Infectious respiratory disease of the dog Flashcards by Saul Levy

kennel cough complex

Infectious canine tracheobronchitis

Canine infectious respiratory disease (CIRD) complex

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kennel cough - aetiology

Canine parainfluenza virus (CPIV)
Canine adenovirus type 2 (CAV-2)
Bordetella bronchiseptica

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Bordetella bronchiseptica

Primary respiratory pathogen
Frequently isolated from dogs with respiratory disease (also found with no clinical signs)
Attaches to cilia in URT
release of bacterial toxins damages respiratory epithelium + MCE (ciliostatic)

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Canine parainfluenza virus (CPIV)

Causes mild respiratory disease
Frequently isolated from dogs with respiratory disease
More severe if in combination with Bordetella

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canine adenovirus (CAV)

Type 2 causes respiratory disease
Not commonly associated with kennel cough in UK - good adenovirus vaccine uptake
Type 1 causes hepatitis (ICH) (can cause respiratory disease as well)

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agents frequently present in dogs with CIRD

Canine herpesvirus 1 (CHV-1)
Canine respiratory coronavirus (CRCoV)
Mycoplasmas (esp M. cynos)
canine pneumovirus

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canine herpesvirus (CHV)

Systemic + often fatal disease in neonate puppies, under 3 days (vaccine for dams available) - thermo-sensitive virus
Isolated from adult dogs with respiratory disease
Detected in 25% of dogs with severe clinical signs
Potential reactivation of latent virus due to other disease?
necrosis in kidneys + liver

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canine respiratory coronavirus (CRCoV)

Associated with mild respiratory disease
Highly contagious
Vaccine currently under development
Distinct from canine enteric coronavirus (CECoV)
Vaccines for canine (enteric) coronavirus do not cross protect

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mycoplasmas

Many different species in dogs

Mycoplasma cynos is associated with resp disease

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Epidemiology of CIRD complex

Very common in dogs that are housed in groups
Very contagious
Transmission by aerosol/droplets during contact with infected dogs

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CIRD - pathogenesis

Infection of resp epithelialcells by viruses/Bordetella
Cell damage by viruses + bacterial toxins
Inhibition of ciliary clearance by damage to ciliated cells
Potential secondary bacterial infections
Different mix of infectious agents may produce same clinical signs

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CIRD - clinical signs

Usually apparent 3-7 days after exposure
Cough (dry or productive), retching - particularly during exercise + on lead
Nasal +/- ocular discharge, sneezing
In most cases recovery after 1-3 weeks

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CIRD - systemic disease

depression, pyrexia, inappetence
Progress to bronchopneumonia by secondary bacterial infections
Canine distemper virus
strep equi subsp. zooepidemicus

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CIRD - diagnosis

History and clinical signs
tests usually only needed if no improvement after 2 weeks or if signs of systemic disease
Tests are also useful in cases of persistent problems in boarding kennels, vet hospitals or rehoming centres

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CIRD - diagnositic tests

Isolation of bacteria - antibiotic sensitivity
Viral isolation or PCR to rule out distemper virus
done on tracheo-bronchial wash but in practice usually a deep pharyngeal swab
Serology: only useful if paired serum samples
Faecal smear/serology: rule out Angiostrongylus sp.
Haematology - neutrophilia
Radiography and rhinoscopy

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CIRD - treatment

rest
antibiotics
Cough suppressants, bronchodialtors, mucolytics

CIRD - prevention + control

vaccine - Prevent/reduce severity and length of disease

many infectious agents - vaccine may not always be 100% successful

vaccines against respiratory viruses - Parenteral vaccines

induce high antibody (mainly IgG) conc in bloodstream

IgA and IgG concentration on mucosal surface lower than for intranasal vaccines

vaccines against respiratory viruses - Intranasal vaccines

stimulate mostly IgA and mostly on mucosal surface

Serum IgG also produced but at lower levels compared to parenteral application

intranasal vaccine - advantages

Stimulate local immune response in respiratory tract

Act more rapidly compared to systemic vaccines

intranasal vaccine - disadvantages

Shorter duration of immunity

Difficult to administer to uncooperative dogs

B. bronchiseptica vaccines

Live attenuated 
At least 5 days before kennelling 
Often compulsory for boarding kennels 
Immunity is short lived 
Live attenuated strains are old and may be different from current field isolates

canine parainfluenza vaccines

Live attenuated

Either included in systemic combination vaccine or intranasal application

canine adenovirus vaccine

CAV types 1 and 2 cross protect

Systemic vaccines containing either CAV-1 or CAV-2 protective against both types

canine distemper - spread

canine distemper virues (CDV) shed in all body fluids spread by aerosol or close contact Ferrets – highly susceptible to CDV

canine distemper - pathogenesis

Virus enters via the respiratory tract Spreads to tonsils and local lymph nodes Infects monocytes/macrophages Viraemia, systemic dissemination 2-3 weeks after infection dogs which are able to develop a good humoral and cellular immune response will recover or develop a mild form of the disease In dogs with insufficient immune response CDV spreads to epithelial cells of the respiratory, gastrointestinal + genitourinary tract as well as the CNS CDV causes immunosuppression - secondary bacterial infections

canine distemper - clinical signs

``` Nasal and ocular discharge Cough Diarrhoea Vomiting Depression Anorexia ```

canine distemper - CNS signs

Seizures, Incoordination, Paresis/Paralysis, Muscle tremors Ocular lesions (degeneration of retina, optic neuritis) Sometimes develop without obvious other clinical signs of distemper Neuronal destruction Demyelination

hard pad/nose disease

hyperkeratosis of foot pad/nose | caused by some CDV strains

distemper teeth

In dogs that develop distemper before they have their permanent teeth Hypoplasia of the enamel infection of ameloblasts

canine distemper - diagnosis

Clinical signs and history Haematology: lymphopenia Serology: IgM indicative of recent infection Virus isolation/PCR: specialist laboratories Immunofluorescence on conjunctival smears Cerebrospinal fluid: CDV specific antibody detection in dogs with neurologic signs

canine distemper - treatment

Antibiotics to prevent secondary infections Fluid therapy Sedatives, anticonvulsive drugs CNS signs may improve with time

canine distemper - prevention + control

Live attenuated vaccines widely available 8 weeks, 10-12 weeks and 1 year - boosters every 2 years Isolation of dogs Disinfection of kennel

influenza virus

Outbreaks of respiratory disease initially at greyhound racetracks in USA Some dogs developed mild respiratory disease 8/22 died from haemorrhagic pneumonia Influenza virus closely related to equine influenza virus H3N8

canine influenza virus (CIV)

direct transfer of equine virus rather than reassortment Spread within the canine population by dog to dog contact presence of influenza virus in subsequent outbreaks of non-fatal resp disease vaccine in USA

Streptococcus equi subsp. zooepidemicus

fatal in dogs In recent years increasingly reported in dogs Pyrexia, haemorrhagic nasal discharge and sudden death PM: severe necro-haemorrhagic and fibrino-suppurative bronchopneumonia unknown if outbreaks linked to contact with horses

Streptococcus equi subsp. zooepidemicus - diagnosis + treatment

isolation from lung samples or swabs | : i.v. fluid therapy and antibiotics