Diagnosis. Clip or shave skin. Examine in warmth: skin and mucosæ,
where uninjured by rubbing, moisture, dryness, color, odor, discharge.
Soapy wash. Exudation into skin: pliancy: rigidity: eruption:
tenderness, itching, history, association, feeding, watering,
exposure, housing, harnessing, driving. Coincident disease. Prognosis.
Microbian dermatosis, parasitic dermatosis, external irritants,
ingested irritants, toxic systemic products, constitution, renal
disease, movement of joints, harness.
The thick hairy covering of animals, and the vicious energy with which
they often rub, scratch and bite themselves, thus turning simple into
extensive and severe lesions, interfere seriously with a satisfactory
diagnosis. The following precautions are usually demanded:
1st. Clip the animal close to the skin to allow of careful examination.
In some affections, this may be dispensed with, but as a rule it should
be followed. What appears to be a circumscribed eruption may be shown to
be general, or at least extensively diffused over different regions. Or
what was shown only by scurf or scab may be seen in its earlier and more
characteristic stage as erythema, papule or vesicle. It may even be
desirable to shave the affected part, care being taken, not to slice off
the characteristic papules, etc.
2d. Make the examination in a clear day in full sunshine if possible. In
dark, cloudy weather, and in dimly lighted stables it is impossible to
identify the different lesions. Artificial light is very unsatisfactory.
Warmth, as in sunshine, or in a warm day or room, increases any itching
and the cutaneous circulation and congestion, and renders more lively
and active the animal parasites that may be present. These may be found
in the surface scrapings taken in warmth, and not at all if taken in
cold. A hand lens will assist in the discovery of the larger parasites,
while for the smaller ones the microscope must be employed.
3d. Examine carefully all parts of the skin and even the visible mucosæ,
estimating whether any lesions of the latter indicate extension from the
skin, by proximity, or a general constitutional affection. Scrutinize
particularly such parts as have not been abraded by mechanical
injury—those which show the primary character of the lesion. Is the
affected portion of the skin dry or moist? Some eruptions like impetigo
or grease are always moist, others like pityriasis or dry eczema are
habitually dry apart from mechanical injuries. Ascertain the color, odor
and consistency of any discharge. It may be a limpid or reddish serum in
grease, honey like in impetigo, oily in farcy, greasy in swine plague.
The odor is fœtid in grease, canker and thrush of the frog, cheesy in
variola, and mousy in favus.
4th. To learn the true nature of the eruption a warm, soapy wash may be
essential to remove scurf, scab, and other encrustations.
5th. Note the depth and extent of the skin lesions, the thickening of
the skin, its pliancy or rigidity, its adhesions to subjacent parts or
free movement upon them, whether it is contracted into folds or ridges,
the degree of congestion, the nature of the eruption, uniform congestive
redness, papule, vesicle, pustule, squama, sore, ulcer, nodule, slough,
etc. Are the individual lesions isolated or confluent?
6th. The presence of itching and its degree are important data. Pruritus
is always excessive in ordinary acariasis, marked in eczema,
phthiriasis, and some neuroses, and very slight in a number of skin
affections (pityriasis, ringworm, grease, thrush, contagious acne). The
abrasions and sores caused by rubbing, scratching, etc., will usually
give a key to the degree of pruritus, and handling the part will render
the condition evident.
7th. The history of the case is always important. Is it chronic or
acute? Continuous or intermittent? Associated with any special
conditions of proximity to other diseased animals, to special feeding,
watering, exposure, housing, harnessing, driving, which might account
for it? Did there coincide with its eruption any indigestion, gastric or
intestinal, or any hepatic, urinary or nervous disorder on which it
might be dependent?
_Prognosis._ This is subordinate to the nature, causes, course, duration
and complications of the disease.
=Microbian dermatosis= (variola, aphthous fever, rouget) usually follows
a rapid course and recovery is perfect with some measure of immunity.
=Parasitic dermatosis= (acariasis, phthiriasis) is liable to have
serious secondary results (infection to man or animals, loss of wool,
tender skin), and to run a chronic course.
=Maladies from external irritants= (chafing, caustics, traumas,
vegetable, or animal irritants), do not tend to chronicity and are often
promptly curable.
=Maladies due to ingested irritants= (urticaria, distillery waste
eruptions), also tend to recovery when the source of irritation is cut
off.
=Maladies due to toxic products of the system= will be obstinate or
incurable, in ratio with the incurability of the causative factor. Those
due to the absorbed products of a simple indigestion, will tend to
terminate with the removal of the cause, while those dependent on
chronic and perhaps irremediable disease of the digestive organs, liver,
or kidneys will be correspondingly inveterate or incurable.
=Maladies due to a constitutional vice=, in sanguification, nutrition,
innervation, etc., are likely to be irremovable or only temporarily
curable.
=Burns and some other skin diseases= are liable to become complicated by
renal embolisms, albuminuria, indigestions, etc., which may render the
skin affection inveterate or incurable.
=Dermatitis= on the folds of articulations or on the seats of harness,
are sustained by the local irritation, and may necessitate long rest, or
abstention from work requiring the use of such harness.
All dermatites are liable to show special features of inveteracy, or
amenability to treatment according to surrounding conditions—hygienic or
otherwise.