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Flashcards in Cat Respiratory Tract Infections Deck (26)
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Where is "Cat Flu" more of an issue.
What is the main cause of respiratory disease in cats?

Rescue Shelters, Boarding catteries and kittens
Main cause: Feline Calicivirus


Define aetiology

cause, set of causes, or manner of causation of a disease of condition


Aetiology of feline respiratory disease

1. Feline herpesvirus
2. Feline calicivirus
3. Bordetella bronchiseptica
(less so)
4. Chlamydophila
5. Mycoplasmas (feline infectious anaemia)
6. Bacteria
7. Haemophilus felis


What is virus classification based on?

1. Genome (RNA or DNA)
2. Number and sense of RNA/ DNA strands
3. Morphology
4. Genome sequence similarity
5. Ecology


Facts about feline herpesvirus

o Double stranded DNA virus, relatively conserved and complex biology
o Single serotype – not so much variability
o Lipid envelope (relatively fragile in environment
o Relatively severe respiratory disease
o Similar to humans in fact that inc stress inc shedding


Clinical signs of feline herpesvirus

1. Sneezing
2. Nasal discharge- can start quite liquidy and become more mucousy
3. Conjunctivitis
4. Ocular discharge/ disease (image, cat on RHS severe keratitis)
• Corneal ulceration
• Conjunctivitis
• Keratitis
• Use topical analogues to treat OD
5. Hypersalivation
6. Pyrexia
7. Lethargy
8. Dyspnoea


Facts about Feline Calicivirus

o Single stranded RNA virus
o No envelope
o Very variable – large number different strains


Clinical signs of feline calicivirus

2. Pyrexia
3. Oral ulceration (major sign)
4. Nasal discharge
5. Conjunctivitis
6. Sneezing
7. Pneumonia – rare
8. Lameness
9. Chronic stomatitis, not rare
10. Virulent systemic disease, rare


Talk about lameness in feline calicivirus

• In young cats
• Shifting lameness (changing leg)
• Resolves spontaneously
• Often pyrexic
• In joints can find small amounts FCV antigen


Talk about Chronic stomatitis and virulent systemic disease in cats. And which disease is this associated with?

Associated with Feline Calicivirus
1. Chronic stomatitis, fairly common
- ulceration
- it is associated and NOT CAUSED by FCV
- Lots of cats need teeth out, immunosuppressants, long standing antibacterial therapy.
- lot end up being put down:(
2. Virulent systemic disease
- rare
• Unusual in fact get sporadic outbreaks v severe signs. Not just resp signs but
o Oedema, necrosis, ulceration, resp disease, pyrexia, haemorrhage from nose and in faeces, jaundice
• Haemorrhagic syndrome
• Rapid death


Talk about Bordetella bronchiseptica

o Less important to cats, more so in dogs
o Gram negative coccobacillus
o BACTERIA not virus
o Can infect – dogs, pigs, horses, rabbits, small mammals and humans (potential zoonoses, unlike FCV and FeHV)
o Associated with resp disease
 Incubation period – 6 days
 Attaches to ciliated epithelium
 Replicates and produces virulence factors
 Ciliostasis – releases toxins causing this


Clinical sings Bordetella bronchiseptica

 Pyrexia
 Sneezing
 Nasal discharge
 Cough
 Submandibular lymphadenopathy – not feature FCV or FHV (enlarged lymph nodes)
 Bronchopneumonia (severe)
• More LOWER respiratory


PAthogenesis of Feline calicivirus

direct contact with the saliva, nasal mucus and eye discharge of infected cats and through aerosol droplets that spread when cats sneeze
 Attaches to upper respiratory tract cilia
• Cause cilia stasis
 Stops mucociliary clearance
 Bacteria then colonise in the respiratory tract, causing disease


Talk about Chlamydophila

1. Associated with respiratory disease
o Gram negative
o Obligate intracellular parasite
o Transmitted by close contact
o Unilateral becoming bilateral conjunctivitis
o Chemosis (swelling eyelid)
o Diagnosed by PCR
o Treat with systemic doxycline
o Control by vaccination in high risk situations
o Only really seen when lots of cats housed together


define pathogenesis

The manner of development of disease


Feline herpes virus pathogenesis (the manner of development of disease)

o Oronasal infection
o 2-6 day incubation period
o Virus multiplies in the oral/respiratory tissue
o Low mortality
o Clinical signs resolve within 20 days, uneventful recovery
o Can lead to longer lasting chronic disruption of innate immune response of nose – leading to rhinitis if turbinate epithelium damaged chronic snotty sneezing which can ruin wallpaper!
 Often need regular bouts of prolonged antibacterial therapy – shouldn’t undertake lightly!


General epidemiological factors in resp disease

• Generally, direct cat to cat
• Herpesvirus lasts less than a day outside of the cat
• Calicivirus last less than a week outside of the cat
• Indirect contact through contamination of personnel, fomites and environment
• Aerosol transmission not of major importance – sneezing is the way


Epidemiology of carriers of feline herpes and calcicvirus

• Herpesvirus is latent and then reactivated
• Calicivirus is a persistent infection
• Both widespread in cat population
• FCV carriers spread virus for 30 days after clinical signs
o Most clear the virus eventually (75 day half life)


How to diagnose FCV and FeHV

• Clinical signs
• Oral pharyngeal swab – virus transport media (inhibits bordetella = why not used)
• Virus isolation
o Swab into VTM
o Can take up to 2 weeks
• PCR - main
• Serology to look for Ab but v little use
• Histopathology


How to diagnose Bordetella bronchiseptica

• Oropharyngeal or nasal swab – has to go in different transport media, charcoal amies transport medium (full of antibiotics to inhibit other bacteria in cat mouth.)
• Histopathology


Main control of Resp disease

• Vaccination
-Reduce clinical disease
• Population management


Contrasts in FCV and FHV clinical disease

1. Oral ulceration
2. Oculonasal discharge
3. Conjunctivitis
4. lameness
2. Pyrexia
5. Conjunctivitis
6. Sneezing
7. Pneumonia – rare
9. Chronic stomatitis, not rare
10. Virulent systemic disease, rare

1. Sneezing
2. Nasal discharge- can start quite liquidy and become more mucousy
3. Conjunctivitis
4. Ocular discharge/ disease (image, cat on RHS severe keratitis)
• Corneal ulceration
• Conjunctivitis
• Keratitis
• Use topical analogues to treat OD
5. Hypersalivation
6. Pyrexia
7. Lethargy
8. Dyspnoea


Contrasts in FCV and FHV carriers

1. Herpesvirus is latent and then reactivated
2. Lifelong
3. Intermittent shedding - low level shedding in population
4. Cat infected, acute infection, clinical disease, sheds, 2-3 weeks later latently infected (in brain) = clinically normal stop shedding.
5. In brain switches off almost all protein expression. Being in CNS it is in a immune privileged site where immune response can’t get to it
6. Stress - reactivated, starts shedding again
7. clinical sings at time of activation --> recrudescence
1. Calicivirus is a persistent infection
2. Not life long
3. Usually infected, acute infection, shed for 30 days. After become carrier
4. High prevalence in cats - high level shedding
5. Believe cats clear infection, measureable immune response then long enough, this disappears and and then can become reinfected
d. Means at 30 days 100 ctas shedding, 75 days later 50 shedding, 75 days later 25 shedding. Means only a minority of cats shed for long time. Perhaps only 1-2% shed for life.


Important to remember when cat arrives with suspected respiratory tract disease

virus transport media inhibits bordetella if see cat with resp signs, typically 2 swabs – one virus TM and one charcoal amies


Live vaccine

1. Virus weakened (attenuated so less liekly cause disease
2. virus still "live"
3. Limited replication stimulated immune response
4. May udner rare condiiotns cause infection adn mild disease


Killed vaccine

1. Virus "killed"
2. No chance of causing infection or disease
3. Need adjuvants to stimulate immune response
4. Greater association with sarcomas
5. Licensed during pregnancy