Feline Upper Respiratory Tract Infection

Question 1

what is FHV-1 and what are the clinical signs?

Answer 1

Feline Herpes Virus (FHV-1): aka, Feline Rhinotracheitis
* Sneezing; nasal congestion; serous or mucopurulent nasal discharge; ocular changes
* Ocular changes: blepharospasm & blepharitis (eyelids); conjunctivitis (inflammation of conjunctiva), serous or mucopurulent discharge;
* ‘herpes keratitis’ that may cause corneal ulceration (dendritric ulcers), chemosis (swelling of conjunctiva)
* *Note: keratitis and associated corneal ulceration is not a common clinical sign seen in general practice, more commonly seen in shelter population of cats but corneal staining should be done if you are suspicious!

Question 2

what is FCV and what are the clinical signs?

Answer 2

Feline Calicivirus (FCV)
* Sneezing; serous nasal discharge; ocular discharge; limping syndrome; oral changes inappetence/anorexia, pyrexia
* Limping syndrome: transient fever & lameness, multiple limbs, sometimes noted as ‘shifting’ lameness from limb to limb, *can sometimes also be seen post vaccination with modified live FCV vaccine – it is transient.
* Oral changes: ptyalism (drooling); halitosis (bad breath); oral ulceration (tongue, gingiva, thin red line just above teeth), fauces, hard palate)

Question 3

how are FHV and FCV shed?

Answer 3

Sick cats will shed virus through oral, nasal and conjunctival secretions

Question 4

for FHV and FCV, can recovered cats be carriers?

Answer 4

yes, for both

Question 5

how long after FCV infection might a cat shed the virus for?

Answer 5

Cats with FCV may shed continuously for at least 1 month post infection

Question 6

how long after FHV infection will a cat shed for?

Answer 6

• Cats with FHV-1 may shed intermittently for at least 3 weeks

Question 7

incubation period of FHV-1? How long does disease take to run its course? does it remain in the system post infection?

Answer 7

incubation period of virus is 2-6 days, disease generally runs it course in 10-20 days. Once infected, FHV-1 remains latent in the trigeminal nerve ganglia - so all cats in effect become ‘chronic carriers’.

Question 8

what is recrudescence? why does it occur? are there clinical signs?

Answer 8

a term used to describe the reactivation of a latent virus

Stressful events are often the reason for a recrudescence. For FHV-1, recrudescence can occur 4-12 days after a stressful event! Recrudescence may or may not be associated with clinical signs – obviously easier to clinically detect when they show clinical signs.

Question 9

how many days after a stressful event might we see recrudescence of FHV-1?

Answer 9

4-12 days

Question 10

how can we take recrudescence into account to avoid spreading infections?

Answer 10

Consider building in a buffer time for the possibility of recrudescence if cat is going to mingle with other cats after a recognised stressful event

Question 11

what are the clinical signs of Bordetella bronchiseptica in cats?

Answer 11

• Sneezing, coughing, conjunctivitis & nasal or ocular discharge
• Research is still undecided on the relevance of B. bronchiseptica in cats. Once thought to be a secondary or opportunistic invader but research is accumulating that it may be a primary agent and more widespread than initially thought
• Coughing may occur but not a hallmark as it is in canine infectious tracheobronchitis (kennel cough – next lecture :)

Question 12

what are the clinical signs of chlamydia felis? What other viruses does it interact with and in what ways?

Answer 12

• Sneezing; serous nasal discharge; ocular discharge & conjuctivitis (often unilateral to begin then progress to bilateral); occasionally decreased appetite.
• Often considered to be a ‘co-infection’ with FHV-1 & FCV. Clinical signs are not much different from FHV-1 & FCV but suspicions of Chlamydia arise clinically when URTI signs are getting worse or not responding to supportive care

Question 13

what are the clinical signs of mycoplasma species in cats? is it a primary or secondary pathogen?

Answer 13

• Non specific clinical signs of sneezing, coughing, ocular or nasal discharge
• May be implicated or cultured as a secondary or opportunistic bacterial pathogen in upper or lower respiratory tract infections in cats

Question 14

most diagnoses for URTIs are based on what? WHat other options do we have?

Answer 14

Clinical diagnosis is predominately based on +/- clinical signs

-PCR: Nasal, oropharyngeal or conjunctival swabs possible for FHV-1 & FCV
* Bacterial culture: possible for B. bronchiseptica, Mycoplasma & Chlamydia felis

• Serological testing (antibody detection): typically unrewarding/not specific as vaccination & exposure are considered widespread.
• Consider practicality and costs (& spectrum of care) of testing for individual companion cats.
• Sampling sites may yield varying results for the same agent! *See article on sampling sites for detection of FHV-1, FCV & Chlamydia felis

Question 15

what age are most cats with a URTI?

Answer 15

young (<1yr old) and old cats (~>10years) and cats with immunosuppressive disease.

Question 16

what is required for transmission of a URTI? ie. biggest risk factors? How can we avoid transmission?

Answer 16

• Transmission: A lot of cats living together in close contact (e.g. breeding facilities, shelters,
  multi-cat households)
• Transmission of all components is via nasal, ocular, mouth, airway secretions – so, close contact is needed to transmit. Aerosolization is unlikely (not impossible) mode of transmission
• Incidence of fomite transmission may occur - always good practice to wash your hands, change your scrub top, wipe down your stethoscope before seeing the next patient
• Always wipe down the exam table, walls near the exam table with a antiviral/antibacterial spray before seeing the next patient. May consider wiping down all surfaces, moping the floor and leaving the room unused until all surfaces are dry
• Cages and feeding/water bowls must be washed/disinfected and dried
• Coming home to your own cat after examining a suspect cat-flu cat? All of the above precautions apply

Question 17

how do we treat and manage a URTI in a cat?

Answer 17

Supportive & symptomatic. Goal = control clinical signs associated with viruses & (secondary) bacterial infections, maintain comfort and appetite
* Fluid therapy if dehydrated
* In-clinic treatment will require isolation of URTI patient from other cats and dogs
* Treat secondary bacterial infections when suspected: e.g. doxycycline for Mycoplasma, B. bronchiseptica & Chlamydia
* Topical eye preps to treat conjuctivitis, blepharitis and ulceration when present e.g. antibiotics such as chloramphenicol, tetracycline, tobramycin. *Do not use topical corticosteroid in cases where corneal ulceration are present
* Anti-mucolytic agents e.g. bromhexine ‘Bisolvon’ oral powder
Treatment and management (contd):
* Room humidification/ vaporiser treatment to help with nasal congestion
* Wipe away nasal and ocular discharge
* L-lysine may help with severity of FHV-1 conjunctivitis clinical signs *see article posted for more info. Works much better as a prophylactic than as a cure *1000mg/day is recommended dose
* Fresh, warm, palatable, soft food (esp. in cases with oral ulceration)
* Appetite stimulants can help e.g. mirtazapine
* NSAIDs if persistently pyrexic and or severely depressed
* Feeding tubes may be indicated to bypass oral/pharyngeal passages in cases of severe oral ulceration and or in cases of anorexia
* Antiviral drugs may be considered e.g. topical famcyclovir for herpesvirus keratitis
* Support and management often required for 2-4 weeks while viruses run their course

Question 18

prognosis of URTI in cat and possible sequelae

Answer 18

Unless very young or severely compromised individual, prognosis for clinical recovery is very good!

• Chronic rhinitis, stomatitis, and/or conjunctivitis can occur – these are generally medically manageable
• Stress is a known trigger factor for latent FHV-1 and can cause recrudescence!
• Prepare and educate your clients on what is recrudescence and why/when it may happen :). Investigate and ask you client about cat’s lifestyle, surroundings, family’s lifestyle? Give them a heads up about what might be considered a stressful event for that individual cat based on their answers
• Preventing or putting stress mitigation/behavioural modification practices in place may be the best prophylactic for recrudescence.

Question 19

how long should we wait to start treating URTI? What do we want to avoid?

Answer 19

Get treatment/support started early…do not take the wait and see approach. We don’t want cats to stop eating!

Question 20

Once cats have had clinical cat flu, will you recommend vaccinating that cat for FHV- 1 & FCV in the future? What are that cat’s risk factors?

Answer 20

-is cat entering a high risk environment? then maybe consider vaccination
-but cat has just had cat flu, maybe cat has immunity and is going to be ok without vaccine; could skip this vaccine, reasonably

Question 21

what should we consider is mucus is very thick, yellow, sticky?

Answer 21

secondary invader, consider antibiotics