PROBLEM OF DISEASE DIAGNOSIS
Continued from last week…
DISEASE may be defined as an injurious deviation from normal. A lesion may be defined as a pathological change in an organ or in part of the tissue of that organ, and it may be microscopic or macroscopic.
Lesions interfere with function. When they occur on the surface of the body, they may be seen and handled, for example an abscess.
A symptom is any evidence that indicates the presence of diseases and is usually observed by a layman or person in charge of the animal.
Examination methods, interrogation of the animal is not possible, a person who is aquanited with the animal would entirely depend on his ability to ascertain by clinical examination the details of each case.
The observant owner can be of immense help in describing the abnormal behaviour of the animal. Continued practice will greatly increase the amount of value of the information to be obtained in the examination of the animal.
It is up to the individual to master the methods that he may take in animal examinations. The following are the aids to carry out diagnosis of the animal:
Inspection, this is the visual examination of the animal using one’s eyes.
Palpation, it is the act of handling the tissues by the act of firm but gentle pressure with fingers, using one or both hands. Palpation may reveal the presence or absence of pain in particular tissues, and it may demonstrate abnormalities in shape, size or consistency of organs or tissues.
Auscultation, the act of listening to the sounds produced by functional activity in various parts of the body. It may be carried out by direct application of the ear to the part e.g. the chest walls.
Sense of smell, certain diseases are associated with the development of characteristic odours, and their recognition may be of assistance in diagnosis e.g. the smell from the breath of a cow suffering from acetonaemia, or the smell of diseased muscle tissue in Black- Quarter.
Other diagnostic procedures, this has to do with other instruments such as probes or catheters, exploratory punctures, rectal examination, the use of instruments such as an ophthalmoscope or radiography but this is at an advanced level.
Preliminary general examination, this examination is designed so that the general condition of the animal may be determined and an indication obtained as to the systems and regions of the body that are principally involved in the disease process.
Owner’s complaint, most cases would come to the notice of the examiner as the result of the written or verbal complaint, and later the past immediate history will be obtained, together with the description of the animal i.e. species, breed, age, sex, and individual identity.
The history may be obtained by discreet questioning from the owner or the person in attendance on the animal.
Avoid asking leading questions which may tempt the person giving the history to make statements that have no real foundation in fact. In most instances a satisfactory history containing all the relevant details is readily obtained.
Most owners are careful and accurate observers. However, the history may contain much irrelevant detail particularly when dealing with a verbose individual or an owner who may be overanxious about his animal when it may become coloured by the person’s own idea of the case.
In exceptional cases a deliberately untrue history may be given, but this may be done to cover the effects of incompetence, negligence, or fraudulent action.
Probably the most common inaccuracy met in case histories is the claim that the illness is of recent origin when it is obvious that the diseased state must have been present for a very considerable time.
One should remember, however, that many diseased states are only obvious to a skilled observer, and it may be difficult to pinpoint the commencement of a chronic illness.
The inarticulate person, or ignorance on the part of the individual may lead to statements that, if accepted, would be grossly misleading. With such a person it is frequently profitable to indulge in a little general conversation before bringing the discussion round to the case in point. This makes him feel at ease and will build up his confidence in
you. The history of a case is divisible into two main parts, (1) the past history and (2) the immediate history. In past history information is sought as to previous illness or deaths.
The introduction of new animals into the herd, and their source of origin may prove to be the source of an outbreak of infectious disease. The methods of feeding and sudden changes of foodstuffs may lead to what appears to be an outbreak of epidemic disease.
Such changes in feeding methods may be a predisposing factor to the outbreak of an infectious disease e.g. Swine Erysipelas or Enterotoxaemia in sheep. Seasonal incidence also has a bearing on the probable nature of the disease being investigated.
The immediate history deals with the present case and it is necessary to determine its onset and thus assess
the length of the illness. One may have to enquire what symptoms the animal showed when the illness began and what other symptoms have been subsequently noticed.
Enquiries of this nature may deal with such symptoms as coughing, straining, attacks of frenzy. Information may be required in regard to appetite, thirst, defecation, urination, rumination and lactation.
It is also necessary to find out what steps may have been taken to deal with the condition. Some form of treatment may have been adopted and some of the symptoms now shown may be due to this and not to original disease.
The information on this point may be unreliable, as there may be a desire to hide the fact that an attempt has been made to treat the animal.