Poultry Flashcards
Marek’s disease pathology
Nerves: loss of striations, thick and dull, gray/yellow discolouration (neural lymphomatosis)
All visceral organs affected (tumours). Enlarged feather follicles (skin leukosis)
Pathogenesis of Marek’s disease
Lymphotrophic herpesvirus affecting cytokine expression resulting in immunosuppression
Marek’s diagnosis
2-5 month old chickens affected
- “late Marek’s
Marek’s disease signs
Classical: ataxia, flaccid paralysis (neck + limbs) –> neoplasms
Acute: paralysis, death in 24 - 72 hours
Marek’s control
Vaccine (good cross protection) SQ or in ova
Avian sarcoma/leukosis
Retrovirus, 10 subgroups, persistent low mortality (1-2%, up to 20%). Lymphoid, erythroid, myeloid types (Marek’s only lymphocytes)
What ages does avian leukosis/sarcoma affect?
> 14 weeks, highest mortality from 24 - 40 weeks
Clinical signs of avian leukosis/sarcoma
Inappetance, weakness, dehydration, emaciation, enlarged abdomen, enlarged and lumpy bursa of Fabricius, depressed egg production.
Why is avian leukosis hard to control/eradicate?
Vertical transmission, rapid change makes vaccines ineffective
Two types of erythroblastosis
Proliferative form (liver, spleen, kidney enlargement) Anemic form
Osteopetrosis
Viral interference of growth and differentiation of osteoblasts
Control of osteopetrosis ALV
Testing breeding hens, eliminate vertical transmission (negative egg albumen, vaginal swab testing, hatching in small groups in isolation, disinfection, cleaning, AIAO, non-reusable chick boxes, etc.)
At what age does the bursa of Fabricius begin to involute? When is the thymus its maximum size?
bursa: 14 - 20 weeks
thymus: 17 - 23 weeks
Some examples of avian lymphoid tissue
Bursa of Fabricius Thymus Bone marrow Cecal tonsils Spleen HALT GALT RALT
Infectious Bursal Disease affects what demographic?
Only chickens 3-6 weeks old
