Respiratory Diseases Flashcards
In ruminants significant pulmonary dz can be present without _____________
Auscultate abnormality
Bovine Respiratory Dz Complex
Lower resp. dz of cattle: bronchopneumonia, interstitial pneumonia, metastatic pneumonia
Bronchopneumonia
Invasion of pathogens through bronchi to the lungs
Signs: sepsis, effusion, abnormal lung sounds (crackles, wheezes) and consolidation
Bacterial agents of BRDC
Normal inhabitants of bovine nasopharynx:
Manheimia haemolytica , pasteurella multocida, histophilus somni, mycoplasma bovis
Mannheimia (Pasteurella) haemolytica
Gram- aerobic
A1 most common serotype (pathogenic)
Most common bacteria in feedlot cattle with pneumonia
Pasteurella multocida
Gram- aerobic
Serotype A most commonly found in BRDC
Histophilus somni
Gram- aerobic
Found on genital + resp. mucosa
Causes a variety of dz + resp (TEME)
Mycoplasma bovis
Mycoplasmas bound by a single membrane and lack a cell wall
Causes multiple dz (arthritis + tenosynovitis)
Viral agents of BRDC
Infectious bovine rhinotracheitis virus (Herpes)- DNA
Bov Resp. Syncytial virus- RNA
Bov Parainfluenza virus- RNA
Bov viral diarrhea virus- RNA, immunosuppressive
Bov Resp. coronavirus- RNA
How is Bov. respiratory syncytial virus related to humans?
Related to human resp. syncytial virus and an important cause of resp. dz in young children and elderly
How is Bov. parainfluenza virus related to humans?
Related to human PI-3 and used as intranasal MLV in infants
BRDC distribution
Younger immunodeficient calves (enzootic calf pneumonia) or in adult stress cattle (shipping fever)
BRDC transmission
Bacteria: aerosol, dust
Viruses: aerosol, direct contact and fomites
What factors influence BRDC?
Interaction of agents (bacteria, viruses), hosts (susceptible hosts), environment (cold, wet, dusty, windy)
Common CS of BRDC?
Fever, depression, anorexia, nasal discharge, tachypnea, pleuritis, crackles, wheezes over cranioventral lung lobes
Other CS that histophilus somni causes with BRDC
Joint effusion/ infertility or abortion/ otitis/ conjunctivitis/ neuro signs
Other CS that mycoplasma bovis causes of BRDC
Joint effusion/ colitis or conjunctivitis
Pathology of BRDC (viruses)
Infects epithelial cells and ciliated epithelium in upper resp. and bronchi →destruction of cells →↓ mucocillary clearance and ↑ susceptibility to secondary infection
Immunosuppression →↓ neutro chemotaxis and ↓ lympho blastogenesis and expression of MHC
Pathogenesis of mannheimia (BRDC)
Exotoxin (leukotoxin → cytolysis of neutros)
Endotoxin → inflamm by initiating complement cascade activiating neutros and macros to produce cytokines
Leukopenia
Pathogenesis of other bacteria (BRDC)
Pasteurella: endotoxin
Histophilus: lipooligosaccharide → endotoxemia
Mycoplasma: CM expressed surface proteins (Vsps)
Pathogenesis of infectious bov rhinotracheitis
Latent infection in neural tissue
Lesions of BRDC
Cranioventral lung consolidation
Fibrinopurulent exudate in resp. passages
Dx for BRDC (bacteria)
CS
Bacteria: cx from trans-tracheal aspirate or resp. tissues @ necropsy
Dx for BRDC (virus)
CS
Nasal swabs or resp. tissues @ necropsy for virus isolation or immunofluorescent assays or PCR
Tx for BRDC
Abx (amoxicillin, ceftiofur, enrofloxacin, etc- rotate between abx)
Anti-inflamms: flunixin meglumine
Prevention and control for BRDC
Reduced exposure to dust, wind, cold and reduced crowding
Vaccines: inactivated/ killed**, attenuated/ modified live
Tuberculosis
Consumption, scrofula, TB
Debilitating dz, formation of nodular granulomas (tubercles)
Zoonotic and reportable
Casual agent of tuberculosis
M. Bovis (domestic animals)
M. Tuberculosis, M. Avium
Acid-fast bacilli
Mode of transmission for tuberculosis
Resp route via aerosol droplets
Ingestion (horses)
In feces, urine, semen and milk
Which animals are more susceptible to tuberculosis
Cattle and goats
Sheep resistant
Horses
Factors influencing tuberculosis
Housing, crowded conditions
Main reservoirs: cattle and man
Pathogenesis of tuberculosis
TB bacilli stimulate formation of granulomas in lungs
Form primary complexes: focal necrotic area surrounded by granuloma containing mononuclear cells and disseminate to other organs
Lesions associated with tuberculosis
Thick encapsulated granulomas with pus
Granulomas in LNs, lungs and liver
Dx of tuberculosis
Screening test: Intradermal tuberculin test in cd. tail fold
Confirmatory test: comparative cervical test in side of neck
Tx for tuberculosis
Cull infected animals due to risk of transmission to animals
Rifampin and isoniazid in horses
