CNS & Enteritis Flashcards
Avian encephalomyelitis (AE) Pathogen
• Picornaviridae, Enterovirus
– 1-2 weeks of age
– „epidemic tremor”
• Nonsuppurative encephalomyelitis/encephalitis = lymphocytes and histiocytes (not heterocytes)
– Cerebellum, medulla, spinal cord (ventral horn)
– Neuronal degeneration, gliosis, mononuclear perivasculitis
– Lymphoid tissue proliferation (glandular, gizzard, heart muscle, pancreas)
Major lesions in CNS
In different areas of the CNS
(basal part of the brain, medulla oblongata, cerebellum, cervical & lumbal part of the myelon):
• neuron degeneration
• focal gliosis
• perivascular lymphohistiocytic infiltration
Avian encephalomyelitis (AE) Pathogenesis
Per os infection
viraemia → the virus reaches the target organs (inflammatory cell infiltration)
– propria of the proventriculus
– myocardium
– interstitium of the pancreas
-gizzard
• in these organs focal lymphocytic infiltration develops
• epidemic tremor
(head, neck)
• later ataxia
Occasionally central opacity (blindness) and/or uveitis is developed
Arthritis and tenosynovitis
caused by Orthoreoviruses
• infectious synovialitis
• orthoreoviruses like to proliferate on synovial membranes
– mainly the trypsin-sensitive strains
– the trypsin-resistant viruses start to proliferate in the mucous
membrane of the intestinal tract
• Infection:
– in ovo
– per os from the infected birds (• orofecal)
• Other (trypsin-sensitive) strains enter through the airways or skin
1) proliferation in the port of entry
2) viraemia – unnoticed in most of the birds
3) during viraemia reach the joints, tendon sheaths and bursa
4) proliferate
• acute serous, sero-fibrinous(-purulent) inflammation, later chronic
• Appearance: chicken, hen, turkey, goose, Muscovy duck
• Secondary: Staphylococcus aureus, Mycoplasma synoviae
Disease in geese and Muscovy
ducks caused by orthoreoviruses
• Pathogen: – different strain of orthoreovirus • Infection: same • Pathogenesis: similar • no lesions develop in the gut • the viraemia by orthoreoviruses is fatal – mainly in young animals • arthritis and tenosynovitis also occurs
Pathology of the small intestine
Viral enteritides
• Parvovirus enteritis • Adenovirus enteritis • Astrovirus enteritis • Reovirus enteritis • Rotavirus enteritis • Coronavirus enteritis • PEMS – poult enteritis mortality syndrome (young turkeys)
General pathogenesis of viral
enteritides
Multiplication of the virus takes place in the epithelial cells of the intestinal villi (villus-atrophy)
– in the enterocytes
• degeneration of the enterocytes occurs due to destruction of the enterocytes
• decreased production of enzymes
– malsecretion
• abnormal digestion processes
– maldigestion
• imperfect, incomplete absorption
– malabsorption
Because of malsecretion, maldigestion and malabsorption
• osmotically active decomposition products are produced
• these substances bind fluid
– increased fluid amount in the intestines- osmotic diarrhoea=> ORANGE
-faecal balls on the toes
General pathogenesis of viral
enteritides
Outside the intestines
due to malnutrition
viraemia follows the proliferation
– feathering problems (helicopter feather)
– osteopathies
• ricketts and other diseases
– dyschondroplasia, epiphysiolisis (bone is bending and cartilage)
– vitamin E deficiency
– atrophy of the immune organs
Runting-stunting (syndrome), maldevelopment
Enteric disease complex in chickens
– Clinical symptoms – In the flock » Huddling, litter ingestion » Diarrhoea consequences » Poor production, fail to grow » Heterogenous flock Runting-Stunting Syndrome (RSS) – Cause – Not completely cleared – Several factors » VIRUSES Astroviridae Coronaviridae Reoviridae Rotaviridae PARVOVIRIDAE
Pathogenesis of enteric diseases
• Dilatation of the intestinal loops – Changes in the quality of the content =>Maldigestion-malabsorption syndrome • Villus degeneration – Destruction of the epithelial layer » Villus denudation » Villus atrophy / fusion
