Neuro cow

History

·    How long been going on for?

o  Acute onset – nervous ketosis, staggers

o  Or more slow/progressive?

·    Only one animal affected or multiple? Age of animals affected?

·    If dairy cow, what stage lactation/pregnancy? – peak lactation/transition phase = nervous ketosis

·    What neurological signs have been seen?

o  Dull/depressed mentation?

o  Ataxia? – nervous ketosis, staggers, CCN, listeria, nervous coccidiosis

o  Circling? – CCN, nervous ketosis

o  Apparent blindness? – CCN, nervous ketosis

·    Has there been any progression in disease/clinical signs? – listeria

·    Any other clinical signs? – haemorrhagic D+ = nervous coccidiosis

·    Any recent management/diet changes? – weaned calves with diet change = CCN

·    Vaccinated?

·    Known deficiency on pasture?

·    Potential access to toxins?

Approach

·    Full general clinical examination

o  TPR – pyrexic = early listeriosis

o  Look at eyes – uveitis = listeriosis, blindness = CCN, NK, bulging eyes = tetanus

o  Look at mouth – ketone breath = NK, wild facial expression = staggers, lockjaw = tetanus, drooling/flaccid tongue = listeria

o  Feel muscles – tremors = NK, staggers, spastic paresis = tetanus,

o  Look at back end – elevated tail head = tetanus, spasmodic urination/defecation = staggers

·    Neurological exam

o  Assess mental status – abnormal mentation = cerebrum affected

o  CNs

o  Gait and posture

o  Postural reflexes

o  Spinal reflexes

o  Response to pain

·    Localise neurological lesion

o  Brain affected = lesion rostral to foramen magnum

§ Abnormal mentation = cerebrum

§ Normal mentation – whole body affected = cerebellum, just head/face = CNs, brainstem

o  Brain not affected = lesion caudal to foramen magnum

§ All limbs affected = C1-T2

§ Just HLs = T3-L6

§ Just tail/perineum = S1-S3

o  Opisthotonos = cerebrum affected

·    Further investigations

o  If suspect nervous ketosis (dairy cow peak lactation/transition, ataxia, muscle tremous, sudden onset) – take blood sample for BHB – if BHB normal then contact APHA as BSE high on differentials now

o  If sudden death or dead animal – PM exam and submit samples for histopathology, sample vitreous humour – rule out anthrax

Treatment

·    General supportive treatment – assisted feeding, rehydration, correct electrolyte imbalances

·    Nervous ketosis – 500ml 50% dextrose IV, then oral propylene glycol 300ml for 5d

·    Staggers – IV Ca + Mg added, slow infusion, listen to heart

·    CCN – IV thiamine 10gmg/kg, supplement diet long term

·    Tetanus – tetanus antitoxin, high dose penicillin, nursing care

·    Listeriosis – double dose penicillin q12h for 10d + supportive (nutrition, fluids, NSAIDs, eye lube) – early tx required for success

·    Euthanasia if needed – nervous coccidiosis (poor prognosis)

Causes of neurological signs

Metabolic causes:

·    Grass staggers

o  Acute form = ataxia, collapse, seizures, hyperaesthesia

o  Subacute form = wild facial expression, muscle tremors, hypermetric gait, spasmodic urination/defecation

o  If sudden death, need to differentiate from anthrax, which is notifiable

·    CCN = decreased mentation, sudden onset blindness, ataxia, circling, head pressing

o  Weaned calves with recent history of diet change

·    Nervous ketosis = sudden onset, circling, ataxia, hyperaesthesia, apparent blindness

o  Increased ketones + decreased glucose ® negative effects on brain function

o  Need to differentiate from BSE – if cannot then contact APHA as notifiable

·    Vitamin A deficiency = night blindness, weak HLs, ataxia, paralysis

Infectious causes:

·    BVDV = cerebellar hypoplasia in calves

·    Listeriosis – silage eye (from poorly made silage), young animals with teeth coming through at high risk (easier access for listeria into the body)

o  Early signs = separation, depressed, pyrexic, ataxic

o  Later signs = recumbent, depressed, facial paralysis, drooling, flacid tongue, uveitis

o  Final signs = death due to respiratory failure

·    BSE = dull, ataxia, weight loss – if suspect then notify APHA as notifiable

·    Tetanus = elevated tail head, abducted legs, anxious expression, bulging eyes, lockjaw, bloat, recumbency in 2-5d, seizures, spastic paresis, death

o  Prevention: vaccination

·    Botulism = recumbency, flaccid paralysis, sudden death

o  Prevention: good hygiene/cleanliness (clean up carcasses, prevent contamination of feed/silage), care when using broiler litter as source of nitrogenous fertiliser

·    Nervous coccidiosis = GI signs first (haemorrhagic D+) then cerebral signs – depression, ataxia, recumbency, seizures, opisthotonos, death