Ruminant respiratory ID

Cattle respiratory viruses

• bovine respiratory syncytial virus (BRSV)

• Parainfluenza virus 3 (PI3)

• Bovine herpesvirus 1 (IBR)

• Bovine viral diarrhoea (BVD)

• Bovine coronavirus

pathogenesis of paramyxoviridae (BRSV and PI3)

• proteins are required for attachment to target cell

  • G protein for RSV

  • HN glycoprotein for PI3

• fusion proteins induce fusion between viral envelope and target cell membrane

• virus nucleocapsids released into cytoplasm

what pathology does BRSV cause?

• interstitial pneumonia

• interstitial emphysema

• formation of multi-nucleated giant cells, containing eosinophilic inclusion bodies

—> on histo - see less alveolar air spaces + increase in inflammatory material between alveolar air spaces

—> on gross specimen - see airfilled bullae (bubbles of air)

what pathology does PI3 cause?

• bronchitis

• bronchiolitis

• alveolar cell thickening + hyperplasia

• possibly also giant cells

• intracytoplasmic inclusion bodies in lungs days 5-7

what are features of IBR (BHV1)?

• DNA virus, enveloped

• neurotropic - neural ganglia

• latency - then during stress can become shedder again to spread virus

• vaccines available

• more in older young stock + adults (6-18 months)

what pathology does IBR cause?

• sloughing of epithelial cells in URT

• necrosis —> open to bacterial infection

how can we detect IBR clinically?

listen to trachea with stethoscope - loud rasping noise

what pathology does bovine coronavirus cause?

• damages mucociliary escalator

• linked to pneumonia in calves

• diarrhoea in calves (possibly adults)

what bovine respiratory pathogens have vaccines available?

• PI3 (parainfluenza 3)

• BRSV (bovine respiratory syncytial virus)

• BHV (bovine herpesvirus) - causes IBR

• BVDV (bovine viral diarrhoea virus)

• bovine coronavirus

what pathology does BVDV cause?

• destroys alveolar macrophages

• depletes lymphoid tissue

—> doesn’t directly cause disease of respiratory system - but makes it prone to other viruses

if a persistently infected cow with BVD (due to dam being infected in second trimester) is infected with cytopathic biotype, what does this cause?

no antibodies to fight it off —> mucosal disease (ulceration of mucosa)

• high mortality

sheep respiratory diseases

• betaretrovirus (retrovirus)

• Maedi (retrovirus)

what pathology does betaretrovirus cause?

ovine pulmonary adenomatosis

• oncogenic - forms tumours

• targets type II pneumocytes

• multifocal lesions

• chronic wasting disease

how can we identify ovine pulmonary adenomatosis clinically?

wheelbarrow test - lift up back legs, and see white discharge drain from nose

what pathology does Maedia cause?

• infects monocytes

• progressive lymphoid infiltration

• smooth muscle hyperplasia in lungs

cattle bacteria causing respiratory disease

• Mannheimia haemolytica

• Pasturella multocida

• Histophilus

• Mycoplasma

what are features of Pasteurellaecea bacteria (Mannheimia haemolytica, Pasturella multocida, Histophilus)?

• gram negative, facultative anaerobes

• bacilli or coccobacilli

• host-specific RTX toxin

what pathology does pasteurellaceae cause?

fibrinous pleurisy and intra-alveolar fibrin deposition

What causes shipping fever in cattle?

• IBR followed by Mannheimia haemolytica

• brought on by stress of transport

what pathology does shipping fever cause?

• pleurisy

• pneumonia

• histo - lots of inflammatory cells and blood vessels, loss of alveolar air spaces

• gross - blood filled spaces on cut surface of lung

what bacteria that is commensal in the genital tract, can cause respiratory disease?

Histophilus somni

what pathology does Histophilus somni cause in respiratory tract?

• thrombus formation

• histamine release —> massive inflammatory response

what are features of Mycoplasma bovis?

• no cell wall

• gram positive

• can survive in epithelial and inflammatory cells

• found in URT and LRT

what pathology does Mycoplasma bovis cause?

• cuffing pneumonia

• septic arthritis

• otitis media

• mastitis

sheep respiratory bacteria

• mycoplasma ovipneumoniae

• pasteurellosis - Mannheimia haemolytica, Bibersteinia trehalosi

how can we diagnose sheep respiratory diseases?

• post mortem examination

• Maedi-visna - ELISA

• Mycoplasma ovipneumonia - no test

how can we diagnose cattle respiratory diseases?

• serology (for viruses, Mycoplasma, H. somnus)

• PCR on nasopharyngeal swabs or tissue (for IBR, PI3, BRSV)

• post mortem - histology, tissue PCR