Pathology and Microbiology of Respiratory Infections - Cattle & Sheep Flashcards
viruses
Bovine herpesvirus
Respiratory syncytial virus
Bovine parainfluenza virus
bacteria
Mannheimia Pasteurella Histophilus Mycobacterium Mycoplasma Actinomyces Actinobacillus
Bovine respiratory disease complex (aka Enzootic pneumonia or ‘Shipping fever’)
Bovine parainfluenza virus (PI3) Respiratory syncytial virus (RSV) Bovine herpesvirus (IBR) Mycoplasma bovis Followed by: Pasteurella multocida + Mannheimia haemolytica
bovine herpes virus (BHV)
Infectious bovine rhinotracheitis (IBR), “red nose”
Intranuclear viral inclusions
Vaccines available
bovine respiratory syncytial virus (BRSV)
Paramyxoviridae
URT infections, bronchitis/chiolitis
vaccines available
bovine parainfluenza
Paramyxoviridae
aka parainfluenza 3 (PI3)
URT infections
vavvines available
manheimia haemolytica
Commensal in the nasopharynx of ruminants
Epizootic (epidemic) pneumonia in cattle = shipping fever
Bovine pneumonic pasteurellosis
Pasteurellosis in sheep
β-haemolytic on sheep blood agar, Growth (weak) on MacConkey, Oxidase-positive
Pasteurellosis in lambs less than 3 months-old -septicaemia, severe pleuritis & pericarditis
severe mastitis in sheep + goats
Pathology of pneumonic pasteurellosis in cattle
M. haemolytica and P. multocida - in 80% of cases of bovine respiratory disease
bronchopneumonia is fibrinous to necrotising – leukotoxin/LPS
pleuritis frequent
infection also implicated in outbreaks of meningitis, sometimes with polyarthritis in 2-4 month-old housed calves
sporadic cases of peracute fatal mastitis in cow where suckling calves may transfer the organism
vaccines for M. haemolytica
Cattle - Natural protection sheep - need vaccine Bacterins - not effective. [used in US] Leukotoxin - not effective Iron-restricted OMP (expressed in vivo), in combination with Leucotoxin may be better.
pasteurella trehalosii
Acute or peracute septicaemia in older lambs: 5 - 12 months
vaccinate sheep
Histophilus somni
commensal in genital tract, transient in URT
Cause of peracute death in young calves
Acute thromboembolic meningoencephalitis
Pneumonia
Myocarditis
mycobacterium
Gram-positive, Acid-fast
Pathogenic mycobacteria
Atypical mycobacteria (environmental saprophytes)
Strict aerobes, very slow growing
Resistant to drying and chemical agents
Virulent species fully resist intracellular killing
bovine tuberculosis
Chronic, eventually fatal, pneumonia and wasting.
Worldwide distribution; control by test and slaughter Commonest where intensive dairying practiced
Transmission by an animal shedding into environment
Open case = continuous shedding into the environment from lesions excreting to the exterior eg. kidney, udder
incidence of disease cases increasing in the UK
bovine tuberculosis - diagnosis
Comp. ID Test by injection of PPD;
New methods coming to use eg. Gamma interferon release from cultured bovine leucocytes on contact with PPD
Pathology of bovine tuberculosis
Granulomatous pneumonia and lymphadenitis
Nodules have caseating (‘cheesy’) cut surface
mycoplasma infections
smallest living bacteria
inhabit mucosal surfaces
acquire host antigens to evade the immune response
infection may decr performance by up to 9%
in Bovine Respiratory Disease Complex
No cell wall - Not susceptible to β-lactam antibiotics
Pathology of Mycoplasma (‘cuffing’) pneumonia in calves
Caused by M. bovis.
Part of calf pneumonia complex
not notifiable in UK
Pathology of Mycoplasma (‘cuffing’) pneumonia in calves - microscopic
lymphoid nodules + follicles around airways
follicles may compress bronchial lumina
mixed cellular exudate in airways
partial alveolar collapse
slight thickening of alveolar walls with lymphocytes
Pathology of Mycoplasma (‘cuffing’) pneumonia in calves - gross
progressive cranioventral consolidation
exudate in the main airways of affected lobules with thickening of the surrounding connective tissue
Pathology of Contagious Bovine Pleuropneumonia (CBPP) - M. mycoides
Fibrino-necrotic bronchopneumonia with fibrinous pleuritis
dorsocaudal areas may be affected
interstitial septa markedly widened by fibrinous exudate and oedema
necrotic areas may be encapsulated (sequestra)
lung involvement is often unilateral
respiratory viruses of sheep
Parainfluenza virus (PI3)
Respiratory syncytial virus (RSV)
Adenoviruses (ovine and bovine)
May predispose to infection with Mannheimia
haemolytica
PI3 may occasionally cause pneumonia in lambs
No vaccines licensed for PI3, RSV or adenoviruses in sheep
fungi in respiratory disease
Aspergillus
Micropolysporum
Repeated small doses - Chronic disease
Infrequent large dose - Acute disease
