_Causes._ These may be classed as mechanical, chemical, microbian and
other irritants. In the horse it is often due to the reckless
administration of irritant liquids as remedies. Owing to the length of
the soft palate the horse can refuse to swallow any liquid as long as he
chooses, and some of the worst cases of stomatitis I have seen resulted
from the retention in the mouth of caustic alkaline liquids given under
the name of “_weak lye_.” Strong acids and caustic salts dissolved in
too little water or other excipient, or suspended in liquids in which
they cannot dissolve, or made into boluses which are crushed between the
teeth are not infrequent conditions. Too hot mashes given to a hungry
horse is another cause of this trouble. Fermented or decomposed food is
often most irritating. Coachmen will sometimes induce it by attaching to
the bit bags of spicy or irritant agents, to cause frothing and make the
animal appear spirited.
Fungi in fodders are among the common causes. The rust of wheat
(puccinia graminis), the caries of wheat (tilletia caries), the blight
(erysiphe communis), ergot (claviceps purpurea), the fungus of rape
(polydesmus excitiosus) and the moulds (penicillium and puccinia) have
all been noticed to coincide with stomatitis, and charged with producing
it. On the other hand, at given times, one or other of these cryptogams
has been present extensively in the fodder without any visible resultant
stomatitis. The apparent paradox may be explained by the fact that these
fungi vary greatly in the irritant or harmless nature of their products
according to the conditions under which they have grown, and the stage
of their development at which they were secured and preserved. Ergot
notoriously differs in strength in different years, on different soils,
under various degrees of sunshine, shade, cloud, fog, etc. In different
States in the Mississippi valley it is not uncommon to find stomatitis
in horses in winter, fed on ergoted hay, while cattle devouring the same
fodder have dry gangrene of feet, tail and ears. Yet in other seasons
the ergot fails to produce these lesions. Rank grown, watery vegetation,
especially if it contains an excess of chlorophyll is liable to cause
stomatitis. Red and white clover, trefoil, hybrid and purple clover, and
alfalfa have all acted more or less in this way, though in many cases,
the food has become musty or attacked by bacterial ferments. Some of the
strongly aromatic plants, and those containing acrid principles (cicuta
virosa, œnanthe crocata, mustard, etc.) cause buccal inflammation and
salivation.
The irritation in many such cases is not due to one agent only, the
vegetable or other irritant may be the starting point, acting but as a
temporary irritant, the action of which is supplemented and aggravated
by the subsequent attacks of bacterial ferments on the inflamed,
weakened or abraded tissues. The bacteria present in the mouth, food or
water would have had no effect whatever upon the healthy mucosa, while
they make serious inroads on the diseased. On the other hand the
vegetable, mechanical or chemical irritant would have had but a
transient effect, but for the supplementary action of the bacteria.
In horses that have the bad habit of retaining masses of half masticated
food in the cheeks the growth of cryptogams is greatly enhanced and such
food often becomes violently irritating.
Among other mechanical causes may be named pointed or barbed hairs or
spines (barley awns, spikes, thorns, etc.) which, lodging in a gland
orifice, or in a wound of the gum or mucosa, form a source of irritation
or a centre for bacterial growth and abscess.
Again, irritants of animal origin must be named. These are not taken by
choice, but when lodged in fodder, or in the pastures they are taken in
inadvertently with the food. In this way poisonous insects, and
especially hairy caterpillars, cantharides, potato bugs, etc., gain
access to the mouth.
It must not be overlooked that stomatitis occurs as an extension,
sympathetic affection or sequel of diseases of other organs. Gastritis
is usually attended by redness and congestive tenderness of the tongue,
especially of the tip and margins, and other parts of the buccal mucosa,
notably the palate just back of the incisors, are often involved. In
other cases it appears as a complication of pharyngitis, laryngitis, of
affections of the lower air passages, of the teeth and periodontal
membrane or of the salivary glands.
It appears also in a specific form in certain fevers, as in horsepox,
pustulous stomatitis, aphthous fever and even in strangles. Mercurial
stomatitis, rarely seen at the present time, is one of the worst forms
of the disease, and like the infectious forms will be treated
separately.
_Lesions and Symptoms._ At the outset and in the slighter forms of
congestion there is merely heat and dryness of the buccal mucosa.
Redness may show on the thinner and more delicate portions of the
membrane, as under the tongue, on the frænum, and on the sublingual
crest. But elsewhere it is hidden by the thickness of the epithelium,
and the manifestations are merely those of suppressed secretion with
local hyperthermia.
As the congestion is increased there is seen, even at this early stage,
a slight thickening or tumefaction of the mucosa, especially on the
gums, lips, the sublingual area, the orifices of the salivary glands,
and the palate back of the upper incisors. On the dorsum of the tongue,
the cheeks and lips, generally the lack of loose connective tissue tends
to prevent the swelling.
With the advance of the inflammation the redness of the mucosa extends,
at first in points and circumscribed patches, and later over the entire
surface. The epithelium drying and degenerating in its surface layers
forms with the mucus a sticky gummy film on the surface, which, mingling
with decomposing alimentary matters gives out a heavy, offensive or even
fœtid odor.
The different parts of the mouth are now tender to the touch, and this,
with the fœtor and even bitterness of the bacterial products combine
with the general systemic disturbance in impairing or abolishing
appetite. In any case mastication becomes slow and infrequent, and
morsels of food are the more likely to be retained, to aggravate the
local condition by their decomposition.
The dry stage is followed by the period of hypersecretion, and in this
the salivary glands take a prominent part, so that ptyalism (slobbering)
becomes the most marked feature of the disease. The saliva mixed with
the increasing secretion of mucus and the abundance of proliferating and
shedding epithelium, escapes from the lips and falls in stringy masses
in the manger and front of the stall. When there is much motion of the
jaws and tongue it accumulates as a froth around the lips.
A careful examination of the mucosa will sometimes detect slight conical
elevations with red areolæ, representing the tumefied orifices of the
obstructed mucous follicles, and later these may show as minute
erosions. Even vesicles have been noticed (Weber, Dieckerhoff, Kosters),
but when these are present one should carefully exclude the specific
stomatites such as horsepox, contagious pustular stomatitis, aphthous
fever, etc.
Erosions of the mucosa and desquamation of the epithelium have been
noticed in horses fed on purple (hybrid) clover, buckwheat or ergot, and
in some of these cases the inflammation has extended (in white faces
especially) to the skin of the face, the mucosa of the nose, and the
adjacent glands, and as complications icterus, constipation, colics,
polyuria, albuminuria and paresis of the hind limbs have been observed.
These latter are common symptoms of cryptogamic poisoning.
_Prognosis._ In uncomplicated cases the disease is not a grave one,
lasting only during the continued application of the local irritant, and
recovering more or less speedily when that has been removed.
Complications are dangerous only when due to some specific disease
poison (glanders, actinomycosis, strangles, etc.), and even poisoning by
the usual cryptogams of leafy or musty plants is rarely persistent in
its effects.
_Treatment._ This resolves itself into the removal of the irritant cause
and the soothing of the irritation. When the cause has been definitely
ascertained the first step is easy.
In the direction of soothing treatment, a careful selection of diet
stands first. Fibrous hay and even hard oats, barley or corn may have to
be withheld, and green food, or better still, bran mashes, gruels,
pulped roots or fruits allowed. Scalded hay or oats, ensilage, sliced
roots, or ground feed may often be taken readily when the same aliments
in their natural condition would be rejected or eaten sparingly.
Medicinal treatment may often be given in the drinking water which
should always be allowed in abundance, pure and clean. In the way of
medication chlorate of potash, not to exceed one-half to one ounce per
day according to the size of the animal, may be added, together with an
antiseptic (carbolic acid, borax, permanganate of potash, common salt,
naphthol, creolin, hyposulphite of soda). In case of severe swelling, a
cap made to fit the head with strips wet in alum and vinegar or other
astringent solution maintained against the intermaxillary space may be
desirable. Support for the tongue may be necessary as mentioned under
glossitis.
In case of complications on the side of the bowels, liver or kidneys,
laxatives, diuretics and antiseptic agents may be called for.