INTRODUCTION OF LIVESTOCK AND POULTRY DISEASES

CONCEPT OF HEALTH AND DISEASE

general, the normal structural (anatomical) and functional (physiological) well-being of an animal are called health. According to the World Health Organization (WHO), health is a state of complete physical, mental and social well-being, and not merely the absence of disease or infirmity. Here, health indicates the general condition of a person in all aspects. It is also a level of functional and/or metabolic efficiency of an organism. Animal health is the subject matter of veterinary science. Normal urination and defecation, normal growth, production and reproduction, normal physiological attributes like body temperature, respiration and pulse rates, normal behavior, and workability are the indications of good health of animals. Any deviation from the normal state of health is called disease. Like human beings, domestic animals may also suffer from various types of diseases, which may lead to havoc loss in animal business through the death of animals or reduced production. Animals cannot express their complaints. So, diagnosis of animal disease is a very difficult task. History taking (based on asking suitable questions to the animal keepers) is the key for an accurate diagnosis of animal disease, besides various clinical and laboratory investigations. On the other hand, the cost of animal treatment is increasing day by day. So, it is truly said that prevention is better than cure.

SIGNS OF ILL HEALTH OF ANIMALS

Observation of various signs of ill health helps in the early diagnosis of the disease. The most common signs of ill health of livestock are indicated below:

1. Change in normal posture and behavior: Change in normal posture and movement indicates an early disease condition. Animals standing alone at the corner of the shed separating from others or animals standing with head down, pushing the head against a wall, charging at various objects, and acting aggressively are warning signs. Some specific postural changes of animals are observed in some specific diseases like keeping the head on flank region in milk fever of dairy cows, stiff gait and locked jaw in tetanus, walking in a circle in gid of goats, etc. Different abnormal postures in animals are observed in paralysis, fracture, dislocation of the hip, sprain, injury, inflammation, etc. Some specific behavioral changes may be observed in some specific disease conditions like excitement in nephritis, difficulty in defecation in impaction, or constipation, etc.

2. Loss of appetite: There may be partial loss of appetite (inappetence) or complete loss of appetite (anorexia). Conditions like Suspended rumination or no rumination may be seen in ruminant animals.

3. Dry skin, falling of hair, and change of color of skin: Dry skin and falling of hair may indicate disease. It may be caused due to deficiency of nutrients (like zinc deficiency) ectoparasitic infestation (like lice or mange infestation, etc.). In Swine disease, red-violet colored patches are seen on the skin. Erysipelas

4. Dry muzzle: Dry muzzles indicate dehydration and hyperthermia or fever.

5. Abnormal secretion: Abnormal secretions like Mucoid or mucopurulent discharge and blood-stained discharge from the nose (in respiratory infection), fresh blood from the nose (epistaxis), excessive saliva from the mouth (in FMD, PPR), discharge from the eye (1lachrymation), and the presence of glue in the eyes, abnormal discharge from genitalia like pus, blood, foul-smelling discharge in pyometra, metritis).

6. Change of color of urine: Normal urine color is straw-washed water. Sometimes, red urine (haematuria/hemoglobinuria) is seen.

7. Change of consistency of feces: Loose stool/diarrhea and constipation are very common. It commonly indicates digestive problems. The normal consistency of feces of different livestock species is cattle and buffalo: semi-solid, sheep and goat: the aggregate of small globules, chicken: droppings.

8. Sudden reduction of milk yield and mastitis:Milk yield may be reduced suddenly in some diseases (like FMD). Watery milk, blood in the milk, curd, and flakes in milk, hot painful udder, swollen udder and teats are the indications for mastitis (inflammation of the udder).

9. Abnormality in body structures: Enlarged joints with joint pain (arthritis), swelling (abscess, cyst, neoplasm, haematoma), abnormal abdominal distension (bloat/tympanitis), etc. indicate ill health.

10. Change of physiological norms: Variation in common physiological norms like body temperature (rectal temperature), respiration rate and pulse rate indicate ill health of animals. However, female animals in advanced pregnancy, young animals, and animals after exercise or grazing on the field usually show higher body temperature, respiration and pulse rates than normal. On chilly days, weak and debilitated animals usually show sub-normal body temperature.