Читать книгу Canine and Feline Epilepsy - Luisa De Risio - Страница 262

Several clinical syndromes associated with distemper have been recognized in dogs:

ACUTE DISTEMPER. Acute distemper occurs in susceptible young dogs unable to mount an adequate immune response. Respiratory and gastrointestinal signs predominate and are often exacerbated by secondary bacterial infections resulting in mucopurulent conjunctivitis, chorioretinitis, rhinitis, coughing, dyspnoea, pneumonia, diarrhoea and vomiting. Neurologic signs (mainly seizures) may occur later in the clinical course but dogs may die before these signs develop. Histological findings are consistent with a polioencephalomyelitis.

Table 5.3. Viral diseases of the CNS in dogs and cats (Lackay et al., 2008; Gunn-Moore and Reed, 2011; Lorenz et al., 2011; Addie, 2012; Bowen and Greene, 2012; Greene and Vandevelde, 2012; Greene et al., 2012; Henke and Vandevelde, 2012; Tipold and Vandevelde, 2012; Wensman et al., 2012).

Fig. 5.6. Mix-breed dog with pseudorabies. The dog is stuporous. Note the hypersalivation. The intense pruritus has caused cutaneous hyperemia and abrasions on the left side of the face.

CHRONIC DISTEMPER ENCEPHALOMYELITIS. Chronic distemper encephalomyelitis occurs in young dogs that survive the acute stages of the disease and in mature dogs without signs of systemic disease. Animals vaccinated against CDV may be affected. Enamel hypoplasia and hyperkeratosis of the foot pads and nose may be observed in dogs that survive subclinical or subacute infections. Neurological signs are commonly progressive and include obtundation, head tilt, nystagmus, ataxia (usually vestibular and/or cerebellar), paresis, constant repetitive myoclonus (constant repetitive sudden involuntary contractions, followed immediately by relaxation of a specific muscle group) involving head or appendicular muscles, and generalized or focal seizures. Constant repetitive myoclonus may persist while the animal is asleep. The so-called ‘chewing gum fits’ described in dogs with CDV are characterized by rhythmic biting movements of the mandible and may represent a form of focal seizures associated with temporal lobe polioencephalomalacia. Visual deficits can occur due to chorioretinitis and optic neuritis. Histo-logical findings are characterized by severe demyelinating meningoencephalomyelitis.

Lesions are most common in the cerebellum, cerebellar peduncles, cervical spinal cord, optic tracts and periventricular white matter.

OLD DOG ENCEPHALITIS. Old dog encephalitis is a rare form of CD that appears to be a manifestation of chronic viral infection after years of latent brain infection. There are no related systemic signs. The most common initial neurological sign is visual impairment. Other neurologic signs are progressive and include personality changes, obtundation, compulsive circling and head-pressing against objects. Histological findings are characterized by perivascular mononuclear cuffs, microglial proliferation, astrogliosis, neuronal degeneration and neuronophagia mostly within the cerebral cortex. Necrosis of cerebral grey matter may be observed.

Clinical signs may also be associated with combined infections (e.g. Toxoplasma gondii or Neospora caninum).