Changes

Canine Distemper Virus (view source)

Revision as of 16:32, 12 August 2010

2,080 bytes removed , 16:32, 12 August 2010

Line 35: Line 35:

===Clinical Signs===

−

Canine distemper is characterised by a biphasic fever, with the first peak 3-6 days post-infection and the second peak several days later and intermittently thereafter. ~~Pyrexia~~ is ~~ussualy~~ associated with ocular and nasal discharges, ~~depression~~ and ~~anorexia~~. ~~Gastrointestinal~~ and~~/or~~ respiratory signs ~~follow the initial fever, and these~~ are often ~~enhanced~~ by secondary bacterial ~~infection~~. Lesions may occur on the retina and optic neuritis can develop. Some strains of CDV ~~aslo~~ cause hyperkeratosis of the footpads and the nose. In neonates, hypoplasia of the tooth enamal is common following infection, causing "distemper rings".

+

Canine distemper is characterised by a biphasic fever, with the first peak 3-6 days post-infection and the second peak several days later and intermittently thereafter. The second peak of pyrexia is usually associated with the onset of other clinical signs. These initially include conjested conjunctiva and nasal mucosa leading to serous ocular and nasal discharges that become mucopurulent. The animal is depressed and anorexic, and vomiting, diarrhoea and pneumonia commonly follow. These gastrointestinal and respiratory signs are often complicated by secondary bacterial infections. Lesions may occur on the retina and optic neuritis can develop. Some strains of CDV cause hyperkeratosis of the footpads and the nose, and retinal lesions and optic neuritis can occur. In neonates, hypoplasia of the tooth enamal is common following infection, causing "distemper rings". Pustular dermatitis may also be seen on the abdomen of infected puppies.

−

Many, but not all, infected dogs develop CNS signs after systemic disease but this is dependent on the strain of the virus. Either the white matter or the grey matter may be affected. Grey matter disease affects the cerebral coretx, brainstem and spinal cord, and may give a non-suppurative meningitis, seizures, stupor, hysteria or ataxia. Dogs with grey matter disease may die within 2-3 weeks, recover, or alterntatively progress to white matter disease. In this, mutlifocal lesions mean that the signs are variable: cerebellovestibular signs are common, as well as spinal cord paresis, ataxia and occasionaly myoclonus. Once white matter disease has developed, some dogs die with a non-inflammatory, demyelinating disease 4-5 weeks after intial systemic infection. Other animals may recover with minimal injury to the CNS.

+

Many, but not all, infected dogs develop CNS signs after systemic disease but this is dependent on the strain of the virus. Either the white matter or the grey matter may be affected. Grey matter disease affects the cerebral coretx, brainstem and spinal cord, and may give a non-suppurative meningitis, seizures, stupor, hysteria or ataxia. Dogs with grey matter disease may die within 2-3 weeks, recover, or alterntatively progress to white matter disease. In this, mutlifocal lesions mean that the signs are variable: cerebellovestibular signs are common, as well as spinal cord paresis, ataxia and occasionaly myoclonus. Once white matter disease has developed, some dogs die with a non-inflammatory, demyelinating disease 4-5 weeks after intial systemic infection. Other animals may recover with minimal injury to the CNS but may still suffer neuromuscular tics or "chewing gum" seizures.

5.2. Clinical manifestations

Line 76: Line 76:

such as a persistent myoclonus.

−

Canine distemper is usually an acute, febrile disease, especially of young dogs, although older unprotected dogs are also susceptible. The first clinical manifestation of distemper is a diphasic febrile response. The first response may be overlooked, but the second generally occurs 2 - 3 days later in conjunction with other clinical signs, which initially include congested conjunctiva and nasal mucosa with subsequent serous to mucopurulent discharges. Pneumonia, depression, anorexia, vomiting, and diarrhea usually follow. Neurologic disturbances, such as neuromuscular tics, "chewing gum" seizures, and paresis are frequent sequelae in dogs that recover from acute disease.

+

−

~~Hyperkeratosis of the nose and digital pads ("hard pad") develops in some cases. Pustular dermatitis may be seen affecting the abdomen of puppies.~~

−

Gross necropsy lesions characteristic of pneumonia and enteritis may be present. Thymic atrophy may be noted in young dogs. Microscopic lesions are widespread in visceral organs and the brain and characteristic viral inclusion bodies are commonly found in brain, lung, stomach, and urinary bladder.

−

Dogs that recover may years later develop what has been called "old dog encephalitis" as a result of a persistent infection. This manifestation is usually recurrent, with a few to several episodes of neurological manifestations within weeks to months that usually end with death of the dog.

* Clinical specimens: Conjunctival scrapings, blood (buffy coat) smears, lung, urinary bladder, stomach, and brain.

Line 87: Line 84:

* The prognosis is poor for dogs with CNS involvement.

−

*'''Clinical signs''':

−

**Mucopurulent oculonasal discharge

−

**Keratitis

−

**[[Lungs Inflammatory - Pathology#Interstitial pneumonia|Interstitial pneumonia]]

−

**Severe clinical pneumonia follows secondary infection with [[Bordetella bronchiseptica|''Bordetella bronchiseptica'']]

−

**Smelly sometimes bloody diarrhoea

−

**Eruptions on the skin including hyperkeratosis of the nose and pads (hardpad)

−

**[[PNS Repsonses to Injury - Pathology#Segmental Demyelination|Demyelination]] (especially in cerebellum) -> incoordination or muscle tremors -> paralysis and coma or convulsions -> death

−

**Encephalitis

−

**Secondary pyogenic infections associated with immunosuppression and damage to epithelia

−

**Recovered animals may have persistent or spasmodic chorea

−

**The severity of the disease may vary; if enough neutralising antibody develops in the early stages, the virus maybe kept restricted largely to the lymph nodes

−

*Variable mortality depending on virulence

−

*May occur '''subclinically'''

−

*Involvement of central nervous system generally results in death

*Can contribute to [[Canine Infectious Tracheobronchitis|Infectious Canine Tracheitis]]

Lizzies

6,502

edits