Causes: irritant gases, smoke, dry air, dust, pollen, microbes,
insects, seeds, chaff, awns, sand, dust, quicklime, coal dust, hairs,
whips, canes, branches, stubble, fences, nails, claws, teeth, iodine,
chlorine, bromine, formalin, turpentine, rain, hail, sleet, glare of
sun, ice, snow, white sand or clay, filaria, acari, infectious
diseases. Symptoms: closed lids, epiphora, redness diffuse on lids,
ramified on sclera, projected nictitans, milky flocculent discharge,
later purulent, matted lashes or tarsi. No photophobia. Fever
variable. Lesions: exudate: cell proliferation: papillæ enlarged:
desquamation: swollen lymphoid bodies: hyperplasia: abscess: ulcer.
Treatment: remove cause, sterilized syringing, antiseptic and
astringent collyria, sublimate, zinc sulphate, lead acetate,
pyoktannin, silver nitrate, morphia, atropia, cocaine, vaseline,
cupping, leeching.
Under this head may be noted the simple forms of conjunctival
inflammation, which result from direct injuries, irritant gases from
manure, smoke, very dry air, dust, pollen, and in which no specific nor
contagious element is a prominent feature. Strictly speaking, all
purulent conjunctivitis are probably infecting, as all may be held to be
associated with the presence of pus microbes. As early as 1864, de
Graefe said every inflammation of the conjunctiva which “secretes, is
inoculable and therefore transmissible,” and Warlomont concurs, saying
that “conjunctival ophthalmias have one character in common: all can
produce a secretory product which, when brought in contact with a sound
conjunctiva, is capable of provoking the different affections of this
mucosa.” The exposure of the conjunctiva of man and beast alike, to the
germs borne on the dust or carried in liquids or on solids, renders this
structure preëminently susceptible to infection, while the lachrymal and
mucous secretions furnish a favorable culture medium. Fortunately in the
lower animal the danger of infection is greatly reduced, since there are
comparatively few opportunities for the transference of the germ through
water, soap, sponge or towel, to which man is exposed, not only in
public lavatories but even in private families. Thus in the animal the
single case remains isolated and in a sense sporadic, only because there
have not been the means of transferring and inoculating the morbid
product.
_Causes._ The contact of mechanical and chemical irritants of all kinds,
insects, seeds of gramineæ, chaff, particles of fodders, barley and
other awns and spikes, grains of sand, dust, quicklime, coal dust,
smoke, hairs, blows with whips, canes, branches, stubble, fences, etc.
Also erosions caused by nails, claws, teeth, and by falls must be
considered.
Irritant gases and vapors whether from accumulation of manure in the
stables, or from chemical products of fires and factories are direct
causes. The mere exposure for some time to the warm, dry air from a
furnace is injurious to the mucosa, and the emanations from certain
medicines, iodine, chlorine, bromine, formaline, turpentine are strongly
irritant.
Exposure in a cold draught, or in a blast of cold rain or hail, or even
to a cold dry wind, in the case of hunting dogs working much in water,
are potent factors.
The glare of the sun through a window at the front of a stall, or from
a white surface of snow, ice or water or even from white sand, lime or
clay is an active cause. The overdraw check exposing the eyes directly
to the sun is often injurious. We must include the irritations caused
by the filaria lachrymalis and by various lesions already
described—trichiasis, entropion, ectropion, stenosis of the lachrymal
duct, etc.
In certain animals a distinct predisposition exists, often as the result
of a previous attack, and such are readily attacked under slight
disturbing causes.
It should not be forgotten that hyperæmia and even inflammation of the
conjunctiva, often accompanies different infective diseases—strangles,
influenza, contagious pneumonia, rinderpest, canine distemper, etc.
_Symptoms._ The discharge of tears and the closure more or less complete
of the eyelids are among the earliest and most marked symptoms. The
general conjunctiva is congested and that on the inner side of the lids
especially, so as often to hide the individual vessels, while on the
sclerotic portion they usually remain distinct, tortuous and freely
movable with the mucosa upon the sclera beneath. The membrane is more or
less infiltrated, swollen and opaque. In two or three days this has
increased so that the lids are visibly swollen, and completely closed,
or the paw is projected over the cornea. The discharge has become milky
or flocculent, and mats the cilia together, or holds the eyelids closed.
Unless the cornea has been directly injured it usually remains clear,
and there is no photophobia nor contraction of the pupil. The lids,
however, are tender and nervous animals show active resistance to any
attempt to examine the eye. In aggravated cases a free muco-purulent
discharge takes place, and the red, swollen mucosa projects between the
eye and the tarsus, constituting _chemosis_. In such circumstances the
inflammation may extend to the cornea causing opacity and photophobia or
to the iris and choroid or other deep-seated parts.
In the milder forms of the affection there may be little or no
hyperthermia, while in severe attacks the febrile reaction may be
considerable.
_Lesions._ The non-traumatic cases which are not complicated by varied
wounds and injuries, show exudation and cell proliferation in the
palpebral conjunctiva and to a less extent in the bulbar. The
conjunctival papillæ are swollen and become visible to the naked eye and
in aggravated cases stand out like fungous masses. The superficial layer
of cylindroid epithelium is found swollen, opaque and sometimes
desquamating. The lymphoid bodies which are most abundant in the depth
of the conjunctival sac, are infiltrated, swollen, and bulging in
reddened masses.
Other lesions in the nature of granular or follicular hyperplasia,
abscess and corneal new growth and ulcers may follow, but will be better
considered under separate headings.
The tendency of simple uncomplicated conjunctivitis is to recovery which
may be completed in a week or ten days. In case of contused wounds,
abscess, ulcer, special infection in a lymphatic subject like the ox,
the affection is more likely to be prolonged or followed by grave
lesions.
_Treatment._ The first object must be to remove the cause, hence foreign
bodies, displaced lids or cilia, irritant gases, excess of light, cold
draughts or exposure, etc., must be sought and corrected. For the
removal of the foreign bodies, fine forceps or various common articles
(hair pin, lead pencil, a pin head, a folded clean handkerchief, or even
the clean finger) may be used. In case of wounds especially, they should
be first sterilized. Boiled water which has been cooled to luke warm may
be used from a sterilized syringe.
Locally antiseptic and astringent collyria (sublimate solution—1:5000),
zinc sulphate—1:1000, lead acetate, alum, tannin, silver nitrate, etc.,
are valuable and may even be thrown under the eyelids from a syringe
with a finely rounded nozzle and many orifices. Even a 2 per cent.
solution of silver nitrate may be applied in the conjunctival sac twice
daily, or as being less irritating, a solution of pyoktannin (1:1000).
If the irritation is great a soft rag wet with the solution may be
attached to the headstall of the bridle and hung loosely over the eye,
care being taken to prevent drying. A few grains of morphia added to the
collyria will be specially soothing. Irrigation of the eyelids or
bathing for ten or fifteen minutes at a time with luke warm water, will
often greatly relieve. When the eyelids become agglutinated during sleep
or prolonged closure, as in the small animals, cleanse with a tepid
sublimate solution, and smear with vaseline. In severe cases local
depletion may be resorted to. The hair may be shaved off from an area of
2 inches below the orbit, and a cup applied for ten minutes.
Scarification may or may not be resorted to. Or a leech may be applied
to the same part.
A laxative often proves an excellent derivative especially useful in
costive conditions.