Vet Med Chapter 9

Chapter 9-Lesson 1: Genetics & Disease

Genetics: The study of heredity and how characteristics are passed from one generation to the next.
Heredity: Transmission of traits from parent to offspring via genes contained in chromosomes.
Genes: Segments of DNA located on chromosomes that determine traits and characteristics.
Chromosomes: Structures that hold genes, typically exist in pairs from both paternal and maternal origins.
Alleles: Variations of a gene that can be dominant or recessive.

Genotype: The genetic constitution of an individual for a specific trait (e.g., DD, Dd, dd).
Phenotype: The observable traits of an individual (e.g., hair type, body type).
Homozygous: Individuals with two identical alleles for a trait (DD or dd).
Heterozygous: Individuals with two different alleles for a trait (Dd).
Example: Crossing a homozygous normal cow (DD) with a homozygous dwarf bull (dd) results in all normal appearance (phenotype) offspring but half being carriers (Dd).

Offspring with hereditary defects may inherit two recessive alleles, leading to genetic diseases.
Carriers: Heterozygous individuals who have one normal allele and one abnormal allele but show no symptoms themselves.
Expected outcomes from breeding: In the case of two carrier parents (Dd x Dd):
- 1/4 homozygous recessive (dd) - affected
- 1/4 homozygous dominant (DD) - normal
- 2/4 heterozygous (Dd) - carriers

Genetic diseases: Include dwarfish, albinism, anal atresia, etc. Specific deformities affect development and health.
List of genetic structural deformities:
- Anal atresia: Lack of rectal opening.
- Scrotal hernia: Ruptured scrotum.
- Cryptorchidism: Undescended testes.
- Albinism: Lack of pigment.
- Hip dysplasia: Deformed hip joints.
- Cleft palate: Opening in the roof of the mouth.
- Over-shot jaw and other immune and structural deficiencies.

Diseases spread through contact with infected hosts or contaminated environments.
Reservoir: Site where a disease agent lives before transmission.
Primary sources of diseases: Infected animals, contaminated animals (manure, blood, etc.), and vectors (e.g., ticks, mosquitoes).

Direct transmission: Close contact between host and new host; examples include bites, ingestion, or inhalation.
Indirect transmission: Involves vectors (e.g., insects) and vehicles (e.g., contaminated food or water).
- Biological vectors develop and transmit the disease (e.g., through bites).
- Mechanical vectors transfer the disease without development (e.g., flies).

External parasites: Transmitted through direct contact or by arthropods.
Internal parasites: Reproductive stages passed in feces, infecting other hosts via contaminated environments.

Definition: Diseases that can be transmitted between animals and humans.
Pathogens may be bacterial, viral, or parasitic with various transmission methods.

Bacterial zoonoses:
- Anthrax: Caused by Bacillus anthracis, affects humans mainly via contaminated meat.
- Brucellosis: Caused by Brucella species, primarily from unpasteurized dairy products.
Viral zoonoses:
- Rabies: Transmitted through bites from infected mammals, causing severe symptoms.
- Hantavirus: Spread by rodent droppings and bodily fluids.

Use hygiene, proper cooking methods, vaccination, and education to minimize risk factors associated with zoonotic diseases.

Impact on food production: Diseases lead to lower productivity and increased food product condemnation.
Food safety: Animals with health issues may carry contaminants, necessitating strict quality control measures before food reaches consumers.

Obvious economic losses: Include treatment costs, losses from death, and condemnation of food products.
Hidden economic losses: Include lower efficiency and performance, which may not be immediately noticeable but are detrimental in the long run.

Enhances social, psychological, and physical interactions.
Seen in therapeutic settings, helping those who are elderly, disabled, or in rehabilitation.
Demonstrates positive influences of animals on mental and emotional wellbeing.