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A disease can be defined as any abnormality in the functions of the tissues, organs or system of the animal body. In other words, disease is any condition in which there is a deviation from normal state of health or normal functioning of any or all the tissues and organs of the animal body.
Animal diseases are generally caused by viruses, bacteria, fungi, protozoa and malnutrition.
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Difference between resistance and susceptibility to diseases
The difference between resistance and susceptibility to diseases is that an animal is said to be resistant to disease when it is not affected by an invading pathogenic disease-causing organism or pathogen while the animal is said to be susceptible to disease when it is not able to ward off the effect of the invading pathogenic organism, in which case it manifests disease symptoms.
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Economic Importance of Animal Diseases
(1) The diseases bring about poor growth of animals.
(ii) Diseases lead to poor feed utilization by animals due to loss of appetite or anorexia.
(iii) Diseases bring about low yield of products
(iv) Diseases in animals produce low income for farmers due to reduced quantity and quality of products and death of the animals.
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Factors that could predispose animals to diseases include:
(1) Health status of the animal: Animals with poor health stand the risk of getting infected with diseases faster than animals with good health.
(2) Nutrition: Animals which are poorly fed
are easily infected with diseases than animals that are well-fed with balanced diet.
(3) Sanitation: Poor or improper sanitation, including dirty environment could predispose animals to diseases .
(4) Management: Poor management of the ‘ animals such as non-administration of vaccines and drugs at appropriate doses and time could predispose animals to diseases.
(5) Breeds of animals: Poor breeds of animals are in position to get infected with diseases than good breeds.
(6) poor housing :This pre-disposes farm animals to diseases due to unfavourable climatic conditions like heavy rainfall, high temperature, etc. Diseases and parasitic infestation can also breakout due to poor housing.
(7) Unfavourable climatic conditions Extremes of temperature, winds, rainfall,etc., do pre-dispose farm animals to diseases. .