Bovine Respiratory Disease Flashcards
what does bovine herpesvirus 1 do?
replicates in and destroys airway epithelial cells
latency
what is bovine herpesvirus 1 termed?
bovine infectious rhinotracheitis (IBR)
how do viral particles spread cell to cell?
directly: avoid neutralizing antibodies in extracellular fluid
what are the immunosuppressive effects of bovine herpesvirus 1?
induction of apoptosis in CD4+ T cells
MHC I and MHC II molecule expression down regulated
lysis of ciliated epithelial cells: decreased mucociliary clearance
what are two paramyxoviruses that infect the bovine respiratory tract?
bovine respiratory syncytial virus (BRSV)
parainfluenza-3 (PI-3)
what is the hallmark of infectious bovine rhinotracheitis?
erosions and ulcers in upper respiratory tract
what is the etiologic agent of contagious bovine pleuropneumonia (CBPP)?
Mycoplasma mycoides var. mycoides small-colony (SC) type
where is contagious bovine pleuropneumonia prominent?
Africa
Aisa
sometimes Europe
eradicated from US in 19th century
what is Mannheimia haemolytica?
gram negative bacterium associated with acute fulminating pleuropneumonia in cattle
what are the virulence factors of Mannheimia haemolytica?
protein adherence to tracheal epithelial cells
endotoxin
secreted enzymes
specific leukotoxin produced during log phase growth
how does the leukotoxin that Mannheimia haemolytica secretes lyse cells (high contentrations)?
forms transmembrane pores that allow ion influx and ultimately cell rupture
what organism is most commonly associated with bovine respiratory disease complex (shipping fever pneumonia)?
Mannheimia haemolytica
what is Mannheimia haemolytica pneumonia characterized by?
cranioventral fibrinopurulent pleuropneumonia
what happens in bovine respiratory disease complex (BRDC/shipping fever) after bacteria enter the deeper lung tissues?
cranioventral pneumonia characterized by fibrin exudation, neutrophil and macrophage influx, capillary thrombosis, and coagulation necrosis
what does enzootic calf pneumonia cause?
young calves
mild cranioventral pneumonia to extensive fibrinopurulent pneumonia
can result in long-lasting chronic infections and slow growth
what bacterial pathogens are associated with enzootic calf pneumonia?
Mannheimia haemolytica
Pasteurella multocida
Corynebacterium pyogenes
what is the causative agent of calf diptheria?
Fusobacterium necrophorum
common soil inhabitant
what does Fusobacterium necrophorum do?
colonizes pharyngeal tissue: extensive necrosis with inflammation and edema in mouth, pharynx, larynx, and possibly lungs
what causes acute bovine pulmonary edema and emphysema or fog fever (ABPEE)?
tryptophan ingested, to 3-methyl indole, metabolized by pulmonary Clara cells enzymes
pulmonary cells injured by final toxin
when is acute bovine pulmonary edema and emphysema or fog fever seen?
14 days after moving cattle to grass pasture: dry summer grass to better quality grass
dairy cattle on late spring grass after first cutting of hay
what substance other than tryptophan can cause acute bovine pulmonary edema and emphysema or fog fever?
4,ipomeanol: produced by mold
what happens in hypersensitivity pneumonitis (bovine farmer’s lung)?
cattle develop hypersensitivity pneumonitis to Micropolysporum faeni: common mold that grows in hay
what develops in hypersensitivity pneumonitis?
immune complexes of IgG and mold antigen in alveolar spaces
recruitment of neutrophils, phagocytosis, and inflammation
what causes verminous pneumonia?
Dictyocaulus viviparus
trichostrongylid nematode with a direct life cycle
what happens in bovine septic thromboembolism?
liver abscesses form after change in diet
emboli from abscesses to lungs and erode through
poor prognosis
where can bovine herpesvirus 1 infect in the animal?
respiratory
fetus
reproductive tract
conjunctivitis
how does bovine herpesvirus 1 induce cell death?
necrosis and apoptosis
as cell membrane integrity is lost, calcium influx directly results in lysis and release of viral particles
what acts as a receptor for the leukotoxin of M. haemolytica in bovine herpesvirus 1?
B2-integrin on bovin alveolar macrophages and neutrophils
what are the clinical signs associated with bovine herpesvirus 1?
erosions and ulcers in upper respiratory tract
fever, reduced appetite, rapid respiration, dyspnea
what does ovine herpesvirus type 2 cause?
malignant catarrhal fever
mucopurulent inflammation of the conjunctiva and oral and nasal mucosa
ulcerations of mouth, tongue, esophagus
why may bovine viral diarrhea virus contribute to bovine respiratory disease complex?
immunosuppressive
what does bovine respiratory syncytial virus do?
infects respiratory epithelial cells
who is Mycoplasma mycoides large-colony type pathogenic for?
sheep and goats
not cattle
does Mycoplasma mycoides survive well in the environment?
no
what disease has similar lesions to Mannheimia haemolytica?
porcine contagious pleuropneumonia: Actinobacillus pleuropneumoniae
what type of lesions are associated with Mannheimia haemolytica?
carnioventral fibrinopurulent pleuropnuemonia
hemorrhage/coagulation necrosis to whole lung lobes
what has Histophilus somni been associated with?
pneumonia
septicemia
myocarditis
abortion
thrombotic meningoencephalomyelitis
synovitis
what is characteristic of Histophilus somni infection?
formation of thrombi in vessels
what does Pasteurella multocida cause?
pneumonia associated with stress, transportation, overcrowding, and co-mingling
what is bovine respiratory disease complex?
pneumonia of variable severity
cranioventral pneumonia: fibrin, neutrophils/macrophages, capillary thrombosis, coagulation necrosis
