What Does Ionophore-Free Mean?

What Does it mean to be Ionophore-Free?

You may have heard about “ionophores” and/or “ionophore-free” feeds when it comes to choosing a concentrate for your horses. This is because the risk to your horse’s health and wellbeing is real if their feed is accidentally contaminated with ionophores. There are multiple instances where horses have died throughout the United States after accidentally ingesting ionophore contaminated horse feed. 

Tribute Superior Equine Nutrition is 100% Ionophore-Free

Because even small amounts of ionophores are toxic to the horse, Tribute Superior Equine Nutrition only produces horse feed in a mill that is completely ionophore free. In addition, Tribute Superior Equine Nutrition requires any ingredients brought into our mill to come from facilities that are also ionophore free. With no ionophores in our manufacturing facility, there is zero chance for cross contamination or operator error. You can trust Tribute Superior Equine Nutrition to deliver on the promise to put your horse’s health and wellbeing first. Safe manufacturing is the foundation of our brand.

What Are Ionophores?

Ionophores are a class of antibiotics that are used as a feed additive in livestock and poultry feeds. While they are classified as an antibiotic, they are not used to treat disease. Rather, their purpose when fed to cattle is to encourage feed efficiency and weight gain. In poultry, ionophores help gut health and reduce coccidia (parasite) populations.  The types of ionophores used in cattle or poultry feed include Rumensin (monensin), Bovatec (lacalocid), narasin, salimnomycin, laidlomycin, among others.  

The most important takeaway when discussing ionophores is they should never be fed to horses. This is one of the main reasons it is never advisable to feed any other type of livestock feed to horses. There may be additives like ionophores included, or the feed was mixed in the same equipment that may be contaminated with ionophores. Horses have a very low tolerance for ionophores and if fed enough it can and does lead to illness and even death. Rumensin (monensin) is the most common cause of ionophore toxicity in horses. A horse consuming as little as 1 mg of Rumensin can lead to death.

What is Ionophore Toxicity in Horses?

Horses are one of the species that are the most susceptible to ionophore toxicity. The signs and symptoms of ionophore toxicity for horses will depend on how much they ingest but they can include:

  • Cardiovascular issues. Horses may exhibit abnormal heart beats (arrhythmia) or even suffer cardiac arrest. 
  • Digestive upset. Horses may experience severe colic or diarrhea. 
  • Muscle impacts. Horses may experience muscle weakness, stiffness, trembling or difficulty walking. 
  • Lethargy. The horse may be depressed or appear weak. 
  • Respiratory issues. May experience trouble breathing. 

In severe cases, ionophore toxicity can lead to sudden death. If your horse experiences any symptoms of ionophore toxicity, you should contact your veterinarian immediately. While there are no “cures” to ionophore toxicity, supportive care can help manage and stabilize your horse. 

If you do suspect your horse feed might be contaminated by ionophores you can take the following steps:

  • Stop feeding the suspected concentrate immediately and remove access to it from any horse. 
  • Isolate the affected horse and contact your veterinarian immediately. You can explain the situation and receive guidance. 
  • Monitor your horse for any further deterioration. Note any changes. 
  • Sample the feed and packaging for potential testing. 
  • Report your concerns to the manufacturer as they may be interested in investigating the issues and take corrective actions. 

The most important takeaway is to take a proactive approach to having your horse assessed by a veterinarian. 

How Can You Prevent Ionophore Toxicity?

The only foolproof prevention measure is to only feed concentrates from companies that ensure their horse feeds are produced in ionophore free facilities. This means that the horse feed being made in a manufacturing plant has no chance of being contaminated with ionophores. Tribute feeds are made in a facility that is completely ionophore free and there is no risk of putting any horse’s health in jeopardy. 

The reality is any feed produced in a facility that contains ionophores like rumensin is at risk. 

Some feed mills use sequencing or flushing to try and minimize any chance of crossover of ionophores in their horse feeds. Yet, this puts horses at risk if the sequencing or flushing was not successful. 

If you have multiple species of livestock on your farm, also be mindful of the feed you are purchasing for species like cattle. Horses should never be fed feed designed for other species and you also will need to take steps to ensure that horses cannot accidentally gain access to unsecured feed.

Take Home Message

The risk of ionophore toxicity is real. While it does lead to the death of some horses each year, you can eliminate this risk by purchasing horse feeds made in ionophore free facilities. You can read more about other ways horse feeds are safely made in our Is Your Horse Feed Safely Made article. It also serves as a reminder that feeds formulated for other species (i.e., cattle feed) should never be fed to your horse. If you have any concerns about what you are feeding your horse or need further information, please feel free to contact us

Article By:
Chris Mortensen, Ph.D.
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