by Ben Sturgeon, Bsc, BVM&S, Cert EP, MRCVS
An apt subject given perhaps the indulgences this time of year? I’m sure we’re all feeling a little worse for wear? Whilst it is common knowledge as to the dangers of obesity in equids with laminitis being the number one complication. That this still remains difficult to treat, presents long term recurrence and management issues and is a welfare and ethical issue for chronically lame horses and ponies living a life of virtual starvation and exercise intolerance is or should be warning enough. It is the converse however, that we are starting to see increasingly and especially over the winter periods. This is compounded somewhat, although by no means a complaint, by the fact that our animals are definitely living longer so we are witnessing diseases and conditions of degeneration and chronic deterioration. These latter presentations can often be extremely difficult to effectively treat, with the initiating changes long since passed or the repeated small insult developing into a situation where major changes have now arisen due to the overall accumulation.
The first example of this is in dental disease, still the number one cause of poor condition, lack of condition or of weight loss. The equid’s jaw is classified as hypsodont, wider on the top than the bottom, and combined with the modern diet incorporating less fibre and increased concentrate means that the simple action of chewing is reduced. This quite naturally results in the emergence of small and sharp enamel overgrowths which will cause cheek or tongue lacerations and ulcers. With more time and increasing size of the overgrowths the mechanical action of the opposing maxilla and mandible will become affected with a “shear mouth”. The loss of the “prehensive” phase of digestion will obviously impact upon weight and condition and can also predispose to colic due to the lack of digestive efficiency.
If the horse has a compounding condition such as a parrot mouth or sow mouth, fractured, extra-numary (extra-teeth), or maleruptions then the emergence of the overgrowths will be more extreme. The overgrowths however can and should be dealt with early and simply with routine rasping, the frequency of which will depend on the level of oral abnormalities found. Of greater difficulty is the treatment of a very common oral condition in weight loss cases, diastema, or “gaps” between the teeth. The incidence of these diastema is high and in some horses, run between every tooth. These can be developmental and disappear with age and tooth eruption but in many cases they are permanent. The gaps allow the packing of food material and a subsequent gingivitis leading to recession and even bone involvement. Therapy is dependent upon the severity and is requires frequent re-evaluations. Diet changes are recommended but the exact diet (to reduce food packing) is controversial with some recommending short chopped feed and others longer fibre, experimentation is necessary. Removal of the food is always helpful but brushing a horses’ teeth is not easy!
Training the horse to accept a hose pipe wash out can be done but often management will not truly aid the problems. Again routine examination and rasping should identify the problem, removal of overlying overgrowths called “transverse ridges” is the mainstay in early cases, if it is more advanced (grade 2) food removal, vigorous cleaning of the gingival margins for a few days before packing with dental glues is the norm although the various packing materials are all temporary and rarely last beyond three months. For more advanced (grade 3) cases widening of the gaps to encourage less food impaction can be done although practically difficult in some smaller mouths, followed lastly by dental extraction where bone involvement is recorded and dental pain evident.
Management is in my experience number two one the list. This does not mean abject idiocy but failure to recognise a change in field and population dynamics. Old or young horses are often down the dominance pecking order and so lose out on feeding opportunities. Where compounded by common dental changes the older horse also requires a significantly longer time to feed or have access to feed and in a field situation this can be lost with more aggressive field maters. This should also serve as a reminder that such horses will often “do” better on a more frequent feeding protocol utilising smaller feeds incorporating highly and easily digestible feed stuffs fed perhaps 3-4 times daily rather than in one or two larger feeds. The simple addition of oil (a calorie dense, easily prehensible and digestible, and cheap option) can often provide excellent results in these animals.
Parasitism can never be ruled out in any case. This could be despite the fact that worm egg counts are low as the results depend upon the technique used with most only detecting large strongyles rather than the more injurious cyathostomes and tapeworms. Additionally, it is recognised that the small red worm can remain in hibernation for several years, resulting in a low or zero faecal egg count. This is the reason a modern worming protocol will still advocate use of anthelmintics for the encysted cyathostomes and tapeworms at least once during the winter period to deal with any in that category. Of course worm damage can be present within a gut despite worm management, a large burden as a youngster can have consequences much later in life. Of more concern though is the possibility that if indeed you do find high faecal egg counts, that you have a resistance problem to the drugs used or that you are using them ineffectively (under-dosing being commonest). This should always be discussed if you find your horse has repeated high counts.
Metabolic conditions such as Cushings disease are always a consideration where the horse has lost muscle, has a pot bellied appearance or more commonly shows evidence of laminitis, hirsutism, recurrent infections, changes in mentation, excessive drinking &/or urination. Whilst the condition tends to be in the older animal cases have been recorded in animals as young as 4 years of age. Although not every horse should be blood sampled for Cushings where weight loss is evident, the failure to maintain condition especially in the face of potentially more subtle signs should give cause for thought.
Abdominal disease is lower on the list of differentials. Inflammatory bowel disease and liver disease are commonest with the former being recognised more in middle aged horses and the latter in much older animals or those in very poor grazing where hepatotoxic plants such as ragwort are eaten. Conditions such as kidney disease, peritonitis or abdominal tumour formation, whilst recorded, are rare.
Lastly infectious or inflammatory conditions should be considered. Any chronic condition such as recurrent airway obstruction, especially if deteriorating will impact upon the metabolic status of the animal. Infections such as Anaplasma and even widespread skin conditions such as rain scald, mud fever and Staphylococcus Aureus have much the same influence.
In short then the horse or pony in a poor condition can have a multiplicity of possibilities. It can be very difficult to accurately diagnose the causal relationship because for example, with dental treatment, the result will only be seen a few months later. As a result the diagnostic and therapeutic approach tends to be more scatter gun, ruling out more sinister conditions and treating the more common ailments irrespective of their exact level of significance. This combined with a review of the management and feeding protocols usually results in a good response although only after an acceptable period of recovery.