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Y4 Farm - GI > Weight loss in sheep > Flashcards

Weight loss in sheep Flashcards

1
Q

How many sheep are lame?

A
  • ~10% = 3,000,000
  • lower in well managed flocks (~2%)
  • some is driven by outbreaks of footrot, CODD, erysipelas and joint ill in lambs
  • joint ill is most commonly Strep dysgalactiae
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2
Q

Ddx for weight loss in sheep

A

Degenerative
- broken mouthed
- lame

Neoplastic
- OPA

Nutritional
- various dietary deficiencies

Infectious
- Johne’s dz
- CAE/MV
- CLA
- border dz

Parasitic
- fluke
- PGE
- haemonchus
- ectoparasites (scab [Psoroptes ovis], lice)

Toxic
- ingested plant toxins
- copper toxicity

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3
Q

Lameness scoring

A

0 – even weightbearing, even rhythm, flat back. Cannot identify a limb to be lame on

1 – uneven walking, obvious head nods, shortened strides

2 – non-weightbearing on one or more limbs

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4
Q

Ovine Pulmonary Adenocarcinoma

A
  • Caused by a betaretrovirus called Jaagsiekte sheep retrovirus (JSRV)
  • Commonly known as Jaagsiekte, ovine pulmonary carcinoma, sheep pulmonary adeomatosis.
  • Tumours grow in lungs so impair lung function
  • Tumours may secrete fluid, further impairing lung function
  • Spreads/passes through lineages in flocks
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5
Q

OPA - CS

A
  • Chronic wasting
  • Progressive respiratory distress (see increasing tachypnoea and abdominal effort to breathing) as SOL and increasing in size
  • Appetite remains good
  • Leads to death
  • ~1/3 don’t produce any fluid, even at stage of death
  • Incubation can be months or years
  • Very little serological response
  • Pre-clinical detection will be vital for effective OPA control and potential elimination
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6
Q

OPA – ultrasound scanning

A
  • Transthoracic ultrasonography (TTUS) is currently the only widely used method to diagnose preclinical or subclinical ovine pulmonary adenocarcinoma (OPA) in the live sheep
  • However, little is known about the test characteristics of TTUS
  • Hyperechoic lesions
  • Maybe up to 100% sensitive
  • Maybe up to 100% specific
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7
Q

Maedi Visna

A
  • Multi-organ disease
  • Icelandic term for “Dyspnoea-Wasting”
  • Lentivirus, retrovirus family
  • Maedi – slowly progressive interstitial pneumonia of adult sheep
  • Visna – slowly progressive encephalomyelitis of adult sheep – also arthritis and mastitis
  • Wasting is the cerebral form
  • Dyspnoea is the lung form
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8
Q

Maedi Visna spread

A
  • Horizontal transmission by aerosol
  • Vertical transmission through colostrum and milk
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9
Q

Caeseous Lymphadenitis

A
  • Corynebacterium pseudotuberculosis
  • Lasts well in the environment
    – Up to 20 weeks in the corners of sheds in purulent material
    – Up to 8 weeks on organic fomites
    – 24 hours in sheep dips
  • Spreads well at shearing
  • Superficial infection -> Lymph nodes -> suppurating infection -> haematological spread -> abscesses in internal organs
  • Prevention is through good hygiene
  • Efforts continue to develop a UK licensed vaccine
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10
Q

PGE

A

= parasitic gastroenteritis
- Trichostrongyles, Nematodirus, Ostertagia, Haemonchus
- Nematodirus causes pre-patent dz rather than wasting
– So tx before get WEC
– Trying to predict when it erupts -> period of cold weather then suddenly warms up
- Haemonchus lives in the abomasum but causes anaemia and wasting in this way

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11
Q

Border Disease

A
  • Pestivirus
  • Similar to BVD in cattle
    – ~25% of BDV in sheep is actually BVD
  • Causes:
    – abortion and still birth if infected early
    – strange development of primary hair follicles giving halo fibres
    – hairy shaker lambs
    – PI’s
    – tonic clonic skeletal muscular contractions
    – this may look similar to hypomyelinogenesis in CNS

Control: Detect and eradicate

Note- vit B1 deficiency also cause cerebrocortical necrosis

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12
Q

Johne’s dz

A
  • Mycobacterial dz of the intestines which results in poor protein absorption
  • Subclinical carriers are likely to propagate the dz since even intermittent low level shedding can cause maintenance of infection
  • Good environmental survivability
  • Faecal-oral transmission route
  • Some animals exposed will clear the bug
  • Many more will become subclinical carriers
  • Slow growing, within macrophages of peyers patches
  • Develop a chronic granulomatous enteritis
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13
Q

Ddx at Johne’s at flock level

A
  • Poor nutrition
  • Fasciolosis
  • Chronic parasitism (poor management or resistance)
  • Virulent footrot
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14
Q

Ddx of Johne’s at individual sheep level

A
  • Dentition
  • Chronic septic focus
  • Chronic severe lameness
  • OPA
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15
Q

Diagnosis of Johne’s vs Fascioliasis

A
  • PME can be equivocal
  • Blood albumin:globulin ratio in 10 affected animals is most useful
  • It is more likely that you will just get acid-fast bacteria in clumps from the mesenteric lymph nodes
  • Albumin is lost across the gut wall.
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16
Q

Laboratory diagnosis of Johne’s vs Fascioliasis

A
  • Johnes = normal globulins, low albumin
  • Fascioliasis = low globulins, low albumin

This remains the most sensitive herd level test if there are clinically affected animals. Different to doing serology in cattle.

ELISA +ve only in 60% of clinically affected cases so poor sensitivity, although specificity >95%

Fasciola is a more generalised protein losing condition as the biliary ducts become damaged and leak proteins, so lose all protein.

In progressed cases of Johnes, globulins will fall also. This is as adult fluke move through the liver.

Faecal exam not great – same reasons as cattle but even les shedding

17
Q

Why is globulin normal in Johne’s?

A
  • malabsorptive d+ as can’t get it from diet, but globulins don’t come from diet
  • so globulins are unaffected by Johne’s but albumin is
18
Q

Johne’s tx and prevention

A
  • no tx
  • vaccine (may not wish to use)
    – Gudair
    – lose control of infection
    – may reduce shedding sufficiently to act as a firebreak
    – haven’t got a DIVA test to distinguish between affected and vaccinated animals
  • control is as Johnes control in cattle
  • very small amounts of faeces is enough to cause disease, therefore keep adult faeces away from youngs mouth
19
Q

Johne’s vs fluke (CS)

A
  • Clinical disease seen in individuals = Johne’s
  • Seasonal = Fluke
  • Infected at or around birth = Johne’s
  • Has an intermediate host = Fluke
  • Can be diagnosed by faecal examination = both
  • Can be treated = Fluke
  • A vaccine exists = Johne’s
  • See gut wall thickening at PME = both
  • See bottle jaw = both
  • See brisket oedema = both
  • Expect normal globulin = Johne’s
  • Expect normal albumin = neither
  • See weight loss = both

Y4 Farm - GI (14 decks)

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