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
Foot disease complex
- what do the diseases in this complex look like?
- Foot scald > Interdigital skin mascerated, inflamed, sole unaffected
- Foot rot > Foot scald + underrunning of sole, mild to very severe
- Foot abscess > Foot scald + deep involvement, may include P2/P3 joint
Foot disease complex
- dx, tx?
- control?
- Trimming helpful to diagnose, NOT a treatment
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Treatment - foot bathing: - 10% zinc suplphate – stand 20-30 min, or 3% formalin walk through (painful) – twice 1 week apart
- Hold on dry cement 1 hour
- Isolate lame, return sound to clean pasture
- House lame in dry lot, cull non-responders
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(or) Treatment – antibiotics: - Long acting oxytetracycline (sheep/goats), or tilmicosn
(sheep)
<><><><> - Vaccination – available in other countries, efficacy?
- Genetic susceptibility also involved
Joint ill
- what is this?
- signs?
- associated with what other conditions?
- pathogens and their characteristics, disease, tx
- Polyarthritis – many causes, often opportunistic
- Causes stiffness, lameness
- Associated with failure of passive transfer
- Typically secondary to navel infection (add navel dip)
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Erysipelothrix rhusiopathiae & Strep. spp. - Fibrinous polyarthritis in animals 2 weeks – 6 months
- Bacteria present in soil
- Respond well to penicillin if treated early
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Chlamydia pecorum - Associated with pinkeye in lambs (kids, only pinkeye)
- Responds well to tetracycline
Ocular disease
* Common causes:
- Entropion in lambs > Less common in goats
- Contagious opthalmia/infectious
keratoconjunctivitis > Sheep and goats
Entropion
- what is this? who gets it?
- origin?
- tx?
- Young lambs with blepharospasm, keratitis
- One or both eyes
- Inverted eyelids (lower more common)
- Inherited – dominant (typically 1-5% prevalence) - Don’t breed
<><><><> - Treatment – roll out eyelid
- Inject bleb of penicillin
- Clips, surgery
- Repeated unrolling by hand
Pinkeye
- what is this?
- signs? prevalence?
- pathogens?
- AKA infectious keratoconjunctivitis, contagious opthalmia
- Blinking, watery eyes, 15 – 30% affected
<><> - Causative agents:
- Mycoplasma conjunctivae – most common
- Chlamydia pecorum - Associated with joint ill in kids/lambs
- May see listeria causing conjunctivitis - ‘silage eye’
Pinkeye
- usual presentation
- other associated conditions
- dx?
- tx?
- Most have mild signs, resolve 3-4 days
- Some will have keratitis, uveitis, corneal
ulceration - Lab dx? Swabs conjunctiva in early cases
<><> - Treatment:
- Do not treat mild cases or will reoccur!
- Need to develop immunity
- If severe, single LA oxytet or tulathromycin
- Irritation signs usually resolve quickly
Take home messages
- important neuro diseases > causes, signs, tx, dx…
- Polio is caused by a thiamine deficiency, associated with high grain feeding or high dietary sulfur– classic sign is cortical blindness, responds well if treated early
- Listeria should be suspected for unilateral neurologic signs in animals on ensiled feeds – tx = antibiotics, steroids, NSAIDs, supportive care
- Rabies (R) causes unusual signs – always keep this on your DDx list!
- Scrapie (R) causes neurologic signs and intense pruritis – genetic susceptibility in sheep (+ control program), no genetic test in goats
Take home messages
- foot scald, foot rot, foot abscess
> pathogens, lesions
- risks, transmission, control
- Foot scald = infection of the interdigital area with F. necophorum +/- benign strains of D. nodus
- Foot rot = foot scald + D. nodus, causes lesions on the sole
- Foot abscess = foot scald + T. pyogenes, causes deep abscesses
- Bacteria can live ~ 1 week in the environment when warm and moist
- Treatment = footbathing or injectable antibiotics
- Hold lame animals on a dry lot to avoid re-contamination, move healthy animals to clean pasture
