Final Exam Review Notes

Final Exam Review Overview

• Last class meeting before final exam; consultation days are upcoming (no regular class scheduled).
• Students encouraged to email for appointments on Thursday or Friday for assistance with exam preparation.

Important Terminology

• Morbidity: Refers to sickness or unhealthiness in a population. Example: Morbidity percentage of semen indicates how many sperm cells are non-viable (dead).
• Mortality: Refers to the death rate within a population. Important for assessing risks in livestock.

Disease Terms

• Infectious Diseases: Capable of invading and growing in healthy tissue; they invade a host and reproduce. Can be confused with contagious diseases.
  • Contagious Diseases: Transmitted from one host to another; requires exit from one host to infect another.
  • Non-Contagious Diseases: Typically non-infectious; often nutritional deficiencies, like selenium deficiency.

Clinical Signs in Animals

• Observations are crucial; animals may mimic eating behavior while actually not consuming food, especially prey animals.
• Need to identify signs like:
  • Depression: Animal appears lethargic, with drooping ears and lowered head position.
  • Weakness: Difficulty moving; less active than usual.
  • Gauntness: Notable weight loss; visible skeletal structures.
  • Respiratory Issues: Difficulty breathing or coughing, which could indicate pneumonia or other respiratory diseases.

Acute vs Chronic Diseases

• Acute Diseases: Rapid onset, can lead to severe illness or death overnight. Examples:
  • Overeating disease (Enterotoxemia) in sheep (from clostridia bacteria).
  • Milk fever in dairy cattle (calcium depletion post-calving).
• Chronic Diseases: Develop over time; periods of flare-ups and decline. Examples:
  • Asthma in humans is akin to chronic pneumonia in livestock; stress can trigger flare-ups in dormant infections.

Pathogens in Livestock

• Bacteria: Have a cell wall; vaccines and antibiotics can target their cell walls. Example: E. coli and its variants.
• Viruses: Lack cell walls; challenging to create vaccines because of rapid mutation rates. Treatment is usually supportive therapy. Examples include the flu or common cold.
• Protozoa: Single-celled organisms larger than bacteria. They require a living host and can survive in cyst form, making eradication difficult. Example: Coccidia in sheep.
• Prions: Misfolded proteins that damage brain tissue leading to diseases like scrapie in sheep or chronic wasting disease in deer.

Observing Animal Health

• Importance of understanding normal animal behavior and feces characteristics to detect diseases early.
• Common clinical signs:
  • Nasal discharge (color can indicate type of infection: white for viral, yellow/green for bacterial)
  • Changes in appetite (e.g., going off feed)
  • Signs of dehydration (skin elasticity tests)

Disease Entry and Transmission

• Diseases can be transmitted through:
  • Fecal Matter: Ingestion of contaminated water or feed (E. coli, Campylobacter).
  • Nasally: Airborne droplets from sneezing/coughing.
  • Bloodborne: Via external or internal parasites.
  • Importance of good management practices to mitigate disease spread, especially in high-density animal settings.

Specific Animal Health Issues

• Recognition of dehydration in livestock by observing specific physical signs (like skin elasticity and gauntness).
• Attention to young livestock is crucial; they are vulnerable to rapid decline from infections.
• Regular check-ups for all livestock to identify clinical signs promptly and respond accordingly (e.g., providing fluids or antibiotics as needed).