Page 482 - The Veterinary Laboratory and Field Manual 3rd Edition

Common clinical problems 419

Table 10.10 Summary of some common causes of neurological disturbance in
livestock.

Principle sign Location of lesion and comments Example
Tremor Can be moderate and generalized but a) Shaker pigs, border disease in lambs
potentially leading to paralysis (a), or b) congenital cerebella hypoplasia
intention tremor (b) (neonates)
Convulsions Can have independent episodes a) Idiopathic or traumatic epilepsy, b)
associated with a lesion in the cerebral encephalitis associated with increased
cortex (a) or continuous and intermittent intracerebral pressure. May also be
leading to paralysis (b) seen with hypomagnesaemia in cattle
and hypocalcaemia in piglets
Compulsive rolling Can be due to disturbance in balance (a) a) Vestibular disease due to infection or
and sweating or associated with pain (b) toxic change b) can be seen with colic
in horses
Compulsive walking May be associated with the end stage This can be seen in cases of chronic
and head pressing of systemic disease and altered mental toxicity, e.g. ragwort poisoning in
state horses and other causes of liver
damage
Circling Variable presentation, can be due to a) Brain abscesses due to Listeria
vestibular disease (may also have monocytogenes and other bacteria, b)
nystagmus) (a), may be associated with otitis media due to infection or trauma/
lesions in the inner ear or vestibular fractures of the skull causing damage
nuclei in the brain (b), can also result in to the cranial nerves, c) brain abscesses
deviation of the head and/or compulsive and cysts in cerebrum or medulla (could
behavior with lesions in the cerebrum or be due to a tapeworm cyst, i.e. as in gid
medulla (c) or bacterial abscess)
Inability to chew Can be due to a sensory deficit (a), a) Peripheral nerve damage due to
damage to focal nerves (b), lesions in trauma to head/jaw or toxin, b) guttural
the mouth (c) pouch mycoses in horses, toxins
c) wooden tongue in cattle due to
Actinobacillus sp.
Inability to swallow Variable signs but usually drops food or a) Could have a foreign body, tumour
regurgitates (a), may show distress if causing a blockage, b) could be caused
unable to swallow i.e. after peripheral by trauma, toxins (e.g. botulinum,
nerve damage (b) tetanus) and also rabies (always be
careful when examining the mouth)
Weakness and Could be associated with primary a) Prion (BSE, scrapie) and viral causes
staggering neurological disease (a) or due to b) milk fever, peracute systemic
metabolic crises or toxic insult (b) infection, tick paralysis
Flaccid paralysis This can involve all four limbs (a) or can a) May occur as part of the paralytic
be localized to one or two (b) signs associated with rabies induced
spinal cord meningitis or can occur
secondary to fractures of spinal
vertebrae b) localized trauma
Tetany May be generalized due to a toxic insult Tetanus, hypomagnesaemia, trauma
or a metabolic disease or can occur
secondary to acute spinal cord trauma

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