Top 10 Poultry Part 1

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Feeling chicken about taking Boards?

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Only 6 poultry Qs on NAVLE® count (2%)!

5 Poultry conditions to know for boards success:

  1. Newcastle disease (avian pneumoencephalitis)

      Torticollis, a sign of Newcastle disease

                    Petechiae in proventriculus and gizzard; inflammation of duodenum (outside & inside view), Newcastle disease

    • Classic case: high mortality rate
      • Acute onset severe respiratory and/or neurologic and/or GI signs:
        • Respiratory:
          • Gasping, sneezing, coughing
          • Facial edema ("square head")
          • Reddened lower eyelid (over lymphoid patch)
        • Neurologic:
          • Paralysis, tremors, droopy wings
          • Torticollis, circling
          • Bright and alert despite severe neurologic deficits
        • GI: Watery green diarrhea
      • Sometimes sudden death
      • Decreased egg production with thin shells and watery albumen
    • Dx:
      • Etiology: RNA avian paramyxovirus-1 (APV1 or PMV-1)
      • Gold standard test: virus isolation
        • Dead birds: lung, kidney, GI tract
        • Live birds: nasopharyngeal and tracheal exudate swabs
      • RT-PCR for pathotyping and genotyping
      • Intracerebral pathogenicity index (ICPI): inoculating day-old chicks to determine virulence
      • Hemagglutination positive
      • Almost pathognomonic necropsy lesions: multifocal necrosis, hemorrhagic intestinal mucosa (especially at lymphoid foci - cecal tonsils)
    • Rx: None, CULL all birds on premises
      • Prevention:
        • Good management practices, spreads quickly through facility via aerosol exposure
        • Indoor operations better, outdoor flocks at higher risk
        • Vaccines in countries where virulent virus disease outbreaks occur
    • Pearls:
      • APV1 are labeled depending on how fast they kill chick embryos post-innoculation
        • Lentogenic (slow), used in vaccines and not reportable
        • Mesogenic (medium)
        • Velogenic (fast); further divided into:
          • Viscerotropic (GI) velogenic Newcastle disease (VVND)
          • Neurotropic (brain) velogenic Newcastle disease (NVND)
      • Clinical signs vary with strain
      • Strains vary by differences in surface glycoproteins: hemagglutinin-neurominidase (HN) and fusion (F)
      • Mesogenic and velogenic Newcastle disease are REPORTABLE in USA
      • ZOONOTIC: transitory conjunctivitis in humans

  2. Marek's disease

                    Normal eye on left, grey eye (from lymphocytic infliltration of iris) on right, Marek's disease

                    Enlarged sciatic nerve on left, Marek's disease

    • Classic case: Clinical signs based on which organ/tissue T-lymphocytes infiltrate
      • Sciatic nerve paralysis (one leg forward, one backward)
      • "Grey eye" (due to lymphocytic infiltration of iris)
      • Young chicken (2-5 mos)
      • Decreased growth rate and egg production
      • Enlarged feather follicles (cause for condemnation)
    • Dx:
      • Etiology: Oncogenic lymphotrophic alphaherpesvirus (genus Mardivirus)
      • Virus isolation, PCR (for viral DNA in lymphoid tumors), AGID
      • Enlarged peripheral nerves (esp. sciatic) at necropsy
      • Lymphoid tumors in liver, spleen, gonads, heart, lung, kidney, muscle and proventriculus
      • Bursa is rarely affected and usually atrophic (distinguishes from lymphoid leukosis)
      • Histopathology and immunohistochemistry
    • Rx: None
      • Supportive care in pet poultry
      • Prophylaxis: vaccinate in ovo or day-old chicks decreases shedding
    • Pearls:
      • Virus causes in lymphoproliferative disease/neoplasia in chickens
      • No vertical transmission; horizontal transmission is mainly via inhalation of aerosolized "chicken dander" & can travel on the wind between flocks
      • Virus practically ubiquitous; assume flocks infected
      • Silent recovered lifelong carriers are main reservoir

  3. Avian influenza (AI)

                    Hemorrhaging of the limbs with HPAI

    • Classic case: Depends on pathogenicity/strain
      • Low-pathogenicity AI (LPAI): often subclinical
        • Mild to moderate respiratory signs
        • Poor weight gain
        • Egg drop
      • High-pathogenicity AI (HPAI): "Fowl plague"
        • Peracute death, prostration
        • Cyanosis of head appendages, petechiation in viscera, oral/nasal bloody discharge
        • Diarrhea
        • Neurologic signs
        • Hemorrhages of the limbs
        • Spreads rapidly!
    • Dx:
      • Etiology: Orthomyxovirus, influenza type A
      • Virus isolation in eggs from clinical samples with rRT-PCR for typing
      • Hemagglutination positive
      • Haemagglutinin and Neuraminidase (H and N) typing and subtyping also done by inhibition tests using antisera (H5 & H7 HPAI subtypes are most commonly implicated)
    • Rx:
      • Prevention: autogenous vaccination (requires state veterinarian approval) and strict biosecurity
      • HPAI: no treatment, depopulate
      • Supportive care and antibiotics for LPAI
    • Pearls:
      • Highly contagious
      • HPAI is REPORTABLE, possibly ZOONOTIC (H5N1, H7N7 can be fatal to humans)
      • Often carried long distances by subclinically infected waterfowl or seabirds
      • Gene re-assortment occurs in developing countries or markets where humans, fowl, and swine intermix, creating new genotypes

  4. Infectious laryngotracheitis

                    Dyspneic chicken, infectious laryngotracheitis

    • Classic case:
      • Acute outbreak of gasping, coughing, conjunctivitis, dyspnea, depression
      • +/- Bloodstained beaks in chickens under 4 weeks
      • Decreased egg production
      • Mortality variable, often high
      • Chronic: poor weight gain in broilers
      • Latent infection in survivors, can recrudesce when birds stressed
    • Dx:
      • Etiology: Gallid herpesvirus I
      • Necropsy: blood, mucus, caseous exudate, or hollow cast in trachea
      • Intranuclear inclusion bodies
      • Clinical cases: virus isolation, PCR
      • Screen flocks with ELISA or virus neutralization (VN) serological tests
    • Rx:
      • No treatment
      • Immediately vaccinate adults during outbreak
      • Prevent with biosecurity and vaccination
    • Pearls:
      • Highly contagious
      • Worldwide; transmission horizontal through aerosol, fomites
      • Vaccination with attenuated vaccines has regularly resulted in disease through serial virus passage in vaccinates
      • Recovered birds are lifelong carriers
      • REPORTABLE

  5. Infectious bronchitis

                    Upper respiratory signs with infectious bronchitis

                    Wrinkled egg, infectious bronchitis

    • Classic case:
      • YOUNGEST birds: acute onset upper (sneezing, conjunctivitis, swelling) and lower (rales, coughing, dyspnea) respiratory signs
      • Breeders & layers: SHARP decrease in egg production and misshapen or wrinkled egg shells
      • Variable mortality, but almost 100% morbidity
    • Dx:
      • Etiology: RNA coronavirus
      • Necropsy: white urates in renal tubules
      • NEGATIVE hemagglutination reaction
      • Virus isolation in chick embryo
      • Paired serology
    • Rx: None, supportive care
      • Antibiotics for secondary infections
      • Prophylaxis:
        • Vaccines
        • Strict biosecurity
    • Pearls:
      • Worldwide, common, contagious
      • Reportable in some states
      • Some strains cause reproductive issues, some are nephrotrophic

Images courtesy of The Poultry Site (torticollis/Newcastle, laryngotracheitis), USDA (grey eye/Marek's, avian influenza), Raketenpilot (walking chickens), Lucyin (Marek's sciatic nerves, Newcastle hemorrhages), Copyleft (wrinkled egg), Dr. Marina Brash (infectious bronchitis), Benjamint444 (silkie), and Dimus (turkey).