27. Feline infectious rhinotracheitis.

Question 1

Occurence, causative agent?

Answer 1

Infectious rhinotracheitis of cats

• contagious,
• upper respiratory inflammation of cats with febrile general signs

Causative agent:

• Felid herpesvirus 1 (FeHV-1) (Alphaherpesvirinae)
• Worldwide distribution, frequent
• Isolation on feline kidney cells
• VN cross-reactions with BHV-1 & SuHV-1
• Domestic cat & other felids (i.e. lions) are susceptible
• Upper resp infection, eye lesions are common (conjunctivitis ʹ also part of upper resp tract),
• abortion may also be a consequence but is very rare

Question 2

Epizootiology, Pathogenesis?

Answer 2

Epizootiology, pathogenesis

• The virus is shed through nasal discharge ʹ contact, air-borne infection ʹ very contagious
• Predisposing factors:
• winter, young (<6m ʹ in the growing period = 100% of population will get the infection & high proportion dies due to secondary infections e.g. Bordatella)
• or old age,
• pregnancy/lactation, crowded keeping, weak condition, stress
• Virus multiplication in the respiratory mucosa ʹ necrosis, inflammation
• Viraemia ʹ infection of the foetus ʹ abortion
• Latency in the pharyngeal lymphatic tissue & in the trigeminal ganglion
• Colostral protection until the 7th-10th week of age

Question 3

Clinical signs?

Answer 3

Clinical signs:

• 3-6 days incubation
• Fever, loss of appetite, lacrimation, nasal discharge, coughing, sneezing, conjunctivitis, nasal mucosa
• oedema
• In the beginning serous, latermuco-purulent conjunctival & nasal discharge eyelids cohere,
• nose holes are blocked
• 4-7 days; with secondary bacterial infections for weeks
• Frontal sinusitis & empyema (Bordatella, Strep.)
• Keratitis, corneal ulcers (pinpoint or dendritic in shape), keratoconjunctivitis sicca, corneal sequestra
• Nasolacrimal duct infection ʹ epiphora (excess tearing) ʹ wet face
• Ulcerative skin disease can also develop (due to wetness, secondary bact infection)
• Cats not cleaning themselves properly
• Abortion: usually at the 6th week of gestation, may be due to systemic effects of the infection
• Early age infection ʹ permanent damage of nasal & sinus tissue ʹ disruption of ciliary clearance of
• mucus ʹ predisposing to chronic bacterial infections

Question 4

Diagnosis?

Answer 4

Diagnosis

• Anamnesis (age, vaccination, season), clinical signs
• Virus isolation, IF
• Histopathology: tonsils, nasal tissue, ictitating membrane (3rd eyelid) ʹ intranuclear inclusion bodies
• Serology: VN (~1.64 ʹ 1:128 titres)

Question 5

DD?

Answer 5

Differential diagnosis:

1. calicivirus!,
2. chalydia,
3. Bordatella bronchiseptica

Question 6

Treatment preventiom,immunisation?

Answer 6

Treatment:

• Symptomatic: cleaning of nose & eyes
• Palliative AB therapy
• Eye: nucleoside analogues (iodoxuridine, ganciclovir, famciclovir), corticosteroid, L-lysine
• IV fluid therapy, pasty food, feeding tube, O2 therapy, hyperimmune serum
• High % of cats with both symptomatic & asymptomatic cases will survive

Prevention: immunisation

• Attenuated (intranasal) or inactivate vaccines
• Monovalent or combined (+FPV, FCaV, rabies, Chlamydia)
• Basic immunisation of kittens from the 7th week of age, possibly with monovalent vaccines
• Basic immunisation: 2x with 3-4 weeks difference; repeat yearly (or in 2-3 years) Don’t learn
• Usually low titres, but protect from the clinical disease (not from the infection)