Individual and flock approach to ovine pneumonia

What are the BCS references for sheep in different stages?

fat= good! because thin means vulnerable to disease

What are the general causes of ill thrift?

poor nutrition

parasitism (fluke in adults/ haemonchus as it gets warmer)

chronic respiratory disease

dental disease (molars and incissors)

gastrointestinal disease

lameness

skin disease

others (mastitis, CLA, scrapie)

What are common causes of severe respiratory disease?

chronic suppurative pneumonia (abscessation)

jaagsiekte (ovine pulmonary adenocarcinoma- OPA)

maedi

laryngeal chronditis

pneumonic pasteurellosis

shipping fever

CLA not generally the UK

What are other causes of respiratory disease to remember?

atypical/chronic pneumonia/chronic non-progressive pneumonia (mycoplasma)

lungworms

oestrus ovis (needs heat)

enzootic nasal tumor (not UK)

inhalation pneumonia

tuberculosis

What is the cause of atypical/chronic pneumonia/chronic non-progressive pneumonia?

mycoplasma ovipneumonia

found in normal and diseased lungs

multiple strains in an infection

may have a role in permitting other pathogens ‘in’

usually 4-7 month old lambs

What is the progression in location of atypical/chronic pneumonia/chronic non-progressive pneumonia?

frequently found in the nasal cavity, where it moves from ewe to lamb

then invades the bronchi

What are the clinical signs of that disease?

mild

reduced growth

remember calf ‘cuffing pneumonia’

What is the treatment for that disease?

generally self-limiting

most non-aminoglycoside AB’s (even broad spectrum penicillins)

it’s a slow disease so you have to think improvement will take a fortnight

How do you prevent that disease?

lower stocking densities

avoid multiple stress events

keep healthy sheep

What are causes of chronic suppurative pneumonia?

basically we have no clue why they get it

inhalation of bacteria (eg fusobacterium necrophorum, trueperella pyogenes)

almost always secondary bacterial infection of compromised lung tissue

some will have haematogenous spread from septic focus

secondary to mannheimia haemolytica

What are clinical signs of that disease? And how to diagnose?

weight loss, depression, tachypnea, cough, usually normal temp

may have or may not have these signs

it’s difficult to diagnose- ultrasound may identify pleural abscesses, auscultation?

What is the treatment for it?

most ABs have some effect, however, effectiveness will be improved with drugs concentrating in lungs/abscesses and having long persistence

How do you prevent it?

have healthy sheep

ie control the things one can and the sheep will be in a better place to control infections

can’t actually stop it happening because we don’t actually know how it happens

using pasteurella vaccination?

What is ovine pulmonary adenomatosis (OPA)?

contagious lung tumor

retrovirus (jaagsiekte virus)

long incubation period: 3-4 year old sheep which makes control difficult

secondary bacterial infection (mannheimia haemolytia)

What are signs of OPA?

initial weight loss (appetite maintained) with exercise intolerance, increasingly tachypnoeic, crackles over lung field- loads and loads of fluid

How do you diagnose jaagsiekte?

‘wheelbarrow test’ diagnostic- clear frothy fluid from nostrils

no detectable immune response- no blood tests- it’s an intrinsic virus so it’s part of the sheep genome so it’s seen as self

ultrasound: sharp demarcation from normal lung tissue- basically looking for what looks like liver in the lung and that’s the tumor but it’s tough because the tumor would have to be right up against the body wall where you are scanning

post mortem confirmation of diagnosis

What is the treatment for jaagsiekte?

no treatment: cull affected sheep and offspring

difficult to control: regularly inspect flock for weight loss/signs of respiratory disease

don’t buy it in

What is maedi (ovine progressive pneumonia)?

chronic respiratory disease caused by lentivirus (retrovirus)- closely related to caprine arthritis and encephalitis virus (CAEV)

sheep infected as lambs through milk because it likes to reside in the udder

clinical disease is rare in animals cause of long incubation period

lymphocytic infiltration of lungs, udder, joints, nervous tissue

What are clinical signs of maedi?

exercise intolerance, weight loss, progressive tachypnea/dyspnea, indurative mastitis

How do you diagnose maedi?

detection of antibodies to MVV- AGIDT or ELISA but body is slow to introduce antibodies so there’s a 6 month diagnostic gap

How would maedi affected lungs feel on post mortem?

firm, rubbery, heavy lungs, do not collapse (often concurrent pasteurellosis or jaagsiekte)

How do you control/prevent maedi?

go in and test every 6 months and pull out the positives

test and cull seropositive animals and offspring

artificial rearing of lambs- probability of being affected is low

purchase replacements from accredited MVV free flocks

USA has a genetic test for susceptibility to disease

What is laryngeal chondritis and what are clinical signs?

abscessation of arytenoid cartilages in larynx- non-specific environmental bacteria

CS: progressive, severe inspiratory dyspnea, open mouth breathing, cyanosis, painful larynx- often die

What is treatment?

early cases- corticosteroid (if in respiratory difficulties) and high dose broad spectrum antibiotic for 3-4 weeks

tracheotomy in emergency might save the animal

How is ovine lungworm controlled?

normally non-pathogenic

controlled in young lambs with routine GI nematode treatments

adult sheep seem to develop a degree of immunity

What are the 3 main species of ovine lungworm?

dictyocaulus filaria

muellerius capillaris

protostrongylus, multiple species

Which species of ovine lungworm will show up in almost all sheep you post mortem?

m capillaris and protostrongylus spp