In this article we will discuss about the Disease in Animals:- 1. Classification of Disease 2. Etiology or Cause of the Disease 3. Diagnosis.
Classification of Disease:
Disease may be classified in various ways, such as:
1. Hereditary, Congenital and Acquired Disease:
In the broad sense, any disease transmitted from parents to offspring is called hereditary. In the more restricted sense, a disease is only regarded as hereditary if it is directly transmitted to the ovum or sperm (genetic disease). A congenital disease must be distinguished from a hereditary one. It is really a disease which is acquired in utero and it is appreciable at birth. An acquired disease is neither hereditary nor congenital and most frequently develops after birth.
2. General and Local Disease:
A general disease is one in which systematic disturbance receives a local change or is early associated with it. Local disease is one in which local change is primary in some organ or part of the body and remains essential and predominant feature throughout. In such a case, it is implied that the disease condition first involves a single organ or tissue, the disease may, however, be very extensive and yet designated local disease — as in the case of some skin affections.
3. Structural and Functional Disease:
Structural disease is one in which there is appreciable alteration in some organ or part of the body. Functional disease is one in which certain symptoms are shown without any appreciable change in organs of the body which can be connected with the symptoms.
Some diseases are regarded as functional simply because no change can be found in any organ. Examples of these are — palpitation of the heart, spasm of diaphragm, epilepsy etc.
4. Contagious and Non-Contagious Disease:
Contagious disease is one which is caused due to special organism or virus and is usually capable of transmission from one animal to another. The term Specific is frequently applied to contagious diseases.
Non-contagious disease is one which is not transferable from one animal to another and is not regarded as being due to a special organism or virus. On the other hand, disease due to a specific cause often attacks an individual animal but shows no tendency to spread to other animals. Such diseases are called sporadic diseases.
For convenience, we deal with the diseases in the following order:
1. Contagious or Specific disease
2. Diseases of doubtful origin or disturbed metabolism
3. Local diseases
4. Diseases due to animal parasites.
Etiology or Cause of the Disease:
It is the study of the Causation of disease.
Causes of disease are grouped as:
1. Exciting
2. Predisposing
1. Exciting Cause:
An exciting cause is one without which a disease cannot be set up, i.e. to say, it is directly responsible for the production of disease.
It includes a:
(a) Living organism such as animal or vegetable, these are the most common causes.
(b) Mechanical agents such as injuries, overexertion, pressure, friction, impaction by foreign bodies (calculi).
(c) Irregularity in food and water.
(d) Chemical causes (poisons).
(e) Thermal agents such as extreme temperature, heat stroke, frost bite, burns, electrical cause, lightning stroke.
2. Predisposing Causes:
Are those agencies which appear to render the animal body or any of the parts less resistant to the action of the exciting causes:
(a) Age—such as Strangles, Distemper, Joint- ill, — these are the diseases of young animals. The old animals, too, become affected with the disease associated with debility, e.g. chronic rheumatism. But in the majority of cases, these are associated with young animals.
(b) Sex.
(c) Temperament.
(d) Colour—Such as Melanotic tumours in grey horses and red cattle.
(e) A previous disease.
(f) Idiosyncrasy.
(g) Heredity.
(h) Sudden changes of temperature (chills).
(i) Debility.
Causes are also classified as:
(a) Extensive or Exopathic.
(b) Intrinsic or Endopathic.
An Extensive or Exopathic cause is one which enter or act upon the body from without—e.g. chill.
An Intrinsic or Endopathic cause is one which is believed to arise within the animal body and is not dependent on an external agency as in the case of debility of tissue, e.g. debility.
Diagnosis of the Disease:
It is the determination of the seat and the nature of a disease.
The diagnosis is said to be:
1. Clinical:
When it is made from the observation of the symptoms alone.
2. Differential:
When the symptoms of the different conditions are compared and the comparison points to the presence of one of those diseases. Sometimes, it is made by method of exclusion, from pathological examination, by physical signs or in other ways. In the attempt to form a diagnosis, it is necessary to make a complete systematic examination of the patient, to obtain all the information that can be supplied by the attendant regarding the history and symptoms.
And, if necessary, to apply certain tests or make bacteriological or chemical examination. The information supplied by the attendant can be believed only when it is compatible with what is seen. It is necessary to make a diagnosis before commencing treatment but occasionally it cannot be done in the first instance and, in these cases, the symptoms shown should be relieved and, the patient examined again after a short interval.
The difficulties of diagnosis are caused by two factors:
1. Some of the symptoms are not constant and a very few are peculiar to any particular disease.
2. That complications of one or more diseases are not uncommon and this may obscure the original affection.