Animal Diseases

1. Conserving Animal Health for a
Better Tomorrow
Deepa Raju Menon
Post-doctoral Research Associate,
Southern Research & Outreach Centre,
University of Minnesota, MN.

2. Overview
 Definitions
 Animal diseases - impact
 Signs of health and disease
 Classification of diseases
 Disease control and prevention
 PRRS
 Summary
 Conclusion
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3. Definitions
• Health - a state of complete physical, mental
and social well-being and not merely the
absence of disease or infirmity (WHO, 1946)
• Epidemiology - is the science that studies the
incidence, distribution, causes and control of
diseases in a population
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4. What is Disease?
Any disruption of the normal function and
health of an animal that is typically
manifested by distinguishing signs and
symptoms
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5. Impact of Animal Diseases
• Loss of animal productivity
• Cost of treatment
• Market disruption
• Affecting human health
• Loss of income
• Food insecurity and poor nutrition
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6. Types of Diseases - Population
• Endemic - farm level - constant presence
• Epidemic or transboundary - highly infectious,
sudden increase, one country
• Pandemic - several countries, newer organism
• Sporadic - infrequent, irregular
• Outbreak - limited area
• Zoonotic - man animal
(Perry et al., 2001)
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7. Classification of Diseases - Etiology
• Bacterial - Brucellosis, Tetanus
• Viral - Avian influenza, Pox
• Parasitic - Mange, Taeniasis
• Fungal - Aspergillosis, Ringworm
• Protozoal - Coccidiosis, Babesiosis
• Managemental - Indigestion, Poisoning
• Metabolic - PEM, Rickets
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8. Disease is Multifactorial
• Agent (infectious) factors
• Host animal factors
• Environmental factors
– Management
– Feed and water quality
– Ventilation
– Comfort
– Weather
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9. Disease / Epidemiological Triangle
HOST
ENVIRONMENTPATHOGEN
DISEASE
Resistance, age and immunity
Facilities and management
(Temperature, pH)
Virulence and persistence
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10. Transmission
• Disease occurs when the host’s defences are
overwhelmed by stressors, malnutrition, or
high levels of infectious agent
• Vertical
• Horizontal
• Direct
• Indirect - air borne, fomite, vector
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11. Factors in Disease Proliferation
• Reservoirs: - where organisms live
• Amplifiers: reservoirs where organisms proliferate
• Vehicles: inanimate objects / materials - fomites
and biologicals
• Vectors: carriers
– Mechanical vectors: biting insects
– Biological vectors: must propagate in the vector
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12. Ports of Entry and Exit for DiseaseAgents
Source: Epidemiology Concepts for Disease in Animal Groups http://people.vetmed.wsu.edu/jmgay/courses/EpiMod2.htm
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13. Spectrum of Disease Severity
Source: Epidemiology Concepts for Disease in Animal Groups
http://people.vetmed.wsu.edu/jmgay/courses/EpiMod2.htm 13

14. “Iceberg”Concept-Infections
EXPOSURE WITHOUT INFECTION
INFECTION WITHOUT
CLINICAL ILLNESS
MILD ILLNESS
SEVERE
DISEASE
DEATH
Clinical Disease
Sub Clinical Disease
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Source: Epidemiology Concepts for Disease in Animal Groups
http://people.vetmed.wsu.edu/jmgay/courses/EpiMod2.htm

15. Signs / Evaluation of Health
• Postures, alertness, activity
• Skin, eyes, nose/ muzzle, mouth
• Appetite, thirst and elimination
• Body temperature, respiration, heartbeat and
pulse
• Body condition, weight and production
• Hematology and biochemistry
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16. Record Keeping for Assessment
• Feed and water intake
• Occurrence, clinical signs and time of death
• Occurrence of abortions
• Occurrence of mortality and culls
• Lesions at slaughter or post mortem
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17. Disease Prevention
Susceptible animal
Infected animal
Exposure
Remove infection
Detect and remove or treat
Stop transmission
Direct and indirect
Enhance resistance
Acquired, passive, active or inherent
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18. Steps to Manage Health Risks
Biosecurity
• Isolation
• Acclimation
• Testing
• Vaccination
• Disinfection
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19. Why Biosecurity?
• Improved animal welfare
• Improved production, productivity, profit
• Increase value of the herd
• Decreased use of medicines
• Less antibiotic resistance
Prevention is better than cure
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20. Prevention and Control of Diseases
• Maintain a closed herd
• Isolate, test and treat incoming animals
• Control visitors and motor vehicles
• Avoid contact with wildlife and domestic
species
• Feed and water - free of contamination
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21. • Truck and foot dips
• Using all-in, all-out flow
• Using shower-in, shower-out
• Keeping facility clean, disinfect
• Fencing, fans and curtains
• Rodent, bird and insect control
SOPs for Biosecurity
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22. Quarantine
• All incoming stock - quarantined in isolation
• Initial 30-days - any signs of illness
• Another 30-days period - acclimation
• Reputed suppliers
• Retest animals if necessary
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23. Pathogen Elimination
• Blanket treatment - antibiotics, vaccine
• Identifying carriers (test and cull)
• Depopulation
• Complete cleaning - sanitation
• Repopulation with pathogen free stock
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24. Disinfection
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• Remove all excess dirt / debris
• Wash with detergent or soap
• Immerse or wet with a disinfectant
• Phenolic-based (Lysol) or quaternary ammonium-
based (Roccal D) are most effective
• Bleach is effective against most viruses and bacteria
but it's inactivated by organic material

25. Porcine Reproductive and
Respiratory Syndrome
• Blue-eared pig disease
• Mystery swine disease
• Swine Infertility and Respiratory Syndrome (SIRS)
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26. PRRS
• Etiology: RNA virus
• Genus: Arteri virus
• Family: Arteriviridae
• Two distinct strains
–Variants of varying virulence
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27. PRRS - Epidemiology
• Highly contagious
• Reproductive failure in sows
• Respiratory disease in young pigs
• Enters swine herd
• Immunosuppression
• Survives in cold wet conditions
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28. PRRS - Why a Big Problem
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Spreads through:
• Milk, colostrum, intrauterine, semen
• Feces, urine, saliva, blood
• Windborne -aerosol up to 6 miles
• Contaminated needles and flies
• Infected hands, boots and protective clothing

29. PRRS - Reproductive Form
• Late gestation abortions
• Stillbirths
• Mummified fetuses
• Weak neonates
• High rate of return to estrus
• Problem may persist and recur for many months
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30. PRRS - Respiratory Form
• Anorexia
• Fever
• Dyspnea, polypnea, coughing
• Unthriftiness
• High mortality in young pigs
• Low mortality in older pigs
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31. Healthy v.s Diseased
Signs Healthy Diseased
Postures
Appetite
Respiration rate
Body temperature
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32. Differential Diagnosis - PRRS
• Parvo virus
• Mycoplasmosis (Mycoplasma hyopneumoniae)
• Pasteurellosis (Pasturella multocida)
• Brucellois (Brucella suis)
• Leptospirosis (Leptospira pomona)
• Streptococcus suis
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33. PRRS - Treatment
• Maintain a closed herd
• Segregate and rear young pigs off site
• Antibiotic therapy
• Depopulate and thoroughly clean weaner unit
• Routine procedures - not done during the acute
phase of the disease
• Serum inoculation of naive gilts
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34. PRRS - Control
• Difficult, unreliable and frustrating
• Infection of breeding stock results in immunity
• Maternal immunity in piglets from seropositive
sows
• Eradication of the virus
• Create a stable positive system - swine herd lives
with the disease
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35. PRRS - Challenges
• Highly infectious-only small amount of virus
necessary to infect a herd
• Persistent infection up to 200 days -shedders
• Mutates easily- commercial vaccines less effective
• Simple blood tests cannot differentiate between
field strain and vaccine strain of virus
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36. PRRS - Testing
• Rope sampling of oral fluids
• Blood testing
ELISA
PCR
FAT
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37. References
• Pugh, D. G and Baird, N. (2011). Sheep and Goat Medicine.
2nd ed., Elsevier.
• Mathew, G. J. (2009). Diseases of the Goat. 3rd ed., Wiley-
Blackwell.
• Merck Veterinary Manual 10th Edition (2010). Kahn, C. M.
and Line, S. Eds., Merck.
• Straw, B. E., Zimmerman, J. J., D'Allaire, S., and Taylor, D. J.
(2006). Diseases of swine 9th ed., Blackwell Publishing.
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38. References
• Biosecurity protocols for the prevention of spread of PRRS virus -- by
Andrea Pitkin, Satoshi Otake and Scott Dee.
https://www.aasv.org/aasv/PRRSV_BiosecurityManual.pdf
• PRRS.org -- the official site for USDA's PRRS Coordinated Agricultural
Project (CAP) research and educational outreach resources.
• Spickler, Anna Rovid. "Title of Factsheet." "Date of Factsheet (Last
Updated)." At http://www.cfsph.iastate.edu /DiseaseInfo/factsheets.php
• Control of Communicable Diseases Manual.
http://navybmr.com/study%20material/CCDM.pdf
• Dohoo, I., martin, W., and Stryhm, H. Veterinary Epidemiological
Research (2005) 2nd ed.
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39. Summary
Define: Disease, health and epidemiology
Classifications: Etiology, Population, Clinical signs
Epidemiological Triangle
Proliferation: Reservoirs, Amplifiers, Vehicle, Vectors,
Transmission: Vertical, Horizontal, Direct, Indirect
Iceberg Concept
Biosecurity
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40. Conclusion
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Understanding epidemiology helps us to prepare better to
control and prevent diseases, reduce health hazards and
economic losses, thus ensuring healthier animals for a
better tomorrow.