The Grange advance. [volume] (Red Wing, Minn.) 1873-1877, 1877-02-14
House, Farm and Garden.
Blindness Among Sheep.

sheep in the United States may be af.
fected by disease we have nomeans of
ascertaining, but that they are not
wholly free from eye diseases is pref
ty we'll known to most sheep breeders.
The English Agricultural Gazette, in
referring to what is technically called
"blinds," among sheep, says that it
sometimes occurs as an epizootic, but
more frequently appears here and
there, attacks a few animals of the
flock, affording in it's rise and progress
no indications which assist the in.
quirer in his search for the causes of
the malady. 1t has long since been
remarked that sheep are peculiarly
subject to inflammation of the mem.
brane which covers the front of the
eye and lines the eye]ids (conjunc-
tiva).
Youatt, in his well-known work on
the sheep, published nearly 40 years
ago, remarks on this tendency, and
adds that the disease commonly goes
on to blindness. Several diseases of the
eye, as ophthalmia, cataract, and loss
of nervous power, are all crowded in
one description as causes of blindness;
but there is no doubt that the affec-
ton which Youatt refers to as inf1am-
nation of the conjunctiva, is closely
allied to, if not identical with the dis
ease which, in the present day, is
known by the term ''blinds,'' or, in
scientific language, opacity of the cor
nea.
In the early stages of the affection
the symptoms are not very marked,
and it is not probable that the shep.
herd will suspect anything wrong un.
til it has so far advanced as to inter.
fere with the animals vision, and cause
it to blunder in travelling. A small
spot OF opacity first appears nearly
in the center of the cornea as in many
cases, and from this point the white
cloud gradually spreads until the entire
surface of the cornea is covered and
the sheep becomes totally blind.
Opacity of the cornea is frequently
associated with Inflammation of the
membrane of the eyelid, and a puru-
lent discharge issues from the eyes,
often causing their lids to adhere to-
gether; this affection is. however, quite
distinct from the one above described
it is, in fact, ordinary ophthalmia,
and it's spreading among the flock leads
to a suspicion of infection; there is no
doubt that the discharge from the eyes
in ophthalmia of the human subject is
charged with injecting matter in a
high degree, and it is not unlikely that
the same characteristic may belong to
the disease in the sheep; but in the
case Of simple opacity of cornea, I'm.
accompanied with discharge, there is
no ground for refer, ing the spreading
of the disease to infection.
Many speculations have been ad.
vanced to account for the appearance
of the "blinds'' in flock. The affec
ton is more common during a hot
summer than any other time, and
therefore it has been assumed that the
rays of the sun, reflected from the
hard and heated ground, have caused
inflammation.
Attacks have occurred under exactly
opposite conditions, during the pre-
valence of cold winds and rain, anC
the sheep which have been kept il
the most exposed situations suffer
most severely but there remains the
probability that the disease which oc
ours under the latter conditions is
more allied to opthalmia, than to thu
peculiar disease which commences BY
white speck in the center of the eye
Another explanation of the occur
renee has been offered. The appear
ance of minute point of opacity il
the first instance has led to the sug
gestion that one of the gadAy family
has deposited an egg in this situation
in the same way that it often does OF
the skin and other parts of animals
and the prevalence of the disease in
the summer months gives color to thi.
suspicion. 1t has been asked, in re.
ference to this theory, why the mat
ter has not been decided by the aid OF
the micrOScOna hut tho anou,or hoe
always been ready. In very rare
cases is the affection detected in the
fret ctane 1uhan it is tho auo aonno