Clinical Diagnosis
The clinical diagnosis is a systematic way enables the vet to recognize an ailing animal from a healthy animal. Obviously an important requisite is complete familiarity with states of health and a sound knowledge of Anatomy, Physiology, Pathology and behaviour of all species. The presence of disease is revealed by certain changes in the structure of an organ or tissue and/or its function, as well as in the behaviour of whole living organism. Such changes are described as clinical signs and the process of deducing the nature of disease from them is the diagnosis.
Diagnosis is an art of recognizing a disease and of distinguishing it from other diseases with help of externally visible or otherwise appreciable changes in the condition of an animal or its organs. In other words diagnosis is the determination of the nature of the disease.
Diagnosis consist of three parts–
- Symptoms of disease
- Disease organ
- Character of the disease and name
Classification of diagnosis
Clinical Diagnosis is classified in these types-
- Symptomatic diagnosis
- Tentative diagnosis
- Direct or definitive diagnosis
- Confirmatory diagnosis
- Snapshot diagnosis
- Test therapy diagnosis
- Exclusion diagnosis
- Laboratory diagnosis
- Herd diagnosis
Symptomatic diagnosis
Based on the prominent clinical signs, but the site and course of the primary abnormality are unknown, the diagnosis is said to be symptomatic.
Examples of Symptomatic diagnosis are Jaundice, Colic or Abdominal pain in horses and dogs etc.
Tentative diagnosis
If a disease is not recognizable with certainty, the diagnosis is a tentative one. Often an absolute diagnosis cannot be made at once. So, tentative diagnosis is made on the basis of available information immediately but subject to change.
Direct or definitive diagnosis
When a disease is clearly recognized by observing structural lesions or pathognomonic lesions directly, it is direct or definitive diagnosis. Direct diagnosis includes physical diagnosis, that is, diagnosis through inspection, palpation, percussion & auscultation.
Confirmatory diagnosis
Confirmatory diagnosis denotes the actual disease condition of an animal. Confirmatory diagnosis is diagnosed through clinical, clinical-pathological and immunological investigations.
Snapshot diagnosis
Snapshot diagnosis is a diagnosis that is declared at the very approach of a patient at a glance. That is just by having a look at the case. Majority of the times this type of diagnosis depend on-
- Experience of clinician
- His skills and
- Some important clinical signs of specific disease
Example of snapshot diagnosis-
- Severe brisket oedema – Suspected for TRP
- Enlargement of parotid lymph nodes –Tropical Theileriasis
- Snoring disease- Nasal Schistomiasis
- Patella fixation- Dragging disease
- Crepitation of heavy muscles- Black Quarter
Snapshot diagnosis may be biased and liable to the erroneous. For example, A cow that is paretic shortly after calving may not have parturient paresis but septic metritis resembling milk fever.
Test therapy diagnosis
When the diagnosis of the disease depends on the response of the animal to a particular drug or medicine, it is said to be test therapy diagnosis.
For example, Polioencephalomalacia in calves or sheep can be diagnosed by the favorable response to IV administration of thiamin hydrochloride within few hours.
Exclusion diagnosis
Exclusion diagnosis is the determining of disease by excluding all other diseases.
Laboratory diagnosis
Laboratory diagnosis denotes the diagnosis of disease through clinical pathology on the basis of examination of stool, urine, blood, milk etc.
Herd diagnosis
In some cases a disease affects whole herd resulting in considerable loses.
Examples are loss of production, decreased work efficiency, death of the animals and inability to attain/gain weight.
The herd diagnosis is made by following principles–
- Complete clinical examination of affected animal showing pronounced/clinical signs.
- Investigating the environment in which the animals are kept grazing, posture, condition, feed offered and drinking water provided.
- PM examination of dead animal
- If dead animal is not available, then seriously ill animal is sacrificed and PM examination is done for rapid diagnosis.
- Dispatch of sample for specific laboratory investigation.
Difficulties faced by veterinarian in making confirmatory diagnosis when compared to humans are–
- His animal patient unlike human patient cannot express its subjective feelings. He has to depend on his own observation.
- Owners / attendants may not reveal the correct picture of illness. Very often they try to mask the actual history; it makes the task of diagnosis more troublesome.
- Non co-operation of the animal patient. for example, Ruminal motility has to be checked but if animal is not cooperating then it is very difficult for diagnosis.
- Various species of animals with their different structures and functions of body systems makes the process of diagnosis more complicated
- A wide variety of variation in normal physiology (temperature, pulse, respiration rate etc.) in different species of animals with distinct behaviour of them makes the task of diagnosis more cumbersome than medical clinician.