Phocine Distemper in Seals (with notes on Bears)

Summary Information
Diseases / List of Viral Diseases / Disease description:

This disease page is currently predominantly used in Wildpro to link different data types and demonstrate inter-relationships. Whilst basic information is available, It does not contain detailed information.

Alternative Names Phocine morbillivirus infection
Disease Agents Phocine distemper virus (PDV) (B209.2.w2)
Infectious Agent(s)
Non-infectious Agent(s) --
Physical Agent(s) -- Indirect / Secondary
General Description
In seals:

Clinical signs:

  • Serous to mucopurulent oculonasal discharge, conjunctivitis, ophthalmitis, keratitis, coughing, dyspnoea.
  • Fever, lethargy, diarrhoea, nervous signs, abortion.
  • Cervical and thoracic area subcutaneous emphysema, therefore inability to submerge.

Clinical pathology:

  • Haemoconcentration
  • Leucopaenia
  • (B209.2.w2)


  • Respiratory:
    • Airways containing mucopurulent, bloodstained or frothy exudate.
    • Pneumonia; lungs congested, oedematous, fail to collapse.
    • Interlobular, subpleural, mediastinal emphysema.
    • Pulmonary abscesses
    • Parasitic granulomas
    • Pleuritis
    • Hydrothorax
    • Haemothorax
    • Commonly heavy lung nematode infections.
  • Lymph node enlargement: mediastinal, mesenteric, retroperitoneal.


  • Respiratory: Bronchointerstitial pneumonia - serofibrinous exudate, leucocytes, macrophages and other mononuclear cells in lumen of alveoli and bronchi.
  • Intra-alveolar hyeline membranes
  • Haemorrhage
  • Suppurative bronchopneumonia associated with abscess formation; bacterial colonisation of airways and alveoli. Infiltration of walls of alveoli with leucocytes and mononuclear cells; fibroplasia in chronic cases, proliferation of type II pneumocytes, formation of intra-alveolar, intra-bronchiolar and intrabronchial syncytia.
  • Acidophilic inclusion bodies (10-20um diameter, round to ovoid, single or multiple, with distinct borders) both intracytoplasmic and intranuclear, in nasal, tracheal and bronchial epithelial cells; also in type II pneumocytes.
  • Secondary bacterial and parasitic infections may obscure pulmonary syncytia and inclusions.
  • Central nervous system: nonsuppurative encephalitis. Cerebral cortical necrosis (necrosis of neurons and glial cells, often in a laminar pattern), perivascular cuffing, astrocytosis, microglial infiltration, neuronophagia, focal demyelination. Astrocytes and neurons may contain acidophilic inclusions (intranuclear and intracytoplasmic).
  • Lymphoid: spleen, lymph nodes, thymus, gut-associated lymphoid tissue; marked necrosis and depletion of lymphocytes. Occasionally intracytoplasmic inclusions in lymph nodes.
  • Epithelial: Intranuclear and intracytoplasmic inclusions may be seen in epithelial cells of; urinary bladder, renal pelvis, biliary ductules, pancreatic ductules, gastrointestinal tract.


  • Virus may be shed by the respiratory, urinary, faecal and ocular routes. 
  • Transmission is probably by aerosol and by direct and indirect contact. 
  • Transmission may be facilitated by behavioural factors such as hauling out and the formation of large social groups.
Further Information
In seals:


  • Clinical signs are not sufficient for diagnosis.
  • Inclusions or viral antigen in smears from conjunctiva, nasal mucosa, buccal mucosa, peripheral leucocytes.
  • (B209.2.w2)

Post mortem examination findings:

  • Suggestive findings: lymphoid organ depletion of lymphocytes, type II pneumocyte hyperplasia and formation of syncytia in lungs, airways, brain or lymphoid tissues.
  • Pathognomonic: Acidophilic intranuclear and intracytoplasmic inclusions in cells of respiratory, gastrointestinal, urinary, lymphoid or CNS tissues.
  • (B209.2.w2)


  • Immunoperoxidase or immunofluorescent labelling of morbillivirus antigens in tissue sections (paraffin or frozen). Morbillivirus antigen may be detected in sections of e.g. trachea, lung, brain, spleen, lymph nodes, thymus, gastric mucosa, bladder epithelium, renal pelvis epithelium.
  • Antigen-capture ELISA on tissues.
  • Nucleic acid hybridisation from tissue extracts.
  • RT-PCR may be used for increased sensitivity.
  • Virus isolation.
  • Antibodies may be detected and titres determined using virus neutralisation tests or ELISA.
  • (B209.2.w2)

Differential diagnosis:

  • For individual animals: other diseases causing respiratory, enteritis and nervous signs, ocular and skin lesions, abortion.
  • For mass mortalities: e.g. algal toxins.
  • (B209.2.w2)


  • Avoid exposure to morbilliviruses.
  • Ensure quarantine of new animals.
  • Inactivated canine distemper virus vaccines may be useful.
  • Vaccines have been developed (inactivated whole virus canine distemper vaccine, and immunostimulatory-complex-matrix subunit vaccine) and provided protection against severe disease but not necessarily against respiratory tract infection.
  • (B209.2.w2)


  • Supportive, including antibiotics, fluid therapy.
  • Possibly anthelmintic treatment.
  • Euthanasia if severe clinical signs.
  • (B209.2.w2)
In Bears:
  • A study of sera from 200 Ursus maritimus - Polar bears in the Canadian Arctic, collected 1989-1000, using a virus neutralisation test, detected antibodies to phocine distemper virus (PDV) in six bears; all six individuals (plus a further 42 which were PDV antibody negative) were also seropositive to canine distemper virus (CDV); in five of the bears the titre to CDV was higher than the titre to PDV. The results were taken to indicate infection of polar bears with a morbillivirus, more similar to CDV than to PDV, since at least 1989. (J1.40.w5)
  • A survey of 191 serum samples from Ursus maritimus - Polar bears collected from in the Bering, Chukchi and East Siberian seas, 1987-1992, detected antibodies to morbillivirus in 68 (35.6%). This included a two-year-old seropositive cub with a seronegative dam and litter-mate. All seropositive cubs were in the two-year-old cohort. It was not possible to determine whether the antibodies detected were to canine distemper virus, phocine distemper virus or an unidentified morbillivirus. (J3.138.w6)
  • Antibodies to phocine distemper virus were detected in 3% of 38 Ursus americanus - American black bears, 47% of 36 grizzly bears (Ursus arctos - Brown bear) and 35% of 60 Ursus maritimus - Polar bear in Canada, from samples collected 1994-2001. (J3.155.w2)
Techniques linked to this disease
Host taxa groups /species Further information on Host species has only been incorporated for species groups for which a full Wildpro "Health and Management" module has been completed (i.e. for which a comprehensive literature review has been undertaken). Host species with further information available are listed below:

(List does not contain all other species groups affected by this infectious agent)

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