41. Infectious central nervous diseases Flashcards
Canine distemper?
Viral CNS Diseases
CANINE DISTEMPER
Morbilivirus spp.; Paramyxoviridae
Clinical signs
Polysystemic signs
§ Apathy § Diarrhoea
§ Mucopurulent discharge § Cough
§ Hyperkeratosis § Fever
Neurological signs
§ Brainstem signs § Seizures
§ Cerebellar signs § Myoclonus
§ Menace deficits* § Circling*
§ Visual impairment* § Hyperkinesia*
§ ↑ Mental depression* § Ataxia*
§ Head depressing*
*Seen in older dogs only
Diagnosis
§ PCR (from urine sample)
§ Conjunctival/bronchial smear → Inclusion bodies
§ IF test
Treatment: Symptomatic (poor prognosis)
Rabies?
RABIES (ZOONOTIC)
Lyssavirus spp.; Rhabdoviridae
Infection
§ Transdermal inoculation via wounds
§ Infectious material in contact with mucosa/skin lesions
§ Virus cannot penetrate intact skin
Incubation period for 2-3 months
Pathophysiology
- Virus → CNS via retrograde axoplasmic transport
- Replication → Pathological effect on nerve cells
- Peripheral nerves → Adjacent non-nervous tissue
(salivatory gland)
- Dissemination throughout the body
Clinical signs
Furious & paralytic forms of the virus are described
Initially, non-specific
§ Ø Eating § Withdrawal
§ Ø Drinking § Lethargy
§ Vomiting § Fever
§ Anorexia
Later, nervous signs
§ Cranial nerve dysfunction § Ataxia
§ Weakness § Paralysis
§ Dyspnoea § Seizures
§ Abnormal behaviour § Dysphagia
§ Excessive salivation § Aggression
Once the animal shows CSx: Death within 6 days
Diagnosis
Post mortem only
§ Brain histology: Inclusion bodies; Inflammation
§ IF test
§ Mice inoculation test
§ Virus isolation
Differential diagnosis: Aujeszky’s disease
Pseudorabies?
PSEUDORABIES (AUJESZKY’S DISEASE)
Varicellovirus spp.; Herpesviridae
Incubation period: 3-6 days
Clinical signs
General CSx
§ Ptyalism § Vomiting
§ Restlessness § Fever
§ Anorexia
CNS CSx
§ Incoordination § Rubbing
§ Furious scratching § Vocalisation
§ Muscle spasms § Self-mutilation
Diagnosis: History; CSx; Course
Prognosis: Bad; Usually leads to death
Feline Borna Disease Virus?
FELINE BORNA DISEASE VIRUS
Orthobornavirus spp.; Bornaviridae
In cats, causes non-suppurative meningoencephalomyelitis or
“Staggering disease”
Not readily transmitted between cats; Vectors such as ticks play a
role; Shrews act as reservoir hosts
Clinical signs
§ Gait disturbances
§ Ataxia
§ Pain in the lower back
§ Behavioural changes
Diagnosis: RT-PCR
Tick Encephalititis?
TICK ENCEPHALITIS
Flavivirus spp.; Flaviviridae
Clinical signs
§ Convulsions § Fever
§ Strabismus § Apathy
§ Excitement § Ataxia
§ Facial paralysis § Paraplegia
§ Proprioception disorders § Tremor
§ Aggressiveness § Nystagmus
§ Sensation disorders § Mydriasis
§ Anisocoria
Diagnosis – Lab. D
§ Leukopenia
§ Lymphopenia
§ Monocytosis
Treatment: Symptomatic; Unfavourable prognosis
Feline Infectious peritonitis(FIP)?
FELINE INFECTIOUS PERITONITIS (FIP)
Also see topic 22; Alphacoronavirus spp.; Coronaviridae
Affecting the primary intracranial & spinal cord structures
Typically associated with dry pyogranulomatous FIP
Immune complex vasculitis
Clinical signs
Nervous CSx in 30% of cases
§ Motoric disorder § Tremor
§ Cerebellar ataxia § Stupor
§ HL paralysis § Dementia
§ Aggressiveness § Mydriasis
§ Nystagmus § Anisocoria
§ Anterior uveitis § Chorioretinitis
OTHER VIRUSES
§ Feline immunodeficiency virus (FIV)
§ Canine herpesvirus
§ Feline parvovirus – Panleukopenia virus
§ West Nile virus
Bacterial CNS diseases?
Bacterial CNS Diseases
The CNS is protected from bacteria by the BBB; Once pathogens
enter the CNS, they can be highly detrimental to the host
Aetiology: Direct invasion; Local source invasion; Haematogenous
invasion
General CSx
§ Cervical hyperaesthesia § Fever
§ Altered mental state § Ataxia
§ Imbalance § Paresis
§ Paralysis
Diagnosis
§ History; CSx
§ CSF examination: Cytology; Biochemistry (↑protein;
↑glucose); Culture
Treatment
§ Antibiotics: Ampicillin; Enrofloxacin; Metronidazole
§ Glucocorticoids
LISTERIA MONOCYTOGENES
Bacteria invades via oral mucosa lesions → Nerves → CNS →
Cranial nerve damage
Clinical signs
§ Laryngeal paralysis
§ Vestibular signs
§ Circling
§ Ataxia
Treatment: Doxycycline; Penicillin
Protozoal CNS diseases?
Protozoal CNS Diseases
TOXOPLASMA GONDII
Definitive host: Cat (but also affects dogs)
Encephalitis; Myelitis; Peripheral neuropathies; Myositis
Clinical signs
May be absent in older animals
§ Lethargy § Anorexia
§ Pneumonia § Lethargy
§ Hyperextended pelvic limb § CNS signs
NEOSPORA CANINUM
Definitive host: Dog
May be infected vertically whilst in the uterus
Frequently a complication of Canine Distemper
Encephalitis; Myelitis; Peripheral neuropathies; Choriomeningitis;
Myositis
Treatment: Clindamycin; Potentiated sulphonamide
Fungal CNS Diseases?
Fungal CNS Diseases
§ Cryptococcus spp. § Histoplasma spp.
§ Coccidioides spp. § Aspergillus spp.
§ Blastomyces spp.
Diagnosis: CSF shows mixed cell pleocytosis
Treatment
Antifungal drugs that cross the BBB
§ Fluconazole
§ Flucytosine
