Respiratory diseases of adult sheep Flashcards
What are some generalised clinical signs of respiratory disease in sheep?
- Coughing
- Weight loss
- Nasal discharge
- Dyspnoea
- Sudden death
Name some example causes of respiratory disease in sheep
- Chronic suppurative pneumonia
- Maedi visna
- Ovine pulmonary adenomatosis
- Laryngeal Chondritis
- Mannheimia haemolytica
Ovine pulmonary adenomatosis is caused by what kind of virus?
Retrovirus
What is the disease of ovine pulmonary adenomatosis?
Progressive and fatal pulmonary carcinoma
Why does ovine pulmonary adenomatosis become widespread in a flock? (list two reasons)
- Survives several weeks outside the host
- Long incubation period in the host
Name 4 clinical signs seen in cases of ovine pulmonary adenomatosis
- Sudden death
- Weight loss
- Increased respiratory effort
- Exercise intolerance
Describe the test used to diagnose ovine pulmonary adenomatosis
Wheelbarrow test
- Accumulation fluid in lungs “tip sheep up”
- Distressing for sheep, quickly, stop as soon as fluid appears
How else can ovine pulmonary adenomatosis be diagnosed?
Postmortem for a definitive diagnosis
Hoe can ovine pulmonary adenomatosis be treated and monitored?
No treatment - PTS
Monitor in flock by PM of cull ewes
How can ovine pulmonary adenomatosis be controlled in clean flocks?
- Biosecurity
- Source from farms known history
- Double fencing (nose to nose contact)
- Closed flock (don’t buy in)
How can ovine pulmonary adenomatosis be controlled in infected flocks?
- Cull thin sheep or sheep respiratory signs
- Don’t keep offspring for breeding
- Disinfection of housing
- Reduce close contact housing/ stocking rates I.e. consider outdoor lambing
- Avoid trough feeding
- Don’t sell breeding stock
Maedi visna is caused by what kind of virus?
Lenti-virus
Describe the two forms of disease caused by Maedi visna virus
Maedi = chronic respiratory disease and chronic mastitis
Visna = neurological disease
How is a flock/individuals infected with Maedi visna?
When young in mothers milk/colostrum
Lung discharges via respiratory route
Describe the incubation period for Maedi visna and when clinical signs are seen
Several years
>2yrs - usually 4-5
Describe the clinical signs seen in a sheep with Maedi visna - respiratory form
Progressive and fatal
- Weight loss
- Increased respiratory effort
- Exercise intolerance
Describe the clinical signs seen in a sheep with Maedi visna - neurological form
Progressive and fatal
Less common
- weight loss
- abnormal gait
- ataxia
- incoordination
- paralysis
- circling
- head tremor
Other than respiratory and neurological signs, what else may be seen in a sheep infected with Maedi visna?
Chronic mastitis
On pathology of a sheep infected with Maedi visna, what secondary bacterial infection may also been seen?
Mannhaemia haemolytica
How is Maedi visna diagnosed?
- Pathology: thick mucous in trachea, swollen, heavy lungs
- Serology: ELISA
How may sheep with Maedi visna most commonly present?
No clinical signs of respiratory disease but chronic wasting and poor performance
How can Maedi visna be controlled?
- Very difficult, by time clinical signs seen 50% flock could be infected
- Test and cull
- Don’t breed from any infected
- Reduce stocking rates, don’t house
What is the main pathological change seen in sheep with chronic suppurative pneumonia?
Lung abscesses
What is the agent that causes chronic suppurative pneumonia?
Trueperella pyogenes - or mixed infected e.g. with Pasturellosis
List the clinical signs of Chronic suppurative pneumonia
Clinical signs often vague
- Chronic weight loss
- Increased resp effort
- Cough
- Nasal discharge
- High temperature
‘Texel throat’ is a name often given to describe which disease?
Laryngeal Chondritis
What animals are most commonly affected by Laryngeal chonditis?
- Mostly Beltex and Texel
- Rams>Ewes>Lambs
Describe the pathology of laryngeal chondritis
- Larynx very narrow and swollen: nodules and abscesses
- Obstruction of the larynx worsens until the animal dies of suffocation
How does laryngeal Chondritis present clinically?
Loud inspiratory dyspnoea
Sudden death
What features of Texel breeds make them more likely to develop laryngeal chondritis?
- Texel larynx is shorter in length and height. vocal cords closer and narrows to a funnel shape
- Trachea is also narrower than in other breeds
How can laryngeal Chondritis be treated?
- Early in infection
- Corticosteroids + Broad spectrum, long term antibiotics
Suggest an antibiotic that could be used to treat Laryngeal chondritis
Penicillin
How can laryngeal chondritis be controlled?
Breeding, don’t breed from affected rams, also review their genetic line
Laryngeal chondritis may be associated with what other condition?
Chronic diaphragmatic trauma
‘Pink eye’ is the term given for what condition in sheep?
Ovine infectious keratoconjunctivitis
What is the name of the agent that causes Ovine infectious keratoconjunctivitis?
Mycoplasma conjunctivae
At what times does spread of Ovine infectious keratoconjunctivitis most commonly happen?
Tupping time
Feeding
Mixing of sheep
How can Ovine infectious keratoconjunctivitis be treated?
- Early cases respond better
- Isolate affected sheep
- Look at risk factors for close contact
- LA oxytetracycline i/m, repeat 4 days
- Topical eye antibiotics
‘Silage eye’ is the term used to describe which disease?
Anterior uveitis
What is the agent that causes anterior uveitis?
Listeria monocytogenes
Anterior uveitis is associated with what type of feeding?
baled silage in ring feeders
What are the features seen with anterior uveitis?
- Blepharospasm
- Cloudy cornea
- Swollen, folded iris
How can anterior uveitis be treated?
- Sub-conjunctival oxytet and dexamethasone (1mg)
- Systemic penicillin
- Remove source
How may poor welfare lead to thin ewes?
Undernutrition
Disease
Old age
How do thin ewes effect the economics on a farm?
- Fertility
- Low lamb birth weights
- Twin lamb disease and poor colostrum
- Low milk production -> poor lamb growth
- Ewe death
Name 4 chronic respiratory diseases that can lead to thin ewes
- Ovine pulmonary adenomatosis
- Maedi-visna
- Chronic suppurative pneumonia
- Caseous lymphadenitis
Name 5 chronic GI diseases that can lead to thin ewes
Johnes
PGE
Fluke
Pharyngeal lesion
Teeth/oral lesions
What would you asses on the clinical exam of a thin ewe?
- Body condition score
- Teeth, age
- Anaemia
- Lameness
- Lymph nodes
What are some appropriate diagnostic samples to collect when on a farm with thin ewes?
- Faeces (Fluke egg count, Nematode Worm Egg Count, Johnes PCR and/or culture)
- Serology (MV or Johnes, CLA )
- Haematology (anaemia, acute/ chronic infection)
- PM
