Disease is a deviation from normal health and is revealed by changes in the animal. Any animal that has a disease will show some form of abnormality, which can be observed through changes in behavior, structure, or function. A sick animal will appear dull and weak (lethargy), isolate itself, and may refuse to eat (anorexia).
Dairy animals may show a decrease in milk production. Abnormalities in the shape of certain body parts can also be noticed, depending on the affected area or organ. These changes can vary in severity and may be either qualitative or quantitative.
The observable changes in a sick animal are referred to as symptoms or clinical signs. Some symptoms are common to most diseases, while others are specific to certain conditions. Common signs of illness in animals include refusal to eat, fever (pyrexia), and lethargy.
These changes serve as the foundation for diagnosing the cause of the illness, with diagnosis being defined as the art and science of determining the nature and causes of diseases, as well as distinguishing between them.
The first step in diagnosing a disease is to observe the clinical signs exhibited by the affected animal. Following this, laboratory tests should be conducted to arrive at a definitive diagnosis.
Read Also: Most Beautiful Flowers: All You Need To Know About
Recognition of Sick Animals
Diseases cause disturbances in the normal behavior, activity, or performance of animals. These changes can often be observed directly. General signs or symptoms of sick animals include:
1. Anorexia (Inappetence): The animal stops eating or refuses feed.
2. Fever (Pyrexia): A rise in body temperature above the normal range.
3. Weakness (Lethargy): The animal appears weak or less active.
4. Depression: The animal exhibits a lack of interest or energy.
These symptoms may not always be present in every disease. For instance, an animal suffering from helminthosis (worm infestation) may not show fever unless there is a concurrent infection.
Factors Affecting Animal Health
A. Environmental Factors
Environmental factors, which are physical in nature, significantly affect the health status of animals, though they may not be controllable in the field. However, they can be managed in animal facilities depending on the species and facility sophistication. Key environmental factors include:
1. Temperature: While animals can withstand severe temperatures, prolonged exposure to extreme conditions can lead to stress, making animals more susceptible to disease.
2. Humidity: High humidity promotes the growth of microorganisms such as fungi, while low humidity may irritate the mucous membranes. In poultry, humidity is critical, as these animals lack sweat glands and lose heat through the respiratory tract.
3. Solar Radiation: Solar heat, especially in hot, humid climates, increases the heat load on animals. This becomes problematic when exotic breeds are imported from temperate regions. Animals with little pigmentation are more affected. Shaded areas and pens can mitigate these effects.
4. Air Movement: Proper air circulation aids in heat loss through evaporation and conduction, providing fresh air and removing toxic gases.
5. Rain: Excessive rainfall can cause cooling or lead to marshy conditions, increasing the risk of diseases such as foot rot in ruminants. Adequate shelter and drainage help reduce this risk.
6. Climate/Season: The climate or season can affect the health of livestock, influencing the prevalence of infectious agents and parasites. For example, helminth infections are more common during the rainy season, as temperature and moisture influence the survival of parasites outside the host.
B. Management Factors
1. Hygiene: Good hygiene practices reduce disease risk within a herd or flock. Cleaning living spaces and changing bedding or flooring can help disrupt the life cycle of disease-causing agents like gastrointestinal parasites.
2. Nutrition: Proper nutrition enhances disease resistance and supports maximum production. Inadequate feeding weakens animals and makes them more susceptible to diseases. During feed shortages, especially in dry seasons, supplementing livestock feed becomes necessary to maintain health.
3. Type of Housing: Housing conditions influence the risk and severity of infections, especially parasitic ones. For example, ruminants housed in areas with suppressed pasture growth or elevated feeding/watering troughs are at lower risk of gastrointestinal parasitism. Housing choices should minimize infection risks and promote animal health.
4. Ecology/Pest and Wildlife: Many parasites depend on intermediate hosts like pests or wildlife to complete their life cycles. Close contact between livestock and wildlife increases the risk of disease transmission. This is a common problem with nomadic farming, where ruminants often interact with wildlife, facilitating the exchange of parasites.
5. Introduction of New Animals/Animal Numbers: Introducing new animals to an existing herd can introduce new parasites. To prevent this, new animals should be quarantined and treated before introduction. Additionally, increasing animal numbers can raise the risk of disease transmission, as it enhances contact between animals and increases parasite accumulation, especially in confined areas. In poultry farming, houses should be cleaned and disinfected before introducing new birds.
Read Also: Bouqs Flowers: All You Need To Know About
Classification of Livestock Diseases
Livestock diseases can be classified using different criteria, including the species affected, the body system involved, and the causative organisms. The most common classification method is based on the causative organism:
1. Bacterial Diseases: Examples include Anthrax, Mastitis, Salmonellosis, Fowl Typhoid, etc.
2. Viral Diseases: Examples include Foot and Mouth Disease, Rinderpest, African Swine Fever, etc.
3. Protozoan Diseases: Examples include Coccidiosis, Trypanosomiasis, Babesiosis, etc.
4. Rickettsial Diseases: Examples include Anaplasmosis, Cowdriosis, Infectious Keratoconjunctivitis, etc.
5. Fungal Diseases: Examples include Aspergillosis, Ringworm, Epizootic Lymphangitis, etc.
6. Endoparasitic Diseases: Caused by worms such as Fascioliosis, Haemonchosis, etc.
7. Ectoparasitic Diseases: Caused by ticks, lice, and fleas, such as Mange and Fleabite Dermatitis.
8. Deficiency Diseases: Examples include Vitamin Deficiencies and Pregnancy Toxaemia.
9. Toxicoses: Examples include Nitrate Poisoning.
Diseases can also be classified by their method of prevention into the following categories:
1. Neonatal Diseases: Affect very young animals, typically characterized by diarrhea.
2. Vector-borne Diseases: Transmitted by living vectors, such as Trypanosomiasis.
3. Soil-borne Diseases: Caused by aerobic and anaerobic spore-forming bacteria, e.g., Botulism.
4. Contact Diseases: Epidemic diseases like Rinderpest and Foot and Mouth Disease.
5. Parasitic Diseases: Including Haemonchosis and Fascioliosis.
6. Nutritional and Metabolic Diseases.
Disease Diagnosis in Livestock
To diagnose a disease, comprehensive information about the animal is required. The components of diagnosis include:
1. History Taking: Gathering details about the animal’s identity (species, age, sex, breed, color), the onset of symptoms, and the duration of the illness.
2. Physical Examination: Observing the animal for abnormalities, measuring temperature, pulse rate, and respiratory rate. This may also include inspecting the animal’s living environment and the quality of feed and water provided.
3. Laboratory Examination: Collecting samples such as blood, feces, skin scrapings, urine, or organs (in cases of dead animals) to test for disease-causing agents. Feed samples can also be examined. Laboratory results are crucial in confirming a definitive diagnosis.
Diagnosing animal diseases not only aids in improving animal health for production purposes but also contributes to human well-being, as some animal diseases may be zoonotic.
The practical aspects of this guide emphasize identifying common diseases in livestock and systematically diagnosing them, along with recommending appropriate treatment and control measures.
Do you have any questions, suggestions, or contributions? If so, please feel free to use the comment box below to share your thoughts. We also encourage you to kindly share this information with others who might benefit from it. Since we can’t reach everyone at once, we truly appreciate your help in spreading the word. Thank you so much for your support and for sharing!
Frequently Asked Questions
We will update this section soon.