Unit 6: Disease management of livestock

1. Introduction to Livestock and Poultry Diseases

1.1 Concept of Health and Disease

• Health: A state of complete physical, physiological, and functional well-being of an animal, not merely the absence of disease. A healthy animal eats, drinks, ruminates (if applicable), and behaves normally with normal physiological parameters (temperature, pulse, respiration).
• Disease: A condition where the normal function or structure of any part of the body is altered, leading to impairment of normal physiological functions. It is a deviation from the state of health.

1.2 Classification of Diseases

Diseases are broadly classified based on their etiology (cause):

1. Infectious Diseases: Caused by pathogenic microorganisms.
   • Bacterial: e.g., Anthrax, Haemorrhagic Septicaemia, Mastitis.
   • Viral: e.g., Foot and Mouth Disease (FMD), Peste des Petits Ruminants (PPR), Newcastle Disease.
   • Fungal: e.g., Ringworm, Aspergillosis.
   • Parasitic:
     • Endoparasites: Tapeworms, Roundworms, Flukes.
     • Ectoparasites: Ticks, Mites, Lice.
     • Protozoan: Coccidiosis, Babesiosis, Theileriosis.
2. Non-Infectious Diseases: Not caused by pathogens and not transmissible.
   • Metabolic: Milk fever (Hypocalcemia), Ketosis.
   • Nutritional Deficiency: Rickets (Vitamin D/Calcium), Anemia (Iron).
   • Mechanical/Physical: Fractures, wounds, bloating.
   • Toxic: Poisoning (Urea, Cyanide, Pesticides).

1.3 Signs of Health vs. Disease

To manage diseases, one must recognize the deviation from normal behavior.

2. General Prevention and Control Strategies

Effective disease management relies on the principle: "Prevention is better than cure."

2.1 Biosecurity

Biosecurity refers to measures designed to prevent the entry and spread of pathogens.

• Isolation: Keep new animals separate from the main herd for at least 21–30 days (Quarantine). Isolate sick animals immediately.
• Traffic Control: Restrict movement of people, vehicles, and equipment into the farm. Use footbaths containing disinfectant (e.g., Potassium Permanganate or Phenol) at entry points.
• Sanitation: Regular cleaning of sheds, waterers, and feeders. Proper disposal of manure and carcasses.

2.2 Sanitation and Disinfection

• Cleaning: Removal of organic matter (dung, urine, litter) is crucial before applying disinfectants, as organic matter neutralizes many chemicals.
• Disinfection: Application of chemical agents to destroy pathogens.
  • Lime powder: Sprinkled on floors/ground.
  • Phenol/Phenyl: Floor cleaning.
  • Formalin: Fumigation of enclosed poultry houses/hatcheries.
  • Sodium Hydroxide (Caustic Soda): 2% solution for viral outbreaks.
  • Flame gun: Burning floor surfaces to kill parasite eggs/oocysts.

2.3 Vector and Parasite Control

• Deworming: Regular administration of anthelmintics to control endoparasites.
• Ectoparasite control: Dipping or spraying animals with acaricides to control ticks/mites which act as vectors for diseases like Babesiosis and Theileriosis.
• Pest control: Control of flies, mosquitoes, and rodents which carry pathogens.

2.4 Proper Disposal of Carcasses

• Burial: Deep pit (min. 6 feet), covered with lime and soil.
• Burning (Incineration): The most sanitary method, especially for spore-forming diseases like Anthrax.

3. Vaccination Schedules

Vaccines contain weakened or killed pathogens that stimulate the immune system to produce antibodies.

3.1 Cattle and Buffalo Vaccination Schedule

3.2 Sheep and Goat Vaccination Schedule

3.3 Poultry Vaccination Schedule (Commercial Layers)

4. Important Diseases of Livestock: Etiology, Symptoms, and Control

4.1 Cattle and Buffalo Diseases

1. Foot and Mouth Disease (FMD)

• Etiology: Apthovirus (Picornaviridae). Highly contagious. Seven serotypes exist (O, A, C, Asia-1, SAT-1, 2, 3).
• Transmission: Direct contact, aerosols, contaminated feed/water.
• Clinical Signs:
  • High fever (104–106°F).
  • Profuse frothy salivation ("ropy" saliva).
  • Vesicles (blisters) on the tongue, gums, dental pad, and interdigital space (between hooves).
  • Lameness due to foot lesions.
  • Sudden drop in milk production.
  • "Panting" in recovered animals.
• Treatment: No specific antiviral treatment. Symptomatic treatment: Antiseptic wash for ulcers (Potassium permanganate), antibiotics to prevent secondary infection.
• Control:
  • Regular vaccination (biannual).
  • Strict quarantine and ring vaccination during outbreaks.
  • Ban on animal movement.

2. Haemorrhagic Septicaemia (HS)

• Etiology: Pasteurella multocida (Bacteria).
• Host: Buffaloes are more susceptible than cattle.
• Clinical Signs:
  • Sudden onset, high fever.
  • Severe swelling of the throat and dewlap (edema).
  • Respiratory distress (loud snoring sound/grunting).
  • Death usually occurs within 24 hours.
• Treatment: Antibiotics (Sulpha drugs, Oxytetracycline) effective only if given in very early stages.
• Control: Prophylactic vaccination before the rainy season (HS Vaccine).

3. Black Quarter (BQ)

• Etiology: Clostridium chauvoei (Spore-forming bacteria). Soil-borne infection.
• Target: Young stock (6 months to 2 years) in good condition.
• Clinical Signs:
  • High fever.
  • Hot, painful swelling on heavy muscles (thigh, shoulder, neck).
  • Crepitus: On palpation, the swelling makes a crackling sound (due to gas bubbles).
  • Lameness.
• Treatment: Penicillin in massive doses (early stage). Often fatal.
• Control: Annual vaccination; burning of carcasses (do not open carcass to prevent spore release into soil).

4. Brucellosis (Contagious Abortion)

• Etiology: Brucella abortus (Bacteria). Zoonotic (causes Undulant Fever in humans).
• Clinical Signs:
  • Abortion in late pregnancy (last trimester/6-9 months).
  • Retention of placenta.
  • Orchitis (inflammation of testicles) in bulls.
  • Infertility in females.
• Control:
  • Vaccination of female calves (4–8 months) with Cotton Strain-19 vaccine.
  • Test and Slaughter: Positive animals should be culled (in developed strategies).
  • Safe disposal of aborted fetus and placenta (burning/deep burial).

5. Mastitis

• Etiology: Complex multifactorial. Major pathogens: Staphylococcus aureus, Streptococcus agalactiae, E. coli.
• Clinical Signs:
  • Inflammation of the udder (hot, swollen, painful, hard).
  • Changes in milk: Watery, flakes, clots, blood, pus.
  • Systemic reaction (fever) in severe cases.
• Prevention & Control:
  • Milking Hygiene: Clean hands/machine.
  • Teat Dipping: Dipping teats in antiseptic (iodophor) immediately after milking (Post-milking teat dip is the most effective control measure).
  • Dry Cow Therapy: Antibiotic infusion during the dry period.
  • Treatment with intramammary antibiotic infusions.

4.2 Sheep and Goat Diseases

1. Peste des Petits Ruminants (PPR) / "Goat Plague"

• Etiology: Morbillivirus.
• Clinical Signs:
  • High fever.
  • Ocular and nasal discharge (crusting around nose).
  • Necrotic lesions (erosions) in the mouth (stomatitis).
  • Severe diarrhea (often foul-smelling) leading to dehydration.
  • Pneumonia.
• Control: Highly effective live attenuated vaccine (provides immunity for 3 years).

2. Enterotoxaemia (Pulpy Kidney Disease)

• Etiology: Clostridium perfringens Type D.
• Trigger: Sudden change to lush green pasture or high-grain diet.
• Clinical Signs:
  • Often found dead without symptoms.
  • Nervous signs: Circling, convulsions, opisthotonos (star-gazing posture).
• Control: Vaccination and gradual transition of feed.

4.3 Poultry Diseases

1. Newcastle Disease (Ranikhet Disease)

• Etiology: Paramyxovirus.
• Clinical Signs:
  • Respiratory distress (gasping).
  • Nervous signs: Torticollis (twisted neck), paralysis of wings/legs.
  • Greenish diarrhea.
  • High mortality (up to 100%).
• Control:Strict vaccination (F1/LaSota strains). No treatment.

2. Infectious Bursal Disease (IBD / Gumboro)

• Etiology: Birnavirus. Affects the Bursa of Fabricius (immune organ).
• Target: Young chicks (3–6 weeks).
• Clinical Signs:
  • Whitish diarrhea.
  • Prostration, trembling.
  • Swollen, hemorrhagic Bursa of Fabricius (post-mortem).
  • Immunosuppression (makes bird susceptible to other diseases).
• Control: Vaccination (Live intermediate strain).

3. Coccidiosis

• Etiology: Protozoa (Eimeria tenella, E. necatrix).
• Clinical Signs:
  • Bloody diarrhea (Caecal coccidiosis).
  • Ruffled feathers, weight loss, anemia.
• Treatment: Coccidiostats (Amprolium, Sulpha drugs) in water.
• Control: Litter management (keep litter dry).

4. Avian Influenza (Bird Flu)

• Etiology: Influenza Type A virus (H5N1, H7N9). Zoonotic.
• Clinical Signs:
  • Sudden death.
  • Cyanosis (blue discoloration) of comb and wattles.
  • Swelling of head.
  • Respiratory distress.
• Control:
  • Notifiable disease.
  • Stamping Out: Culling of all birds in infected zone.
  • Strict biosecurity.