Individual & Flock Approach to Ovine Pneumonia Flashcards
what are some common reasons adult sheep die
Mastitis
Acute fluke
OPA
Pasteurella bronchopneumonia
Chronic pulmonary abscesses
what are common reasons lambs die
Gut worms
Coccidiosis
Pulpy kidney
Pasteurella septicemia
Pasteurella pneumonia
Other reasons besides pneumonia that are important in lambs
what should BCS be at mating, mid preg and lambing for lowland ewes
mating: 3-3.5
mid preg: 2.5-3.0
lambing: 2.5-3
what should BCS be at mating, mid preg and lambing for hill ewes
mating: 2.5-3.0
mid preg: 2.0-2.5
lambing: 2.0-2.5
what are general causes of ill thrift
Poor nutrition
Parasitism (fluke or haemonchus in adults)
Chronic respiratory disease
Dental disease (molar & incisors)
On PM look at dentition
Gastrointestinal disease
Lameness
Skin disease
Others (mastitis, CLA, scrapie)
what are common respiratory diseases
Chronic suppurative pneumonia (abscessation)
Jaagsiekte (ovine pulmonary adenocarcinoma OPA)
Maedi Visna virus
Laryngeal chondritis
Pneumonic pasteurellosis
Caseous lymphadenitis (CLA)
what are other respiratory diseases to consider that are less common (6)
- Atypical/chronic pneumonia/chronic non-progressive pneumonia
- Lungworms: doesn’t generally kill sheep
- Estrus ovis (anthelmintic use)
- Enzootic nasal tumour
- Inhalation pneumonia
- Tuberculosis
what are the causes of atypical/chronic pneumonia/chronic non progressive pneumonia
Mycoplasmia ovinpneumonia
is Mycoplasmia ovinpneumonia commensal or not
yes
found in normal and diseased lungs
what role does Mycoplasmia ovinpneumonia play in the health of the sheep
Most commonly a permissive disease to other diseases!
what is the signalment of atypical/chronic pneumonia/chronic non-progressive pneumonia
Usually 4-7 month old lambs —> more prevalent in housed lambs (orphan)
how does mycoplasma ovinpenumonia invade the lungs and what does it cause
Frequently found in nasal cavity, where it moves from ewe to lamb — then invades the bronchi
- No air exchange
- Pus
- Bronchial cuffing with immune cells
Ciliostasis
how does mycoplasma ovinpneumonia lead to infection of other pathogens
Ciliostasis
what are the clinical signs of atypical/chronic pneumonia/chronic non-progressive pneumonia
Mild
Reduced growth
Remember calf ‘cuffing pneumonia’
how is atypical/chronic pneumonia/chronic non-progressive pneumonia treated
Generally self limiting
Most non-aminoglycoside antibiotics (even broad-spectrum penicillins)
Longer recovery than shipping fever —> a week
how is atypical/chronic pneumonia/chronic non-progressive pneumonia prevented
Lower stocking densities
Avoid multiple stress events
Keep healthy sheep
what are the causes of chronic suppurative pneumonia
inhalation of bacteria
Fusobacterium necrophorum
Trueperella pyogenes
what does chronic suppurative pnuemonia cause
secondary bacterial infection of compromised lung tissue
hematogenous spread from septic focus
secondary to mannheimia hemolytica
what are the clinical signs of chronic suppurative pneumonia
Weight loss (chronic ill thrift ewes)
Depression (depends on if the infection is walled off)
Tachypnea (compromised lung tissue)
Cough (variable, depends on whether abscess has burst)
Usually normal temperature
Smaller, slower growing lambs
what hematogenous spread from septic focus can lead to chronic suppurative pneumonia
Mastitis
Metritis
Chronic lameness
Blood goes from systemic circulation into the lungs and the lungs filter it out
why is chronic suppurative pneumonia difficult to diagnose
Auscultation (?)
Difficult to diagnose on clinical exam
Ultrasound may identify pleural abscess
Pleuritis, etc
how is chronic suppurative pneumonia treated
Most antibiotics have some effect, however effectiveness will be improved with drugs concentrating in lungs/abscesses and having long persistence
- Macrolides
- Penstrep x2 normal dose for 14-21days (long term residues and meat withdrawal)
Most of the time you won’t succeed in treatment (unless its a valuable sheep don’t bother)
how is chronic suppurative pneumonia prevented
Healthy sheep
Control the things one can and the sheep will be in a better place to control infections Pasteurella vaccination?
what is jaagsiekte or ovine pulmonary virus
contagious lung tumour
what causes jaagsiekte or ovine pulmonary virus
retrovirus
jaagsiekte virus
what is the incubation period of jaagsiekte or ovine pulmonary virus
3-4 year old sheep
what are the clinical signs of jaagsiekte or ovine pulmonary virus
initial weight loss (appetite maintained) with exercise intolerance
increasingly tachypneic
crackles over lungfield
what secondary bacterial infeciton does jaagsiekte or ovine pulmonary virus cause
mannheimia hemolytica
how is jaagsiekte or ovine pulmonary virus diagnosed
“Wheelbarrow test” diagnostic — clear frothy fluid from nostrils
No detectable immune response — no serological tests at present (PCR on BAL is a research technique)
US:
- Sharp demarcation from normal lung tissue
- Lung that looks like liver is diagnostic
- Secondary abscesses
Post mortem confirmation of diagnosis
how is jaagsiekte treated
Cull affected sheep and offspring
why is jaagsiekte difficult to control
Difficult to control:
Regularly inspect flock for weight loss/signs of respiratory disease
Don’t buy it in (how do you tell?)
what is shown here
jaagsiekte
Consolidated lung
Heavy, non compressive
Not elastic
Solid if cut into it
Pus from secondary bacterial infection
what is maedi
ovine progressive pneumonia
Chronic respiratory disease caused by lentivirus (retrovirus) — closely related to caprine arthritis and encephalitis virus (CAEV)
how are sheep infected with maedi
Sheep infected as lambs:
Colostrum/milk
what is the incubation period of maedi
clinical disease rare in animals <3 years old
what does maedi cause
Lymphocytic infiltration of lungs, udder (flaccid that doesn’t produce much milk), joints, nervous tissue (visna)
If animal is seropositive doesn’t necessarily mean the animal will develop the disease but at risk of spreading it
what are the clinical signs of maedi
Exercise intolerance
Weight loss
Progressive tachypnea/dyspnea or hyperpnea
Indurative mastitis
Arthritis (USA)
how is maedi diagnosed
Detection of antibodies to Maedi Visna virus
AGIDT or ELISA
But there is a 6 month diagnostic gap (implications when exporting, importing, quarantine)
what is the appearance of the lungs on PM with maedi
Firm
Rubbery
Heavy lungs
Do not collapse (often concurrent Pasteurellosis or Jaagsiekte)
Marks of ribs
Concurrent secondary infection —> abscessation, etc
Light pink colour
how is maedi controlled/prevented
Test & cull seropositive animals and offspring
Artificial rearing of lambs
Purchase replacements from accredited MVV-free flocks
USA have a genetic test for susceptibility to disease
SRUC Premium Health Scheme
what might be the caustive agent of the lung pathology
post mortem
maedi
what is laryngeal chondritis
Abscessation of arytenoid cartilage in larynx — non-specific environmental bacteria
when is laryngeal chondritis commonly seen
Terminal sire tups
Higher prevalence in certain breeds: dished face breeds
Texel
Southdown
what are the clinical signs of laryngeal chondritis
Progressive
Severe inspiratory dyspnea
Open mouth breathing
Cyanosis
Painful larynx — often die
how is laryngeal chondritis treated
Early cases — corticosteroid (if in respiratory difficulties) and high dose broad spectrum antibiotic for 3-4 weeks
Macrolides
tracheotomy
what is shown here
laryngeal chondritis
what are other causes of respiratory signs to consider
lungworms
nasal bots (oestrus ovis)
pneumonic pasteurellosis
enzootic nasal tumour
inhalation pneumonia
tuberculosis
what is ovine lungworm
Normally non-pathogenic
Controlled in young lambs with routine GI nematode treatments
Adult sheep seem to develop a degree of immunity
what species cause ovine lungworm
Dictyocaulus filaria
Muellerius capillaris
Protostrongylus sp
what is the PPP of dictyocaulus filaria in sheep
5 weeks
what is shown here
dictyocaulus filiaria
what is the lifecycle of Muellerius capillaris & Protostrongylus sp
indirect
snails and slugs
what is shown here
Muellerius capillaris & Protostrongylus sp
lungworm
