ase and decrease in the secretion of horn from the coronet will bring
it about. Thus, in an animal at grass, with, according to the weather
conditions, an alternate moistness and dryness of the pasture, with its
consequent influence on the horn secretion, these rings nearly always
appear. The effects of repeated blisters to the coronet make themselves
apparent in the same way, and testify to the efficacy of blisters in this
region in any case where an increased growth of horn is deemed necessary.
From this it is clear that the condition depends primarily upon the
amount and condition of the blood supplied to the coronary cushion. Thus,
fluctuations in temperature during a long-continued fever, or the effects
of alternate heat and cold, or of healthy exercise alternated with
comparative idleness, will each rib the foot in much the same manner.

_Treatment_.--The condition is so simple that we may almost regard it
as normal. Consequently, treatment of any kind is superfluous. Where
constitutional disturbance is exerting an influence upon either the quality
or quantity of the blood directed to the part, then, of course, attention
must be paid to the disease from which it is arising.

F. THE HOOF WITH BAD HORN.

(_a_) THE BRITTLE HOOF.

_Definition_.--As the name indicates, we have in this condition an
abnormally dry state of the horn.

_Symptoms_.--These are obvious. The horn is hard, and when cut by the
farrier's tools gives the impression of being baked hard and stony, the
natural polish of the external layer is wanting, and there is present,
usually, a tendency to contracted heels. With the dryness is a liability to
fracture, especially at points where the shoe is attached by the nails.
As a consequence, the shoes are easily cast, leading to splits in the
direction of the horn fibres. These run dangerously near the sensitive
structures, giving rise in many cases to lameness. Even where pronounced
lameness is absent the action becomes short and 'groggy,' and the utmost
care is required in the shoeing to keep the animal at work.

_Causes_.--To a very great extent the condition is hereditary, and is
observed frequently in animals of the short, 'cobby' type. In ponies
bred in the Welsh and New Forest droves the condition is not uncommon,
especially in the smaller animals. Animals who have had their feet much
in water--as, for instance, those bred and reared on marshy soils--and
afterwards transferred to the constant