Neurologic disease, Lameness, & Ocular disease Flashcards
Neurologic disease
* Common:
* Uncommon but reportable:
Common:
* Polioencephalomalacia
* Listeriosis
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Uncommon but reportable:
* Rabies
* Scrapie
Polioencephalomalacia
* Presenting complaint:
* cause
* risk factors
- Presenting complaint:
> Single case, acting bizzare, blind - Caused by thiamine deficiency (B1)
- Dietary + synthesized in the rumen
<><><><> - Risk factors:
- High level of carbohydrate (grain) in diet
- Molasses
- Toxic plants (bracken fern, horsetail)
- High sulfur in water/feed
Polioencephalomalacia
* Clinical findings:
- Stiff, stilted gait
- Opisthotonus
- Cortical blindness (still has PLR, no menace)
- May go down
- Die within 1-2 days if not treated
Polioencephalomalacia
* Post-mortem findings
- Cerebral/cerebellar edema
- Fluoresces with UV light
Polioencephalomalacia
* Treatment
* considerations, prognosis
Treatment
* Thiamine – TID x 3 days
* Dexamethasone to reduce cerebral swelling
* Flock level – can add to feed
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* Early treatment is often successful
* If no response by 24h, poor prognosis
* No harm in treating with thiamine – add to treatment plan for all suspect cases
Listeriosis
- type of disease?
- prevalence?
- risk factors
- pathogenesis, lesions
- Bacterial infection typically via ensiled feeds
- Outbreaks of 2 – 10 % of the flock/herd
<><> - Risk factors:
- Silage/haylage with pH > 5.0
- Contamination with dirt/manure
- Forages fed on the ground, rodents, manure
<><> - Entry via bloodstream or trigeminal nerve
- Incubation 10 – 21 days
- Microabscesses in brainstem
Listeriosis
* Clinical findings:
* prognosis
* who is susceptible?
* other signs sometimes?
- Fever (> 40.0 C)
- Unilateral cranial nerve signs
> Circling, headtilt
> Facial paralysis
<><><><> - Often very severe
- High case fatality
<><><><> - Sheep/goats more susceptible than cattle
- Also can be a cause of abortion
Listeriosis
* Treatment, control
Treatment:
* Antibiotics: oxytetracycline, penicillin or TMS
* Dexamethasone for cerebral swelling
* NSAIDs
* Extended nursing care
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Control
* Metaphylactic treatment with LA oxytetracycline
* Remove source of infection
* Feed off the ground, keep silage face fresh
Rabies
- significance?
- signs?
– REPORTABLE!
* Local Public Health Unit if human exposure
* OMAFRA veterinarian if domestic animal exposure
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* Lots of variation in clinical picture – acting weird
Typically seen in animal on pasture, but can be in a barn
* Exposure typically two weeks prior
* Treat all neuro cases as potentially rabid, even if
low on your list
Scrapie
- significance?
- what is it?
- pathogenesis, transmission, progression
- who is susceptible?
– REPORTABLE!
* Prion disease of both goats and sheep
* Named for the intense pruritis associated
* Sheep have a genetic predisposition or resistance to development of disease
* Infection of youngstock occurs at lambing (environmental contamination) when ewe is infected and has susceptible genetics
* Susceptible lambs can develop disease (2-5 yrs)
* Goats are very susceptible, and no genetic test exists
Scrapie
- clinical signs
- progression
- Causes intense pruritis, increased grooming
- Locomotor incoordination – high stepping, stumbling, abnormal head carriage
- Progresses to recumbency within weeks-months
Scrapie diagnosis, control
- Testing can be done using lymphoid tissue (live animal) or obex (dead)
- Genetic testing of sheep for susceptibility
- Sheep certification program
Lameness
* Common causes:
Foot disease complex:
* Foot scald
* Foot abscess
* Footrot
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* CAE arthritis
* Joint ill in lambs and kids
Foot disease complex
- prevalence?
- signs?
- what diseases are part of this complex? pathogens?
- transmission / presence on farm
- Lameness, usually > 5 % of the flock
- Eat on knees
<><> - Etiology:
- Food scald – Fuscobacterium necrophorum, +/-
benign strains of Dichelobacter nodus - Food rot – above + Dichelobacter nodus
- Foot abscess – above + Trueprella pyogenes
<><> - D. nodosus survives off food 1 week if warm and moist (not if hot/dry or cold)
- Can only spread sheep/sheep if warm/moist
Foot disease complex
- pathogenesis
- Moisture (muddy yard, wet pasture)
> Softens interdigital skin
> Invasion of tissues by
Fusobacterium necrophorum +/- benign Dichelobacter nodosus
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possible outcomes: - Deep invasion by trueperella pyogenes > foot abscess
- interdigital dermatitis, foot scald
- presence of more severe strains of Dichelobacter nodosus > Footrot