Lecture 7: Canine 2 Flashcards
What is the viral family and characteristics of canine distemper virus
Family: Paramyxoviridae
* (-)ssRNA, 1 serotype
What are the populations that can be infected by canine distemper virus
Epidemiology
* Affects a wide range of animals including Canindae and Felidae
* Unvaccinated domestic/feral dog = primary reservoir for infecting wildlife
What iss the pathogenesis of canine distemper virus? What is the route of transmission? Location of replication? Target cells?
- Multiply in lymphoid tissue, lamina propria, Kupffer cells
- Transmit via aerosol
- Target cells: lymphocytes, ameloblasts, keratinocytes, nerve cells
What are the clinical signs of canine distemper virus
- If adequate host immune system = subclinical (virus may enter CNS)
o Most (50-70%) - If inadequate host immune system = no or low Ig response = mild dz or severe multisystemic disease = virus cleared/remain in lungs or persist in tissue
o 30% all cases result in neurologic dz
What are features of clinical dz of canine distemper virus
- Biphasic fever curve: 3-4d and again at 14-15d
- Acute: conjunctivitis, fever, anorexia, vomit, diarrhea
- Chronic: ataxia, tremor, myoclonus, seizure, moribund
- CNS effects: demyelinating encephalitis, axonal injury, plasmocytic or lymphocytic infiltrates
- GI + Resp + Cutaneous effects = multisystemic dz
o Most recover from resp and GI signs - Enamel hypoplasia: in young (<6mo), destroy ameloblasts
- Hard Pad dz: hyperkeratosis of foot pads/nasal planum
What is observed when looking at canine distemper virus affected tissue via histology
- Inclusion bodies in cytoplasm
- Perivascular cuffing
- Demyelination of white matter
How to diagnose canine distemper virus
- rtPCR, serological assays (IgM confirms infection), pathology/histo (IF/IHC)
o can’t distinguish vx and infected - must submit 2 serum samples – 1 in clinical phase and another 2 weeks after
What are the features of the vaccines used to control canine distemper virrus
- attenuated modified virus vaccine – long lasting immunity
o contraindicated in immunosuppressed, pregnant or non canine - Recombinant canarypox vectored vaccine
o Protect against dz not infection
o For ferrets/zoo animals
o Effective against canarypox and canine distemper - Inactivated vaccine
o Protect against dz not infection
What is the global distribution of rabies? What animals does it affect?
- Birds/amphibians/reptiles = resistant, all mammals get (rrodents = rare)
- Only absent in New Zealand
What are the sources of rabies in Canada and AB
- Source in CA: bats/skunk/racoon/fox
- Source in AB: bats < skunk < cat
What are 3 characteristics of the rabies virus
- (-)ssRNA, enveloped
- Family = Rhabdoviridae
- Genus = Lyssavirus
How is rabies transmitted
- Canine and wildlife reservoirs transmit between
o Reservoirs can infect non-reservoir domestic and livestock animals and people - Transmit via skin damage/mucus membrane/aerosol
o Clinical signs not required for virus shedding
What is the pathogenesis of rabies infection?
- Retrograde transport in neurons to CNS
- Incubation: day to months
o Time to CNS infection depends on how far the wound is from the CNS (100mm/day)
What are the clinical consequences of rabies? How does it differ between species?
Clinically: 100% mortality
* Once virus in CNS
* Furious form (aggressive behaviour): cats
* Paralytic form (paralysis): horse, cattle, bats
* Dogs get both types
What is the histology you would see as a result of rabies virus infection
Histo
* Non-suppurative encephalomyelitis
* Ganglioneuritis/glial nodules (babes nodules)
* Intracytoplasmic inclusions (Negri bodies)