Past their best dates need to be adhered to, but they aren’t always obvious

How medications are stored matters a great deal, and manufactured feed doesn’t last forever

Modern horse keeping carries a responsibility of housekeeping that pertains to periodically reviewing the expiry dates of products routinely used in the care of the horse.

Most horse owners will immediately consider the expiry dates of drugs and medications, however, there are other items that also carry expiry dates that may be even more relevant to the health of the horse.

First let us consider the most obvious expiry date — that of drugs. Drug safety authorities require drug manufacturers to stamp expiration dates on the products that they sell. The expiration date on the label is the latest date for which the manufacturer can guarantee the full safety and potency of the drug. This is much like the expiry dates on items at the grocery store except most drug products have an expiration date that is one to five years from the date of production. It is not that the drug is no longer ‘any good’ or ‘unsafe’ after the expiry day, rather that drug stability, safety, and potency are no longer assured after the date stamped on the product.

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Most medications are remarkably stable, however, stability is greatly affected by storage conditions. If a product was stored outside the recommended temperature range listed on the label (such as in a tack room, vehicle, or horse trailer where it could have got too hot, cold, or damp) the stability of the drug will be negatively impacted as well as the predictability of its actions in the body.

Tablets and powders seem fairly resilient. Stability is a bit more of a concern for liquid drugs, pastes, and gels. Liquid drugs, especially combinations tend to be even less stable, often becoming discoloured, cloudy or precipitating out. Procaine penicillin preparations, a commonly used antibiotic in equine medicine is particularly troublesome when accidentally ‘overheated’ as the ‘procaine’ portion often becomes more soluble and thus more clinically active in the solution. If used it can lead to a higher number of adverse reactions than expected following injection.

Expiry dates apply to dewormers as well. If an improperly stored or expired dewormer is utilized, the horse will likely not receive a sufficient dose and the product will fail to adequately address the horse’s parasite infection. Underdosing is one of many factors than can contribute to parasite resistance.

Herbal products can also suffer from physical instability due to plant quality and processing, presence of impurities, and improper storage and handling.

The use of vaccines beyond their expiry date has very little to no latitude. Vaccines are particularly susceptible to reduced efficacy and increased adverse reactions when ill handled or used beyond their manufacturer’s instructions.

Once a little cache of expired products have been separated it is important to ensure responsible disposal of the products. Most local drugstores and veterinary clinics offer drug disposal programs free of charge. If professional disposal isn’t available the next option is to discard the drugs in a small zip-lock bag with a mixture of undesirable wastes such as coffee grounds or kitty litter.

The expiry dates that are not so obvious in the horse industry are those which pertain to feed products. Human food is tightly regulated with food processors, distributors and retailers complying to ensure the food products placed on the shelves are within date. Unfortunately this does not apply for most horse feeds. Shelf life significantly affects the quality of a horse feed. Shelf life is the length of time a feed is considered to have the nutritional quality and physical characteristics as intended when it was produced by the manufacturer.

Alone, straight grains, flaxseeds and even hay can be stored for years in ideal conditions. However, when the grains, seeds and/or forage are broken or heated during processing and oils, molasses or other liquids have been added, their shelf life is dramatically shortened. Many manufacturers will recommend consumption of commercial grain mixes, textured, pelleted and extruded feeds within 30 to 90 days of manufacturing if the product is stored under proper conditions.

Proper conditions include low humidity and the ‘cooler’ temperatures of the storage facility (including both the feed dealer’s warehouse and the farm), absence of rodents or insects, and that the integrity of the bag be maintained to limit exposure to air. High temperatures, high humidity, pests and air exposure rapidly degrade feed quality. Degradation includes growth of mould and bacteria as well as oxidation that results in loss of vitamins and causes rancidity of oils and essential fatty acids.

Horses are often fed vegetable oils such as soya, corn, and canola through a number of sources — top dressed or in high ‘fat’ textured and/or extruded kibble feeds. High ‘fat’ feeds is a bit of a misnomer since fats are derived from an animal source and are generally not fed to the horse because of their poor palatability. Vegetable oils which are the oils from plants are fed to the horse with increasing frequency.

Although the horse’s appetite will naturally avoid rancid oils, the rancidity of the oil is often masked with grains, molasses and other feed additives. Rancid oils are extremely detrimental to the horse’s digestive system, liver and cellular tissues. Oils vary in their stability depending upon their chemical makeup and type of processing or handling.

Not all oils are the same and the metabolic effects of oils vary from beneficial to extremely harmful depending on the type of oil, how it is processed and how it is fed. Since expiry of the nutritional value of the oils through oxidation and/or rancidity in feed rations amplifies a detriment to the horse’s tissues it becomes a very important expiry date to the health of the horse.

About the author

Contributor

Carol Shwetz is a veterinarian focusing on equine practice in Millarville, Alberta.

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