Full Circles

It always amazes me how things go round in circles – what was fashionable thirty years ago is about to come back in style (so keep those psychedelic leg warmers, just in case) and it’s no different in the equine industry.

Ten years ago, maybe more, rubber matting was introduced to the bulk of equestrians. It’s non-slip, better for the legs than standing in concrete, and means you can use less bedding. It was the answer to all our questions, regardless of the question.

Now, however, new problems in equine care are coming to light.

I have become aware in recent years of an increased smell of ammonia at some stables, and I had assumed it was the fault of the stables – bad drainage, dirty bedding for example.

I read an interesting article last weekend from a vets, about the effects of the use of rubber matting in stable environments and the subsequent evolution from deep litter bedding to thinner beds.

With rubber mats, we’re encouraged to use less bedding, so when a horse urinates there is less bedding to soak up the liquid and the liquid runs down into the gap between the mats and sits between the mats and concrete floor, leading to the air becoming contaminated with ammonia gas. Bedding such as straw is not that absorbent so in order to be an effective bed it needs to be of a sufficient depth. Stables often have a slight slope to aid drainage, but the slope is usually insufficient to actually drain away much urine. So a combination of rubber mats trapping urine and insufficient bedding not absorbing it creates a urine “footprint” which releases ammonia gas.

But what’s the problem with ammonia gas in the stable? And how do you know if there’s a significant amount in the environment?

Firstly, as with humans, the gas is harmful to the respiratory system of the horse. The HSE has set out the following guidelines for the human workplace:

the maximum permitted 8-hour workplace exposure ammonia level for people at 25pmm.

However, the level of ammonia in stables can be as high as 250ppm, if not more. Apparently if you can clearly smell ammonia in a stable, or on your clothes after mucking out (there’s that standing joke about being the whiffy person in the supermarket after you’ve been mucking out) then the level is likely to be over 50ppm, which is deemed unsafe. When you consider that horses are in their stables for a minimum of sixteen hours a day in winter, and sometimes up to twenty four hours a day if they are on box rest, you can quite see that high levels of ammonia can cause damage to the respiratory system. High ammonia levels irritate the respiratory tract, which causes excess mucus to be produced which inhibits oxygen intake, which means that the horse will struggle to perform to the best of their ability. I think it could also be related to the development of COPD and other respiratory problems.

To overcome this problem, either the amount of ammonia production needs to be reduced, or the ventilation improved to reduce the concentration of ammonia in the stable air.

  1. Use more bedding. A thicker layer of bedding with a larger surface area will absorb more urine so less is converted into ammonia gas.
  2. Have natural floors to the stables, such as earth and clay. They will absorb excess liquid which will reduce the ammonia gas in the environment. I think this is probably the main reason I don’t remember the stables of my childhood being stinky; we had earth floors to many stables, as well as a deep litter system.
  3. Use more absorbent bedding. Personally, I find the best bedding is wood pellets, and when Otis was on box rest his stable was much drier, less smelly, and more economical when he was on wood pellets rather than shavings. If moving away from straw is too complicated, there is the option of using a more absorbent bedding underneath the straw. It is also vitally important to remove soiled bedding and to replace it with fresh bedding to minimise ammonia production.
  4. Remove the horse from the stable when mucking out. When wet bedding or floor is exposed, it raises the levels of ammonia in the air. This can take a couple of hours to settle, so it’s best to leave the stable empty for a couple of hours afterwards. If your horse is in an American Barn style yard, then there is the effects of neighbouring stables being nicked out whilst your horse is in his stable to be considered. I like to muck out my stables in the morning and leave any wet patches exposed so that they dry during the day and then set the bed down in the afternoon just before the horses come in.
  5. Use a stable disinfectant. A powdered stable disinfectant or powdered garden lime can be sprinkled on the exposed stable floor to inhibit the action of the bacteria which converts urea to ammonia.
  6. Lift the rubber mats regularly and disinfect under them to reduce the build up of urine.
  7. Ensure the rubber mats have minimal spaces between them: for example have the mats fitted to the stable and cut to size, seal between the mats when they are first laid. You can also have liquid rubber poured onto the stable floor which sets into one large solid mat.
  8. Ensure your horse isn’t receiving too much protein in their diet because an excess of protein results in more urea being excreted, thus resulting in more ammonia being produced.
  9. Improve ventilation by having two air inlets as far apart as possible to create a through flow of air. Windows can be opened, doors left open – with a stall guard securing the horse when they are supervised of course. Of course, if you are concerned about the air flow creating a draught and giving the horse a chill then firstly check how warm the horse actually is, and secondly put a thicker rug on them.
  10. Teach your horse to urinate on command. This means that you can either lead your horse to a patch of grass to urinate before going into their stable, or catch their urine in a bucket. My friend, who quite often brought Otis in for me, used to catch his pee in the skip bucket because he would perform every time he went into a bedded down stable. Obviously the more urine caught or done outside of the stable means less ammonia in the stable.
  11. Reducing the time spent in the stable, by increasing turnout as much as possible and grooming and tacking up outside the stable to ensure the horse is not exposed to high levels of ammonia for so long.

A lot of this stable hygiene is common sense, but I thought it was interesting that these problems have developed in recent years, and has been linked to a change in the way we bed our horses down and manage the stable environment. Whilst I think rubber mats still have a useful job, especially at the front of a stable where there tends to be no bedding and the horse will stand for long periods, it’s worth remembering that rubber mats don’t replace bedding and it is important to maintain high standards of cleanliness when mucking out.

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