Chapter 11 Feline Infectious Respiratory Disease
ETIOLOGY
Viruses
Most infectious upper respiratory disease in cats is caused by these two highly contagious viruses:
TRANSMISSION
Routes of Infection
• Fomites: These etiologic agents can survive and remain infectious on fomites such as contaminated cages, examination tables, food and water dishes, and human hands and clothing.
Subclinical Carriers as Sources of Infection
Feline Herpes Virus
• In recovered carriers, FHV persists lifelong in a latent form in the trigeminal ganglia and other tissues. Carriers may shed the virus intermittently coinciding with reactivation of latent virus infection. Recrudescence of shedding and clinical signs in latent FHV carriers can be triggered by stress, parturition, lactation, or glucocorticoids.
Feline Calicivirus
• Recovered FCV carriers shed the infectious virus from the oropharynx continuously for many months and sometimes years. Subclinical carriers are prevalent. Isolation rates of FCV from healthy cat populations are 5% to 10% for pet cats, 20% for show cats, and 40% for colony cats.
• FCV is highly resistant with survival outside the host of 8 to 10 days, causing a high risk of fomite transmission.
Chlamydophila felis
• Primarily shed from conjunctival secretions; prolonged shedding up to 18 months has been documented after experimental infections
CLINICAL SIGNS
Typical clinical signs of feline URI are sudden onset of anorexia, depression, fever, and naso-ocular discharge. Other signs specific to each etiologic agent are detailed in the following sections. Illness is more severe in young kittens and milder in previously vaccinated cats. Clinical disease caused by FHV and FCV is usually self-limiting within 5 to 10 days; however, some cats take 3 weeks to recover. See Table 11-1 for a comparison of the clinical manifestations of FHV and FCV.
Table 11-1 CLINICAL MANIFESTATIONS OF FELINE VIRAL RESPIRATORY DISEASE
| Manifestation | Feline Herpesvirus (FHV-1) | Feline Calicivirus (FCV) |
|---|---|---|
| Incubation | 2–6 days | 1–5 days |
| Duration | 5–10 days (rarely to 3 weeks) | 5–7 days (rarely to 2 weeks) |
| Anorexia, depression | Severe and frequent | Mild and inconsistent |
| Fever | Frequent | Inconsistent (diphasic) |
| Nasal signs | Sneezing—severe | Sneezing—mild |
| Discharge—marked | Discharge—mild or absent | |
| Ulcerated nares | Ulcerated tip of nose | |
| Turbinate necrosis | ||
| Sequelae—chronic rhinosinusitis, nasopharyngeal stenosis | ||
| Ocular signs | Conjunctivitis—severe (serous to mucopurulent discharge, chemosis, photophobia) | Conjunctivitis—mild |
| Ulcerative keratitis | ||
| Panophthalmitis (neonates) | ||
| Sequelae—sicca, corneal sequestrum | ||
| Oral signs | Hypersalivation, rare ulcers | Frequent oral ulcers (tongue, palate) |
| Sequelae—chronic stomatitis, gingivitis, faucitis | ||
| Pulmonary signs | Rare bacterial pneumonia | Occasional viral pneumonia |
| Other signs | Abortion | Limping syndrome (arthritis, arthralgia, myalgia) |
| Peracute neonatal death (hepatic necrosis) | Interdigital paw ulcers | |
| Ulcerative dermatitis | Enteritis (diarrhea and vomiting) | |
| Acute hemorrhagic fever syndrome | ||
| Postrecovery carrier | Lifelong | Months to years |
| Shedding pattern | Intermittent (after stress; lasts 1–2 wks) | Persistent |
Feline Herpesvirus
• FHV has an affinity for conjunctival, nasal, and upper airway (laryngotracheal) epithelium. Multifocal epithelial necrosis at these sites causes rhinitis, tracheitis, laryngitis, and conjunctivitis. FHV can also cause nasal turbinate necrosis and osteolysis.
• Signs include sneezing, lacrimation, serous to mucopurulent naso-ocular discharge, cough, hypersalivation, and loss of voice.
• Corneal involvement causes keratitis and herpetic ulcers. Ulcers can have a punctate, oval, or branching (dendritic) pattern (see Chapter 134).
• Infection during pregnancy may result in abortion or in a severe generalized form of infection in newborn kittens, characterized by fatal encephalitis or focal necrotizing hepatitis. Neonates also may develop panophthalmitis (ophthalmia neonatorum) that can permanently damage the eyes.
• Secondary bacterial complication of the lesions may worsen and prolong FHV disease. Bacterial pneumonia is a serious complication in young kittens.
• Extensive turbinate damage may lead to fibrosis and stenosis of the nasal passages and predispose the patient to chronic rhinitis.
Feline Calicivirus
FCV Respiratory Disease
• Infection is manifested most often as oral ulceration (tongue, palate, and fauces), mild rhinitis (sneezing), and conjunctivitis. Oral ulcers begin as vesicles that subsequently rupture and ulcerate. In some cats, the tip of the nose may be ulcerated and crusted.
Other FCV Syndromes
• One FCV isolate reportedly causes consistent footpad and interdigital ulcers along with oral ulcers (“paw and mouth disease”).
• FCV has been isolated from cats with chronic ulcerative or proliferative lymphocytic gingivitis, stomatitis, and faucitis. This may be a hypersensitivity response to persistent FCV infection, but the role of FCV in chronic oral disease is uncertain.
• Some FCV strains cause acute synovitis, fever, and joint pain (arthralgia and myalgia), with or without concurrent respiratory signs.
• FCV has been isolated from the urine of cats with lower urinary tract disease, but a causative role has not been established.
Acute Hemorrhagic Fever Syndrome
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
