EVOLUTION

ANIMAL BREEDS

DISEASES

MEDICATIONS

FOOD/FEED

BEHAVIOUR

EXOTIC ANIMALS

SPECIAL SECTION

Viral Disease - Canine Distemper

Introduction

Acute febrile contagious disease of dogs caused by paramyxovirus and characterized by FEVER: Acute catarrhal inflammation of various mucous membrane, pneumonia and in some cases skin lesions and involvement of CNS

Etiology

Paramyxoviridae- morbillivirus

Species affected

Dog, wild felidae, Hyaenas and African lions.

Occurrence

world wide- India

Route of infection

Ingestion and Inhalation.

CD almost always occurs with secondary Bacterial infection Bordetella bronchoseptica (pneumonia), Salmonella Sp (GI Lesion)

Incubation period

5 days.

Clinical signs

I. Mild or subclinical infection

Mild lethargy, fever

Cough, oculonasal discharge possible

Often unnoticed

II. Systemic infection

Most common in young puppies, unvaccinated adults, and immunosuppressed animals

First clinical signs: fever and general malaise

Respiratory signs common

  • » Serous or mucopurulent oculonasal discharge soon after onset of fever
  • » Dry cough that becomes productive, and/or dyspnea

GI signs common

  • » Anorexia, vomiting, dehydration, diarrhea
  • » Shock from hypovolemia or secondary bacterial sepsis and/or endotoxemia

III. CNS infection

Signs often occur 1 to 3 weeks after recovery from systemic signs, but may be delayed for months to years after infection.

CNS manifestations may be the only signs of CDV infection.

CNS signs vary from multifocal to localized, with variable progression.

Neurological signs include seizures, vestibular disease, myoclonus, behavioral changes, hyperesthesia, tetraparesis, paraparesis, and cervical pain.

  • » Myoclonus (involuntary, repetitive muscle contraction of a specifi c area) is common, with or without other CNS signs.
  • » Classic focal facial seizures ("chewing gum seizures") may occur.

IV. Additional manifestations

Dermatological: hard pad disease

Ocular: keratoconjunctivitis sicca, chorioretinitis

Dental enamel hypoplasia (pock marks)

Trans placental infection possible

Peracute form

Sudden death

Acute form

Biphasic fever, respiratory, digestive and nervous signs

Late form

Old dog encephalitis, salivation,chorea, ataxia & ascending paralysis, hyperkeratosis of foot pads

Nervous symptoms

Epilepsy, chewing movements, salivation, in coordination, muscular twitching, torticollis, Nystagmus Convulsions, muscular twitching in face, head, neck or shoulder muscles.

Necropsy

Respiration tract

catarrhal/Purulent exudates in nasal and pharyngeal mucosa.

Purulent exudates in Bronchioles - Broncoilitis capillaries

In pure CD-Interstitial pneumonic in. second. Bact. Infection: Purulent Broncho pneumonia

GI tract

acute catarrh

Swelling of peyer's patches a nodes.

Heart: Hydro pericardium, fatty degeneration and small hemorrhages of myocardium

Liver: Parenchymatous degeneration/'Nut meg' liver

Eye: Catarrh of conjunctivitis

Diagnosis

Cytology & histopathology

Virus isolation

Elisa- bronchial exudate

FAT

DNA sequencing

RT-PCR,

Nested pcr

Differential Diagnosis

Respiratory signs: infectious tracheobronchitis, aspiration, bacterial or parasitic pneumonia, rickettsial diseases, dysautonomia

GI signs: CPV or CCV, bacterial enteritis, toxin ingestion, foreign bodies, intussusception, metabolic disease

Neurological signs: hypoglycemia, toxins, hepatic encephalopathy, hypocalcemia, rabies, other causes of CNS disease

Treatment

Maintain adequate hydration.

Administer antibiotics for secondary bacterial infections.

Provide good nursing care with physical therapy (chest coupage) as needed.

Consider the use of bronchodilators.

CNS therapy may involve the following:

  • » Phenobarbital 2.5 mg/kg PO, IM, or IV BID to TID
  • » Diazepam 0.3 to 1.0 mg/kg IV to effect or 1 to 2 mg/kg per rectum during seizures
  • » Diazepam, pentobarbital, or propofol IV for refractory or recurrent seizures
  • » Myoclonus often refractory to medication and usually persists for life
  • » Prednisone 0.5 to 1.0 mg/kg/day PO for 2 weeks, with gradual tapering, for progressive CNS signs, refractory seizures, and late-onset encephalitis

Monitoring and Prevention

Isolate sick dogs.

Maternal Ab is usually gone by 12 weeks of age, but may interfere with initial vaccination

MLV vaccines are administered 3 to 4 weeks apart, with at least one vaccine given after maternal Ab has waned.

  • » Annual to triennial vaccines are currently recommended to booster protection
  • » Measles vaccine provides cross-protection against CDV and may be given as an initial puppy vaccination at 6 to 12 weeks, when maternal Ab interferes with CDV vaccine response.
  • » Inactivated (i.e., killed virus) vaccine is used in pregnant or immunosuppressed animals, but it confers a lower degree and duration of immunity than MLV vaccines.
  • » MLV vaccines are contraindicated in pregnant or immunosuppressed animals.

Vaccination complications can occur.

  • » Encephalitis may develop in severely immuno suppressed puppies or in puppies whose dam received MLV vaccination while pregnant.
  • » CDV vaccine is inactivated by hyperthermia, and an attenuated response may occur with concurrent parvovirus infection or chemotherapy

Recovery from natural infection provides prolonged immunity.

CDV is inactivated by various disinfectants.


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