ID - Canine Viral Infections Flashcards by Toby Anderson

What family and genus does canine distemper virus belong to?

Paramyxoviridae and Morbillivirus

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What species can canine distemper infect?

Dogs primarily but also ferrets, badgers, and lions

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What diseases are closely related to canine distemper?

Measles mumps, rinderpest, phocine distemper

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What is the pathogenesis of canine distemper?

Oronasal infection.
Multiplies in the lymphoid tissue of the respiratory tract.
Widespread multiplication in lymphoid tissue, bone marrow, and spleen.
Virus spreads to epithelial +/- CNS tissues (entry into CNS tissues depends on the immune response of the host)

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Where does the canine distemper virus multiply?

Lymphoid tissue, bone marrow, and spleen

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What are the clinical signs of canine distemper?

Subclinical
Anorexia, depression, pyrexia
Ocular and nasal discharge
Coughing
Conjunctivitis
Vomiting and diarrhoea
Hyperkeratosis - nose and feet; hard pad
Neurological signs - seen 1-3 weeks after other signs - seizures and myoclonus

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How can you diagnose canine distemper?

History and clinical signs.
RT-PCR - smears, blood, urine sediment.
Virus isolations from secretions is difficult.
Antibody or viral antigen in CSF is diagnostic

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How can you treat canine distemper?

No antivirals; symptomatic and supportive treatment e.g. fluids, anticonvulsants for seizures.
Careful nursing.
Antibacterial cover for secondary infections

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Are there vaccines for canine distemper?

Yes
Modified live
Classically vaccinate when MDA (maternally derived antibodies?) decline to non-detectable levels: approx 8-12 weeks of age
Nowadays higher titred vaccines allow earlier finish vaccination if necessary

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What is the difference between canine adenovirus types 1 and 2?

CAV-1 - systemic disease and can also cause upper respiratory tract disease
CAV-2 - respiratory disease

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What causes infectious hepatitis in dogs?

Canine Adenovirus type 1

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What virus is described by the following?

very hardy, can survive weeks in the environment
disease now uncommon due to vaccination
mainly seen in unvaccinated dogs, or on puppy farms

Canine Adenovirus type 1 or Infectious Hepatitis

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What is the pathogenesis of infectious hepatitis?

Oronasal infection.
Viraemia.
Virus spreads to many tissues.
Virus then localises and causes damage in hepatic cells and vascular endothelial cells.
Virus persists in kidneys and can be excreted in urine for 6-9 months

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What are the clinical signs of infectious hepatitis?

Often dogs <1 year of age.
Pyrexia, depression, lethargy.
Hepatomegaly.
Reluctance to move, abdominal pain.
Petecchial haemorrhages - bleeding from venipuncture sites.
Vomiting and diarrhoea (haemorrhagic).
Coughing.
Corneal oedema and uveitis - during clinical recovery

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How can you diagnose infectious hepatitis?

Virus isolation from faecal samples or oropharyngeal swabs.
Serology.
Histopathology of liver tissue at postmortem - cowdry A type intranuclear inclusion bodies

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How can you treat or prevent infectious hepatitis?

Treatment
- No specific antivirals
- supportive and symptomatic treatments
- antibacterial cover for secondary infections
Prevention
- Vaccination - CAV-2
- CAV-1 vaccines not used due to problems with blue eye - corneal oedema

What virus are the following characteristics of?

Non-enveloped DNA virus
Stable in environment for prolonged periods of time
Tiny Virus
Highly infectious
Invades rapidly dividing cells (intestine, bone marrow)
- causes leucopaenia, severe diarrhoea, vomiting
largely controlled by vaccination

Canine Parvovirus

When and where did this virus come from?

First recognised in 1978.

Believed to have evolved from feline parvovirus - now two strains present

What is the pathogenesis of canine parvovirus?

Faecal-oral transmission.
Virus replication in lymphoid tissue.
Viraemia.
Virus replication in intestine - crypts of villi.
Destruction of normal GI epithelium.
Secondary bacterial infection.

What is the pathogenesis of canine parvovirus when exposed in utero or neonatal (< 8 weeks)?

Virus replicates in myocardium - myocarditis.

Rare nowadays - protection from MDA

What are the clinical signs of parvovirus?

More severe in young rapidly growing pups (< 12 weeks).
Inapparent infection to sudden death.
Range of gastrointestinal signs -vomiting, diarrhoea (haemorrhagic).
Anorexia, depression, pyrexia.
Dehydration.
Sepsis and DIC.

How can you diagnose parvovirus?

History and clinical signs.
ELISA, culture, PCR.
Detection of virus in faecal samples - negative results do not mean no infection - can be virus positive in faecal samples 5-7 days after a live attenuated vaccine.
Serology - care in interpretation, vaccination and MDA

How can you identify parvovirus postmortem?

Intranuclear inclusion bodies in intestinal cells.
Shortening and loss of villi.
Depletion of lymphoid tissue in the gut.

How would you treat parvovirus?

Fluid therapy - need to restore fluid and electrolyte balance.
Antibacterial cover.
Antiemetic agents if vomiting.
Interferon

How is parvovirus transmitted?

``` Virus is shed in faeces for 10-12 days (5-7 days after onset of clinical signs). Direct contact with contaminated faeces. Fomites. Contaminated environment. Hair coats of dogs. ```

Prevention and control of parvovirus?

Vaccination. - live attenuated vaccines based on CPV2 or CPV2b Removal of the virus from contaminated environment. - e.g. sodium hypochlorite (1 in 30 household bleach)

What is the complication with vaccinating neonates?

Maternally derived antibodies can block vaccine. - timing of first vaccination is critical - If MDA lasts a short time there is an immunity gap before vaccination has induced immunity - If MDA lasts too long then vaccination will not work at the usual time

When should puppies (and kittens) be vaccinated against parvovirus?

9, 12, and 16 week vaccinations. Some recommend earlier vaccination to allow earlier socialisation. More common now to allow socialisation with vaccinated dogs.

How often do adults need vaccinating against parvovirus?

Historically annual boosters. Parvo vaccines are very good and likely give much longer DOI. 3 year boosters becoming more common (for parvo, distemper, adeno). Some advocate measuring antibody levels to predict need for vaccination

How is rabies transmitted?

Via bites scratches and licking

What can be affected by rabies?

The CNS of most mammals (usually fatal)

How is rabies controlled?

Quarantine. Vaccination. PETS travel scheme.

Why are you advised to not handle any bat you find?

European bat lyssavirus (EBLV) has been isolated from a UK case of rabies encephalitis. Transmitted by Daubenton's bat.

What is the pathogenesis, clinical signs, and vaccination for canine herpesvirus?

In utero infection; infertility, abortion, still birth Neonatal; severe systemic multi-organ infection Adult dogs; genital and respiratory Vaccination given to dams

What does canine papilloma virus cause?

Host specific, benign self-limiting warts in young dogs

What is significant about Aujeszky's disease/pseudorabies?

primarily found in pigs, is notifiable (in dogs or in general?)

Ebola virus? Why significant for dogs?

Filoviruses. African fruit bats are the normal carrier in nature. Dogs can seroconvert. What role do they play in transmission? - transmission by acting as a fomite?