Banamine® (flunixin meglumine) for Horses: Uses, Dosages & Side Effects

Flunixin meglumine, often sold under the brand names Banamine®, Flunazine®, Vetameg™, and Prevail®, is a common non-steroidal anti-inflammatory drug (NSAID) used in horses. Banamine® is prescribed by veterinarians to help manage clinical signs of pain, swelling, and/or fever.

In horses, flunixin meglumine is typically used to treat osteoarthritis and soft tissue injuries, and to alleviate visceral pain associated with colic. NSAIDs such as Banamine® can help to minimize physiological stress, improve welfare, and increase treatment success for horses. ^[1]

However, when Banamine® is used incorrectly, the risk of serious adverse effects, including gastrointestinal ulcers, kidney damage, and right dorsal colitis, increases greatly. Understanding both the benefits and side effects of Banamine® use is important for horse owners.

The dosage and duration of treatment with Banamine® should be determined by a veterinarian based on the specific condition being treated. Always follow your veterinarian’s guidelines when administering prescription medications to your horse.

Common Uses of Banamine®

As a non-steroidal anti-inflammatory drug (NSAID), Banamine® is effective in treating pain and inflammation, as well as reducing fever in horses.

Horse owners are often familiar with Banamine® in the context of colic treatment, as it is a common choice among veterinarians for alleviating pain associated with abdominal or gastrointestinal issues in horses.

This drug can also be used for other equine health conditions including: ^[1][2][3]

• Muscle or soft tissue injuries
• Lameness
• Corneal ulcers and uveitis
• Cellulitis
• Fever
• Pain management after surgery
• Endotoxemia

Endotoxemia

Endotoxemia refers to the presence of bacterial endotoxins in the bloodstream, and most commonly occurs in horses with severe colic, gastrointestinal infection, or retained placenta. Endotoxemia is a life-threatening disease process that can rapidly lead to death.

Flunixin has been shown to exhibit anti-endotoxic properties, even at low doses, making it a useful medication in the treatment of horses with signs of endotoxemia. ^[4][5][6]

How Does Banamine® Work?

Flunixin meglumine has analgesic (pain-relieving), anti-inflammatory, and antipyretic (fever-reducing) properties.

As an NSAID, it works by blocking two specific enzymes, COX-1 and COX-2, that are involved in regulating inflammation.

These enzymes play key roles in the arachidonic acid pathway, which contributes to inflammation, pain, and fever.

COX-1 Enzyme

COX-1 (cyclooxygenase-1) is present in most tissues, including the gastrointestinal tract, and its job is to produce prostaglandins. These are hormones that are important for maintaining normal bodily processes and functions, such as cardiovascular health, blood clotting, gastric health (including the protection of the stomach lining), and kidney function.

Notably, COX-1 enzymes are expressed continuously, whether the horse is heathy, sick, or injured. This ensures that the body can maintain homeostasis, the process by which biological systems maintain stability. ^[4][7][8]

COX-2 Enzyme

COX-2 (cyclooxygenase-2) is responsible for producing prostaglandins primarily involved in the body’s inflammatory response, including reactions to pain. COX-2 enzymes are produced in higher amounts under certain conditions such as when inflammation is actively occurring in the body. ^[4][7][8]

COX Enzyme Inhibition

The anti-inflammatory and pain-mediating effects of NSAIDs come specifically from blocking or inhibiting the COX-2 enzyme, and not COX-1.

Traditional NSAIDs like Banamine® function by inhibiting both COX-1 and COX-2 enzymes. These medications are known as “non-selective” COX inhibitors because they do not distinguish between the two enzymes but instead block both. Phenylbutazone, commonly known as Bute, is another example of a non-selective NSAID frequently used in horses. ^[1][4]

Another class of NSAIDs includes firocoxib (Equioxx® or Previcox®). Firocoxib is a COX-2 selective drug, which means it does not block COX-1 activity.

This selectivity towards COX-2 is crucial because it reduces the risk of certain adverse side effects, particularly those related to the gastrointestinal tract. The implications of COX selectivity in the development of side effects will be discussed later in this article.

Formulations of Banamine®

Flunixin is a prescription medication that can only be obtained through a licensed veterinarian.

Three approved formulations of flunixin meglumine are available for use in horses:

• Injectable solution
• Oral paste
• Oral granules

Additionally, flunixin meglumine is available in compounded forms, such as oral powder or capsules, from specialized pharmacies.

Intravenous (IV) Administration

The injectable form of flunixin is administered by veterinarians intravenously (IV), typically into the jugular vein. IV administration provides the most rapid onset for pain relief. ^[6]

Horse owners and non-veterinary professionals should not administer Banamine® IV due to the risks involved. Improper administration can result in tissue damage around the jugular vein, thrombosis (blood clot formation) within the vein, or even life-threatening seizures if the drug is mistakenly injected into the carotid artery. ^[9]

Oral (PO) Administration

Oral administration (“per os” or “by mouth”) of flunixin is typically more manageable and safer for horse owners. Banamine® can be administered orally in either paste or granule form.

Studies also show that the injectable form of Banamine® is effective if given orally. ^[10]

The main disadvantage of this method is the delayed onset of the drug’s effects, usually taking about 45-60 minutes, compared to the more immediate impact seen with intravenous (IV) administration. ^[6]

It’s important to note that orally administered Banamine® may take longer to reach its peak effect in horses that have recently eaten. This delay is attributed to changes in gastrointestinal motility, the rate of stomach emptying, gastric pH, and the medication’s potential binding with ingested feed stuffs. ^[6]

Intramuscular (IM) Administration

Horse owners may inquire to their veterinarian about administering the injectable form of Banamine® intramuscularly (IM).

However, the intramuscular injection route is no longer advised due to the risk of abscess formation at the injection site. This infection can be severe and life-threatening. ^[11]

Transdermal (TD) Administration

Recently, a new transdermal liquid form of Banamine® was introduced and approved for use in cattle. This formulation is applied directly onto the skin, where it is absorbed transdermally.

The transdermal form of Banamine® has not been approved for use in horses yet, though studies are investigating its safety and efficacy. ^[12]

Adverse Effects

Non-selective NSAIDs, such as Banamine®, are known to have a higher risk of side effects than COX-2 selective NSAIDs. Although Banamine® is widely used in equine medicine, it has a narrow margin of safety, and improper use can lead to adverse or even life-threatening side effects.

The most common adverse side effects related to NSAID use in horses include:

• Ulceration of the stomach or small intestine
• Right dorsal colitis (RDC)
• Renal papillary necrosis
• Renal (kidney) failure

Toxicity associated with Banamine® can arise from prolonged use, overdosing, or administering it too frequently. Furthermore, individual sensitivity to Banamine® varies among horses, meaning that horses may exhibit different levels of tolerance to the drug. ^[1]

Gastrointestinal Side Effects

Banamine® decreases the synthesis of prostaglandins involved in normal bodily processes, such as protecting the lining of the gastrointestinal tract. This can render the gastrointestinal lining more susceptible to injury and ulceration, potentially leading to conditions such as gastric ulcers or right dorsal colitis in horses. ^[13]

Signs of gastrointestinal side effects linked to Banamine® administration include:

• Poor appetite
• Signs of colic, particularly noticeable around meal times
• Girthiness or sensitivity behind the elbow
• Irritability or other changes in attitude
• Diarrhea

Renal Side Effects

Improper use of NSAIDs, including Banamine®, can lead to serious kidney damage. NSAIDs reduce blood flow to the kidneys, which can impair their function and cause tissue damage.

In severe cases, this reduction in blood flow can lead to acute renal failure, especially in horses that are dehydrated or are being treated with other drugs that are harmful to the kidneys. ^[1]

Signs that Banamine® use may have led to acute kidney injury include:

• Depression and lethargy
• Unwillingness to eat and drink
• Sudden changes in urination, such as passing small volumes of urine or failure to produce any urine

Clostridial Myositis

The intramuscular (IM) administration of Banamine® is now strongly discouraged due to the risk of developing a severe infection known as clostridial myositis. This infection can cause extensive muscle damage and is potentially fatal.

This condition is caused by the proliferation of Clostridium bacteria within the muscle tissue at the site of the injection. Early detection and aggressive treatment are crucial to reduce the risk of death from clostridial myositis. ^[11]

Signs that an IM injection of Banamine® may be becoming infected include: ^[11]

• Heat, pain, and swelling at the injection site
• Crepitus, or the presence of gas under the skin
• Depression and lethargy
• Unwillingness to eat
• Fever
• Reluctance to move the body part injected (often the neck)
• Rapid progression to endotoxic shock, including increased heart rate, increased respiratory rate, and purple mucous membranes

Banamine® Dosage

You should always consult with your veterinarian before administering any medications, including Banamine®, to your horse. Dosages and instructions for use vary depending on the specific formulation of flunixin meglumine you are using. Your veterinarian can determine the appropriate dosage and provide specific instructions based on your horse’s condition and body weight.

The standard dosage of flunixin for horses can be found on the drug label or package insert. Mad Barn does not endorse one formulation or drug manufacturer over another.

The standard dose for flunixin meglumine is 1.1 mg per kg body weight or 0.5 mg per lb body weight. For injectable formulations, this equates to 1 mL per 100 lbs body weight. For paste formulations, this equates to 50 mg per 100 lbs body weight.

Precautions

Banamine® should not be given more often than every 12 hours, unless under direct supervision by a veterinarian.

Administering doses too frequently is the most common mistake made by horse owners using Banamine®, particularly when horses exhibit persistent pain or symptoms of colic. ^[1]

Additionally, it is strongly advised against combining NSAIDs. Using multiple NSAIDs concurrently can significantly increase the risk of adverse effects. As such, only one NSAID should be administered at a time. ^[1][14][15]

Flunixin meglumine should not be used in horses that have shown hypersensitivity to the drug. ^[16]

Banamine® Use in Foals

Foals are more sensitive to NSAIDs, such as Banamine®. This increased sensitivity can be attributed to several physiological differences compared to adult horses, including less total body fluid, different drug-metabolizing enzymes, and lower plasma protein concentrations. ^[1][13]

Research shows that Banamine® has a significantly lower clearance rate and a longer half-life in newborn foals than in older foals or adult horses. ^[1] This means the drug stays in their system longer, potentially increasing the risk of adverse effects.

One study showed that healthy foals aged 48 – 72 hours did not display any negative effects when receiving the recommended dose of Banamine® for five days. However, caution is advised as foals may be more susceptible to toxicity from the drug. ^[1]

Using Banamine® Safely

When used correctly, flunixin meglumine can be very effective for managing signs of pain, inflammation, and fever in your horse. Many veterinarians recommend horse owners include Banamine® in their equine first-aid kits, and become comfortable using it in appropriate situations.

However, Banamine® poses a risk of severe and potentially life-threatening side effects if it is administered incorrectly. For this reason, it is important to give the drug at the recommended dose, route, and frequency as directed by your veterinarian. ^[1]

To further reduce gastrointestinal side effects, your veterinarian may recommend gastroprotectant medications, which can help prevent gastric and colonic ulcers. Also, keeping your horse well-hydrated while on Banamine® helps lower the risk of kidney injury.

Keep the following considerations in mind when using Banamine® for your horse:

• Route of Administration: Horse owners should not administer Banamine® intramuscularly (IM) or intravenously (IV) due to potential complications. ^[9][11]
• Ethical Horsemanship: It is unethical to use Banamine® to mask injuries or pain to keep a horse in competition or before a pre-purchase exam.
• Tell Your Veterinarian: If your horse needs to be examined by your veterinarian for colic or any other condition, make sure to inform them if you have already administered Banamine® or another NSAID. This will prevent accidental overdoses and toxicity. In fact, it’s better to call your veterinarian before administering anything! They may want to examine the horse when the signs are not being masked.

Summary

• Banamine® (flunixin meglumine) is a non-steroidal anti-inflammatory drug that is effective for pain relief and reducing fever and inflammation.
• The use of Banamine® comes with certain risks that horse owners need to be aware of. Understanding the safe and appropriate use of this drug is important to ensure the well-being of your horse.
• Banamine® should not be administered more frequently than every 12 hours. Overdosing or too frequent administration can lead to serious health complications.
• It’s important not to combine Banamine® with other NSAIDs, as this can increase the risk of side effects, particularly those related to the gastrointestinal tract and kidneys.
• Horses with underlying renal disease or those that are dehydrated have an increased risk for adverse side effects with Banamine® use.
• Foals are more sensitive to NSAIDs and at a higher risk for adverse reactions.
• Before administering Banamine® or if you have any concerns about dosage and side effects, always consult with your veterinarian. They can provide guidance tailored to your horse’s specific health needs.