Ovine Resp disease

Question 1

Clinical Signs of pasteurellosis?

Answer 1

• Cough, Inappetance,
• Oculonasal discharge,
• Pyrexia, Toxaemia,
• Hyperpnoea, Tachypnoea, Dyspnoea

Question 2

What risk factors are there for outbreaks of M. haemolytica pneumonia?

Answer 2

• Concurrent infections (esp respiratory) e.g. parainfluenza virus, mycoplasma virus etc.
• Environmental conditions (stocking density, humidity, ventilation, temperature fluctuations)
• Extreme weather
• Stress
• Movement from poor pasture to richer or housing with change of diet.

Question 3

What antibiotic would be your first choice for use in lambs with pasteurellosis and possible mycoplasma involvement?

Answer 3

First choice would be an oxytetracycline, e.g. Alamycin LA, Duphacycline LA and Engemycin LA

Question 4

How could you reduce the risk of pasteurellosis in lambs?

Answer 4

• Reduce stress
• Avoid mixing sources of sheep
• Good ventilation & airflow
• Introduce food change gradually
• Good nutrition
• Vaccinate to improve immune response

Question 5

Clinical signs of Maedi Visna ?

Answer 5

• Maedi – causes dyspnoea & heavy lungs 4-5y post infection (respiratory)
• Visna – progressive nervous signs 2-3y post infection

Question 6

How is Maedi Visna transmitted?

Answer 6

• Close contact - respiratory spread in aerosol
• Milk or colostrum of infected ewe
• Some transfer possible via placenta & semen (very small importance cf. resp spread and milk)

Question 7

How could you control Maedi Visna?

Answer 7

• Prevent contact with neighbouring flocks esp. if accredited – don’t want resp contact.
• Eradication easier if at low level (test & cull)
• If high level of infection cull flock & restock with accredited sheep
• Try and reduce losses through management: e.g. split into older & younger sheep for management and separate so younger sheep are at less risk.

Question 8

How is Caseous lymphadenitis spread?

Answer 8

• Spread at close contact – at Gathering, Clipping, Dipping, Showering – anything where sheep are close together.
• Get abscessation of the lymph nodes esp. around the head and neck.

Question 9

How is Caseous lymphadenitis diagnosed?

Answer 9

• Swab and culture of organism if abscess has already burst (don’t lance abscesses)
• ELISA (however, poor sensitivity, 13% will be a false negative. High specificity so if you get a positive, unlikely to be a false positive.)

Question 10

Is there a vaccine available for caseous lymphadenitis?

Answer 10

• No vaccine available in the UK, what people use is Glanvac, which is Australian.
• Glanvac (6-in-1; Zoetis): clostridial and caseous lymphadenitis in one vaccine.
• Can only use in UK under Special Import License (VMD)

Question 11

What are the common presenting signs of Laryngeal chondritis?

Answer 11

• Acute obstructive upper respiratory condition – esp 18-24mth old Texels, Beltex & Southdowns
• Severe dyspnoea with laryngeal stridor - often fatal.
• More common in rams than ewes (esp texel rams).

Question 12

How is laryngeal chondritis treated?

Answer 12

• 20mg Dexamethasone as one off treatment & one weeks course of antibiotics (suggest amox/clav off licence)
• Emergency tracheostomy often necessary under local infiltration anaesthesia
• Replace tube twice daily initially & then daily.
• If obstruction remains after three weeks then surgery to remove necrotic tissue is necessary though prognosis poor.