Page 1096 - Cote clinical veterinary advisor dogs and cats 4th

546 Influenza, Canine

Epidemiology • Mucopurulent nasal discharge common infection or to rule out other cause of lung
SPECIES, AGE, SEX • Lethargy, fever, tachypnea and/or dyspnea, disease; neutrophilic infiltrate ± secondary
VetBooks.ir • Cats have also been infected with H3N2. pneumonia TREATMENT
bacteria
harsh lung sounds/crackles ± cyanosis: if
• Dogs of any age; often, vaccinated for
CIRDC pathogens other than CIV
GENETICS, BREED PREDISPOSITION Etiology and Pathophysiology Treatment Overview
• Incubation time is 1-5 days after exposure.
Any breed can be infected. Greyhounds have • Clinical signs generally last 2-4 weeks. Treatment consists of supportive care and
developed hemorrhagic pneumonia and sudden • Peak shedding (2-4 days after infection) may prevention/management of secondary bacte-
death from H3N8. occur before clinical signs begin. rial infections. If CIRDC (including CIV) is
• Although viral shedding may be shorter, dogs suspected, isolation from other dogs is crucial.
RISK FACTORS should be considered contagious for up to During outbreaks, coughing dogs may best
• High-density canine populations (e.g., board- 4 weeks (H3N2 > H3N8). undergo initial examination in the owner’s
ing kennels, shelters, grooming facilities, vehicle. Outpatient treatment is preferred unless
doggie day care, dog shows) DIAGNOSIS intensive treatment for pneumonia is required.
• Exposure to other dogs, especially during
regional outbreaks Diagnostic Overview Acute General Treatment
• Unvaccinated for CIV Onset of clinical signs after recent exposure • Maintain hydration (PO, SQ, or IV)
to high-density dog populations, especially • Antibacterial drugs have no effect on CIV
CONTAGION AND ZOONOSIS in endemic areas, is suggestive. Confirmation ○ If empirical treatment is deemed appro-
• Dog-to-dog transmission (spread through requires a positive polymerase chain reaction priate to address secondary bacterial
direct contact), fomites (e.g., humans, food (PCR) or positive CIV antibody titer. Because infection, empirical choices include
bowls, leashes), and aerosol transmission acute phase titer may be negative, paired doxycycline 5 mg/kg PO q 12h for 7-10
• H3N2: may be spread to cats samples should be taken at presentation and days, azithromycin 5-10 mg/kg PO q 24h
• H3N8 and H3N2: no reported zoonotic spread then 2-3 weeks later (convalescent phase). for 3-7 days, or cefovecin 8 mg/kg SC
• H1N1: undocumented reports of canine Combining paired serologic titers and PCR is once.
infection from contact with infected owners optimal. ○ Severe secondary bacterial pneumonia
• H7N2 (avian influenza): transmitted to cats is best guided by airway culture and
in New York and subsequently infected the Differential Diagnosis susceptibility using parenteral, bactericidal
attending veterinarian. CDC considers the Other CIRDC pathogens: drugs (p. 795).
risk to humans to be low. • Bordetella bronchiseptica • Antiviral therapy (e.g., oseltamivir [Tamiflu])
• Other type A influenza virus types (including • Canine parainfluenza virus is not approved for dogs, may promote
seasonal influenza): rarely are transmitted • Canine distemper virus emergence of resistant influenza strains,
from people to pets • Canine adenovirus 2 and is unlikely to be given to dogs quickly
• Canine herpesvirus enough to provide benefit (must be given
GEOGRAPHY AND SEASONALITY • Canine pneumovirus within 36 hours of exposure).
Confirmed CIV has occurred in numerous states • Canine respiratory corona virus • Severe pneumonia may require additional
with several hyperendemic foci that were identi- • Mycoplasma spp treatment.
fied in the Northeast, Midwest, western states, • Opportunistic bacterial pneumonia (Pas- ○ Nebulization and coupage q 6-8h (p.
and Florida. There is no seasonality but may teurella multocida, Klebsiella pneumoniae, 1134)
spread more rapidly during times of increased Escherichia coli, Streptococcus spp) ○ Oxygen supplementation if necessary
travel such as summer vacations or holidays. (p. 1146)
Initial Database
ASSOCIATED DISORDERS During confirmed outbreaks, complete diag- Chronic Treatment
• Bacterial pneumonia nostic testing may be omitted when history and See Bacterial Pneumonia (p. 795).
• Hemorrhagic pneumonia exam are highly suggestive of CIV, especially
where cost is a concern. Possible Complications
Clinical Presentation • CBC, serum biochemistry profile, urinalysis: Pneumonia, sepsis, pulmonary hemorrhage
DISEASE FORMS/SUBTYPES unremarkable, or neutrophilia ± immature
Three forms exist: neutrophils Recommended Monitoring
• Subclinical form: minimal/absent clinical • Thoracic radiographs: ± interstitial to alveolar • At home
signs (≈20% of exposed) pattern ○ Have owner monitor food and water
• Mild upper respiratory form: fever, cough, intake, hydration, membrane color, tem-
nasal discharge (most common) Advanced or Confirmatory Testing perature, and respiratory rate, and provide
• Severe form: as above, with signs of poten- • Serologic testing: commonly used parameters to prompt re-evaluation.
tially life-threatening pneumonia (≈5%-20%) ○ First sample drawn as soon as possible after • In hospital (pneumonia)
onset of clinical signs, second sample 2-3 ○ Repeat thoracic auscultation several times
HISTORY, CHIEF COMPLAINT weeks later daily
• Recent exposure to other dogs (especially ○ Fourfold increase in titer or seroconversion ○ Pulse oximetry or arterial blood gas
high density), endemic geographic area with is confirmatory. (A:a gradient, PaO 2 /FIO 2) if hypoxemia
history of outbreaks • PCR: nasal /pharyngeal swab samples to suspected
• Moist cough (productive or nonproductive), reference laboratory; specific but sensitivity ○ Thoracic radiographs if clinical deterioration
nasal discharge, lethargy, fever, anorexia, depends on disease stage (best early)
depression, and tachypnea/dyspnea • Influenza A ELISA: less sensitive than PCR PROGNOSIS & OUTCOME
but can be done as point-of-care test
PHYSICAL EXAM FINDINGS • Virus isolation: most often used at necropsy • Good with supportive care and antibacterial
• Soft, moist paroxysmal cough (can be a (affected lung) therapy
dry cough, indistinguishable from mild • Airway culture/susceptibility (p. 1073): typi- • Morbidity ≈80%
tracheitis); most consistent finding cally done to characterize secondary bacterial • Mortality 1%-5% (severe form: pneumonia)
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