Diseases of nervous system
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Diseases of Nervous system. Epilepsy. Definition A condition characterized by recurrent seizures (two or more) result from an abnormal and excessive neuronal discharge. epileptic seizures are a sign of cerebral dysfunction. Characteristics.

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Diseases of nervous system
Diseases of Nervous system


  • Definition

  • A condition characterized by recurrent seizures (two or more) result from an abnormal and excessive neuronal discharge. epileptic seizures are a sign of cerebral dysfunction


  • Three main characteristics of epileptic seizures are:

    • the loss of control (in various degrees),

    • the episodic nature of the attacks (they start suddenly and they terminate suddenly), and

    • the repetitive clinical pattern (attacks are identical from episode to episode).


  • Localized: caused by localized area of brain dysfunction (the epileptic focus in cerebral cortex and do not spread) and symptoms are related to area involved.

  • Generalized: The abnormal impulses originate from the cerebral cortex and spread

Origin of localized epilepsy
Origin of localized epilepsy

The abnormal impulses originate from a specific area

of the cerebral cortex and do not spread.

Origin of generalized epilepsy
Origin of generalized epilepsy

The abnormal impulses originate from the cerebral cortex and spread


  • Genetics in some breeds (autosomal recessive trait ) as German shepherd and Collie

  • Infection: distemper, toxoplasma,

  • Head trauma and neoplasia

  • inflammatory condition

  • Idiopathic (unknown cause)

  • Hypocalcemia, hypoglycemia, thiamine deficiency

  • Renal and hepatic dysfunction

  • Lead intoxication

Clinical signs
Clinical signs

  • Localized motor activity e.g., tonic seizures of one leg or facial twitching

  • autonomic signs such as pupil dilatation, salivation or vomiting


  • Detail case history

  • Clinical signs if appeared

  • Lab diagnosis:

    • Urinalysis

    • Serum: hypocalcemia or hypoglycemia

  • Radiographic: fracture, trauma or neoplasia.


  • Treatment of primary cause

  • Antiepileptic Drugs

    • Phenobarbital 3 - 5 mg/kg/day (one daily dosage or divided and administered twice a day)

    • potassium bromide/sodium bromide 20 - 40 (60) mg/kg /day (one daily dosage)

    • Primidone  20-30mg/kg/day

    • Phenytoin 2.0 - 5.0 mg/kg given as a slow IV injection.



  • Narcolepsy is a neurological disorder associated with abnormalities of rapid eye movement sleep with excessive daytime sleepiness

  • Occurs sporadically in dogs and rarely, in cats

  • cataplexy is often the dominant clinical sign, which is characterized by sudden paroxysmal attacks of flaccid paralysis (muscle atony) with conservation of consciousness, that may last from a few seconds to more than 20 minutes


  • Imbalance between cholinergic (e.g., hyperactive) and catecholaminergic (e.g., hypoactive) neurotransmitter systems within the CNS due to

    • diffuse encephalitis

    • Canine distemper

    • Genetic predisposition (recessive trait)

Clinical signs1
Clinical signs

  • Rapid eye movement (REM) during sleep

  • Excessive daytime sleeping

  • muscular twitching, variable vocalization, facial grimacing and chewing movements.

  • Flaccid paralysis (cataplexy)

  • Attacks can be induced in most affected animals by exercise or eating


  • History

  • Clinical sign

  • Stimulation test: Give an affected dog a bone and within seconds it’s on the floor


  • intravenous imipramine at a dose of 0.5 mg/kg.

    • imipramine is an antidepressant act to change the balance of naturally occurring chemicals in the brain (neurotransmitters) that regulate the transmission of nerve impulses between cells

  • Atropine sulfate: 0.1 mg/kg, IV



  • Inflammation of meninges of brain (pia, dura and arachnoid) that may involve brain (meningioencephalitis) or brain and spinal cord (meningioencephalomyelitis), characterized clinically by hyperesthesia and rigidity of the neck

  • most affected dogs are adult, with a mean age around 5 years

Etiology and pathogenesis
Etiology and pathogenesis

  • Bacterial infections of the CNS most often occur via:

  • hematogenous spread from distant foci within the body (e.g., lung or splenic abscess, vegetative endocarditis, pleuritis, and urinary tract infections),

  • by direct extension from sinuses, ears and eyes, as a result of trauma,

  • meningeal spread with entry along nerve roots, or

  • from contaminated surgical instruments (e.g., spinal needle)

Bacteria causing meningitis
Bacteria causing meningitis

  • Pasteurella sp (e.g., P. multocida),

  • Staphylococcus

    • aureus,

    • Staphylococcus epidermidis,

    • Staphylococcus albus,

  • Actinomyces sp, Nocardia sp,

  • Escherichia coli,

  • Streptococcus sp (e.g., S. pneumoniae)

  • Klebsiella sp

Other causes
Other causes

  • Viral:

    • canine distemper,

    • feline infectious peritonitis

  • Mycotic infection:

    • histoplasmosis,

    • cryptococcosis and

    • blastomycosis.

Clinical signs2
Clinical signs

  • hyperesthesia,

  • fever,

  • cervical pain, and frequently, cervical rigidity.

  • In addition, vomiting, bradycardia, anorexia, occasional cranial nerve deficits, and seizures may be observed.

    • Seizures may be caused by high fever, brain edema, or inflammation,

    • while vomiting may result from increased intracranial pressure or from direct effects on the vomiting center

  • Stiff gait and walking with caution (as walking on eggs)


  • Case history

  • Clinical signs

  • CSF examination for

    • color, protein and Gram stain

    • Cells (neutrophilia if bacteria is the cause)


  • Antibacterial: can pass blood-brain barrier

    • Chloramphenicol (50 mg/kg, IV, IM, or SC, bid),

    • metronidazole (10 - 15 mg/kg, PO, tid),

    • trimethoprim-sulfonamide (30 - 60 mg/kg, PO, daily

    • Ampicillin, 5 - 10 mg/kg, IV, every 6 hours

  • Anticonvulsant (antiseizure): Diazepam

  • Anti-inflammatory: prednisone 2mg/kg

  • Osmotic diuretics may be useful for treating increased intracranial pressure secondary to brain edema.



  • Encephalitis is inflammation of brain tissue that may extend to spinal cord (encephalomyelitis) causing seizures, circling and blindness in dogs



  • 1. Canine distemper,

  • 2. Rabies (rhabdovirus)

  • 3. Herpes virus (puppies)

    B- Granulomatous encephalitis (mycotic, e.g. Cryptococcus andHistoplasma).


  • 4. Dirofilaria immitis or

  • 5. Canine Angiostrongylus vasorum infestation

  • 6. Toxoplasmosis (toxoplasma gondi)

    D- Genetic condition

Clinical signs3
Clinical Signs

  • Seizures,

  • Depression,

  • Abnormal gait and incoordination

  • Blindness,

  • Walking in circle

  • Staring off into space,

  • Pressing their heads against the wall or furniture,

  • Ataxia (a staggering walk), and

  • Intermittent screaming.


  • The disease is hard to diagnose since its symptoms often relate to other CNS diseases.

  • Seizures may be caused by many other underlying conditions such as hypoglycemia, canine distemper, rabies,

  • Analyzing the white blood cells in the spinal fluid

  • Most often the disease is diagnosed after the dog die

  • Positive diagnosis may be made through use of immunofluorescent or immunocytochemical techniques to detect canine distemper viral antigen in brain sections and other tissues (e.g., mononuclear cells in blood smears, conjunctival or tracheal washes

  • Magnetic Resonance Imaging (MRI) is a diagnostic test that allows visualization of the structures of the brain)


  • Anticonvulsants, such as phenobarbital, may help control seizures

  • Anti-inflammatory: oral prednisone, 1 to 2 mg/kg/day initially for several days, then reducing the dosage to 2.5 - 5 mg on alternate days

  • Amphotericin B: 0.1 to 0.5 mg/kg body weight, IV, three times weekly (for mycotic encephalitis)

  • Ivermectin: 0.2 mg/kg S/C

5 feline spongiform encephalopathy fse


  • Specific brain disease affecting cats related to bovine spongiform encephalopathy (BSE) and scrapie in sheep.

Etiology and pathogenesis1
Etiology and pathogenesis

  • Oral exposure from consumption of foodstuffs derived from cattle contaminated with the BSE agent which in turn was spread to cattle through animal protein concentrates (e.g., meat and bone-meal) processed from scrapie-infected sheep carcasses.

  • The infectious agent in these spongiform encephalopathies is a protease resistant prion protein (PrP), a product of nerve cells, and considered to be an abnormal post-translational modification of a host-encoded membrane-bound cellular glycoprotein produced by infection that accumulates in the affected brain

Clinical signs4
Clinical signs

  • Muscle tremors

  • Ataxia (especially of the pelvic limbs)

  • Dilated pupils, Jaw champing,Salivation

  • Behavioral abnormalities such as uncharacteristic aggression, biting

  • Hyperesthesia

  • Creeping about the house and hiding

  • Vacant staring

  • Excessive grooming, and being easily startled (fear) by noise

  • Kangaroo-like movements in advanced cases


  • History

  • Clinical signs

  • Microscopic exam: diffuse vacuolation (single or multiple vacuoles) of gray matter and neurons throughout the brain, particularly in cerebral cortex


  • There is no treatment.

  • Prognosis is poor, since all spongiform encephalopathy cases are fatal.