Trimming donkeys feet

J. FOWLER

Wiscombe Grange, Southleigh, Colyton, Devon EX 13

INTRODUCTION

The primary objective in trimming the equine foot is to encourage efficient and comfortable locomotion for the animal, at the same time ensuring that any growth of hoof and wear from usage does not distort the hoof from acceptable parameters between one routine trimming and thenext.

The majority of donkeys in the UKare not, and do not need to be, shod. They produce hoof in sufficient quantity and quality to cope unshod with regular work, evenonmetalled(gravelled) roads.

Trimming, rather than shoeing, is therefore the more common practice. Donkeys who do little work will grow surplus unused hoof and need trimming just as often as their hard working brethren.

Monthly attention is ideal: intervals of 6 weeks should be considered the maximum limit. Trimming the feet should be carried out to the following criteria and each criterion assessed and
implemented in the following order.

1. Angle of incidence with ground

In general terms, donkey feet are between 5o and 10o more upright than horses feet.  However, each individual donkey deserves its own assessment.

The angle of the finished foot should produce a straight (unbroken) hoof pastern axis (Fig 1).  In the healthy donkey which receives regular routine trimming. There is a parallel relationship between the following:

 anterior profile of hoof wall.
 anterior profile of pedal bone (P3).  hoof pastern axis (PI -P2-P3).  spine of scapula.

Therefore, by palpating the pastern and the spine of the scapula with the donkey standing 4-square, the desirable angle can be assessed.  To those unfamiliar with the technique, it may help at this point to chalk or scratch a ‘ground angle’ onto the hoof.

2. Length of foot
           
The ‘rule of  thumb’ guide is literally a ‘rule of thumb’ pressure.

The sole should be trimmed in increments of about 0.25 cm (less as the desired overall shape is achieved). As each increment is removed, apply vigorous thumb pressure to the sole.  At the slightest sign of ‘give’ (i.e. ability to depress) the shortest length has been achieved. The sole should still be about 1cm thick.
           
            Always trim the sole first, for each increment, followed by the occlusal surface of the hoot wall, always keeping parallel to the ‘ground angle’ (Fig 2).

            When the sole has received its last incremental trim (i.e. ‘give’ just detectable) the hoof wall can be finally rasped to match.

The outer perimeter of the hoof wall edge should be bevelled with the fine side of the rasp to prevent splitting.  At this point, it will be seen that H (vertical height of highest point of coronary bond) will be less than L (length of fore-to-aft occlusal surface) (Fig 3).       

The most distal laminal rings on the outer surface of the hoof wall should now achieve a very fine angle of incidence with the ground.
           
It will also be noticed that the donkey’s foot, seen in profile, is a quadrilateral structure with a distinct heel buttress.

If we now examine the weight bearing surface of the foot, further criteria  need attention.

3. Shape of sole

The occlusal surface (sole) of the foot is distinctly U-shaped, often with a slight flare to the heels.  The hoof wall should be approximately the same thickness at the toe and sides.
           
Approximately one third of the true sole (the anterior third) should be in contact with the ground.

The white line (which is only white when freshly cut or rasped) should be uniformly 1 mm width.  Stretching of the white line indicates either disease (e.g. laminitis) or abnormal weight bearing of that part of the hoof wall adjacent to the stretched white line which in turn indicates a need for remedial shaping of that area.

The frog groove must be trimmed open, so that a pencil could be laid in it.  Occluded frog grooves harbour dirt and bacteria and eventually may facilitate bacterial necrosis of both frog and sole.

Similarly, the frog cleft should be opened in a V-shape to facilitate self-cleansing.

If the donkey is to spend  much of its time in muddy conditions, or on ‘deep litter’ type bedding, then the return bars should be trimmed flush with the sole.  Conversely, if the donkey will be working regularly on hard surfaces, (e.g. a driving donkey) the bars should be left level with the heel hoof wall (Fig 4).

AN APPROACH TO CORRECTING GROSSLY OVERGROWN FEET

If a donkey’s feet are left untrimmed for long enough, the foot becomes so long it becomes unstable and overbalances.  This forces the phalangeal joints into hyperextension.

However, because hoof is a dynamic, pliable substance, it responds to the unusual forces by distorting into a curved or corkscrew shape (Fig 5).

Weight is now taken on the heels, which collapse inwards, encircling the unused sole and frog.  The latter grow as a core within the tube of hoof.

The author’s contention is that, if new hoof is to grow in a natural shape, all distorting forces must be immediately removed.

This can be done by applying a ‘blue print’ of a correct shape over the distorted foot. 

One ‘saving grace’ helps us in this.  The extensor process of the third phalanx (pyramidal process of pedal bone)  nearly always remains in the same spacial relationship to the anterior par of the coronary band (if in doubt perform x-ray).  Therefore, the coronary band becomes the datum line to our ‘blue print’. 

All hoof tissue outside the ‘blue print’ should be cut away in increments, as per normal hoof trimming - see above.

During the original process of distortion, many blood  vessels will have ruptured, leaving bright pink / blue staining in the hoof substance.

The veterinarian must have enough confidence in his knowledge of anatomy and in his own technique to realize that this staining does not signify currently sensitive tissue (Fig. 6).

As can be seen from Figure 6, the distortion of the hoof wall includes much tearing of the laminal band between wall and pedal bone (P3).  This may leave a void, or the void may be fille with amorphous hoof substance.  The area may have to be exposed in the remedial process (and require constant cleaning and dressing until the hoof has regrown).  Great care must be taken to avoid rasping, or otherwise abusing, the laminal remnants on the pedal bone.

The final effect will probably look like that in Figure 7.  The exposed laminal area will soon be grown over.  The donkey will adjust immediately to a proper foot stance, unless the deformity has been present for so many years that joint remodelling has occurred ( Figs 8a,b, and c).

ACKNOWLEDGEMENTS                                        

This technique was refined, tried and tested during the author’s tenure as Senior Veterinary Surgeon to the Donkey Sanctuary, Sidmouth, Devon.

Much help and encouragement was received from the late Cristopher Budge, MRCVS and T. F. Williams, FWCF  of the Hereford School of Farriery.

Editor’s Note:  This article is reprinted from a handout given to participants at the Pearls of Wisdom Workshop by Dr. Suzy Burnham, DVM.

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