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Chapter Eight

Basic Animal Health and Disease Control

8.1. Introduction to Animal Health and Disease Control

The best economic returns are realized when animals are kept in good health and disease problems are minimized. Health is the state of wellbeing of an animal. Any departure from the state of health is called disease. A healthy animal attains an acceptable level of production within the farming system in which it is maintained. Loss of appetite and weight, slow growth, reduction in production, reproduction loss and death of the animal are consequences of animal diseases.

8.1.1. Routes of Transmission of Pathogens

Pathogens are disease-causing microorganisms. Animals can be infected with pathogens through different ways. Direct contact with an infected animal or its tissues or fluids (e.g., blood, saliva, urine and droppings) is one of the ways. Ingestion of pathogens from contaminated feed, water and farm equipment (e.g., feed and water troughs) is another route of infection. Pathogens may be spread during mating or before birth through the placenta. Animals also can be infected through inhalation of droplets or dust containing pathogens or through vectors (living organisms, such as insects, carrying pathogens).

8.1.2. Symptoms of Sick Animals

A symptom is a sign or indication of the existence of a disease or other disorder. Sick animals can show a wide variety of symptoms, depending on the disease. These include loss of appetite, weight loss, coughing, being unable to rise, slow movement, lameness, and isolation from the herd or flock. A sick animal may stand with its head and neck down, or appear to have a tired or lazy look. They may have watery, bad-smelling or blood-body openings, sunken eyes, raised hair coat, rough skin, dry muzzle and swelling in joints. There may be variation in body temperature, pulse rate and respiration rate. Disease may also lead to death.

8.2. Major Diseases of Farm Animals

Diseases of farm animals are usually categorized as infectious and non- infectious. The infectious diseases are caused by pathogenic organisms such as virus, bacteria and protozoa. They are communicable from one animal to another animal or a human being. Examples are anthrax, foot and mouth disease (FMD) and Newcastle disease. Non-infectious diseases are neither caused by pathogens nor passed from one animal to another.

Non-infectious diseases may be caused by hereditary factors or by the environment in which an animal lives. Examples are ketosis, rickets and poisoning.

The major animal diseases in Ethiopia include foot and mouth disease (FMD), anthrax, tuberculosis and brucellosis. Contagious Bovine Pleuropneumonia (CBPP), mastitis, Newcastle disease, coccidiosis and trypanosomiasis are also common. The cause, host, transmission, symptoms and preventative/control measures for some diseases are described below.

Foot and Mouth Disease (FMD): This is a highly contagious, acute viral disease. It affects cattle, sheep, goats and pigs. Contact with infected urine, faeces, milk and nasal discharge are the main routes of transmission. This disease is characterized by formation of sores on feet, lips, tongue and cheek.

Symptoms include fever, rough hair coat, salivation, foaming, inability to feed, weakness, lameness and death. Prevention and control measures are quarantine, vaccination, good sanitation and elimination of infected animals.

Contagious Bovine Pleuropneumonia (CBPP): This is a viral disease. It is a respiratory disease of cattle, goats, sheep and pigs. Its transmission is through contact with infected body fluids such as milk and urine. An infected animal will have a dry and painful cough, loss of appetite, difficulty in breathing and inflammation of the lungs.

CBPP causes important productivity losses due to a high mortality (death) and morbidity (having a specific illness) rates. Prevention and control measures include vaccination, isolation and slaughtering of infected animals.

Brucellosis: This is an infectious bacterial disease. It is caused by the bacterium Brucella abortus. It is also known as contagious abortion disease. Brucella can infect cattle, goats, sheep, camels and pigs. The routes of transmission include direct contact with infected animals, tissue or fluids, and ingestion.

The disease causes abortion and infertility. This results in a heavy economic loss. Symptoms include intermittent fever, reduced milk flow and enlarged testicles. Prevention is accomplished by good herd management. Dead animals should be burned or buried. Brucellosis also threatens the health of people if they eat infected (raw or unpasteurized) dairy products.

Anthrax: This infectious bacterial disease that afflicts ruminant animals. It can also affect human. The causative agent is Bacillus anthracis. Animals usually get infected through contact with infected animals or materials and inhalation of spores. The disease is accompanied by high fever, convulsion, rapid breathing and sudden death. Prevention is possible through isolation of infected animals and disposal of the dead ones.

Newcastle disease (NCD): This is a well-known viral disease of poultry. Transmission can be airborne, or through contaminated vaccines and farm equipment such as feeders and drinkers. Birds may show signs of lack of appetite, respiratory difficulties, twisted neck, paralysis of the legs or wings, laying of soft shelled eggs, and watery greenish diarrhea. Culling of sick birds, quarantine and vaccination are recommended measures of prevention and control.

Taeniasis: This disease is also known as tapeworm infection disease. It affects cattle and pigs. Anaemia, vomiting and discomfort are symptoms of the infection. The common mode of transmission is through the soil during feeding. Regular de-worming and good sanitation are recommended control measures.

8.3. Internal and External Parasites of Farm Animals

A parasite is an organism that lives in or on another host organism to get its nourishment. Over 1,000 species of parasites affect domestic animals. Parasites can be broadly classified into internal and external, depending on where they live.

Animal parasites cause loss of production and high mortality rate. This results in negative financial impacts on farmers. They may also cause or transmit diseases. Diseases that occur due to parasites are called parasitic diseases.

Internal parasites (Endoparasites) live in the blood or tissues of the animal’s body. Tape worm, round worm, trypanosome and liver fluke are good examples of internal parasites.

They often interfere with the animal’s digestion and assimilation of food. They share the animal’s food and cause diarrhea, anaemia and loss of condition. The consequence is often death, if there is no effective treatment. This leads to loss of production and income.

External parasites (Ectoparasites) often annoy their hosts by biting, embedding, or irritating the skin. Good examples are ticks, flies, lice, and mites. They attack the blood, skin or hair of the host. They cause anemia, weight/condition loss, restlessness, skin irritation and skin destruction. External parasites may cause serious diseases (e.g., mange and scabies) or transmit diseases (e.g., red water and trypanomiasis). For example, the bite of a tsetse fly transmits trypanosomiasis.

8.4. Effects of Diseases and Parasites on Animal Production

Diseases and parasites are among the greatest constraints in animal production. Their effects may be expressed in different ways. Sick animals eventually fail to produce or reproduce to their ultimate capacity. Such loss of productivity is loss for the farmer. The fate of sick animal may also be death (mortality). Both production loss and mortality are loss to a farmer.

Another effect of animal diseases and parasites is economic loss. These may arise in several forms. Reduction in productivity and mortality result in money loss. Farmer has less product to sell and/or has a reduced number of animals. External parasites attack the coat of animals. This degrades the market value of hide, skin and wool. Diseases and parasites limit the export of live animals and their products to other countries. Costs of control, prevention, diagnosis and treatment are also expensive. Consequently, disease and parasite outbreaks also affect food and job security. Any of these can results in an economic loss to the farmer as well as a nation.

An additional effect of animal diseases and parasites is the public health

concern. Some animal diseases are transmittable to humans. Such diseases

are called zoonotic. Transmission often occurs through the consumption

of food products from infected animals. More than 150 such diseases are

known. Examples are brucellosis, anthrax, salmonellosis and taeniasis.

8.5. Prevention and Control of Common Farm Animal Diseases

8.5.1. Prevention and Control of Diseases and Parasites

The control and prevention of diseases and parasites is an important activity in livestock rearing. Prevention refers to measures that are applied to prevent the occurrence of a disease. Control refers to measures applied to prevent transmission after the disease has occurred. The prevention and control of diseases and parasites involves the following practices.

 Proper hygiene or sanitation: Hygiene or sanitation is an effective strategy for the control of infectious disease and parasite infestations. Washing feed and water troughs well is one helpful measure. Separating sick animals from the healthy ones is another. Dead animals should be either burned or buried.

 Good management: Animals that are provided with the essential nutrients can resist the effect of disease and parasite attacks. Keep animals’ house well ventilated and dry. In pasture grazing, following rotational grazing and avoiding overcrowding is recommended.

 Quarantine and isolation: Purchase only healthy-looking animals from reputable farms. At arrival, quarantine the new animals, by keeping them away from the other animals for two weeks until you’re sure they aren’t sick. Isolate any sick animals to prevent illnesses from spreading.

Medication:Thisisoneofthemostimportantmeasuresincontrolling farm animal diseases. Timely vaccination against diseases and quarantining diseased animals are important. The use of drugs in the form of powder, liquid or solids can be another option.

 Spraying or dipping: Spray animals with chemical solutions or dip them in the solutions. This controls external parasites like flies, lice, mites and ticks. Spraying pens and animals with veterinary chemicals helps to control external parasites. Dipping animals in water containing chemicals such as wettable powders is good for controlling ticks, mites and lice. Farmers are encouraged to dip or spray their animals regularly.

 Deworming: Deworming is giving appropriate drugs to expel internal parasites from animals. De-wormers include piperazine that controls roundworm. Internal parasites are also controlled with drugs, antibiotics or drenches.

 Biosecurity: is Biosecurity refers to measures taken to prevent the introduction and/or spread of harmful organisms to animals and plants. Controlling animal mixing, unnecessary personnel entry to farms and using protective clothing are examples of bio-security measures.

8.5.2. Indigenous Knowledge in Livestock Disease Treatment

In Ethiopia, plant-based remedies are the most important and sometimes the only method of managing livestock diseases. It is an inexpensive alternative to science-based treatments. Farmers mostly acquire ethno- veterinary knowledge from their elders. Indigenous veterinary practices include mechanical, physical, pharmacological, surgical, rituals and managerial methods of treatment.

Several medicinal plant species of veterinary importance are documented. Most medicinal plants are collected from the wild. The plant parts used for livestock health treatment may be leaf, root, rhizomes, bulb, bark, seed, stem, whole parts; alone or in combination.

The preparation methods of traditional medicine are concoction, squeezing, crushing or pounding. Concoction (mixing things together) is the major form of preparation of herbal medicines. Farmers are aware of toxicity and provide antioxidants. They can determine the dose using different household utensils.

 Farmers can also use their own hand. Ethno-veterinary medicines are administered to livestock in different ways. Oral route is the most common mechanism of application of traditional medicines.

A large number of livestock diseases and parasite syndromes are treated by traditional practitioners. Anthrax, black leg, ectoparasites and endoparasites are good examples of livestock disease and parasite syndromes treated using traditional medicines. Rabies, foot and mouth disease, bloat, and colic are other examples of animal diseases treated in this way.

Besides plant-based medications, some animal fluids are used in traditional medicine. For example, the Somali pastoralists in Ethiopia immunize their animals against rinder-pest by employing a solution of urine, milk and faeces obtained from the animal with mild cases of rinderpest.