Activated Charcoal in Horses

Activated charcoal is introduced orally to horses and other animals who have ingested a poisonous substance, to absorb toxic substances and pass them through the gut with minimal absorption. Activated charcoal is oxidized carbonized organic matter that has many pores allowing it to absorb toxic substances. In order to be effective, activated charcoal must be administered shortly after toxic substances have been ingested before the gastrointestinal system has a chance to absorb toxins. Sometimes, activated charcoal is administered in conjunction with a laxative to allow substances absorbed by the charcoal to pass through the gut quicker. Activated charcoal should only be administered on the advice of a veterinarian and needs to be administered shortly after toxin ingestion, your veterinarian may recommend that you administer activated charcoal if you report your horse has ingested a toxic plant or substance and provide directions on administration.

Activated charcoal is usually administered by nasogastric intubation in horses. Standard dosage is 1-4 grams per 1 kg of body weight. Powdered activated charcoal may be diluted with water to a consistency that allows an appropriate dosage to pass through the tube. Granular activated charcoal, which is easier to mix, and premixed solutions also exist. A nasogastric tube is placed into the stomach and activated charcoal instilled by syringe or gravity. Sometimes a cathartic is also administered with the activated charcoal to allow substances to pass through the digestive system more quickly. Repeated doses may be required.

The efficacy depends on the length of time between ingestion of a toxic substance and administration of activated charcoal and the type of toxic substance ingested. The consequences of ingestion of toxic plants or feeds can be significantly mitigated by activated charcoal treatment. However, if absorption in the gut has already occurred, administering activated charcoal will not be effective. Some toxic substances are not effectively treated by activated charcoal. Activated charcoal should not be used when substances such as strong acids, inorganic minerals, alkaloids, alcohols, hydrocarbons, or metals are ingested, as it is ineffective at absorbing these substances.

Recovery from administration of activated charcoal depends on the condition and severity of toxicity for which it is being administered. You will need to provide whatever follow-up care and treatment is required depending on symptoms and effects of the toxic substance on your horse. Horses recovering from toxicity should be monitored for fever, dermatological reactions, and digestive problems such as diarrhea, constipation, or colic. Laminitis can be an additional consequence of toxic reaction in horses that will need immediate medical attention.

The cost of administration of activated charcoal is approximately $100 to $200, however, mileage and additional treatments required will incur additional expenses.

Activated charcoal may have side effects such as constipation, although this is not common.

There is a risk of aspiration with the insertion of the nasogastric tube and care needs to be taken to ensure this does not occur. 

If medical conditions such as a perforated GI tract, dehydration, or ingestion of caustic or corrosive agents exist, activated charcoal is not recommended.

Microbial balance in the gut may be affected by the administration of activated charcoal, although this effect has not been well documented.

Horse owners should be aware of toxic plants that occur in their area and check their pastures regularly for these plants. If toxic plants are found in your horse's turnout area, your horse should be removed from the pasture immediately and the plants eradicated before your horse is returned to the pasture. Ensure that grains and feed supplements are secured away from your horse so they cannot access them accidentally. Reducing the incidence of toxicity will reduce the need to administer activated charcoal to your horse to address toxic incidence.