Diseases of Nervous Diseases of Nervous systemsystem

DefinitionDefinition A condition characterized by recurrent A condition characterized by recurrent

seizures (two or more) result from an seizures (two or more) result from an abnormal and excessive neuronal abnormal and excessive neuronal discharge. epileptic seizures are a sign discharge. epileptic seizures are a sign of cerebral dysfunction of cerebral dysfunction

CharacteristicsCharacteristics

Three main characteristics of Three main characteristics of epileptic seizures are: epileptic seizures are: the loss of control (in various degrees), the loss of control (in various degrees), the episodic nature of the attacks (they the episodic nature of the attacks (they

start suddenly and they terminate start suddenly and they terminate suddenly), and suddenly), and

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

TypesTypes

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

GeneralizedGeneralized: The abnormal impulses : The abnormal impulses originate from the cerebral cortex originate from the cerebral cortex and spreadand spread

Origin of localized Origin of localized epilepsyepilepsy

The abnormal impulses originate from a specific area of the cerebral cortex and do not spread.

Origin of generalized Origin of generalized epilepsyepilepsy

The abnormal impulses originate from the cerebral cortex and spread

EtiologyEtiology1.1. Genetics in some breeds (Genetics in some breeds (autosomal autosomal

recessive traitrecessive trait ) as German shepherd ) as German shepherd and Collieand Collie

2.2. Infection: distemper, toxoplasma, Infection: distemper, toxoplasma,

3.3. Head trauma and neoplasiaHead trauma and neoplasia

4.4. inflammatory conditioninflammatory condition

5.5. Idiopathic (Idiopathic (unknownunknown cause) cause)

6.6. Hypocalcemia, hypoglycemia, thiamine Hypocalcemia, hypoglycemia, thiamine deficiency deficiency

7.7. Renal and hepatic dysfunctionRenal and hepatic dysfunction

8.8. Lead intoxicationLead intoxication

Clinical signsClinical signs

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

autonomic signs such as pupil autonomic signs such as pupil dilatation, salivation or vomiting dilatation, salivation or vomiting

Tonic seizure in limbsTonic seizure in limbs

Dilated eye pupil - epilepsyDilated eye pupil - epilepsy

Diagnosis Diagnosis

1.1. Detail case historyDetail case history

2.2. Clinical signs if appearedClinical signs if appeared

3.3. Lab diagnosis:Lab diagnosis:

1.1. UrinalysisUrinalysis

2.2. Serum: hypocalcemia or Serum: hypocalcemia or hypoglycemiahypoglycemia

4.4. Radiographic: fracture, trauma or Radiographic: fracture, trauma or neoplasianeoplasia..

TreatmentTreatment

Treatment of primary causeTreatment of primary cause Antiepileptic Drugs Antiepileptic Drugs

Phenobarbital Phenobarbital 3 - 5 mg/kg/day3 - 5 mg/kg/day (one (one daily dosage or divided and daily dosage or divided and administered twice a day) administered twice a day)

potassium bromide/sodium potassium bromide/sodium bromide bromide 20 - 40 (60) mg/kg /day20 - 40 (60) mg/kg /day (one daily dosage) (one daily dosage)

Primidone  Primidone  20-30mg/kg/day20-30mg/kg/day Phenytoin Phenytoin 2.0 - 5.0 mg/kg2.0 - 5.0 mg/kg given as given as

a slow IV injection. a slow IV injection.

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

Occurs sporadically in dogs and rarely, in Occurs sporadically in dogs and rarely, in cats cats

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

Definition

EtiologyEtiology

Imbalance between cholinergic (e.g., Imbalance between cholinergic (e.g., hyperactive) and catecholaminergic hyperactive) and catecholaminergic (e.g., hypoactive) neurotransmitter (e.g., hypoactive) neurotransmitter systems within the CNS due tosystems within the CNS due to diffuse encephalitis diffuse encephalitis Canine distemper Canine distemper Genetic predisposition (recessive Genetic predisposition (recessive

trait)trait)

Clinical signsClinical signs

1.1. Rapid eye movement (REM) during sleep Rapid eye movement (REM) during sleep 2.2. Excessive daytime sleepingExcessive daytime sleeping3.3. muscular twitching, variable vocalization, muscular twitching, variable vocalization,

facial grimacing and chewing facial grimacing and chewing movements.movements.

4.4. Flaccid paralysis (Flaccid paralysis (cataplexycataplexy))5.5. Attacks can be induced in most affected Attacks can be induced in most affected

animals by exercise or eating animals by exercise or eating

Sudden bouts of deep sleepSudden bouts of deep sleep

Diagnosis Diagnosis

History History Clinical signClinical sign Stimulation test: Give an affected Stimulation test: Give an affected

dog a bone and within seconds it’s dog a bone and within seconds it’s on the floor on the floor

TreatmentTreatment

intravenous intravenous imipramineimipramine at a dose of at a dose of 0.5 mg/kg.0.5 mg/kg. imipramine is an antidepressant act to imipramine is an antidepressant act to

change the balance of naturally change the balance of naturally occurring chemicals in the brain occurring chemicals in the brain (neurotransmitters) that regulate the (neurotransmitters) that regulate the transmission of nerve impulses between transmission of nerve impulses between cellscells

Atropine sulfateAtropine sulfate: 0.1 mg/kg, IV: 0.1 mg/kg, IV

DefinitionDefinition Inflammation of meninges of brain (pia, Inflammation of meninges of brain (pia,

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

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

Etiology and pathogenesisEtiology and pathogenesis Bacterial infectionsBacterial infections of the CNS most often occur of the CNS most often occur

via: via:

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

2.2. by by direct extensiondirect extension from sinuses, ears and from sinuses, ears and eyes, as a result of trauma, eyes, as a result of trauma,

3.3. meningeal spread with entry along meningeal spread with entry along nerve nerve rootsroots, or , or

4.4. from from contaminatedcontaminated surgical instruments surgical instruments (e.g., spinal needle) (e.g., spinal needle)

Bacteria causing meningitisBacteria causing meningitis

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

2.2. Staphylococcus Staphylococcus 1.1. aureus, aureus,

2.2. Staphylococcus epidermidis, Staphylococcus epidermidis,

3.3. Staphylococcus albus, Staphylococcus albus,

3.3. Actinomyces sp, Nocardia sp, Actinomyces sp, Nocardia sp,

4.4. Escherichia coli, Escherichia coli,

5.5. Streptococcus sp (e.gStreptococcus sp (e.g.,., S. pneumoniae) S. pneumoniae)

6.6. Klebsiella sp Klebsiella sp

Other causesOther causes

1.1. ViralViral: : 1.1. canine distemper, canine distemper,

2.2. feline infectious peritonitisfeline infectious peritonitis

2.2. Mycotic infectionMycotic infection::1.1. histoplasmosis, histoplasmosis,

2.2. cryptococcosis and cryptococcosis and

3.3. blastomycosis.blastomycosis.

Clinical signsClinical signs1.1. hyperesthesia, hyperesthesia, 2.2. fever, fever, 3.3. cervical pain, and frequently, cervical cervical pain, and frequently, cervical

rigidity. rigidity. 4.4. In addition, vomiting, bradycardia, In addition, vomiting, bradycardia,

anorexia, occasional cranial nerve deficits, anorexia, occasional cranial nerve deficits, and seizures may be observed. and seizures may be observed.

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

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

5.5. Stiff gait and walking with caution (as Stiff gait and walking with caution (as walking on eggs)walking on eggs)

Congested MM (fever in meningitis

Rigidity in the neck

DiagnosisDiagnosis

Case historyCase history Clinical signsClinical signs CSF examination for CSF examination for

color, protein and Gram staincolor, protein and Gram stain Cells (neutrophilia if bacteria is the Cells (neutrophilia if bacteria is the

causecause))

TreatmentTreatment1.1. Antibacterial: can pass blood-brain barrierAntibacterial: can pass blood-brain barrier

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

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

3.3. trimethoprim-sulfonamide (30 - 60 mg/kg, PO, trimethoprim-sulfonamide (30 - 60 mg/kg, PO, dailydaily

4.4. Ampicillin, 5 - 10 mg/kg, IV, every 6 hoursAmpicillin, 5 - 10 mg/kg, IV, every 6 hours

2.2. Anticonvulsant (antiseizure): DiazepamAnticonvulsant (antiseizure): Diazepam

3.3. Anti-inflammatory: prednisone 2mg/kgAnti-inflammatory: prednisone 2mg/kg

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

ENCEPHALITISENCEPHALITIS

DefinitionDefinition Encephalitis is inflammation of brain Encephalitis is inflammation of brain

tissue that may extend to spinal cord tissue that may extend to spinal cord (encephalomyelitis) causing seizures, (encephalomyelitis) causing seizures, circling and blindness in dogs circling and blindness in dogs

EtiologyEtiologyA-ViralA-Viral 1.1. Canine distemper, Canine distemper, 2.2. Rabies (rhabdovirus)Rabies (rhabdovirus) 3.3. Herpes virus (puppies)Herpes virus (puppies)B- B- Granulomatous encephalitisGranulomatous encephalitis (mycotic, e.g. (mycotic, e.g.

Cryptococcus andCryptococcus and Histoplasma)Histoplasma)..C-Parasitic:C-Parasitic: 4.4. Dirofilaria immitisDirofilaria immitis or or 5.5. Canine Canine Angiostrongylus vasorumAngiostrongylus vasorum

infestation infestation 6.6. Toxoplasmosis (toxoplasma gondi)Toxoplasmosis (toxoplasma gondi)D- Genetic conditionD- Genetic condition

Clinical SignsClinical Signs

1.1. Seizures, Seizures, 2.2. Depression, Depression, 3.3. Abnormal gait and incoordination Abnormal gait and incoordination 4.4. Blindness, Blindness, 5.5. Walking in circleWalking in circle6.6. Staring off into space, Staring off into space, 7.7. Pressing their heads against the wall Pressing their heads against the wall

or furniture,or furniture,8.8. Ataxia (a staggering walk), and Ataxia (a staggering walk), and 9.9. Intermittent screaming. Intermittent screaming.

DiagnosisDiagnosis

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

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

3.3. Analyzing the white blood cells in the spinal fluid Analyzing the white blood cells in the spinal fluid 4.4. Most often the disease is diagnosed after the dog Most often the disease is diagnosed after the dog

die die 5.5. Positive diagnosis may be made through use of Positive diagnosis may be made through use of

immunofluorescent or immunocytochemical immunofluorescent or immunocytochemical techniquestechniques to detect canine distemper viral antigen to detect canine distemper viral antigen in brain sections and other tissues (e.g., in brain sections and other tissues (e.g., mononuclear cells in blood smears, conjunctival or mononuclear cells in blood smears, conjunctival or tracheal washestracheal washes

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

TreatmentTreatment1.1. Anticonvulsants, such as phenobarbital, Anticonvulsants, such as phenobarbital,

may help control seizures may help control seizures

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

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

4.4. Ivermectin: 0.2 mg/kg S/CIvermectin: 0.2 mg/kg S/C

5- FELINE SPONGIFORM 5- FELINE SPONGIFORM ENCEPHALOPATHY (FSE)ENCEPHALOPATHY (FSE)

DefinitionDefinition Specific brain disease affecting cats Specific brain disease affecting cats

related to bovine spongiform related to bovine spongiform encephalopathy (BSE) and scrapie in encephalopathy (BSE) and scrapie in sheep.sheep.

Etiology and pathogenesisEtiology and pathogenesis Oral exposure from consumption of foodstuffs Oral exposure from consumption of foodstuffs

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

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

Clinical signsClinical signs1.1. Muscle tremorsMuscle tremors2.2. Ataxia (especially of the pelvic limbs) Ataxia (especially of the pelvic limbs) 3.3. Dilated pupils, Jaw champing,SalivationDilated pupils, Jaw champing,Salivation4.4. Behavioral abnormalities such as Behavioral abnormalities such as

uncharacteristic aggression, bitinguncharacteristic aggression, biting5.5. HyperesthesiaHyperesthesia6.6. Creeping about the house and hidingCreeping about the house and hiding7.7. Vacant staringVacant staring8.8. Excessive grooming, and being easily Excessive grooming, and being easily

startled (fear) by noise startled (fear) by noise 9.9. Kangaroo-likeKangaroo-like movements in advanced movements in advanced

casescases

DiagnosisDiagnosis

1.1. HistoryHistory

2.2. Clinical signsClinical signs

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

TreatmentTreatment

There is no treatment. There is no treatment. Prognosis is poor, since all spongiform Prognosis is poor, since all spongiform

encephalopathy cases are fatal.encephalopathy cases are fatal.

QuestionsQuestions