As a custodian of animal health, Veterinarians are charged with the responsibility of making an early and correct diagnosis so that health care interventions can be undertaken well in time. Since inception of health care, diagnosis (understanding the disease and its pathogenesis) has been in the core of all health care systems throughout the world whether it is human health care (Ayurveda, Allopathy, Homeopathy, Chinese medicine, Unani medicine , etc.) or animal health care (Veterinary Medicine) as it provides an explanation of health problems and assists in taking subsequent health care decisions. In earlier days, information gathering through conversation and physical examination of the patient had been the basis of making diagnosis.

Veterinarian’s primary responsibility towards patients and their owners is to establish a correct diagnosis as it is a pre-requisite for rational, effective, eco-friendly and cheap treatment. Diagnosis of a disease is the crux of health problems. An accurate and prompt diagnosis helps in deciding effective treatment options, whereas incorrect and delayed diagnosis often leads to failure in disease outcome. Diagnosis The word “diagnosis” is derived from the Greek word “gnosis” that means knowledge. The diagnosis is not only the identification of the disease but also of disease process correlating with clinical manifestations with an understanding of disease etiology and its influence on the structure and function of the body. In fact making diagnosis is itself a process of ascertaining the nature of the disease or disorder from its signs and symptoms differentiating it from similar looking conditions.

Centesis is a surgical puncture or perforation into body cavity or structure usually done to aspirate fluid, air or tissue. The medical purpose of puncturing body cavities is not only to obtain fluid sample for diagnostic purpose but also to remove excessive fluid for therapeutic purpose for alleviating the respiratory distress owing to excessive fluid accumulation in peritoneal cavity, pleural cavity or pericardial sac. This procedure is usually done to get fluid from abdominal cavity, thoracic cavity, pericardial sac or joint capsule and is aptly known as abdominocentesis, thoracentesis, pericardiocentesis or arthrocentesis respectively.

Catheterization is done for both diagnostic as well as therapeutic purpose. As a diagnostic technique it is employed to collect urine samples, prostatic wash and suction biopsy. As a therapeutic technique it is used for the treatment of urine retention, obstruction and for monitoring urine output. Pneumocystography is a contrast radiography. It is being employed to distinguish the urinary bladder from other organs and to visualize the details of the bladder. Catheterization An appropriate catheter needs to be selected as per the requirement (purpose of catheterization and duration of catheterization). A soft, silicone flexible catheter is appropriate for indwelling purpose. Whereas a rigid catheter is more desirable to unblock a small calculi and collecting samples for diagnostic purpose. Small size catheters are best in order to minimize urethral trauma.

It is an easy, non-invasive, bed side technique for continuous monitoring the saturation of oxygen bound to hemoglobin (SpO2). The technique was invented by Dr. Takuo Aoyagi in 1974 to measure oxygen saturation in the blood. During recent years it has shown great utility in patient care. The oxygen saturation of hemoglobin provides a measure of cardio-respiratory functioning. Pulse oximeters generally used in humans are not appropriate for the use in dogs and cats as these are designed to apply on fingers and programmed with the oxygen hemoglobin dissociation curve for humans. Indications Pulse oximetry is an important standard technique of patient care in cases of heart failure, respiratory failure, multiple organ failure, critical care, emergency, accident and during anesthesia.

Electrocardiography-A noninvasive Technique Electrocardiography is a non-invasive diagnostic technique routinely used to examine the electrical activity of the heart in health and diseases. It is an important tool for the clinical evaluation of the heart. The technique provides important information regarding heart rate, heart rhythm, impulse formation and its conduction. Heart size can also be assessed to some extent in humans and dogs. The process of electrocardiography leads to generation of an electrocardiogram as a consequence of depolarization and repolarization of heart muscle cells during each heartbeat.

Almost all imaging techniques employed in human medicine are being followed in canine medicine but radiography and ultrasonography ( abdominal and cardiac) are the most commonly used clinical diagnostic techniques. Computed tomography, magnetic resonance imaging, and nuclear techniques are also being used in the teaching establishments. Radiography Use of radiography (Figure 42) as a diagnostic technique is wide spread in canine and feline medicine across the world. It is considered the first step in evaluating the skeleton, thorax and abdomen. For evaluating the abdomen, radiography is considered as complimentary to sonography. Canine practice is more like pediatrics requiring assistant to control the patients (dog sand cats). No anesthesia or sedation is generally required for radiography. But if the patient has painful lesion such as fracture or luxation, suitable anesthesia / sedation should be used for making the animal cooperative during radiography for better visualization of the lesions.

Last few decades have witnessed an increasing number of pets attending clinics/hospitals for cardiac care because of changed life style of owners as well as pets, more awareness of the owners and an increase in number of veterinary medical specialist with better diagnostic facilities. Cardiac failure and cardiac arrest are the two important outcome of cardiac diseases with variable treatment result. Heart functioning is affected not only in primary diseases of heart but also in diseases of organs other than the heart. Without correct diagnosis of cardiac abnormalities, treatment may be futile with a fatal outcome. Nowadays diagnosis of cardiac abnormalities is facilitated with the aid of modern diagnostic technology.

The prevalence of skin diseases in dogs is high throughout the world. Skin diseases are one of the main clinical complaint with which dogs and cats are presented at clinics. Skin diseases are numerous and have wide range of underlying etiology ranging from non-specific cause, infections (bacterial, viral, fungal. yeast), hormonal, nutritional to immunological causes. Most of the skin diseases are clinically manifested with focal or diffuse alopecia, itching, papules, pustules, erythema, scaling, scabs, lumps, unpleasant smell, rashes, urticarial plaques, dandruff, hot spots or excessive licking (Figure62) making the straight forward diagnosis a difficult task especially in dogs and cats with chronic dermatological disease.

Otology is the branch of medicine concerned with the study of the ear and its diseases. Ear diseases in canines have multiple etiology varying from allergies (food or environmental), ectoparasites, infections (bacteria, malassazia, fungus), endocrine disorders, immunological disorders (autoimmune diseases), foreign material, neoplasms to keratinization disorders. For rational management, correct diagnosis is a pre-requisite. Diagnostic techniques in otology include history, clinical examination including ear canal palpation and visual inspection of ears, imaging (otoscopy, radiography, CT scan, MRI, and ultrasonography) and cytological evaluation of otic contents/ discharge.

Diseases of gastro-intestinal tract are very common in dogs and cats. Gastro intestinal tract starts from mouth to anus. The first step in making diagnosis of gastro-intestinal disease is to localize the problem. Whether it is buccal cavity, esophagus, stomach, or intestines. Cursory history for seemingly simple complaint like vomiting, anorexia or loose feces may be unrewarding because gastrointestinal diseases may be primary (concerning with only gastro intestinal tract and its functions) or secondary (due to underlying disease/ disorder of organs other than gastro-intestinal tract). Therefore, for ascertaining the cause of gastrointestinal signs (anorexia, nausea, vomiting, regurgitation, constipation, loose feces, bloody feces), a thorough examination of all body systems is more logical. As with other body systems, a comprehensive systematic approach is needed for diagnosing diseases of gastro-intestinal tract also.

The term “Hepatology” is derived from the Greek words “hepatikos” and “logia” meaning liver and study respectively. It is the branch of medicine dealing with the study of structure, function, diseases and abnormalities of the liver, gall bladder, and biliary tree. Liver/hepatic diseases in companion pets vary from multifactorial hepatitis (acute and chronic), cirrhosis, portosystemic shunt, copper storage disease, hepatic lipidosis, and hepatic neoplasm to fulminant hepatic failure. The etiology of liver diseases also varies from infection, auto-immune, metabolic to genetic factors. The hepatic disorders are quite common in canines and felines. Moreover, the diagnosis of liver malfunctioning is loosely given in pet practice without any supportive evidence.

Nephrology Nephritis and renal calculi are the two major problems leading to renal failure in canine and feline nephrology. Chronic renal failure may occur at any age but it is more common in geriatric dogs. Congenital renal diseases may also lead to renal failure at any age. Chronic renal disease or chronic renal failure is a progressive deteriorating condition as compensatory mechanism (glomerular hypertension and hyper filtration) further deteriorate the condition. Hence chronic renal disease remains lifelong. For quality life, an early diagnosis of renal failure is very important. The following techniques are used to diagnose chronic renal failure.

Clinical diagnostic techniques in neurology are generally employed to confirm the existence of neurological disorder and also to localize the lesion. Equipment/Instruments for Neurological Examination  •            Reflex hammer.  •            Cotton tip applicator.  •            Pen torch light or transilluminator.  •            Cotton balls.  •            Haemostats.  •            Lens. Anesthesia/ Sedative • Generally no anesthetic/ sedative is needed for neurological examination. Place of Neurological Examination

Eye is a very sensitive, delicate and unique organ. Its function may be affected with wide range of etiologies ranging from trauma, local and systemic infections, metabolic diseases to vision defects warranting an early and accurate diagnosis employing complete history, detailed ocular examination and or specialized diagnostic techniques such as Schirmer Tear Test (STT), Fluorescence Test, Ophthalmoscopy, Tonometry, Pachymetry, Retinoscopy and Gonioscopy etc. Instruments for Ophthalmic Examination •             Finn off Transilluminator  •            Pen torch  •            Direct Ophthalmoscope  •            Indirect fundoscopic lens (2.2 diopter lens)  •            Schirmer tear test strips  •            Fluorescein strips  •            Tonometer