs. Proceedings: AAFP 2007. 2007. Veterinary Information Network.