In parallel to conditions of the respiratory tract which are located in the upper body, the ammonia has an equally negative effect down below, in attacking the horse’s hooves. The gaseous ammonia which results from the horse’s urine by a process of natural biological decomposition combines with water on floor level and results in sal ammoniac. This equally corrosive liquid is viciously inimical to the equine foot.
The occurrence of many hoof diseases – like thrush, hoof abscesses and even hoof cancer – is encouraged by the horse’s feet coming into constant contact with the aggressive substance sal ammoniac!
The eroded surfaces of the horse’s hooves present less resistance to potential intruders, such as germs, spores and bacteria, than do uninjured and healthy surfaces. Thus pyogenic bacteria for instance find it much easier to penetrate the weakened corneal layer to reach the corium of the hoof, where the organism reacts and tries to expel the pathogen by producing pus. This results in a localised increase in the internal pressure beneath the horn capsula which eventually gives rise to severe lameness.
Here we can see that the quality of the litter in the horse box is an absolutely crucial factor. The litter should not only absorb the moisture coming from the horse completely, it must also store it irreversibly. If it can hamper the formation of ammonia as well, it already offers everything you need for a litter that will be really beneficial to equine health.
The material most commonly used for litter is straw. This absorbs liquid like a sponge.
In its dry state, straw can absorb liquid in large quantities. If wet straw is not removed from the stable, however, the natural decomposition of the urine gives rise to ammonia. This dissolves in the water stored in the straw (likewise originating from the horse’s urine), and becomes sal ammoniac.
As a result of the pressure of the horse’s hooves, the urine and sal ammoniac that have been absorbed may exude from the straw again. As a result, the horse ends up standing in a ‘bog’ made up of straw, water, urine and sal ammoniac. As more and more ammonia arises from the urine, the concentration of ammonia in the atmosphere surrounding the horse goes on increasing. This gives rise to climatic conditions which are highly unpleasant either for horses or for human beings, with the consequences we have described above. A further difficulty with straw, as a purely natural product, is that it is practically unavoidable that germs and spores of mould-generating fungi will be introduced to the horse stable along with the straw. These will find it all the easier to carry out their destructive work on the organs of the horse, which have already been seriously debilitated by the effects of ammonia and sal ammoniac.
For reasons which can easily be understood, the proportion of alternative types of litter on the market has increased enormously in recent years. Based on the frequency of occurrence, wood shavings are the most important, followed by other ‘exotic’ products like litters based on flax, hemp, rape and so on. The latter come with a relatively high price tag, and so have only achieved a modest degree of popularity. Wood shavings, on the other hand, have a market share of around 20%, giving this medium an established second place after the most popular alternative, straw.
Benefits of wood shavings when used as a horse bedding are thought to be the high degree of dryness they offer, along with the unique and outstandingly effective capacity of wood fibre to retain water.
Liquid that has once been absorbed, what is more, is no longer released under the pressure of the horse’s hooves. The ground remains dry until the wood fibres have reached the limits of their capacity. In the interior of the shavings, in what are known as the capillaries, the water is locked in almost irreversibly.
In view of the slightly acid character of the wood fibre, the release of ammonia in the process of urine decomposition is checked by a kind of chemical neutralisation. When stable maintenance is carried out on a more or less regular basis, the dreaded chronic obstructive pulmonary disorder can be completely ruled out.