Small ruminant respiratory diseases Flashcards
Pneumonia complex of small ruminants
- Similar to that of cattle
- Pulmonary defense mechanisms must be violated for occurrence
- Stress –> virus –> bacteria
- Environment and management are important
Age of most small ruminants that get pneumonia complex
- <1 year
Enzootic pneumonia in Sm Rum - how common? age range? pathogenicity high or low?
- Common
- Mostly young
- Low pathogenicity
Etiology of enzootic pneumonia
- Nospecific pathogens
- Mycoplasma ovipneumonia often
- M. haemolytica is a common secondary pathogen
How many sheep tend to get enzootic pneumonia by 4-5 months?
- Up to 85% may have lesions by 4-5 months
- Chronic, mildly pathogenic
How does failure of passive transfer of immunity impact enzootic pneumonia?
- IMpacts onset and occurrence
Significance of enzootic pneumonia
- Decreased performance
- Carcass rejection
- Increased mortality with secondary infections
Clinical signs of enzootic pneumonia
- Insidious, may not see overt clinical signs
- Low/moderate fever, nasal discharge
- Dyspnea, cough, decreased feed intake, decreased weight gain
- Signs vary
- SHEEP ARE TOUGH
necropsy of enzootic pneumonia
- Anterioventral atelectasis
Treatment of enzootic pneumonia
- Often not done
- Individuals can get antibiotics, NSAIDs, and support (three Rs)
- Groups can get mass medications in water
Prevention of enzootic pneumonia
- No specific respiratory vaccines marketed for sheep/goats in the US***
What organism causes pasteurellosis in sheep/goats?
- Pathogenic strains of Pasteurella hemolytica
Severity of Pasteurellosis
- Severe and often fatal
2 forms of Pasteurellosis in sheep/goats
- Pneumonic
- Septicemic
Etiology of Pasteurellosis
- P. hemolytica (types A & T)
- VIRUSES PREDISPOSE AGAIN
Which biotype of Pasteurella (M. hemolytica) causes pneumonic pasteurellosis
- Biotype A
Who gets pneumonic pasteurellosis?
- All ages, but mostly young
- Pasture and feed lot animals
Timeline for pasteurellosis (pneumonic)
- Spring, summer
Factors contributing to Pasteurellosis
- Climate
- management
- Poor nutrition
Primary losses in pasteurellosis
- Death and poor performance
Signs of pneumonic pasteurellosis
- Fever, depression, anorexia
- Cough, dyspnea, frothing
- Mucopurulent nasal discharge
- Increased lung sounds, crackles, wheezes
- Death can occur in 1-3 days
- Chronics can have lung abscesses, adhesions, etc.
Necropsy findings of pneumonic pasteurellosis
- Lung consolidation
- Pleural fibrin
- Pleural effusion
Which biotype causes septicemic pasteurellosis?
- M. hemolytica, biotype T
Who gets septicemic pasteurellosis?
- Lambs <12 months
Contributing factors to septicemic pasteurellosis?
- Stress
- Malnutrition, transport, weaning, etc.
Mortality of septicemic pasteurellosis
- Significant in a pretty short period of time
Clinical signs of septicemic pasteurellosis
- Fever, severe depression, anorexia
- Recumbency
- Frothy, bloody nasal discharge (terminal)
- RAPID course - death in as little as 6 hours
Necropsy findings of Pasteurellosis
- Subcutaneous petechia and ecchymoses
- Bloody forth in airways
- Lungs wet, heavy (little pneumonic lesions)
- Lymphadenopathy
- Fibrin deposition in and on viscera
Shock organ in pasteurellosis
- Lung
Treatment of Pasteurellosis
- Antimicrobials AGGRESSIVELY
- NSAIDs
- 3 Rs (rest, rumen, rehydration)
- MANY DIE DESPITE ALL LEVELS OF TREATMENT *
Prevention of pasteurellosis
- Minimize stress
- Medicate feeds/water
- Metaphylaxis
- Vaccines (NONE)
What is caprine mycoplasma pneumonia?
- Mycoplasma mycoides, sbsp mycoides (large colony type)
- Mmm
What are the three aspects of clinical syndromes in kids with caprine mycoplasma pneumonia?
- Peracute illness (high fever and death in 12-24 hr)
- CNS disease (opisthotonos and death in 24-72)
- Acute to subacute illness (fever, arthritis, pneumonia)
Age range of goat kids impacted by caprine mycoplasma pneumonia?
- 2-8 weeks
- Often normal until then
Clinical syndromes in does with caprine mycoplasma pneumonia?
- mastitis, polyarthritis, pneumonia
Clinical pathology of caprine mycoplasma pneumonia
- Isolate organisms from milk, joints, blood, urine, or tissue
- Bulk milk cultures
What is the key to Mycoplasma pneumonia transmission?
- Nursing
- Organism localized to udder of non-clinical dam
- Kids infected via colostrum
Necropsy of Mycoplasma pneumonia
- Fibrinopurulent polyarthritis
- 50% have pneumonia and fibrinous pleuropneumonia
Treatment of caprine mycoplasma pneumonia?
- Usually not effective (tylosin, tetracycliens)
- Kids get chronic arthritis
- Does get mastitis and are chronic carriers
Prevention of caprine Mycoplasma pneumonia (KEY)
- Monitor and test to maintain free herds
- Feed pasteurized colostrum and milk up to 1 month
- Milking hygiene
- Cull kids with signs (arthritis)
Ovine Progressive Pneumonia (OPP) general characteristics
- Retroviral (lentivirus) disease of sheep
- Slowly developing interstitial pneumonia, mastitis, and eventual death
- OPP and Maedi-Visna related to CAEV
Where is OPP prevalent?
- worldwide
- Variable prevalence in the US up to 70%
Who gets OPP?
- All ages and breeds
Transmission of OPP
- Contact (nasal droplets)
- Colostrum, milk (any tissues with monocytes or macrophages)**
- Vertical (rare)
Morbidity and Mortality of OPP
- Up to 70% morbidity
- 100% mortality
- If they have it, they will die of it
Incubation period of OPP
- ~2 years
- Slowly progressive
Clinical signs of OPP
- Slow progression
- Early on dry cough
- Depression, weight loss, exercise intolerance, minimal nasal discharge
- Dyspnea later on (death from asphyxia)
- May see hard bag, arthritis, and/or encephalitis
Pathophysiology of OPP
- Infection from oral or respiratory transmission
- Infects monocytes/macrophages
- Goes systemically (lungs, mammae, lymph nodes, etc.)
- Virus persists and replicates**
- Aberrant immune regulation**
- Antigen variation**
- Continuous Antigen stimulation (immune mediated inflammation of target tissues)***
Clin Path of OPP
- Mononuclear infiltration in effusions and CSF
Necropsy findings of OPP
- Enlarged, heavy, grey/yellow lungs that don’t collapse
- Enlarged LNs (thoracic)
- Udder: enlarged and firm
- Arthritis
- Non-suppurative encephalitis (monocytes)
Diagnostic tests for OPP
- Serology with AGID
- ELISA
- Clinical signs
- Serology
- Virus isolation
- Necropsy
How old to test animals for AGID or ELISA?
- > 6 months
- Takes time for Antibody response
- Passive antibody declines by 6 months
What does a negative serology mean?
- Not infected or antibody levels are too low
Positive serology meaning?
- Infection (may not be correlated with current disease)
ELISA comparison to AGI
- Increased sensitivity
- Effect of PT? Serial measurements
Treatment for OPP
- None
Prevention of OPP
- Test, separate, cull (repeat testing)
- Pasteurize colostrum (56°C for 30 min and use clean colostrum)
- Immediate removal of lambs born to infected ewes
