Causes, mechanical, cold, irritants, extension, diet, close stables,
infectious disease. Symptoms of acute form, head extended, throat
swollen, tender larynx, cough, in early stage, after exudation,
wheezing in inspiration, dysphagia, fever, œdena glottidis, spasms,
dyspnœa, successive discharges. Lesions, tumefaction, softening,
friability, redness (ramified or not), erosions of mucosa, œdema.
Course, duration, sequelæ, cough, roaring. Subacute form, chronic
form, in old debilitated animals, in those reined too tightly, in
those which perspire with difficulty or bear heavy coats. Symptoms,
local, in breathing, cough, effect of cold air, or water or of dust.
Sequelæ, ossified cartilages, roaring, emphysema, bronchiectasis.
Treatment, hygienic, soothing, sheepskin, compress, poultice, mustard,
sulphur dioxide, laxative, neutral salts, expectorant, sedative,
derivative, tracheotomy, with trochar and cannula, with scalpel,
tracheotomy tubes. Insufflation, injection. In chronic laryngitis,
electuaries, mustard, derivatives, astringents, caustics, tonic
inhalations.
_Causes._ These are the ordinary causes of chest diseases. As special
causes may be noted severe compression of the larynx as in roughly and
repeatedly _coughing_ an animal; the sudden contact of piercing cold
air, of irritant gases, powders or liquids with the membrane, and the
rapid, forcible and continuous current of condensed air through the
glottis during severe exertion.
Among the general causes the most fruitful are the high feeding, hot,
close stables, heats and chills, and other circumstances attendant on
domestication. Laryngitis may be an extension from coryza, pharyngitis,
bronchitis or pneumonia. It may further be but a local manifestation of
influenza or strangles, contagious pneumonia, etc. The disease is
_acute_, _subacute_, or _chronic_.
_Symptoms of acute form._ All acquainted with horses can recognize the
general symptoms of sore throat. The nose is elevated and protruded to
avoid compression of the larynx; it is carried stiffly for the same
reason. There is some swelling around the throat or beneath the root of
the ears. If the cartilages of the larynx are compressed between the
finger and thumb, or if pressure is made in the median line below upon
the connecting crico-thyroid membrane the patient instantly coughs and
throws up the head to avoid a repetition of the suffering. This
tenderness of the larynx to touch is peculiar to laryngitis and serves
to distinguish it from pharyngitis. The cough is at first very hard and
painful and only gives way to a soft mucous type when a free mucous
exudation puts an end to the tense, thickened and dry state of the
mucous membrane. The inspiratory act is accompanied by a whistling or
deep bass sound, particularly after the slightest exertion. This may be
heard at times during expiration as well, though not invariably so.
Sometimes the animal drops the food from his mouth after mastication,
because of the pain attendant on swallowing, but this is really a
symptom of coexisting pharyngitis, and its absence implies the
nonexistence of that complication. There is usually a slight pasty
swelling between the branches of the lower jaw.
There are besides the general symptoms of fever more or less marked,
such as increased temperature, accelerated pulse, red injected eyes and
nose, slightly hastened breathing, the expiration being effected by a
double lifting of the flank as in broken wind, etc.
In two or three days in favorable cases exudation takes place from the
mucous membrane, the cough becomes softer and less frequent, the local
tenderness decreases and the general symptoms subside.
If otherwise the symptoms may become more intense, and breathing may get
loud and difficult in connection with thickening and rigidity of the
mucous membrane, or a serous exudation into it and beneath it (œdema
glottidis) which by closing the glottis renders breathing almost
impossible. The same distressing symptoms may arise from spasm of the
larynx excited by the inflammatory action. As arising from thickening or
infiltration of the membrane these symptoms may come on comparatively
slowly, but in the case of spasm they appear suddenly and have periods
of intermission, reappearing on succeeding days and usually at the
earlier part of the night. In such circumstances the loud, noisy
breathing is heard at a considerable distance, the horse stands
obstinately still, the fore feet apart, his elbows turned out to allow a
firm action of the chest, the flanks working laboriously, the head low,
the nose protruded, the nostrils widely dilated, the mouth open, the
eyes standing out from their sockets red and wild looking, and the face
constrained and pinched, the whole expression being that of intense
agony from impending suffocation.
_Lesions._ In cases where death has supervened, perhaps in connection
with another disease, the laryngeal mucosa, especially on and above the
glottis, is soft, tumid, friable, with ramified or uniform redness and
petechial spots. The epithelial layer may be softened, disintegrated and
shed, leaving pointed or larger erosions, which are, however, usually
superficial. In case of œdema glottidis the mucosa and submucosa are
thickened by an abundant exudate which may extend to the connective
tissue outside the larynx as well. In aggravated cases there may be dark
red or brownish red discolorations of the mucosa.
_Course, Duration._ Fortunately these aggravated forms of the disease
are rare and unless the patient perishes during such an attack or the
inflammation extends down toward the chest, laryngitis rarely proves
fatal. Its duration is from twelve to fifteen days. Its extension to the
lungs may be suspected when the extreme tenderness of the throat
subsides without any corresponding improvement in the health.
Examination of the chest will then rarely fail to detect the presence of
disease.
But although sore throat is rarely fatal its effects are not unimportant
nor trivial. It occasionally merges into a chronic form, with a hacking
cough, tenderness to pressure and an increased liability to other
diseases of the air passages. More frequently it is followed by wasting
and fatty degeneration of the laryngeal muscles and the horse becomes a
confirmed _roarer_. In all cases it leaves a greater susceptibility to a
second attack.
=Subacute Laryngitis.= This form has been chiefly seen in young animals
and up to eight years old. At the outset its symptoms are moderate but
as it is usually associated with serous effusions in and around the
mucous membrane the symptoms above mentioned as indicating imminent
danger of suffocation may suddenly appear and life can only be preserved
by opening the trachea.
=Chronic Laryngitis.= This may follow the acute form or it may come on
independently and by slow degrees. It may accompany nasal catarrh, or
chronic bronchitis. Old animals which have had heavy draught work and
repeated attacks of sore throat, are frequent subjects of it, and as
Fergusson has pointed out it is most prevalent among horses whose
throats have been compressed by the inconsiderate use of the bearing
rein. Reynal has observed it often in horses that are sweated with
difficulty, and in those which remain long wet from the length and
thickness of their winter coats.
_Symptoms._ When acute laryngitis passes into the chronic form all the
symptoms subside except a slight nasal discharge, the cough, tenderness
of the larnyx, and _roaring_. The cough is dry, short, and hacking,
rarely soft, and is heard mainly when the animal feeds, when he leaves
the hot stable for the cold air, and after drinking cold water. During
exercise, it is equally excited, the cough becoming harder, and the
horse extending his head and neck as if to disengage some body from its
throat. The subject may in nearly all other respects maintain the
appearance of vigorous health.
_Course, etc._ This disease is liable to prove obstinate and if of old
standing, often incurable. Unless checked, the continued congestion and
irritation of the larynx, the frequent, hacking cough, and the
consequent violent distension of the lungs bring about extensive and
irreparable structural changes. Among these may be mentioned
ossification of the cartilages of the larnyx; paralysis of the left
laryngeal nerve with wasting of the muscles to which it is distributed,
and _roaring_; dilatation of the bronchial tubes, and permanent
distension and rupture of the air cells (emphysema, broken wind,
heaves).
_Treatment._ _Acute form._ Unless in the very mildest cases
unaccompanied by fever, repose is essential. If available, a roomy,
clean, dry, and airy loose box should be allowed, care being taken to
avoid draughts of cold air and to secure a soft equable temperature
neither too hot nor too cold. Blankets should be used and even flannel
bandages applied loosely to the legs if the weather is cold, or, if
there is any tendency to chills and shivering. The nostrils must be
steamed as directed for _coryza_. A piece of sheepskin with the wool
turned in may be tied around the throat and up to the ears. In very
acute cases a linseed meal poultice or wet pack may be applied to the
throat, while in the milder forms, a mustard poultice or a lotion of
Spanish flies or other stimulant may be employed. Unless the malady has
an epizootic type, with prostration and a weak, rapid pulse, the bowels
may be opened by a laxative (3 or 4 drachms, aloes), and the water or
gruel the animal daily drinks should contain ½ to 1 ounce nitre. As an
expectorant the patient may take salammoniac 1 oz. daily in the drinking
water, or this agent may be evaporated from a clean chafing dish every
two hours and inhaled. Or he may take carbonate of potash or soda, or
iodide of potassium. If the cough is troublesome, half a drachm of
Dover’s powder may be given thrice a day or 1 grain chloride of
apomorphine every hour. Bromide of potassium or sodium may also be
resorted to. Inhalations or spray of sulphurous acid, or vapor of oil of
turpentine and insufflations of calomel may benefit as local
applications. The diet must be confined to sloppy bran mashes, cut
roots, or boiled barley, or oats. Hay should be withheld in the more
acute cases until improvement appears. Under treatment such as the above
and even without the medicinal part of it, the great majority of cases
will do well.
In cases attended with high fever with strong full pulse and bright red
nasal membrane, the purgatives and diuretics are especially called for,
and the former should have their action encouraged by frequent hot water
injections. Twenty drop doses of the tincture of aconite repeated four
times a day, or ten drops every three hours, will be further useful.
When the symptoms are of such a type as portend the access of paroxysms
of threatened suffocation, bleeding has been strongly recommended, but
unless resorted to in the first twenty-four or forty-eight hours is
rarely admissible. Also in weakened constitutions and when the fever is
of a low type, with small, weak pulse and general dullness and
prostration, the temporary relief obtainable from bloodletting will not
often counterbalance the danger of increasing weakness, and the loss of
recuperative power. In all such cases the application of a strong
mustard poultice for several hours in succession, until an abundant
effusion has taken place, into the skin and beneath it, has often the
best effect by virtue of its depletive and derivative action. Active
friction of the limbs to improve their circulation and increase their
temperature is also useful.
=Tracheotomy.= When suffocation becomes imminent not a moment must be
lost in performing _tracheotomy_. This operation is always available in
threatened suffocation from obstruction to the passage of air in the
nostrils and throat.
Different methods of opening the windpipe have been resorted to. One is
by means of a cannula and trochar at least three-fourths of an inch in
diameter and about five inches long and with two large oval orifices in
the middle of the cannula, and on opposite sides. This is made to
transfix the windpipe with its investing skin and muscles from side to
side in the middle of the neck, care being taken to pass it in the
interval between two adjacent cartilaginous rings. The trochar is now
withdrawn and the orifice in the cannula corresponding to the interior
of the windpipe, the animal is enabled to breath freely through the
tube. The cannula has only then to be secured in its place by a tape
carried round the neck.
The more common plan is by introducing a tube through a circular opening
made in the trachea. For this operation are needed, scissors, knife with
a thin narrow blade, needle and thread, and tracheotomy tube. The common
tube is about an inch in diameter, four to five inches long bent upon
itself so as to fit into the trachea, and furnished with a flat shield
to slits in which cords may be attached to fix it in its place. A second
variety is only long enough to reach into the windpipe. It is provided
with a flattened shield externally and from its inner extremity projects
downwards at right angles a plate curved so as to adapt it to the form
of the interior of the trachea. There is an additional plate to fit into
the upper part of the tube, provided with two lips projecting from it at
right angles; the outer lip is screwed to the shield after the tube has
been introduced into the wind pipe and the inner lip is thus fixed
inside the ring of the trachea, immediately above the opening and
effectually prevents any displacement of the tube.
In operating the animal is kept standing with the head as nearly as
possible in the natural position. The hair is removed from the skin
beneath the windpipe between the middle and upper thirds of the neck.
The skin having been rendered tense, (without displacement) by the
fingers and thumb of the left hand, an incision is made in the median
line from above downwards, for about two inches and is carried through
the muscles so as to expose two rings of the trachea. The needle and
thread are passed through the membrane connecting the two rings, and
with the knife a semi-circular piece of cartilage is cut from each of
the two adjacent rings. The thread in the connecting membrane prevents
them from being drawn in by the rush of air. It only remains to
introduce the tube and fix it in position.
Not only does tracheotomy obviate immediate danger of suffocation, but
by removing the source of irritation in the continuous and forcible rush
of air through the narrowed and inflamed tube, and in securing for the
blood a freer æration and a purer constitution it often induces a rapid
change for the better in the character of the inflammatory action. The
wound may be daily cleansed and dressed with sodium hyposulphite.
Some veterinarians following the example of Bretonneau and Trousseau
have treated sore throat from the first by what is called the abortive
treatment. For this purpose a long whalebone prob with a pledget of tow
firmly attached to its end and covered with powdered alum is introduced
through the mouth into the pharynx and larynx even. Violent paroxysms of
coughing are induced, but cures are affected in from two to five days.
Under Delafond’s treatment calves and foals recovered in twenty-four
hours. A more modern method is to inject a solution by means of a
hypodermic syringe inserted between the upper rings of the trachea.
Milder treatment such as the inhalation for an hour several times a day,
of the fumes of burning sulphur and water vapor will be found generally
successful. The air should be impregnated with sulphur fumes only so far
as can be breathed without inducing coughing on the part of the patient.
Such measures should not divert attention from the necessity for general
care, a control of diet, clothing, air, the state of the bowels, nor
from local external applications to the throat.
=Treatment of Chronic Laryngitis.= The patient should have a loose airy
box with an equable temperature. The avoidance of work and exposure must
be sought for the time. Green food, cut roots, boiled grain, or bran
mashes, with little or no hay, or other dry food, must be given. The
bowels must be regulated. An electuary compound of linseed meal,
molasses, and a drachm of belladonna extract to every tablespoonful of
the mixture, may be given to the extent of a tablespoonful smeared on
the inner side of the cheek twice daily. A mustard poultice to the
throat has often a good effect. Light firing over the larynx is
sometimes beneficial.
If secretion is defective and cough hard and dry chloride of ammonium,
carbonates or bicarbonates of soda, potash or ammonium or borax, in
solution or in gaseous form, may be given, the various bitters being at
the same time drawn upon as tonics. If secretion is excessive, with a
loose gurgling cough, astringents are indicated like ferric sulphate or
chloride, (½ dr.), or they may be applied as spray: alum or iron alum
five grains to the ounce, zinc sulphate or sulphocarbolate two grains to
the ounce, silver nitrate one-half grain to the ounce. These may be
introduced through the nose with the head elevated, or in small genera
through the fauces. Tar, oil of turpentine, creosote, carbolic acid or
eucalyptol may be inhaled from hot water.