The chief _causes_ are exposure to wet and cold and especially when the
subject is exhausted and the skin relaxed and covered with perspiration.
In these circumstances a piercing wind, a cold drizzling rain, or a
draught in the stable is particularly dangerous. Sudden alternations of
temperature and especially a change to a warm stable when the general
effect is aggravated by the impurity of the atmosphere and the irritant
emanations from dung and urine. Damp climates are more injurious than
those that are clear, dry, and bracing, and so are equally damp stables
whether the moisture is due to the nature of the soil, such as a cold
impervious and undrained clay, or of the building which, from its
newness, may retain a dangerous amount of moisture in the plaster, or
because of the hygroscopic properties of the building materials which
draw moisture from the surrounding soil. It mainly attacks young horses
after they have passed out of the hands of the breeder or dealer, and
have been placed in new conditions of life alike as regards feeding,
stabling and work. Old and ill-conditioned animals are more susceptible
than the strong and vigorous, and the changes of the coat in spring and
autumn prove strong predisposing causes. Nervous causes are potent in
causing engorgement of the erectile tissue covering the turbinated
bones, and local irritants, like septic dust, lime, ipecacuanha, pollen
of certain plants, smoke, and irritating fogs may precipitate it. Iodine
in large doses produces temporary catarrh. The weakness of the mucosa
from a previous attack predisposes to a second. Occasionally the disease
sweeps over a country, assuming the form of an _epizootic_ when it may
perhaps be preferably considered as a catarrhal fever, strangles or mild
type of _influenza_, _which see_.
_Symptoms._ In the _milder forms_ of _coryza_ the symptoms may be almost
exclusively local, consisting in redness and dryness of the membrane
lining the nose and sneezing, soon followed by the bilateral discharge
of a thin transparent watery liquid, succeeded by a turbid flow
(epithelial cells in excess) and after two or three days by a thick,
white, flocculent, puriform fluid (suppuration diapedesis). With the
supervention of the purulent discharge, comes an abatement of the local
inflammation and the freer the discharge the greater usually is the
relief obtained and the more rapid the recovery. The eyes are usually
red and watery and sometimes the eyelids are swollen. This implies the
continuity of the inflammation through the lachrymo-nasal duct, and the
obstruction to the flow of tears into the nose.
When _constitutional disturbance_ exists a rough or staring coat appears
as one of the first symptoms, the sneezing is more violent, the nasal
mucous membrane is more reddened and swollen, the eyes more dull, sunken
and watery, the mouth hot and clammy, the temperature of the body
raised, the pulse more frequent and having a sharper beat, the impulse
of the heart may often be felt by applying the hand to the chest just
behind the left elbow, the appetite is fastidious and the secretions of
the bowels and kidneys are diminished, the latter being denser and more
highly colored, from the absorption of irritating or infecting matters
the glands under the throat are swollen and the swelling of the mucous
membrane may be such as to impair breathing and even to threaten
suffocation. In severe cases in which the inflammation extends to the
nasal sinuses there is heat and tenderness over the forehead and the
pain and weight are manifested by the pendent head and the red sunken,
watery eyes and tumefied eyelids. When it extends to the throat, the
cough, the difficulty in swallowing and the local tenderness on handling
are characteristic.
_Course._ With the occurrence of suppuration, improvement commences and
if the inflammation does not extend beyond the nasal chambers, and if it
is not kept up by a repetition or continuance of the cause the disease
will have terminated in recovery in eight or ten days. For ulterior
consequences in bad cases see _chronic catarrh_, _conjunctivitis_,
_abscess of the nasal sinuses_, _laryngitis_, _stomatitis_,
_staphylitis_.
_Treatment._ In slight cases the simplest treatment only is required.
Place the animal in a dry, airy, loose box, clear of draughts, and with
uniform temperature of 55° to 60° Fah., if obtainable. In the cold
season blanket warmly, and hand-rub and loosely flannel bandage the
legs. Feed on sloppy bran mashes only and add half an ounce to an ounce
of powdered nitrate of potash daily. Give fresh water _ad libitum_,
solicit the action of the bowels by giving injections of warm water
three times a day, and encourage the nasal discharge by causing the
patient to inhale steam for half an hour or an hour twice daily. This
may be done by giving scalded bran in a nose-bag or by keeping the head
over a bucket containing hay with boiling water poured over it, the
steam being meanwhile directed by a bag open at both ends one of which
is fixed around the animal’s nose and the other round the mouth of the
bucket. As a local astringent, tonic and antiseptic the fumes of sulphur
(burned behind the animal and no more concentrated than can be breathed
with comfort) will do much to cut short the attack. It is more soothing
if combined with steam. Shut doors and windows, add a few drops of
alcohol to some pinches of sulphur and burn on paper laid on a clean
shovel or piece of sheet iron. When enough has been used extinguish by
covering with a cup or other object. Repeat several times a day. Under
this treatment recovery may be completed in three or four days.
In severe cases attended with fever, besides the above a dose of
laxative medicine may be given (three or four drachms of aloes), with
this precaution, that if the fever is of a low type or the malady
epizootic, half the dose only can be safely allowed (2 dr.) on account
of the danger of superpurgation. The nostrils must be more assiduously
steamed and linseed tea may advantageously replace fresh water as a
beverage. If there is much swelling and tenderness of the glands a
poultice should be applied to the throat and between the jaws, and
sulphur fumes as advised above, or anodyne astringent insufflation
powder may be resorted to. Morphia chlorate two grains, bismuth nitrate,
six drachms and finely powdered gum arabic three drachms may be blown
into the nostril during inspiration, or the astringent anodyne injection
advised below for chronic catarrh may be used. Cocaine spray is often
very helpful, or the same agent may be used in the liquid form on cotton
wool inserted in the nasal chamber. If this is without effect a weak
continuous current of electricity will cause constriction and give
prompt relief. It may be repeated every few hours. In the absence of
this the emanations from a weak solution of ammonia or from carbonate of
ammonia may be used. In cases with excessive and persistent
muco-purulent discharge, with presumptive infection from outside
sources, or in the young, from the diseased maternal passages,
insufflation with calomel, painting with a two grains to the ounce
solution of nitrate of silver, or injection with some other germicide
may be resorted to.
In case the fever is of a low type, liquor of the acetate of ammonia (4
ozs.), salammoniac (¼ oz.), or even carbonate of ammonia (½ oz.), may be
given several times a day, with sweet spirits of nitre (½ oz.) and
tincture of gentian (1 oz.) Alcoholic stimulants are often used.
Inhalations of iodine and iodide of potassium with ether and chloroform
are often successful.