Pathology and Microbiology of Respiratory Infections - Cattle & Sheep

Question 1

viruses

Answer 1

Bovine herpesvirus
Respiratory syncytial virus
Bovine parainfluenza virus

Question 2

bacteria

Answer 2

Mannheimia 
Pasteurella 
Histophilus 
Mycobacterium 
Mycoplasma 
Actinomyces 
Actinobacillus

Question 3

Bovine respiratory disease complex (aka Enzootic pneumonia or ‘Shipping fever’)

Answer 3

Bovine parainfluenza virus (PI3) 
Respiratory syncytial virus (RSV) 
Bovine herpesvirus (IBR) 
Mycoplasma bovis 
Followed by: Pasteurella multocida + Mannheimia haemolytica

Question 4

bovine herpes virus (BHV)

Answer 4

Infectious bovine rhinotracheitis (IBR), “red nose”
Intranuclear viral inclusions
Vaccines available

Question 5

bovine respiratory syncytial virus (BRSV)

Answer 5

Paramyxoviridae
URT infections, bronchitis/chiolitis
vaccines available

Question 6

bovine parainfluenza

Answer 6

Paramyxoviridae
aka parainfluenza 3 (PI3)
URT infections
vavvines available

Question 7

manheimia haemolytica

Answer 7

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

Question 8

Pathology of pneumonic pasteurellosis in cattle

Answer 8

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

Question 9

vaccines for M. haemolytica

Answer 9

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.

Question 10

pasteurella trehalosii

Answer 10

Acute or peracute septicaemia in older lambs: 5 - 12 months

vaccinate sheep

Question 11

Histophilus somni

Answer 11

commensal in genital tract, transient in URT
Cause of peracute death in young calves
Acute thromboembolic meningoencephalitis
Pneumonia
Myocarditis

Question 12

mycobacterium

Answer 12

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

Question 13

bovine tuberculosis

Answer 13

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

Question 14

bovine tuberculosis - diagnosis

Answer 14

Comp. ID Test by injection of PPD;

New methods coming to use eg. Gamma interferon release from cultured bovine leucocytes on contact with PPD

Question 15

Pathology of bovine tuberculosis

Answer 15

Granulomatous pneumonia and lymphadenitis

Nodules have caseating (‘cheesy’) cut surface

Question 16

mycoplasma infections

Answer 16

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

Question 17

Pathology of Mycoplasma (‘cuffing’) pneumonia in calves

Answer 17

Caused by M. bovis.
Part of calf pneumonia complex
not notifiable in UK

Question 18

Pathology of Mycoplasma (‘cuffing’) pneumonia in calves - microscopic

Answer 18

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

Question 19

Pathology of Mycoplasma (‘cuffing’) pneumonia in calves - gross

Answer 19

progressive cranioventral consolidation

exudate in the main airways of affected lobules with thickening of the surrounding connective tissue

Question 20

Pathology of Contagious Bovine Pleuropneumonia (CBPP) - M. mycoides

Answer 20

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

Question 21

respiratory viruses of sheep

Answer 21

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

Question 22

fungi in respiratory disease

Answer 22

Aspergillus
Micropolysporum
Repeated small doses - Chronic disease
Infrequent large dose - Acute disease