Distemper

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Mucoid conjunctivitis in a dog with distemper

Canine distemper is a highly contagious, systemic, viral disease of dogs worldwide.

The disease is more typically reported in young puppies (3 to 6 months of age) or unvaccinated or immunocompromized adults[1].

Canine distemper is caused by a canine distemper virus and is endemic in some countries. Sporadic outbreaks occur worldwide[2], presumably due to new virulent strains of the virus[3].

Clinically affected dogs are usually young, and present with a transient fever accompanied with serous nasal discharge due to rhinitis, conjunctivitis and anorexia.

Neurological signs may be present without other clinical symptoms. Adult dogs often present with progressive tetraparesis, altered mental status and blindness[4]. Optic neuritis can occur, and affected dogs can show signs of acute blindness, circling and seizures[5].

Neurological signs may developed, and in severe cases, seizures are present. Encephalitis and meningitis are common sequela but atypical necrotizing encephalitis has been reported[6].

Long-term symptoms include odontodystrophy (enamel hypoplasia), hyperkeratosis of the footpads ('hardpad' disease) and epithelium of the nasal plane may also be observed. In young dogs following post-distemper infection, dental impaction, partial eruption, oligodontia, enamel hypoplasia and dentin hypoplasia may be observed[7].

Chronic distemper encephalitis is marked by ataxia, compulsive movements such as head pressing or continual pacing, and incoordinated hypermetria, may be seen in adult dogs without a history of signs related to systemic canine distemper. The development of neurologic signs is often more progressive. Although canine distemper antigen has been detected in the brain of some dogs with ODE by fluorescent antibody staining, dogs with ODE are not infectious and replication-competent virus has not been isolated.

Thymic atrophy is a consistent postmortem finding in infected young puppies. Depending on the degree of secondary bacterial infection, bronchopneumonia, gastroenteritis, and skin pustules may also be present.

Histologically, canine distemper virus produces necrosis of lymphatic tissues, interstitial pneumonia, and cytoplasmic and intranuclear inclusion bodies in respiratory, urinary, and GI epithelium. Lesions found in the brain of dogs with neurologic complications include neuronal degeneration, gliosis, demyelination, perivascular cuffing, nonsuppurative leptomeningitis, and intranuclear inclusion bodies predominately within glial cells.

Diagnosis is usually established by a combination of clinical signs augmented with fluorescent antibody staining, ELISA[8], PCR and necropsy with histopathology.

No single treatment is specific or uniformly successful. Dogs may recover completely from systemic manifestations, but good nursing care is essential. Because of the highly infectious nature of the virus, multiple pup households hold a high risk of spreading to uninfected pups, and euthanasia should be considered to minimize further spread of the disease.

Vaccinations are essential to minimize outbreaks, especially in kennels, pet shops and large dog populations.

Canine distemper virus is not resistant to disinfectants, but is easily transmitted through aerosols and has a wide host range[9]. Wild canids are thought to act as reservoirs for fresh outbreaks of the disease[10].

References

  1. Greene C & Appel M (2006) Chapter 3: Canine distemper. In: Greene C, editor. Infectious Diseases of the Dog and Cat. 3rd ed. St Louis, Missouri: Saunders/Elsevier. pp:25–41
  2. Schumaker BA et al (2012) Canine distemper outbreak in pet store puppies linked to a high-volume dog breeder. J Vet Diagn Invest Sep 25
  3. Qiao J et al (2011) Characterization of a new dog isolate of canine distemper virus from China. Acta Virol 55(4):303-310
  4. Amude AM et al (2007) Clinicopathological findings in dogs with distemper encephalomyelitis presented without characteristic signs of the disease. Res Vet Sci 82:416–422
  5. Richards TR et al (2011) Optic neuritis caused by canine distemper virus in a Jack Russell terrier. Can Vet J 52(4):398-402
  6. Amude AM et al (2011) Atypical necrotizing encephalitis associated with systemic canine distemper virus infection in pups. J Vet Sci 12(4):409-12
  7. Bittegeko SB et al (1995) Multiple dental developmental abnormalities following canine distemper infection. J Am Anim Hosp Assoc 31(1):42-45
  8. Gray LK et al (2012) Comparison of two assays for detection of antibodies against canine parvovirus and canine distemper virus in dogs admitted to a Florida animal shelter. J Am Vet Med Assoc 240(9):1084-1087
  9. Taguchi M et al (2011) Antibody titers for canine parvovirus type-2, canine distemper virus, and canine adenovirus type-1 in adult household dogs. Can Vet J 52(9):983-986
  10. Cha SY et al (2012) Epidemiology of canine distemper virus in wild raccoon dogs (Nyctereutes procyonoides) from South Korea. Comp Immunol Microbiol Infect Dis 35(5):497-504