1. Learning Objectives

This lecture will be a review of the major diseases of poultry that have been covered in previous lectures. The following are the major disease of poultry that you should know.

2. Nutritional Diseases of Poultry

LINK

2.1. Vitamin A deficiency

• Ocular discharge and reddened conjunctiva - can be confused with Infectious choryza or sinusitis
• Squamous metaplasia

2.2. Vitamin D3 deficiency, Ca/P imbalance

• Rickets
• Swollen joints
• Beaded costochondral junctions

Rickets and growth plate abnormalities see in chickens.

2.3. Vitamin E deficiency

• Encephalomalacia - "crazy chick"
• White muscle disease
• Exudative diathesis

2.4. Perosis - Mn, choline, biotin, folic acid, B6

3. Viral Diseases of Poultry

LINK

3.1. Newcastle disease

Representative strains of avian paramyxovirus
Serotype	Primary Host	Disease
PMV-1	Many wild species (Pigeons)	Variable
PMV-2	Chicken, Turkey, Psittacine	Variable
PMV-3	Psittacine	None
PMV-4
PMV-6	Duck, Goose	None
PMV-7	Pigeon, Dove	None
PMV-8
PMV-9

3.1.1. Mesogenic

Most common form of NDV in chickens Signs, gross/microscopic lesions non-diagnostic Chicks (1-6 weeks) : anorexia, depression, profound respiratory signs, CNS signs common, paralysis, dehydration ; MORTALITY USUALLY >50% Adults (6 mos.+): mild anorexia, +/- depression, laying hens stop laying Definitive diagnosis requires virus isolation or serology.

3.1.2. Velogenic

• Morbidity/Mortality approaching 100%
• Mucosal hemorrhages in GI tract, especially proventriculus and cecal tonsils

Lung tissue from a chicken with Newcastle disease.

3.2. Avian influenza

• Conventional low pathogenic
• Highly pathogenic (fowl plague)
• Attacks vascular endothelium, respiratory and GI tract epithelium
• Cutaneous hemorrhages in comb, wattle and shank ; epicardial petechia
• MORBIDITY > 90%, MORTALITY >90%

3.3. Laryngotracheitis

• Hemorrhagic and/or, fibrinonecrotic tracheitis
• Intranuclear inclusions typical of alpha herpes virus infection
• MORBIDITY >50%, MORTALITY < 20%

Histopathologic lesion of laryngotracheitis virus

3.4. Fowl pox

• Raised, proliferative nodules on non-feathered skin
• Wet pox - proliferative nodules on mucosal surfaces

4. Mycoplasmal Diseases of Poultry

LINK

4.1. Mycoplasma gallisepticum

Mycoplasmal sinusitis in a chicken.

• Chronic respiratory disease -CRD (chickens)
  • always a sub-clinical disease
  • disease symptoms a result of secondary bacterial infection
  • similar lesions seen with chlamydiosis
• Infectious sinusitis (turkeys)
• Infectious choryza ? (chickens)

Chronic airsacculitis compatible with either mycoplasmosis or chlamydiosis.

5. Chlamydiosis in Poultry

LINK

• This disease is far more common in turkeys in comparison to chickens
• Airsacculitis is a common gross lesion
• It is impossible to differentiate this disease from mycoplasmosis on the basis of gross lesions!
• Impression smears are the best method of making a rapid positive diagnosis.

6. Aspergillosis in Poultry

LINK

Brooder pneumonia lesions in a chick.

• Poultry - Brooder Pneumonia - a disease of poor management and overwhelming exposure
• In wild birds it is almost always the result of chronic debilitation, stress or immunosupression

7. Coccidiosis in Poultry

LINK

• E. acervulina
  • mild disease: upper small intestine
  • older chickens
  • laying hens = drop in egg production
• E. necatrix
  • severe disease: mid-small intestine
  • bloody diarrhea
  • death
• E. tenella
  • severe disease: cecae
  • only involves the cecum
  • severe disease in chickens less than 6 mos. old

8. Histomoniasis

• Histomonas meleagridis
• Avian enterohepatitis
• necrotic cecal cores look similar to coccidiosis

9. Infectious Choryza

• Hemophilus gallinarum
• Infectious choryza in chickens
• infectious sinusitis in turkeys
• swollen infraorbital sinus
• caseous exudate in infraorbital sinus

10. Avian Pasteurellosis

LINK

• Fowl cholera
• Pasteurella multocida - chickens, turkeys, wild ducks and geese
• Riemerella anatipestifer - domestic ducks and geese (New Duck Disease)

11. Avian leukosis

LINK

• RNA - oncornavirus
• "B cell" lymphoma
• Affects birds after the onset of sexual maturity (6 months of age)
• Virus can cause fibrosarcoma, erythroblastosis, myeloblastosis avian osteopetrosis.

Lymphoid liver tumor compatible with both leukosis and Mareks disease.

12. Marek's Disease

LINK

• DNA - herpesvirus
• "T cell" lymphoma
• Affects birds before the onset of sexual maturity
• Virus can cause inflammatory as well as neoplastic lesions (gonadal lymphomas are common)

Sciatic nerve and lumbosacral neuritis association with Mareks disease.

13. Ancillary Material