by Dr Derek Cuddeford, Royal (Dick) School of Veterinary Studies, University of Edinburgh
Old horses can run out of teeth before they run out of life! Horse teeth continuously grow and they have quite a lot of dental reserve but once this is used up we have a problem horse. Nearing the end of their growth phase the teeth are less well “rooted” and, as a result, teeth may actually fall out. So the first and probably the most critical issue is the status of the animal’s teeth. This requires a thorough examination by a veterinarian and corrective action taken if necessary. Key indicators of dental inadequacy is the animal dropping half-chewed food from its mouth as it eats (quidding) and whole cereal grains in the faeces together with long pieces of unchewed forage. Your veterinarian will decide if your horse can manage to chew its own food or, if you have to do that for it! During the summer your old horse will be eating grass, a soft, low fibre forage that is easily processed. However, in the winter period it will have to deal with conserved forages which are probably more fibrous and thus need more mouth processing. This being the case then haylages may be a better bet as they usually have a higher feed value than hay. Remember that improperly chewed forage is more likely to cause chokes or impactions. If the old nag still has some teeth get them inspected every 6 months and any corrective dentistry applied ASAP.
The extent of food processing that you have to do on behalf of your horse obviously depends on the state of your old horse’s teeth. Simple processing might mean chopping forage into short lengths or, if this is not possible, buy in a commercial chop. Proximity to a dairy or sheep farm where they feed precision-chopped silage to their animals might provide a ready source of excellent forage. If chewing is seriously compromised then I would purchase pre-ground forages that have subsequently been pelleted. Usually it is possible to buy hay cubes or alfalfa pellets. These are often very hard making them both unpalatable and too hard to chew. To overcome this difficulty soak in water-trial and error will give you the right proportions of each. Each horse is different and whilst one might prefer a light, fluffy concoction another may prefer a gruel that can be “slurped-up”. Soaked sugar beet is another option as it seems palatable, it is soft and I am reliably informed that it is easy to chew or “gum”.
It is essential with an inwintered old horse (how could anyone think of outwintering an old horse in the UK?) to regularly monitor bodyweight and condition (0-5)-ideally3. I know it is all the rage to “fat score” horses but subcutaneous fat on an old horse is a rarer find than a nun in a bikini. Usually it is hard to “hold condition” in old horses and forages are simply not good enough to supply all the protein and calories needed. This leads us inevitably to the conclusion that concentrates must be fed. Do not think that feeding cereals is alright because firstly the horse may not be able to process them properly and secondly, they are unbalanced and supply insufficient protein. This necessitates the use of manufactured feed. It is important to select a feed that has been micronized, extruded or steam-flaked since this means that the material will be highly digestible and thus nutrients will be fully available to the horse. Furthermore these products should be more easily mouth-processed. Assuming correct feeding protocols are in place, small meals should be fed and pre-soaked if necessary. Extruded feeds make a very good gruel after mixing with warm water which can be easily consumed. Steam-flaked and micronized feeds do not soak so well. Pellets are good for soaking because in order to make a pellet the raw materials must be ground into a grist prior to actual pelleting and thus the particulate matter is quite fine.
Provision of pre-processed food to a toothless geriatric is a great help but you must remember the horse has endured a lifetime of parasites so the old guts will not be in the best fettle; some parts may be extensively damaged. Thus absorptive capacity will be affected which might be evident if the horse is fed a ration deemed sufficient in terms of calories etc but it is slowly losing weight. A situation that may necessitate feeding more to compensate any reductions in digestive efficiency. There will, of course, be great individual variation in terms of losses in efficiency so careful monitoring is the watchword in each case. Apparently losses can be as high as 20% and it has been suggested that the large intestine is the worst affected.
Of the nutrients most affected it seems that fibre, phosphorus and protein are the ones to consider. As a result it has been suggested that fibre levels in the diet be reduced. Instead of the normal maintenance levels of protein (10-12%) it is recommended that the old horse be given a 14% protein with a minimum of 0.45% phosphorus and a calcium of between 0.6% and 1% in the ration. Feeding a lot of alfalfa is not recommended since calcium absorption seems unaffected by age and gut damage in contrast to phosphorus. If a lot of calcium is fed there may be a case for providing some bran. However, to avoid any difficulty over mixing and matching feeds there is a good case for buying a specialist “Senior Feed” or “Veteran Feed”. Difficulty in maintaining weight in an old horse/pony can be offset by the use of oil in the diet. As far as we know oil digestion and absorption is not negatively affected by age. Since oil contains so much energy (3x Digestible energy of oats) it can be top dressed on pellets (good softening effect) without creating a chewing challenge! If you replace conventional concentrate then less protein will be supplied. In order to maintain protein intake it may be necessary to feed some soya or similar protein source (NB. Alfalfa also supplies calcium as shown above).
Apart from phosphorus nothing is known about the metabolism of the other major and trace minerals in the old horse so for now, the usual data hold true. Of the vitamins one might suspect that the B group might need some supplementation as large intestinal function could well be compromised. A useful safeguard would be to feed a yeast product since it is a very good source of these B vitamins but it has also been established that certain yeast products assist large intestinal function so their usage creates a “win, win” situation. It has been suggested that the aged 450kg horse may benefit from 10g vitamin C twice daily. One would expect improved immune function amongst other things from this approach.
In conclusion, the old horse kept through the winter will, in many cases, share the same problems as one kept outside during the summer. In the latter situation grass can be the major feed component but of course in winter only conserved forages are available which in most cases are harder to process. Comments have been made above on the special needs of the aged horse which can present owners with some difficulties in practical terms although the availability of specialised products for the senior/veteran horse eases the burden of care.