Drugs on the Farm and Lay Administration

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It goes without saying that horses can get themselves into all kinds of trouble despite the best management. With this in mind, horse owners arm themselves with a comprehensive first aid kit that facilitates dealing with an unexpected crisis. First aid kit supplies include items like wound scrub, bandaging materials, topical antimicrobial medications and eye ointment. But, often there are other medications that fall under the category of pharmaceuticals, referred to as drugs, that are found on the farm.

Pharmaceutical products should be handled with utmost care. Many of these are prescription medications, and it is worthwhile to have a conversation with your veterinarian about specifics in handling and administration, as well as possible adverse effects.

In general, what are some things you should consider about storage, handling, and administration?


  • Always store drugs in a locked cabinet out of reach of children, pets, other boarders or casual visitors to the barn.
  • Store drugs at the manufacturer’s recommended temperature to prevent loss of the drug’s efficacy. Interestingly, DMSO freezes at around 65 degrees, but it still seems to be effective. However, most drugs don’t tolerate freezing or high temperatures. Read the label and/or package insert for the specified storage conditions.

Antibiotic Use

  • Do not use antibiotics indiscriminately without advice from your veterinarian. Overuse of antimicrobials, particularly in cases where they are not indicated, has stimulated antimicrobial resistance on a large scale. This impacts the antibiotic choices we have in treating both animal and human patients; many over-used antibiotics are no longer effective against infections.

Oral Medications

  • When administering oral medication, ensure that your horse’s mouth is clean of food so he doesn’t spit out the paste or solution along with the wad of chewed hay, grass or grain. It helps to hold your horse’s head up and massage the tongue with the oral syringe as you push on the plunger. Tongue movement causes swallowing of the medication. It often helps to mix the medication with applesauce, molasses or Karo syrup or some tasty flavored solution–sugar water, electrolyte drink mix–to improve your horse’s compliance in accepting the treatment.

Handling Injectable Medication

  • Check the expiration date on every bottle, jar and syringe before administering the medication to the horse. If the drug is expired, don’t give it without first consulting your veterinarian. Dispose of outdated medications via incineration rather than flushing down the sink or toilet into the sewer or septic system.
  • When pulling up an injectable medication into a syringe, read the label three times–first when you pick up the bottle, again while pulling medication into the syringe, and finally when you put the bottle down. This avoids inadvertent injection of an inappropriate product.
  • Double check the dose (both amount and concentration) to be given per your veterinarian’s instructions, and ensure that this is the dose you have prepared in the syringe or for oral administration.
  • Double check information on the recommended route of administration–should it be given by intravenous, intramuscular or oral route? Extreme reactions can occur from medication not given by its specified route of administration. For example, injectable phenylbutazone should never be given in the muscle, only intravenously; otherwise it will cause severe tissue reaction and sloughing.
  • Give injectable medication slowly to avoid spray-back that causes loss of drug and/or sprays it into your face. Many medications may be absorbed through mucous membranes of your eyes and gums.
  • Use a clean needle and syringe for every injection to avoid the risk of infection. Never use the same needle on multiple horses–blood contamination can transfer disease as well as infection.
  • When pulling the cap off a needle, use your fingers rather than your teeth so you don’t inadvertently ingest any medication.
  • For an intramuscular injection, after inserting the needle into the muscle, attach the syringe, then pull back on the plunger to ensure that no blood comes into the needle hub. If it does, then back the needle out half way and then reposition it within the muscle or remove it completely and reinsert, once again checking for blood in the hub. Many medications and vaccines should not be given directly into the bloodstream if they are labeled for intramuscular use only.
  • Always cap a needle following use. Used needles should be discarded into a biohazard waste bin like a sharps container, or should be returned to your veterinarian for proper disposal.


  • Discuss with your veterinarian all medications, including supplements that your horse might be receiving. This cautious advice helps to avoid adverse drug interactions.
  • Check with your equine insurance company that your policy coverage allows you to give an injectable medication without supervision by a veterinarian. Usually, an insurance carrier will decline coverage in the event of an adverse reaction from an injectable product given by an owner, particularly if given intravenously.
  • Monitor your horse’s manure output and consistency as well as consumption of food and water following any drug administration. Some medications can alter intestinal motility and/or cause overgrowth of intestinal bacteria.
  • If specific drugs, like progesterone or DMSO, are known to be absorbable through the skin, wear protective, non-porous gloves.
  • If you are pregnant or you have a known allergy to particular medications, advise your veterinarian and find someone else to administer the drug to your horse. When pregnant, contact with dexamethasone, isoxsuprene, prostaglandins, and progesterone or other hormonal products should be avoided.
  • When preparing single doses of powdered medications–as for example putting them into baggies with food or grinding up tablets in a coffee grinder–wear a face mask. Some medications, like phenylbutazone, are extremely toxic if inhaled; “bute” can cause potentially fatal aplastic anemia of the bone marrow. Other medications can be absorbed through inhalation and may cause a person to experience pharmaceutical effects. Although this could occur without lasting harm, it should be avoided.
  • Always wash hands thoroughly before and after handling medication to avoid skin, eye or mouth contact from residue on your fingers.
  • Be conscientious of environmental contamination with drugs or their residues. One example is ivermectin’s adverse effect on invertebrates, such as dung beetles and earthworms. This drug is passed through horse feces in an un-metabolized form and can directly kill invertebrates or affect their food sources. Following deworming, plan to pick up manure daily for a couple of weeks to remove this contaminant from the environment.
  • When using aerosolized medications such as insecticides or disinfectants that create fumes, only administer in a well-ventilated area.
  • Administer medications to your horse in an area free of obstacles. Ensure that other people, children and animals are not roaming about the immediate area and that no equipment is in use nearby that could enter your working area. Keep your focus on your horse and follow safe handling practices. Use a good halter and lead rope and a nose or lip chain if necessary. If your horse is fractious, ask another capable horse person to help or defer the task to your veterinarian.
  • Post contact information for the National Poison Control Center (800-222-1222 or in your barn in the event of accidental human exposure, as well as contact information for Animal Poison Control (888-426-4435) in case of accidental equine or small animal poisoning.






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