Unit 1 - Avian Part 1 (Leukosis to IBV) Flashcards
What are broiler chickens?
Chickens that are harvested at 5-6 weeks of age
What are broiler turkeys?
Turkeys that are harvested 14-18 weeks of age
When do breeders and egg layers begin laying eggs?
At about 18 weeks of age
What problems are unique to avian species?
There are drug residues in the eggs and the broiler chickens have short lifespans so immunization is in-ovo or not at all
What breeds are brown egg layers?
Plymouth Rock, Orpington, and RI Red
What breed is the meat breed of chickens?
Cornish Cross
What are the subgroups of the Avian leukosis viruses and what are they grouped based on?
Subgroups - A, B, C, D, E, and J grouped based on their envelope glycoproteins
What species is lymphoid leukosis/sarcoma clinically significant in?
chickens
Currently, what population of chickens is lymphoid leukosis a problem in?
Broiler chickens
Tumor mortality is ___ in chickens with lymphoid leukosis.
<4%
How do infected hens shed leukosis viruses?
It is shed into the albumen or yolk
True or False: Chickens that become congenitally infected with lymphoid leukosis usually remain viremic for life.
True
Most lymphoid leukosis virus spread is ______(direction) early in life.
horizontal
It is relatively easy to maintain lymphoid leukosis virus-free flocks if you do what?
eliminate the virus from the breeder hens
What is most economic loss caused by lymphoid leukosis due to?
Decreased egg production
What do most leukosis tumors result from?
Induction of bursal cells
What is the most common leukosis tumor type?
lymphoid
What are non-lymphoid leukosis tumors dependent on?
strain of virus, breed of chicken, age of exposure, dose, and route of infection
True or False: Demonstration of a leukosis virus is helpful in diagnosing lymphoid leukosis.
False
What tumors are pathognomonic for lymphoid leukosis?
bursal tumors
Where else can tumors form in lymphoid leukosis cases?
Liver, spleen, and other organs
How do you differentiate between Marek’s disease and Lymphoid Leukosis?
Lymphoid leukosis does not develop any peripheral nerve lesions, Marek’s does
Marek’s also doesn’t commonly effect the bursa
How is lymphoid leukosis controlled/eradicated?
Test eggs from breeder flocks for viral antigen
Discard eggs from positive hens
Rear breeder hens in small groups to limit the possibility of having an infected hen
Grow genetic resistant strains of hens
Is immunization successful for lymphoid leukosis?
No
What causes Marek’s disease (general)?
Alphaherpesvirus with lymphotrophic properties of gamma herpesvirus
What does Marek’s disease infect?
feather follicles
True or False: Marek’s disease is not contagious
False - it is highly contagious
Is Marek’s disease problematic in turkeys?
No
What are the three Marek’s disease viruses?
Gallid Herpesvirus 2
Gallid Herpesvirus 3
Meleagrid Herpesvirus 1
________ Herpesvirus ___ is also known as MDV2 and is avirulent for chickens.
Gallid, 3
________ Herpesvirus ___ is also known as MDV1 and is virulent for chickens.
Gallid, 2
________ Herpesvirus ___ is also known as MDV3 and is avirulent for turkeys.
Meleagrid 1
What are the four subdivisions for Gallid Herpesvirus 2 (MDV1)
M - mild
V - virulent
VV - very virulent
VV+ - very virulent plus
What are the most common Gallid Herpesvirus 2 viruses? Why?
Very virulent plus - it is thought to be a result of routine immunization
What can subclinical Marek’s disease cause?
It causes decreased growth rate and egg production
What main pathology does Marek’s disease cause?
lymphoid neoplasms
What ‘other’ lesions does Marek’s cause?
Transient paralysis, early mortality syndrome, cytolytic infection, atherosclerosis, and persistent neurologic disease
How is Marek’s diagnosed?
Enlarged nerves, enlarged feather follicles, and lymphoid tumors in the viscera
What is the most consistent gross lesion caused by Marek’s disease?
enlarged nerves
What clinical sign is associated with enlarged nerves caused by Marek’s disease?
Paralysis or paresis
What Marek’s disease diagnostic lesion is the cause for condemnation of broilers?
Skin leukosis (enlarged feather follicles)
How is Marek’s controlled?
With strict sanitation
Once in a poultry barn, how does Marek’s transmit?
via feather dust
How long can Marek’s survive in the poultry house litter and dust?
months