Resp disease of poultry

Question 1

Broiler site statistics

Answer 1

• All in all out system
• 7 day turnaround
• ~30,000 birds per house
  
  • If too big, they aren’t economically viable.
• 4-7 houses per site
  
  • Otherwise cannot make a living. Once above 6 houses, will need extra help to look after the birds.
• Whole house brooding
• >20 lux lighting (4 hours dark/day)
• Pan feeders
• Nipple drinkers
• Concrete floors
• Must be on these for hygiene esp. salmonella control.
• Clean shavings are on top of this as bedding.
• Shavings used as bedding
• Controlled ventilation/humidity
• Thinning at 35 days, depleted 42 days
• Stocking level = 33Kg/m² (25kg/m² for broiler breeders)
• Oldest age birds will go to is 42days. Average site as 7-8 crops per year.
  *

Question 2

Laying systems

Answer 2

• Enriched cages 750cm² to include 600cm² of useable area
• Barn layers should be stocked @ 9 birds/m²
• Free-range layers should have the same internal space and there should be no more than 2500 hens/ha on the range

Question 3

UK Turkey Production

Answer 3

• Breeders use artificial insemination due to size discrepancy between males and females
• Young turkeys are reared in brood rings
• Often stags are grown to six weeks, then moved to grow-out accommodation (brood and move)
• Male turkey’s brooded on site and then moved àbiosecurity risk?
• Hens: all in/all out single site systems

Question 4

Clinical Parameters in Poultry

Answer 4

• Body Temperature: 41.9 - 42.0oC
• Heart rate: Hen:- 350 – 470bpm, :-Turkey 200 – 280bpm, :- Quail 500 – 600bpm (very difficult to diagnose tachycardia in a chicken).
• Respiratory rate: 12 – 21 (male) 20 – 37 (female) (cannot count this by watching them – if you auscultate you can. Normal bird does not mouth breathe – this is abnormal).
• Panting threshold: 27 – 29oC (ambient)

Question 5

Respiratory Disease Clinical Signs

Answer 5

• Coughing (snicking)
  
  • Don’t have a diaphragm, so don’t technically cough or sneeze, they snick.
  • Turn houselights down, they will all go to sleep and not drinking, so you will be able to hear if there is a snick.
• Sneezing
• Ruffled feathers
  
  • Can be emaciated underneath.
• Huddling
  
  • Look for even distribution of birds, if ill, they will huddle.
• Ocular/nasal discharges
• Discharge on wing feathers
• bletharospasm
• Conjunctivitis
• Sinusitis
• Head shaking
  
  • If head is full of snot, they will head shake. (sign of UR disease)
• Swollen heads
• Inappetent
• Abnormal water consumption
  
  • Recorded on a daily basis.
• Mortality (flipovers)
  
  • Always put this as a clinical sign!

Question 6

The coughing bird - ddx?

Answer 6

• All Poultry:
  
  • Avian Influenza (see in chickens, turkeys and ducks)
  • Newcastle Disease (see in chickens, turkeys and ducks)
• Hens:
  
  • Infectious Bronchitis (IB) (sneezing)
  • Avian Rhinotracheitis (ART) (sneezing)
  • Infectious Laryngotracheitis (ILT) (gasping)
  • Mycoplasma gallisepticum (Mg)
  • Ornithobacterium rhinotracheale (ORT)
  • Pasteurella multocida
  • Infectious Coryza
  • E. coli
  • Gapeworm (gasping)
• Turkeys:
  
  • Turkey rhinotracheitis (TRT) (sneezing)
  • Pasteurella multocida
  • E. coli
  • Mycoplasma gallisepticum (Mg)
  • Ornithobacterium rhinotracheale (ORT)
• Ducks:
  
  • E. coli
  • Reimerella anatipestifer (sneezing)
  • Aspergillosis

Question 7

Species Affected by Avian Influenza

Answer 7

• Notifiable disease.
• Will infect, but not necessarily affect all poultry species
• Turkeys are most susceptible to mortality
• Very high levels of mortality.
• Waterfowl, esp. ducks, carry disease with no mortality and no clinical signs

Question 8

Why is avian influenza notifiable?

Answer 8

• Massive economic loss in an uncontrolled outbreak
• Welfare issue of high mortality and morbidity
• Possible zoonotic risk (though no human cases of last year’s H5N8)
• LPAI (H5 or H7) could mutate to HPAI
• All HPAI strains are notifiable, but also LPAI H5 and H7 strains are too.

Question 9

The importance of H & N on avian influenza

Answer 9

• Why are H and N so important?
• because:
  
  • (i)H is for attachment to and release within cells,
  • N allows the virus to leave the cell (KEYS)
  • (ii) They define species specificity
  • (iii) We can easily target them with vaccines
• Can cause high mortality and is a welfare problem.

Question 10

Highly pathogenic and low pathogenic strains of influenza

Answer 10

• Highly pathogenic
  
  • severe disease
  • high mortality up to 100%
  • to date only [but not all] viruses of H5 or H7 subtype
  • Swollen comband wattles
• Low pathogenic
  
  • mild respiratory disease, depression, egg production problems
  • may exacerbate other infections/conditions
  • Impossible to diagnose in backyard chickens: little bit sick and drop in egg production, but lots of things cause this. In commercial: resp signs and egg drop and have ruled out endemic differentials, then you should start thinking about low path. Influenza.

Question 11

Avian influenza clinical signs

Answer 11

• High Pathogenic virus infection
  
  • Anorexia
  • Mortality – up to 100% in 36 hours
  • Respiratory signs
  • Coughing (snicking), sneezing, ruffled feathers, swollen heads
  • Tend to show these just before they’re dead.
  • Nervous signs like depression
  • Diarrhoea
  • Egg drop is very important.
• Low Pathogenic virus infection
  
  • Anorexia
  • Respiratory signs (like HP)
  • Nervous signs
  • Diarrhoea
  • Egg production drop
  • Blood seen at nose and cloaca
  • Vague signs.

Question 12

Newcastle Disease

Answer 12

• Paramyxovirus type 1
• Notifiable.
• Should be on your ddx.
  
  • High levels of mortality
  • Egg drop
  • Resp signs
• 5 pathotypes:
  
  • Viscerotropic velogenic – high mortality with haemorrhages
  • Neurotropic velogenic – high mortality following respiratory and nervous signs
  • Mesogenic – low mortality following respiratory & nervous signs
  • Lentogenic respiratory – mild respiratory disease
  • Asymptomatic enteric – inapparent enteric infection

Question 13

Newcastle disease clinical signs

Answer 13

• Respiratory signs
  
  • Coughing, sneezing, ruffled feathers, swollen heads
• Nervous signs
  
  • Depression
  • Ataxia
  • Prostration
• Opisthotonus
• Mortality – similar to AI
• Egg drop
  
  • Soft shelled eggs
  • Concentric rings on shell

Question 14

Vaccination against newcastle disease

Answer 14

• Lots of vaccines available: live, vector and inactivated.
• All commercial layers are vaccinated (2 x live & 2 inactivated in rear)
• All broiler breeders are vaccinated
• Minimum dose = 1000 dose vials
• Hitchner B1(MSD), NDW (Zoetis), Avinew (Boehringer-Ingelheim)
• AI
  
  • No vaccination allowed under control programme

Question 15

Infectious bronchitis

Answer 15

• Corona virus
• Disease first recognised in USA in 1931 (Massachusetts Strain)
• Worldwide problem in chickens
• Now variant viruses common
  
  • 793B, D274, 1466 & Italian O2, QX
• Waves of viruses affect different countries
• Coronaviruses found in intestines of gamebirds and turkeys

Question 16

Infectious bronchitis clinical signs

Answer 16

• Respiratory signs include sneezing, nasal discharge, lacrimation
• Poor performance – weights in pullets
• Egg drop in layers (up to 25%)
• Blind layer syndrome (hydrosalpingitis)
  
  • Ovulate, but so much damage to oviduct, that cannot produce eggs properly.
• Poor egg shell quality (can last 4-6 weeks) – pale shells or thin shells
• Kidney effects (nephritis) – excess drinking / wet litter
  
  • Depending on the strain.
• Control by vaccination
  
  • All commercial birds are vaccinated.
• Farm – Mix of vaccines
  
  • 2 doses – 2 weeks apart
  • Older birds at 10 – 12 week intervals
• Vaccines: (1000 dose vials minimum)
  
  • M41 strain…….. H120, MA5
  • 793B strain…… 4-91, IB88
  • D274 strain….. IB Primer
  • QX 388 strain. QX

Question 17

Avian Rhinotracheitis (ART) Turkey Rhinotracheitis (TRT) Swollen Head Syndrome

Answer 17

• Endemic resp. virus.
• Obvious clinical sign is swollen heads, but not pathognomonic.
• Avian meta-pneumovirus
• A & B strains seen in UK
• C strain in USA
• Started in turkeys in 1978
• Now seen in chickens
• Decreased appetite
• Poor growth in young birds
• Egg production drops in hens
• facial & head swelling
• ocular & nasal discharge
• conjunctivitis, snick, dyspnoea, sinusitis
• Post-mortem lesions:-serous rhinitis and tracheitis, pus in the bronchi
• Live vaccines used extensively in the turkey industry

Question 18

Infectious Laryngotracheitis (ILT)

Answer 18

• Herpes virus
• Only affects chickens (occasionally pheasants) – commonest in young birds
• Respiratory route
• Virus can survive for several weeks on ground – when cold even longer
• Peracute form – sudden death
• Haemorrhagic tracheitis / laryngitis
• Vaccination by eye drop with live vaccines
• Vector vaccines can be used in the hatchery
• On PM, there is a nasty pharyngitis with lots of haemorrhage.
• Most laying hens are vaccinated against it, but not broilers.

Question 19

Mycoplasma infections

Answer 19

• 23 avian species
• Mycoplasma gallisepticum –
• Epithelium of the conjunctiva, nasal passages, sinuses, and trachea are most susceptible to initial colonization and infection; however, in severe, acute disease, infection may also involve the bronchi, air sacs, and occasionally lungs. Once infected, birds may remain carriers for life. There is a marked interaction (polymicrobial disease) between respiratory viruses, Escherichia coli, and M gallisepticum in the pathogenesis and severity of chronic respiratory disease.
• Commonly seen in gamebirds, free range layers and seasonal turkeys. Very rare in breeder birds due to control measures.
• Live attenuated vaccines available
• Seen in backyard chicken. Most likely thing to see in backyard poultry.
• See infraorbital sinusitis swelling.

Question 20

Ornithobacterium rhinotracheale

Answer 20

• A pasteurella-like bacterium
• Unrelated to ART / TRT
• Causes respiratory disease in young turkeys and chickens, and locomotor disease in older turkeys and chickens
• A very common reason for poultry airsacculitis condemnation in processing plants; other lesions include bronchopneumonia, tracheitis and Achilles tendon abcessation
• Spreads vertically and horizontally
• Culture difficult / ELISA serology
• Inactivated vaccine available for breeders
• More a disease of turkey’s cf. chicken’s.

Question 21

E. coli

Answer 21

• Primary pathogenic E. coliexist
• Environmental organism
• Can be typed to determine pathogenicity
• Usually secondary to other conditions e.g. IB/Mg
• Serositis distribution
  
  • Pericarditis
  • Peritonitis
  • Perihepatitis
• Treatment based on Culture & Sensitivity
  
  • Wide range of antibiotics can be successful
  • Live vaccine available

Question 22

Pasteurellosis

Answer 22

• Bacterial respiratory disease
• Pasteurella multocida
• Pasteurella often associated with rodents (rats not mice) or sheep
• Common in layers and turkeys
• Causes severe pneumonia
• High mortality potentially
• High rejects in meat birds
• Poorly responsive to medication other than Enrofloxacin and Amoxicillin
  
  • Enrofloxacin not used in backyard chickens anymore- it is a restricted AB.
• Inactivated commercial and autogenous vaccines used

Question 23

Infectious Coryza (IC)

Answer 23

• Avibacterium avium (formerly Haemophilus paragallinarum)
  
  • Severe respiratory disease first identified in backyard flocks by APHA and now seen in commercial free range layers
  • Impact on egg production
  • Low to significant mortality in non-protected flocks
  • Poor response to antibiotic treatment and no UK licenced vaccines

Question 24

Riemerella anatipestifer

Answer 24

• Probably more widespread in the UK duck industry than first thought
• Certainly common in Asia
• Poor hygiene increases the risk of infection
• Diagnosis on culture (48 hours)
• Responds well to antibiotic therapy: Amoxicillin, Chlortetracycline in food
• Prevention – Hygiene, Autogenous vaccination, Management
• Accounts for a lot of duck mortality when there are respiratory signs.

Question 25

Aspergillosis

Answer 25

• Contaminated bedding usual source: Straw – ducks
• Young chicks often affected most
• With age comes immunity
• Gasping & mouth breathing
• Sudden death
• Fungal lesions in air sacs / lungs
• Change the bedding source if it is a persistent problem
• Not seen in commercial broiler chickens. Sometimes see in free laying hens and definitely in commercial ducks and turkeys on straw. If have back yard poultry in poor conditions – think this.

Question 26

Syngamus trachea – nematode causing gape worm -

• Treatment?

Answer 26

• Very dyspnoeic
• Diagnosis on PM exam or faecal worm egg count

Treatment Regimes

• Licensed products
  
  • Flubendazole
    
    • Flubenvet: Feed for 7 days at 30ppm
  • Fenbendazole
    
    • Panacur Aquasol: In water 1mg/Kg for 5 days
  • Scratching area management
  • Range management (if have birds constantly affected, think about the environment).
    
    • Remove faeces
    • Replace scratching material
    • Harrowing grassland

Question 27

Diagnosis of Poultry Respiratory Diseases

Answer 27

• Clinical signs (nothing pathognomic)
• Performance data
• Post mortem examination
• Culture for bacteria
• Serology
• Tracheal swabs or FTA cards for PCR
• Virus isolation
• Histopathology

Question 28

Post Mortem Examination

Answer 28

• Because of flock sizes kept, mortalities are inevitable
• Post mortem examination of fresh dead allows a unique opportunity to examine the internal organs of the birds
• It is the mainstay of our examinations, but is complemented by other testing
• Sample selection can impact on findings
• Culls vs. Dead
• Ideal batch size ~ 6 birds

Question 29

Blood sampling technique

Answer 29

• Good restraint is very important
• Brachial vein exposed by plucking feathers
• Use 19 – 23g needle or nick vein with sharp blade
• Half fill blood tube
• Bleeding will usually stop once wing is lowered
• Put cap on tube and lie on side to clot
• Send to laboratory asap (with paperwork)
• DO NOT FREEZE

Question 30

Assessment of Antimicrobials in Poultry Treatment

Answer 30

• Sensitivity plates are still the standard test despite limitations
• Must remember in vitro vs. in vivo differences
• Main criteria for success is a drop in mortality
• Other health & performance criteria can also be used
• Most licensed products have a 3 to 7 day treatment period
• Consider -cidal drugs for immunocompromised birds
• In vitro resistance is frequently seen; consider your approach
• Egg dipping & in ovo can impact on hatchability
• Intensive antibiotic use high up the genetic pyramid may dramatically reduce use in commercial birds

Question 31

Routes of administration for poultry vaccines

Answer 31

• Drinking water
• Spray:
  
  • Hatchery cabinets
  • On farm
• Intra – ocular
• In ovo
• Injection (importance of maternally derived antibodies for commercial birds)

Question 32

Vaccine/Medicine administration

Answer 32

• Respiratory live vaccines ideally given by spray
• Live vaccines applied through the drinking water do not provide an upper respiratory tract immunity
• THESE ARE LIVE VACCINES therefore chlorinated mains water will reduce efficacy (need distilled water for the sprayers and Vac Pac plus for drinking system)
• Antibiotics should not be used with in ovo vaccination