Ammonia IS Detrimental to Horses Health Says Study

Study finds stable ammonia has detrimental impacts on your horses health

Ammonia is a relatively unenjoyable smell synonymous with stables and barns, yet its toxicity has never been measured, nor have its effects been analysed on the horse. Haygain veterinary advisor Karen E. N. Hayes measured ammonia levels over a 6 year period during her time as a stud farm veterinarian at a high-end facility in the United States hoping to analyse whether ammonia is harmful for the horse, or just an unpleasant smell.

Each day, the stables were cleaned as normal. A number of different barn types and ventilation systems were used in the study to better quantify the results. Some barns had huge fans beneath the ridgeline of the roof, designed to pull stale air upward and out while pulling fresh air in through the double doors at the ends of each aisle. Some barns lacked whole-barn ventilation systems but had box fans bungee-corded to the bars of the stall fronts, some aiming directly across to the back wall of the stall, some facing the aisle, ostensibly pulling air out from the stall. Some barns had both whole-barn ventilation and individual stall fans. All stalls had solid fronts from ground level to four or five feet up; the upper portion was open, with or without bars.

The results on ammonia levels

The results found that in all facilities, ammonia levels inside the stalls ranged from 80 to 450 ppm (parts per million) when measured within 12 inches of the stall floor. Neither the whole-barn ventilation fans, nor the box fans attached to the stall fronts, had a significant effect on ammonia levels in that low-down 12-inch zone. It was stated that if the human nose could detect the ammonia fumes then the concentration of ammonia in the air was at least 5 parts per million. This high level at floor level is of significant importance to the health of the horse, particularly when they’re resting.

When a horse sleeps, the air he draws into his lungs is at its most toxic. When lying down, the horse breathes a lot slower and deeper, inhaling those toxic fumes deep into his respiratory system. This is of particular concern with foals as well – a foal will spend a lot of time led down with a sensitive respiratory system.

How strong is too strong?

There are 3 strength categories when analysing how detrimental ammonia can be on the horse’s health.

AEGL-1 is considered the most mild level at 30 parts per million or less and is generally considered “non-disabling” even at eight hours of exposure, expected to cause no more than mild and temporary irritation of the eyes, nose and/or throat. It’s also considered non-disabling even if you and/or your horse already have other relevant health issues such as dry eye, eye irritation, eye injury or infection, respiratory or skin allergies, asthma, bronchitis, heaves, or airway hypersensitivity. So, the measurements taken in the high-end stables were consistently well below AEGL-1 only in the aisles.

AEGL-2 exposure to ammonia is 220 ppm for 10 to 30 minutes, 160 ppm for one hour, or 110 ppm for four to eight hours. You, and your horse, exposed to ammonia fumes at these levels, can experience significant irritation of eyes and throat, and an increased urge to cough. You, and your horse, also are at risk for the health consequences of exposure to be irreversible, including the possibility that athletic ability and exercise tolerance will decline. If you, or your horse, have a pre-existing condition (including such things as dry eye, eye irritation, eye injury, eye infection, respiratory or skin allergies, asthma, bronchitis, heaves, or airway hypersensitivity), you can expect this level of exposure to make the condition you already have, worse.

AEGL-3 ammonia exposure is considered potentially lethal. It ranges from a high of 2,700 ppm for 10 minutes (which is associated with working in industrial chemical facilities and exposure to accidental chemical spills), to a low of 390 ppm for eight hours (which is very possible in a horse stall).

Remember, at floor level in many of the stalls in my veterinary rounds, measurements of ammonia levels were at 450 ppm. And, many horses spend far longer than eight hours in their stall in any 24-hour period, meaning they easily meet the criteria for AEGL-3 conditions and are at real risk. It’s worth pointing out that this level of exposure in a stable is not necessarily a take-five-steps-and-die kind of lethality. It’s more likely to cause health effects that can destroy an athlete’s future, cause a trail horse to cough at the slightest exertion and need rest stops to catch his breath and impair even a retired horse’s quality of life.

Where does the ammonia come from?

Ammonia itself isn’t actually present in the horse’s urine. Urine contains urea, which is a byproduct of the digestion and metabolism of protein in the horse’s diet. But urea is odourless. So where does the ammonia come from? From the breakdown of urea, which is done by various bacteria that happen to love urea as a food source. If it’s available to them, they’ll flourish on it. They’re equipped with an enzyme called urease which digests the urea and produces ammonia as a by-product.

But healthy urine is sterile. It doesn’t have bacteria in it. So where do those urea-digesting, ammonia-belching bacteria come from? They’re abundant in many substrates on the ground. If urea is regularly available to them, their originally small population there will explode, and the level of ammonia in the stable will intensify exponentially with every new “delivery” of urea-rich food (your horse’s urine).

Removing from the source

The only effective way to remove the harmful ammonia is to equip new or existing stables with a wall-to-wall, non-porous, seam-sealed and perimeter-sealed rubber mat such as ComfortStall from Haygain. ComfortStall installation resulted in a significant reduction in ammonia within a couple months of installing them over previously porous floors. It is the flooring of choice for Cornell University Veterinary Hospital, where over 1,000 horses a year recover from surgery on the system.

ComfortStall® is a stable flooring system that delivers comfort, healthier horses, better air quality and substantial cost savings. When compared to alternative bedding options, ComfortStall® boasts an impressive 10 benefits to the horse and owner, including the improvement of respiratory and joint health as well as the quality of rest, sees a return on investment of less than a year, requires substantially less bedding and reduces the chances of hock sores.

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