Bovine Respiratory Flashcards
Which bacteria are commonly found as secondary invaders after a primary pathogen insults the respiratory tract?
Mannheimia haemolytica
Pasteurella multocida
Name 2 other non-viral pathogens implicated in respiratory disease in cattle and comment on whether they commonly occur as other clinical presentations
Histophilus somni (also seen as meningoencephalitis) Mycoplasma spp (esp M.bovis); also implicated in aggressive mastitis, metritis, septic arthritis, otitis media
What happens to a calf <4 weeks of age, when the ambient temperature drops below its LCT?
Calf uses energy shivering to maintain body temp -> fails to gain weight, may lose weight
Mucociliary function may be affected -> reduction in defences of the respiratory tract
Which of these NSAIDs is available in a form with a zero milk withhold period? Ketoprofen (Curacef) Carprofen (Rimadyl) Meloxicam (Metacam) Flunixin (Resflor)
Ketoprofen
Carprofen
What differentials would you consider in a cow in a group of beef cattle kept at grass which is breathing heavily and showing profuse hypersalivation?
'Fog fever' (reaction to fructans in grass) Acute pasteurellosis (check for recent stress) Oesophageal obstruction Heat stroke (time of year?)
How is the lungworm vaccine administered and when?
What does it comprise?
‘Huskvac’
Vaccinate healthy animals of 8 weeks of age and older. Can be used during pregnancy. Give 25ml orally.
First vac: 2 doses 4 weeks apart, then a single vaccine prior to each season’s turnout
Comprised of virus antigens
Where are the lungfields on a cow?
Triceps cranially
Attachment of the ribs to the vertebral column dorsally
An imaginary line joining the point of the elbow to the 11th intercostal space
Small lung volume for body size
Give some design issues with the bovine lung
Small lung volume for body size
Large dead space
No collateral ventilation of alveoli
Alveoli are easy to damage and difficult to recover
Poorly developed fibrinolytic systems
Early and substantial vasoconstriction of arteries and arterioles
Give some problems with large dead space in the bovine lung
Limited respiratory reserve
Reduced phagocytic activity in the dead space
Decreased clearance of bacteria
Give some problems with no collateral ventilation of alveoli
No ‘pores of Kohn’ or bronchiole anastomoses, ie if part of lung is compromised, air can’t move to other parts of lung to aerate it
Give some problems with early vasoconstriction of arteries and arterioles
Early vasoconstriction in pneumonia is intended to maintain arterial BP, but also cuts off blood supply to the pneumonic lung
Give some problems with cows having a poorly developed fibrinolytic system
Persistent fibrinous exudate
Lung scarring
What happens to colostrum if left at room temperature?
Bacterial growth
Which part of the respiratory tract do parainfluenza virus and RSV (respiratory syncytial virus) affect?
LRT
Which part of the respiratory tract does IBR (bovine herpes virus) affect?
URT
Give some clinical signs of IBR (bovine herpes virus)
Pyrexia Milk drop Ocular/nasal discharge Conjunctival hyperaemia Coughing
Describe the 3 major types of bovine herpes virus
BHV-1: respiratory and repro systems (abortion)
BHV-2: IPV (infectious pustular vulvo-vaginitis) (no abortion)
BHV-4: endometritis
Give some clinical signs of mycoplasma bovis
Conjunctivitis Pneumonia Septic arthritis Otitis media (head tilt if chronic) Mastitis
How is Mycoplasma bovis transmitted?
Direct cow-cow contact, metritis to udder, resp aerosols, fomites
Give some commensal agents that cause pneumonia
Mannheimia haemolytica
Mycoplasma bovis
Pasteurella multocida
When is BRD most common?
Winter
UV light kills viruses -> less sun in winter
According to guidelines, how many animals should share the same airspace?
No more than 30
What is the PPP of lungworm?
3 weeks
Name the main viruses implicated in calf pneumonia and their common names
Bovine herpes virus (Infectious bovine rhinotracheitis, IBR)
Respiratory syncitial virus (RSV)
Parainfluenza 3 (PI3)
‘Fog fever’ is a reaction to what?
Fructans in grass
Why are cows unlikely to have lungworm if they’ve been housed all their life?
Lungworm is grass-born
What would you expect in a 5 year old cow with a nosebleed?
Vena caval thrombo-embolism
What would you suspect in a cow with a stertorous upper respiratory noise?
How would you treat?
Laryngeal chondritis
May respond to penicillin/anti-inflammatories
May require traceotomy/-ostomy
How would you identify an animal that is trying to take in as much air as possible?
Deep breaths, elbows abducted
How would you identify a cow who experiences pain when breathing?
Shallow breaths
Should you always be alarmed if you find Pasteurella, Mannheimia or Mycoplasma in the URT?
No as they are commensal here
During sampling, what kind of swabs should you use if you suspect anaerobic bacteria is the cause?
Charcoal swabs
What kind of swabs can you use if you suspect IBR?
Nasopharyngeal, conjunctival
If only first lactation heifers are affected, what would that tell you about the disease?
The disease has only entered the herd recently
Finding a disease in adults indicates what?
Current infection
Give 2 indications of inadequate airflow in housing?
Tiger stripes
Cobwebs
A temperature of what value would make you want to treat a cow in a group?
39.5oC or 40oC
Give some antibiotics used to treat bovine respiratory diseases
Oxytetracycline Beta lactams (eg penicillins) Florfenicol Macrolides (eg tulathromycin-'Draxxin') Fluoroquinalones (public health issues)
When should you administer a vaccine to get the maximum benefit?
Before the risk period
How can you differentiate between a cow vaccinated against IBR compared with one that has been naturally infected?
Antibodies in the vaccine are different to those produced against the intact virus so can be differentiated on serology
How are IBR vaccines administered and when?
IM or intranasally (faster but local effects)
6-12 monthly boosters recommended
How would you vaccinate young naive cows against IBR? (ie live or dead)?
Live vaccines initially then dead boosters
Would you use live or dead IBR vaccines if there is an endemic infection?
Dead
What is the desirable value for humidity in housing?
<80%
How much airspace should a calf have when they are <6 weeks old and between 6-12 weeks old?
<6 wks old: 6m3/calf
6-12 wks old: 10m3/calf
How big should the age range be in a group of calves?
Max. 2 weeks spread
What would you see on PM of lungs affected by respiratory syncytial virus (RSV)?
Bullae, coalesced alveoli
Where is IBR (bovine herpes virus) stored in the body?
Ganglia (facial nerve)
Recrudesces under stress
What would you suspect that might effect first lactation heifers that are turned out for the first time?
Lungworm (Dictyocaulus viviparus)
Laryngeal chondritis may be secondary to what?
Calf diphtheria (necrotic smell from mouth)
How can you sample for lungworm?
Faecal sampling (Baermanns apparatus)
Give some reasons for a lack of stack effect in a shed
No outlet
Building is too high
Insufficient biomass (eg calves; too small)
Which macrolide AB is vet administration only?
Tilmicosin
What would you want the inlet and outlet size to be in a calf shed with a monopitch roof?
0.25m2 per calf
What would you want the inlet and outlet size to be in a calf shed with a pitched roof?
Inlet: 0.05m2 per calf
Outlet: 0.04m2 per calf
How does laryngeal paralysis occur?
Damage to recurrent laryngeal nerve -> atrophy of cricoarytenoid muscles -> failure of one or both arytenoid cartilages to abduct during inspiration
