Infectious respiratory disease of the dog Flashcards
What are the 4 main infectious respiratory diseases in the dog?
- ) Kennel Cough (KC) complex
- ) Canine Distemper Virus (CDV)
- ) Canine Influenza Virus (CIV)
- ) Streptococcus equi subsp. zooepidemicus
What is another name for KC? 2
= Infectious canine tracheobronchitis (ITB)
= Canine infectious respiratory disease complex (CIRD)
Aetiology - KC complex - 3
Usually several infectious agents: - Canine parainfluenza virus (CPIV) - Canine adenovirus type 2 (CAV-2) OTHERS: Bordatella bronchiseptica
Outline B.bronchiseptica
Primary resp. pathogen
Frequently found in dogs with resp disease (also healthy dogs)
Attaches to URT cilia and releases bacterial toxins which damage the respiratory epithelium and the MCE (ciliostatic)
Outline CPIV infection
Causes mild respiratory disease
Frequently isolated from dogs with respiratory disease
More severe if concurrent with Bordatella
Most frequent viral cause of KC
Outline CAV2 infection. What about type 1?
Causes respiratory disease
Not commonly associated with KC in UK (vaccine uptake)
Type 1 –> hepatitis (ICH) but has been reported to case respiratory disease as well.
Outline CHV infection
Systemic and often fatal (neonates, <3 days, thermosensitive virus).
Isolated from adult dogs with resp. disease
Potentially reactivated when latent due to other disease.
Outline canine respiratory coronavirus (CRCoV) infection
Associated with mild respiratory disease
Highly contagious
Vaccine being developed
Distinct from canine enteric coronavirus (CECoV)
Vaccines for CECoV don’t cross-protect
Have spike proteins to give corona appearance.
What mycoplasmas are present in dogs?
Many different mycoplasma species
Mycoplasma cynos is associated with respiratory disease
Other spp often normally present (M. canis)
Epidemiology - CRID complex
V. common in dogs housed in groups
Possible history of group
Very contagious - transmission by aerosol droplets
Pathogenesis - CRID
infection of respiratory epithelial cells (viruses or bordatella) - cell damage (viral and bacterial toxins) - inhibition of ciliary clearance (by damage to ciliated cells) - potential secondary bacterial infections (Strep., Pasteurella) - different mix of infectious agents may produce same CS.
Clinical signs - CRID
Usually apparent 3-7 days after exposure Cough (dry or productive) Retching (especially exericse or lead) Nasal +/- ocular discharge Sneezing Most cases recover after 1-3 weeks (no treatment) BUT look out for non-resolving systemic cases.
What should you do for CRID cases that don’t resolve and then show systemic signs?
CS - depression, pyrexia, inappetance
Progression - to bronchopneumonia due to secondary bacterial infections, CDV , Strep equi subsp. zooepidemicus.
Diagnosis - non-resolving (>2 weeks) systemic (pyrexia) CRID - 6
BACTERIAL ISOLATION - test for AB sensitivity
VIRAL ISOLATION or PCR - rule out distemper
BOTH of above on tracheo-bronchial wash or deep pharyngeal swab
SEROLOGY - paired for rising titre
FAECAL SMEAR/SEROLOGY - rule out Angiostrongylus
HAEMATOLOGY - neutrophilia
RADIOGRAPHY or RHINOSCOPY - to investigate other potential causes such as HF, FB or tumour metastasis.
What is rhinoscopy?
nasal endoscopy
Tx - CRID - 4
- Rest + owner pacificiation
- AB - only with culture and sensitivity
- If necessary: cough suppressants, bronchodilators, mucolytics
- Supportive care (if systemic disease, fluids)
Prevention - CRID
Prevent or reduce severity and length of disease (B. bronchiseptica, parainfluenza and adenovirus). BUT other infectious agents cause or contribute to CRID complex and vaccinated animals may still develop disease.
What are the 2 types of vaccine available against respiratory viruses?
PARENTERAL - high Ab titre (IgG mainly), on mucosal surfaces IgA and IgG much lower
INTRANASAL - stimulate mostly IgA, mostly on mucosal surface, serum IgG produced but less than parenteral
Advantages - intranasal vaccines - 2
Stimulate local immune response
Act more rapidly versus systemic vaccines
Disadvantages - intranasal vaccines - 2
Shorter duration of immunity
Difficult to administer to uncooperative dogs.
Role of IgA
Neutralises Ag on cell surface
Neutralises intracellular Ag.
Describe the B.bronchiseptica vaccine
Live, attenuated,
At least 5 days before kenneling (often compulsory)
Short-lived immunity
Strains are old, may be different from current field isolates
Describe CPIV vaccine
Live, attenuated
Either in systemic combination vaccine or available for intranasal application with Bordatella
Annual booster recommendations questionable
T/F: CAV 1 and 2 cross protectec
True - therefore systemic vaccines containing either offer cross-protection
Outline husbandry for KC
- Isolation
- Clean and disinfect
- Good ventilation
- Isolate newcomers
- Avoid high population density
What type of virus is CDV?
A morbillivirus - these cause immunosuppression leading to secondary infections.
How is CDV transmitted?
Shed in all body fluids. Spreads by aerosol or close contact (RNA virus)
Pathogenesis - CDV
VIrus enters respiratory tract - spreads to tonsils and local LNs - infects monocytes/macrophages - viraemia and systemic dissemination - 2-3 weeks after infection dogs are able to develop a good humoral and cellular immune response and will recover from a mild form of the disease. In dogs with an insufficient immune response, CDV spreads to other epithelial cells (respT, GIT and genitourinary tract and CNS).
What usually kills and animal with CDV?
the secondary infection
Clinical signs - CDV
Nasal and ocular discharge Cough Diarrhoea Vomiting Depression Anorexia CNS signs
What are the CNS signs of CDV?
- Seizures, incoordination, paresis/paralysis, mm tremors
- Ocular lesions (retinal degeneration, optic neuritis)
- Neuronal destruction
- Demyelination (especially where CNS signs have a late onset)
- Sometimes develop without obvious other (i.e. respiratory) causes of distemper
What is ‘hard pad’ and ‘hard nose’ disease?
Hyperkeratosis of the foot pads and nose caused by some CDV strains
What are ‘distemper teeth’?
In dogs that develop distemper before they have their permanent teeth –> hypoplasia of the enamel (infection of the ameloblasts)
Diagnosis - CDV - 6
- CS and Hx
- HAEMATOLOGY - lymphopaenia (virus replication in LT)
- SEROLOGY: IgM indicative of recent infection
- VIRUS ISOLATION/PCR: specialist laboratories
- IMMUNOFLUORESCENCE: on conjunctival smears
- CSF: detect specific CDV antigen in dogs with neuro signs.
Treatment - CDV
AB - prevent secondary infections (often succumb to bacterial pneumonia)
Fluids
Sedatives, anti-convulsive drugs
CNS signs may improve with time
What other species is highly susceptible to CDV?
Ferrets
Prevention/control of CDV
Live attenuated vaccine widely available
Protocol: 8 weeks, 10-12 weeks and 1 year. Boost every 2 years.
Control: isolation and disinfection
Where did canine influenza virus (CIV) originate?
USA racing greyhounds. Some developed mild respiratory disease. A third died from haemorrhagic pneumonia. Closely related to equine influenza virus H3N8 (all segments of viral genome derived from this). This indicates DIRECT TRANSFER of equine virus rather than reassortment.
How is CIV spread between dogs?
Dog to dog contact (droplets, aerosols)
Is CIV present in the UK?
No - currently all serological studies are negative here. Vaccine now licensed in the USA.
What is the relationship between Streptococci and the URT?
Found in normal URT.
Beta-haemolytic and is highly virulent in the lung (in lancefield group C which is the most pathogenic due to its M protein, toxins, capsule and superantigen)
Describe Streptococcus equi subsp. zooepidemicus as a respiratory pathogen
Relatively common in horses (abortion and low-grade URT disease). Recent years has been increasingly reported in dogs. Unknown if outbreaks are linked to contact with horses (looking more unlikely)
Clinical signs - Streptococcus equi subsp. zooepidemicus - 3
pyrexia
haemorrhagic nasal discharge
sudden death
What would a PME of a dog with Streptococcus equi subsp. zooepidemicus show? 2
severe necro-haemorrhagic and fibrino-suppurative bronchopneumonia. (lung becomes consolidated and fills with blood/oedema etc. Thoracic cavity usually full of blood. Animal dies due to drowning.
How is Streptococcus equi subsp. zooepidemicus spread?
Dog to dog contact
Probably bu fomites
Horse to dog looking less likely
Diagnosis - Streptococcus equi subsp. zooepidemicus - 2
Streptococcus equi subsp. zooepidemicus isolation from lung samples or swabs (nasal discharge). Soon a rapid PCR test will be available.
Treatment -Streptococcus equi subsp. zooepidemicus
IV fluids and ABs (intensive care, if ID early)
Is Streptococcus equi subsp. zooepidemicus zoonotic??
YES
Mortality for Streptococcus equi subsp. zooepidemicus
High mortality due to sudden onset. That said, there are increasing numbers of ‘carrier’ animals.
