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Basics ⬇

Basics

Definition

Causes an acute disease in domestic and many exotic species of cats, which is characterized by sneezing, fever, rhinitis, conjunctivitis, and ulcerative keratitis.

Pathophysiology

FHV-1-causes an acute cytolytic infection of respiratory or ocular epithelium after oral, intranasal, or conjunctival exposure. This intracellular virus travels from cell to cell and does not stimulate a strong immune response from the host.

Systems Affected

  • Integumentary-herpes dermatitis may occur near the nasal openings.
  • Ophthalmic-often conjunctivitis with serous or purulent ocular discharge; ulcerative keratitis or panophthalmitis can occur.
  • Reproductive-in utero infection owing to infection of pregnant queens may result in severe herpetic infections in neonates.
  • Respiratory-rhinitis with sneezing and serous to purulent nasal discharge; tracheitis may occur; chronic sinusitis may be a sequela.
  • Neurologic-latent virus found in optic nerve, ciliary ganglion, brainstem, cerebellum, and olfactory bulb.

Genetics

N/A

Incidence/Prevalence

  • Common, especially in multi-cat households or other facilities housing large numbers of cats, due to ease of transmission. Catteries and shelters are the source of most infections.

  • Perpetuated by latent carriers that harbor the virus in nerve ganglia, especially in the trigeminal ganglion.

Geographic Distribution

Found worldwide

Signalment

Species

Affects all domestic and many exotic cats.

Breed Predilections

  • None.
  • Brachycephalic breeds have more severe corneal disease and are more likely to have corneal sequestra.

Mean Age and Range

  • Cats of all ages
  • Kittens most susceptible

Predominant Sex

N/A

Signs

Historical Findings

  • Acute onset of paroxysmal sneezing.
  • Blepharospasm and ocular discharge.
  • Anorexia-from high fever, general malaise, or inability to smell.
  • Recurrent signs-carriers.
  • Abortion.

Physical Examination Findings

  • Fever-up to 106°F (41°C).
  • Rhinitis-serous, mucopurulent, or purulent nasal discharge.
  • Conjunctivitis-serous, mucopurulent, or purulent ocular discharge.
  • Chronic rhinitis/sinusitis-chronic purulent nasal discharge; presence of sinusitis cannot be determined without radiographs.
  • Keratitis-ulceration, descemetocele, or panophthalmitis.

Cause

FHV-1, of which there is only 1 serotype.

Risk Factors

  • Lack of vaccination for FHV-1 although vaccines do not bestow sterilizing immunity.
  • Multiple cat facilities with overcrowding, poor ventilation, poor sanitation, poor nutrition, or physical or psychological stress.
  • Pregnancy and lactation.
  • Concomitant disease, especially owing to immunosuppressive organisms or other respiratory organisms.
  • Kittens born to carrier queens-infected at about 5 weeks of age.

Diagnosis ⬆ ⬇

Diagnosis

Differential Diagnosis

  • Feline calicivirus infection-less sneezing, conjunctivitis, ulcerative keratitis; may cause ulcerative stomatitis, pneumonia.
  • Feline Chlamydophila infection-more chronic conjunctivitis, which may be unilateral; pneumonitis; intracytoplasmic inclusions in conjunctival scrapings; responds to tetracyclines or chloramphenicol.
  • Bacterial infection (Bordetella, Haemophilus, or Pasteurella)-less nasal and ocular involvement; often respond to antibiotics.

CBC/Biochemistry/Urinalysis

  • Not diagnostic.
  • Transient leukopenia followed by leukocytosis may occur.

Other Laboratory Tests

  • PCR testing from pharyngeal and conjunctival swabs will identify presence of the virus; more sensitive than other diagnostic modalities. May be transiently positive following MLV FHV-1 vaccination.
  • Immunofluorescent assay-nasal or conjunctival scrapings; viral detection.
  • Viral isolation-pharyngeal swab sample.
  • Stained conjunctival smears-detect intranuclear inclusion bodies.

Imaging

Radiography-open mouth ventrodorsal and rostrocaudal (skyline) views of the skull reveal presence of chronic disease in the nasal cavity and frontal sinuses; infection cannot be reliably distinguished from neoplasia and inflammatory polyps; no abnormal radiographic findings with acute disease. CT provides a more accurate assessment of disease in the nasal cavity and frontal sinus when compared to radiographs. In many cats, it can differentiate neoplasia from inflammation based on the amount of bony destruction.

Diagnostic Procedures

N/A

Pathologic Findings

  • Gross-ocular and nasal discharge; mucosal edema of upper airway epithelium; tracheitis; sinusitis; ulcerative keratitis; panophthalmitis.
  • Microscopic-submucosal edema; inflammatory cell infiltrates of upper respiratory and conjunctival tissues; chronic sinusitis; intranuclear inclusion bodies in epithelial cells.

Treatment ⬆ ⬇

Treatment

Appropriate Health Care

Inpatient-nutritional and fluid support to anorectic cats; prevent contagion.

Nursing Care

  • Outpatient-keep patient indoors to prevent environmentally induced stress, which may lengthen the course of the disease.
  • Fluids-intravenous or subcutaneous; to correct and prevent dehydration; to keep nasal secretions thin.

Activity

Isolate affected cats during the acute phase, because they are contagious.

Diet

  • Outpatient-entice food consumption to avoid anorexia, which induces a cascade of negative consequences; offer foods with appealing tastes and smells.
  • Inpatient-forced enteral feeding for anorectic cats; remove nasal secretions (so nasal breathing can occur) before starting orogastric tube feeding; avoid nasoesophageal tubes because of rhinitis.

Client Education

  • Inform client of the contagious nature of the disease.
  • Discuss proper vaccination protocols and early vaccination of cats in multi-cat facilities and households.
  • Inform client that early weaning and isolation from all other cats except littermates may prevent infections.

Surgical Considerations

Surgically implanted feeding tubes (esophagostomy tube, gastrostomy tube) may be needed when prolonged anorexia occurs.

Medications ⬆ ⬇

Medications

Drug(s) Of Choice

  • Broad-spectrum antibiotics-ampicillin (20–40 mg/kg PO q8h; 10–20 mg/kg IV, IM, SC q6–8h) or amoxicillin (10–40 mg/kg q8–12h PO, IM, SC) for secondary bacterial infections.
  • Antibiotic combinations-ampicillin or amoxicillin and a fluoroquinolone (enrofloxacin [2.5 mg/kg PO, IM, IV q12h], orbifloxacin [2.5–7.5 mg/kg PO q24h], marbofloxacin [2.75–5.55 mg/kg PO q24h]), pradofloxacin [7.5 mg/kg] for secondary bacterial infections.
  • Lysine-lactoferrin (500 mg PO q12h) more effective than lysine alone for treatment.
  • Lysine (500 mg PO q12h) may have some virucidal effect.
  • Ophthalmic antibiotics-for keratitis.
  • Ophthalmic antivirals in order of efficacy-trifluridine, cidofovir, idoxuridine, ganciclovir, aciclovir; for herpetic ulcers; must be instilled q2h for significant effect except for cidofovir which can be given q12h.
  • There is some evidence that administration of an intranasal vaccine 2–6 days prior to exposure will result in lessening of clinical signs. This may be helpful in an outbreak in a multi-cat setting.

Contraindications

  • Idoxuridine ophthalmic may be painful in some cats; discontinue medication.
  • Trifluridine, idoxuridine, acyclovir-toxic if given systemically.
  • Systemic corticosteroids-may induce relapse in chronically infected cats.
  • Ophthalmic corticosteroids-may predispose to ulcerative keratitis.
  • Nasal decongestant drops-0.25% oxymetazoline HCl; decrease nasal discharge; contraindicated because some cats object and some experience rebound rhinorrhea.

Precautions

Death is usually the result of inadequate nutritional and fluid support or immunosuppression due to FeLV or FIV.

Alternative Drug(s)

  • Penciclovir-effectively inhibits FHV-1, doses unknown at this time.
  • Famciclovir-early reports indicate efficacy at 15 mg/kg PO q8–12h.

Follow-Up ⬆ ⬇

Follow-Up

Patient Monitoring

Monitor appetite closely; hospitalize for forced enteral feeding if anorexia develops.

Prevention/Avoidance

Ammonia-based cleaners effectively kill the virus.

Vaccines

  • Routine vaccination with an MLV or inactivated virus vaccine-prevents development of severe disease; does not prevent infection and local viral replication with mild clinical disease and virus shedding.
  • Vaccinate at 8–10 weeks of age, at 12–14 weeks of age, and 16–18 weeks of age and with annual boosters for reasonable protection, especially in high-risk populations.
  • Endemic multi-cat facilities or households-vaccinate kittens with a dose of an intranasal vaccine at 10–14 days of age, then parenterally at 6, 10, and 14 weeks of age; isolate the litter from all other cats at 3–5 weeks of age; then use kitten vaccination protocol to prevent early infections.

Possible Complications

  • Chronic rhinitis or rhinosinusitis with long-term sneezing and nasal discharge.
  • Herpetic ulcerative keratitis.
  • Corneal sequestrum that must be removed surgically.
  • Permanent closure of the nasolacrimal duct with chronic ocular discharge.

Expected Course and Prognosis

  • Usually 7–10 days before spontaneous remission, if secondary bacterial infections do not occur.
  • Prognosis generally good, if fluid and nutritional therapy are adequate.
  • Correlation between severity of acute signs and degree of latent infection.

Miscellaneous ⬆

Miscellaneous

Associated Conditions

Simultaneous viral or bacterial respiratory diseases.

Age-Related Factors

More severe in young kittens

Zoonotic Potential

None

Pregnancy/Fertility/Breeding

Pregnant cats that develop disease may transmit FHV-1 to kittens in utero, resulting in abortion or neonatal disease.

Synonyms

  • Coryza
  • Feline Rhinotracheitis
  • Rhino

Abbreviations

  • FeLV = feline leukemia virus
  • FHV-1 = feline herpesvirus type 1
  • FIV = feline immunodeficiency virus
  • MLV = modified live virus
  • PCR = polymerase chain reaction

Suggested Reading

Gaskell RM, Dawson S, Radford A, et al. Feline herpesvirus. Vet Res 2007, 38(2):337–354.

Horzinek MC, Addie D, Sándor B, et al. ABCD: Update of the 2009 guidelines on prevention and management of feline infectious diseases. J Feline Med Surg 2013, 15:530–539.

Maggs DJ. Update on pathogenesis, diagnosis, and treatment of feline herpesvirus type 1. Clin Tech Small Anim Pract 2005, 20(2):94–101.

Malik R, Lessels NS, Webb S, et al. Treatment of feline herpesvirus-1 associated disease. J Feline Med Surg 2009, 11(1):40–48.

Thiry E, Addie D, Belak S, et al. Feline herpesvirus infection: ABCD guidelines on prevention and management. J Feline Med Surg 2009, 11(7):547–555.

Authors Gary D. Norsworthy and Lisa Restine

Consulting Editor Stephen C. Barr

Client Education Handout Available Online