Page 1976 - Cote clinical veterinary advisor dogs and cats 4th

988 Tracheobronchitis, Infectious (Dog)

RISK FACTORS pneumovirus, canine respiratory coronavirus • Multiple animals should be tested as early
• Unvaccinated status: higher incidence and (CRCV), Mycoplasma spp, Streptococcus equi in the course of illness as possible. Testing
VetBooks.ir • Exposure to infected dogs canine distemper virus (CDV [p. 271]). is ideal. Because secondary pathogens are
infections are more severe
subsp zooepidemicus, pneumovirus, and
3-5 dogs, or 10%-30% of affected animals,
Recently identified canine hepacivirus and
common and false-negatives occur, testing
• Higher prevalence in group housing or
multi-dog settings
CIRDC.
• Stress and crowded conditions increase risk canine bocavirus may also contribute to multiple dogs allows detection of the
common denominator of infected dogs.
of disease. ○ The most frequently identified pathogens • Timing of collection of samples is crucial.
differ with locality and vaccination status; For example, CIV is shed early in the course
CONTAGION AND ZOONOSIS B. bronchiseptica* and Mycoplasma spp are of the disease before clinical signs, and even
• Highly contagious among dogs; some the most commonly identified bacterial a few days’ delay in testing can give false-
pathogens (e.g., Bordetella bronchiseptica) culprits; CRCV, CPIV*, pneumovirus, negative results.
may also be contagious to cats. and CAV-2* are common viral pathogens • False-positive PCR results can occur if modi-
• Immunocompromised people or those with (*vaccine-preventable). fied live vaccines have been given recently.
respiratory disease are at a small risk from ○ Depending on infectious agent, transmis- Some laboratories can help differentiate
some but not all involved pathogens. sion occurs through direct contact, aerosol, vaccination from infection.
• Incubation periods are variable, depending fomite, or oral/fecal route. • Mycoplasma spp are difficult to grow in
on which pathogens are involved (2 days culture; PCR offers a more sensitive means
for influenza, up to 6 weeks for distemper DIAGNOSIS of detection.
virus). • Contact the laboratory before sample col-
• All CIRDC pathogens can be shed before Diagnostic Overview lection for methodologic details. PCR tests
clinical signs are apparent (i.e., dogs may be Presumptive diagnosis is made on history are susceptible to contamination and error;
contagious before they become ill). Shedding (exposure, vaccination status) and clinical use only laboratories with stringent quality
typically lasts 7 days but is variable with each signs. Similar illness in multiple exposed dogs control.
infective agent, and some may be shed for greatly strengthens clinical suspicion of CIRDC.
months (e.g., Bordetella, distemper). For an individual pet, diagnostic tests may TREATMENT
be performed to exclude other, more serious
ASSOCIATED DISORDERS disorders, leaving infectious tracheobronchitis Treatment Overview
Secondary bacterial pneumonia as a diagnosis of exclusion. In complicated cases • For uncomplicated disease, the goal of treat-
or during outbreaks (e.g., boarding facilities, ment is cough suppression and prevention
Clinical Presentation animal shelters), tests may be indicated to of secondary infection; the cough resolves
DISEASE FORMS/SUBTYPES identify specific pathogens. spontaneously (7-14 days).
• Most illnesses are characterized by coughing, • For dogs with pneumonia, the goals are to
sneezing, and mild oculonasal discharge. Differential Diagnosis identify and eradicate any causative bacteria,
Lethargy and decreased appetite may be Acute cough: aspiration pneumonia, airway maintain oxygenation and respiratory epi-
noted. foreign body, heartworm disease, congestive thelial health, and provide supportive care.
• Unvaccinated dogs (especially puppies) or heart failure, noncardiogenic pulmonary edema,
immunodeficient dogs may develop severe pulmonary thromboembolism, exacerbation Acute General Treatment
systemic disease with pneumonia. of chronic condition such as collapsing For dogs with uncomplicated disease, at home
trachea care is preferred.
HISTORY, CHIEF COMPLAINT • Antitussives (contraindicated in pneumonia)
• Usually, history of recent exposure to groups Initial Database ○ Hydrocodone 0.2-0.5 mg/kg PO q 6-12h
of unfamiliar dogs (e.g., animal shelter, • For dogs with a simple cough, presump- prn
boarding, groomer, dog show) tive diagnosis based on history and exam is ○ Butorphanol 0.5-1 mg/kg PO, SQ, or IM
• Cough ranges from soft and moist to deep sufficient. q 6-12h prn
and hacking, often followed by terminal • For dogs with suspected pneumonia ○ Dextromethorphan (available in over-
retch (may be misinterpreted by client as ○ CBC: normal, or neutrophilic leukocytosis the-counter human cough suppressants)
vomiting). ± left shift, lymphopenia 1-2 mg/kg PO q 6-8h. Warn owners
• Owners often think the dog has “something ○ Serum chemistry panel and urinalysis: to avoid products that contain other
stuck in its throat.” assess systemic health; often normal ingredients such as antihistamines and
• Signs of pneumonia (p. 795) ○ Thoracic radiographs: normal or diffuse, decongestants.
unstructured interstitial pattern (viral • Antimicrobial therapy is usually not required.
PHYSICAL EXAM FINDINGS pneumonia), or focal or diffuse alveolar If it is to be given due to concern regarding
• Common: serous to mucoid nasal discharge; pattern (bacterial pneumonia), hyperin- secondary infection or early/mild pneumonia,
ocular discharge with possible conjunctivitis; flation or atelectasis, or complete lobar make reasonable empirical choices:
easily elicited or spontaneous cough (produc- consolidation ○ Doxycycline or minocycline 5-10 mg/kg
tive or dry, often harsh and hacking) ○ Airway lavage (p. 1073; fluid analysis; PO q 12h
• Pneumonia: depression; harsh lung sounds culture and susceptibility): neutrophilic ○ Amoxicillin/clavulanic acid 12-25 mg/kg
with or without crackles and wheeze; inflammation ± bacteria PO q 8-12h
tachypnea ± fever, dyspnea, and/or cyanosis ○ Oxygenation assessment ○ Azithromycin 5-10 mg/kg PO q 12-24h
For dogs with pneumonia, hospitalization in
Etiology and Pathophysiology Advanced or Confirmatory Testing isolation from other dogs may be required
• Usually, the multi-etiologic disease involves Identification of specific pathogens during an depending on disease severity. Infection is highly
one or more agents: B. bronchiseptica (p. outbreak can be useful to guide preventive contagious, and strict biosecurity is essential.
125), canine parainfluenza virus (CPIV), measures. Polymerase chain reaction (PCR) • Antibiotic selection should be based on
canine adenovirus 2 (CAV-2), canine testing with a CIRDC panel from nasal or culture and sensitivity (C&S) results (p. 795).
influenza virus (CIV, H3N2, H3N8 [p. pharyngeal swabs may be the most cost-effective • Further therapy, including oxygen supple-
545]), canine herpesvirus (CHV), canine and least invasive testing method. mentation (p. 1146), bronchodilators, aerosol

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