what is the normal temp of a chicken?
40-42 degree
what is the normal HR of a chicken?
120-160bpm
what is the normal RR of a chicken?
20-30brpm
what are the best sites for blood sampling chickens?
jugular or wing v.
why must blood counts be done manually for birds?
do not have neutrophils - have heterophiles instead
chickens do not have sweat or sebaceous glands BUT they do have some other glands - what are they?
preen gland at the base of the tail
gland in external auditory canal
ventral glands of the cloaca
what is the brood patch?
an area of feathers on the ventrum that cyclically moult and re-grow that is controlled hormonally
what is the brood patch rich in?
thermoreceptors
which feathers are clipped in wing clipping?
the first 10 feathers of one wing only
what is the structure of a chicken GIT?
beak - mouth - crop - proventriculus - gizzard - intestines - caeca - cloaca
what is the cloaca?
the common opening for the GIT and repro tracts
what is the relationship between the proventriculus and the gizzard?
food is passed back and forth between the structures with the proventriculus acting as the true stomach and the gizzard as the teeth
what must poultry have in their diet to allow the gizzard to function correctly?
insoluble grit
what are the main Sx of resp disease in chickens?
nasal discharge coughing / sneezing head shaking gasping noisy breathing
what are the 11 Ddx for resp disease in chickens?
- Infectious bronchitis
- Ornithobacterium rhinotracheite
- Infectious laryngotracheitis
- Aspergillus fumigateurs
- Chlamydiosis
- Avian Influenza
- Pigeon Paramyxovirus
- Newcastle disease
- Avian metapneumovirus
- Mycoplasmosis
- Gape worm
what causes infectious bronchitis in chickens?
type 3 coronavirus
what areas of the body does infectious bronchitis affect?
female repro tract, urinary tract and resp tract
what are the main Sx of infectious bronchitis?
resp disease
egg drop
poor egg quality
egg peritonitis
how is infectious bronchitis Px?
live vaccine for boilers and breeders
what are the main Sx of ornithobacterium rhinotracheite infection?
coughing
egg drop
sneezing
bronchopneumonia
how is ornithobacterium rhinotracheite Px?
autologous vaccination
what causes infectious laryngotracheitis?
gallid herpes virus 1
what are the main Sx of infectious laryngotracheitis?
difficulty breathing
gasping
how can infectious laryngotracheitits be Px? what is the problem with this method of Px?
vaccination
vaccination is live and some birds may become latently infected and shed the virus at times of stress
what causes avian influenza?
orthomyxovirus
which type of avian influenza is classed as high pathogenicity?
type A, H5 and H7
which strain of avian influenza is of public health concern? why?
H7N9
low pathogenicity in chickens BUT high mortality in humans
what are the main Sx of avian influenza?
egg drop, resp distress, D+, sudden death
what causes Newcastle disease?
paramyxovirus
what are the 4 types of Newcastle disease and what pathology is associated with each?
viscerotropic - GIT haemorrhage
neurotropic - resp and neuro lesions
mesogenic - resp and neuro lesions
asymptomatic enteric
what is the difference between the neurotropic and mesotropic forms of Newcastle disease?
neurotropic = high mortality mesogenic = low mortality
how is Newcastle disease Dx?
via oropharyngeal swabs
how is Newcastle disease Px?
live vaccine in layers and breeders
what does avian metapnuemovirus cause?
rhinotracheitis
what are the four subtypes of metapnuemovirus?
A,B,C and D
what are the main Sx of rhinotracheitis?
resp disease
egg peritonitis
how does infection with avian metapneumovirus differ in chickens cf. turkeys?
milder disease seen in in chickens BUT may lead to swollen head syndrome
how can avian metapneumovirus be Px?
live vaccine for subtypes A and B
which two mycoplasma spp affect chickens?
M. gallisepticum
M. synoviae
how might mycoplasma infection of a flock affect the owner economically?
UK flocks must be free from myocoplasmosis for export
what are the main sx of mycoplasmosis in flocks?
resp. disease
swollen hocks / arthritis
egg drop
sternal bursitis
how can mycoplasmosis be Px?
vaccination
what is the gape worm?
syngamus trachea - a hookworm causing mechanical damage to the trachea, asphyxiation and coughing
which diseases are notifiable in chickens?
avian influenza
Newcastle disease
pigeon paramyxovirus
what are the regions of the female repro tract of birds?
infundibulum magnum isthmus uterus vagina cloaca
what is the function of each region of the female repro tract?
infundibulum = capture ovum magnum = addition of albumin isthmus = addition of shell membranes uterus = addition of the egg shell
what is ‘candling’?
a procedure done at 9-10d after incubation to determine fertility of the eggs
how long are chicken eggs incubated for cf. turkey and duck eggs?
21d cf. 28d
what are the 7 main problems which affect the repro tract of chickens?
oviduct infection egg peritonitis IBV infection M. synoviae egg bound vent gleet pyometra
why might a chicken become egg bound?
lack of Ca in diet
which 4 viruses can be transmitted vertically in chickens?
Retrovirus - lymphoid leucosis
Reovirus - viral arthritis
Adenovirus - egg drop syndrome
Astrovirus
which 4 bacterial spp can be transmitted vertically in chickens?
salmonella
e. coli
staph
mycoplasma
what are the 3 main immunosuppressive diseases seen in chickens?
infectious bursal disease virus
chicken anaemia virus
marek’s disease
what does IBDv affect?
the bursa and B-cell production
what are the effects of IBDv infection?
mortality of up to 40% and immune suppression, bursal lesions
how is infection with IBDv Px?
live vaccine for boilers
inactivated vaccine for layers and breeders
what does chicken anaemia virus affect?
the thymus and T cells
what is the difference between CAV maternal Ab +ve vs -ve chicks?
\+ve = protected from disease -ve = susceptible to disease from 2wks age
what lesions are seen with CAV?
thymus and spleen - atrophy and immunosuppression via T cells
bone marrow - anaemia
when are clinical Sx of CAV seen and what are they?
infected > 7d, Sx from 12-17d
anorexia, depression, low PCV, leukopenia, immune suppression
how is CAV Px?
live vaccine in breeding birds
what is Marek’s disease?
tumour caused by an oncogenic herpes virus - mardivirus
what characterised Marek’s disease?
nerve swelling and tumours
how is Marek’s disease Px?
SC vaccine at 1d of age
How is Marek’s transmitted?
mature virus excretion by feather follicles –> inhaled
high virus load in dust
what are the 4 manifestations of Marek’s and what type of lesions do they cause?
a. neurological - floppy broiler syndrome = paralysis of legs and wings, eye lesion due to sciatic and brachial n. being affected
b. visceral - tumours of the heart, gonads, muscles and lungs
c. cutaneous - tumours of the feather follicles
d. ocular - uni or bilateral eye tumours
What virus causes avian encephalomyelitis?
Picornavirus
Which bone is affected by dyschondroplasia in chickens?
Proximal tibiotarsus
What is the pathogenesis of egg Peritonitis?
Oviduct fimbriae fail to catch egg yolk - deposited in abdomen - Peritonitis
Which bacterial agent is involved in egg Peritonitis?
E. Coli
What causes egg drop syndrome?
Adenovirus
What is egg drop syndrome?
Drop in egg production by 5-50% over 3-4wks caused by adenovirus
Shell quality may be affected - loss of pigment, rough, thin, soft