Introduction to basic Veterinary Neuroology

1. Dr. Ajith Y., MVSc, PhD
Assistant Professor
Department of Veterinary Medicine
FVAS, Banaras Hindu University, Mirzapur

2. CNS - Spinal cord, Brain stem, Cerebellum, and Cerebrum (Higher centers)
PNS - Neurons of the cranial and spinal nerves (26 pair spinal and 12 pair cranial)
a) Sensory/afferent neurons – Nociception (pain), Proprioception (position),
equilibrium, touch, temperature, taste, hearing, vision, and olfaction
b) Motor/efferent neurons - Upper Motor Neurons (starts from brain)
UMN from cortex – voluntary movements
UMN from brain stem – flexion of limbs/inhibit extensors
Lower Motor Neuron-LMN (starts from spinal cord)
Spinal compression – extensor weakness/paresis/paralysis
INTRODUCTION

3. Autonomic Nervous System (ANS)
• Sympathetic
• Parasympathetic

4. • Functions:
Sensory motor system: Maintenance of normal posture and gait
ANS: Activity of internal organs; Homoeostasis
Sense organs
Psychic system: Mental and behavioural state
• Dysfunction:
Increased response to sensory stimuli
Failure to respond to sensory stimuli
Transmission of impulses enhanced or depressed
Complete failure of transmission

5. Reflex
Sensory neuron (PNS) – Internuncial neuron (CNS) - Lower Motor Neuron (PNS)
Higher center not involved. No Perception
Monosynaptic reflexes - Patellar reflex
LOCATION OF LESION????.....

6. Paralysis -> Paresis Vs Plegia
• Paresis: Partial loss/weakness/Impaired voluntary
movement
• Plegia or Paralysis: Inability/ complete loss of voluntary
movement

7. NERVOUS DYSFUNCTION
CAUSES: congenital or familial, infectious or inflammatory,
toxic, metabolic, nutritional, traumatic, vascular,
degenerative, neoplastic, or idiopathic
• Exaggerated activity:
Excitation (irritation) signs
Release of inhibitory control
Neuropathic pain
• Depressed activity:
Paresis or paralysis due to tissue damage
Nervous shock

8. Neurologic Evaluation/Description
1)The anatomic location(s) of disease
2)The problem may be defined as
- diffuse, multifocal, or focal
- symmetric or asymmetric
- painful or nonpainful
- progressive, regressive or static
- mild, moderate, or severe
3) Clinicopathology (serum/blood/urine/feces/CSF)
4) Plain and Contrast radiography, CT, and MRI

9. EXCITATION (IRRITATION) SIGNS
• Increased activity of reactor organ
• Increase in nerve impulses received
Excitation of neurons
Facilitation of passage of stimuli
• Motor system: Tetany, convulsions etc.
• Sensory system: Hyperaesthesia, Paresthesia

10. Clinical Manifestations of Diseases of the
Nervous System
ALTERED MENTATION - Excitation states
a) Mania - acts in a bizarre way and appears to be
unaware of its surroundings. Maniacal actions
include licking, chewing of foreign material and
sometimes themselves, abnormal voice, constant
bellowing, apparent blindness, walking into strange
surroundings, drunken gait, and aggressiveness in
normally docile animals.
Eg: Rabies, Aujeszky’s disease, PEM, nervous ketosis,
pregnancy toxemia, acute lead poisoning, severe hepatic
insufficiency

11. b) Frenzy - violent activity, movements are uncontrolled
and dangerous
eg: Hypomagnesemic tetany, Aujeszky’s disease,
Acute colic, ammonia poisoning
c) Aggressive Behavior: willingness to attack other
animals, humans, and inert objects
Eg: early rabies, postparturient hysteria in sows

12. Clinical Manifestations of Diseases of the
Nervous System
DEPRESSIVE STATES
a) Coma
b) Syncope
c) Narcolepsy (Catalepsy)
d) lassitude
e) Somnolence
COMPULSIVE WALKING OR HEAD PRESSING
Eg: PEM, Increased ICP
AIMLESS WANDERING

13. Clinical Manifestations of Diseases of the
Nervous System
INVOLUNTARY MOVEMENTS
A) Tremor: continuous, repetitive twitching of skeletal muscles
If local skin only  fasciculations
eg: early stages of hypocalcemia in the cow
B) Tics: spasmodic twitching movements made at much longer
intervals than in tremor.
C) Tetany: Sustained contraction of muscles without tremor.
eg: C. tetani infection
D) Myoclonus: brief, intermittent tetanic contraction of the
skeletal muscles that results in the entire body being rigid for
several seconds, followed by relaxation.
eg: canine distemper

14. E) Convulsions: Convulsions, seizures, fits, or ictus are violent
muscular contractions affecting part or all of the body and
occurring for relatively short periods. result of abnormal
electrical discharges in forebrain neurons
Stage I - Prodromal phase or aura (lasts for minutes to hours, restless)
Stage II – Ictal phase (Proper convulsions)
Stage III – Post Ictal phase (Fatigue, rest, loss of conciousness)
E) Involuntary Spastic Paresis:
eg: Stringhalt in Horses – hind leg flexion
Clonic convulsions (Paddling in Meningitis) Vs
Tonic Convulsions (Strychnine/Tetanus)

15. Clinical Manifestations of Diseases of the
Nervous System
ABNORMAL POSTURE AND GAIT
A) Posture Abnormality: Vestibular disease
B) Gait Abnormality: Weakness (Paresis) and Ataxia(Swaying)
- Hypermetria (increased range of movement/Overreaching)
- Dysmetria (goose stepping –pantothenate def.)
- Cerebellar ataxia (BVD) and Sway back (Cu def.)

16. • Stimulant drugs and mild degrees of those influences
that in severe form causing depression of excitability
(hypoxia, inflammation, poisons, edema, increased ICP)
• Fluctuation in Intensity of signs due to discharge and
re-accumulation of energy
• Sign and extension of symptoms varies with the focus
of lesion

17. RELEASE OF INHIBITORY CONTROL
• Release of inhibitory effects of higher centres over lower
nervous centers
• Decerebrate rigidity due to transection of brain stem
• Cerebellar ataxia: combined limb movements exaggerated

18. PARESIS OR PARALYSIS DUE TO TISSUE DAMAGE
•Destruction of nervous tissue
Infection
depressed metabolic activity
•Failure of oxygen and nutrient supply
General absence
Failure of local circulation
• Motor system: Muscular paralysis
• Sensory system: Anaesthesia, hypoaesthesia

19. Suprascapular Neuropathy in Horses (Sweeney)

20. Schiff-Sherrington Phenomenon
• Due to acute, severe lesions of the spinal cord between
T2 and L3, the pelvic limb paralysis is accompanied by an
extensor rigidity of the thoracic limbs

21. NERVOUS SHOCK
An acute lesion of the nervous system, which
causes damage to nerve cells in the immediate vicinity
of the lesions, but there may be, a temporary
cessation of function in parts that are not directly
affected.
eg: Stunning

22. Horner syndrome
• Sunken appearance to the eye (enophthalmia)
• Small pupil (miosis)
• Droopy upper eyelid (ptosis)
• Absence of sweating of the face (anhidrosis)
• Prominent third eyelid.
• Loss of Sympathetic innervations to eyes and face

23. CONCLUSIONS
• Determining type of lesions is difficult: Limited range of
mode of reaction
• Destruction of tissue or reduced nutrient supply
• Proper Anamnesis and Special examination is essential
for proper assessment
• Sign time relationship:
Rapidly developing lesions: maximum disturbances
Slow developing lesions: Compensation

24. References:
•A Text book of diseases of the cattle, sheep, goats, pigs
& horses 10th edition by Otto M Radostits, Clive C Gay,
K W Hinchcliff, P D Constable.
•Duke’s Physiology of Domestic animals 12 th edition
edited by William O Reece