Respiratory disease (Yr4) Flashcards
what are the design issues of the bovine lung?
small lung volume for body size
large amount of dead space (limited respiratory reserves and decreased bacterial clearance)
no collateral ventilation of alveoli
alveoli easy to damage but difficult to recover
early vasoconstriction cuts of blood to pneumonic lung
poorly developed fibrinolytic system (leaving persistent fibrinous exudate and scarring)
what is the cut off for failure of passive transfer in serum total protein?
<52g/L
what organisms cause respiratory disease in cattle?
bovine respiratory syncytial virus, parainfluenza virus, infectious bovine rhinotracheitis, bovine viral diarrhoea
pasturella, mannheimia, histophilus, trueperella
mycoplasma
dictycaulus viviparous
what disease causing organisms are found as commensals in the URT of cattle?
Pasteurella and Mannheimia
why do respiratory viruses thrive in the winter?
they are killed by UV light (less light in shed in winter)
they decay faster in dry conditions (damp wet sheds)
why may animals with lungworm present pyrexic?
if they have secondary infection
what is the lifecycle of lungworm?
adult lungworm in trachea/bronchi produce eggs which hatch and are passed as larvae in faeces
they develop to L3 on pasture, and then dispersed by Pilobolus fungi, then they are ingested
the larvae migrate through the intestinal walls to the mesenteric lymph nodes and moult to L4 then migrate through blood vessels or lymphatics to the lungs
they moult to L5 in the bronchioles
how does lungworm survive to cause infections the following year?
some larvae will reside in the trachea until the subsequent year
what is reinfection syndrome? (lungworm)
cattle with prior partial immunity can become reinfected with lungworm, which triggers an allergic reaction that can be fatal
when is fog fever seen?
4-10 days after the introduction to lush pasture (acute pneumonia)
what causes fog fever?
rumen can’t adjust quick enough to the high proteins so certain amino acids are absorbed and travel through the portal circulation, it is converted to toxic substances in the Clara cells of terminal bronchioles which causes a diffuse interstitial pneumonia
what are the clinical signs of fog fever?
open mouth breathing, frothing, tachypnoea
what causes calf diphtheria?
Fusobacterium necrophorum
what are the clinical signs of calf diptheria?
ulcerative necrosis of mouth, pharynx and larynx
pyrexia
difficulty eating/swallowing
halitosis
what pathogens are associated with shipping fever?
Mannheimia haemolytica and bovine herpes virus 1
