Page 338 - Clinical Small Animal Internal Medicine

306 Section 4 Respiratory Disease

VetBooks.ir Box 31.1 Common differential diagnoses for CCB Box 31.2 Recommended laboratory tests
Complete blood cell count (CBC)
Bacterial pneumonia – Escherichia coli, Klebsiella,
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Pasteurella, Pseudomonas sp., Streptococcus, and
Urinalysis
Staphylococcus are commonly associated with pneu- ● ● Biochemistry profile
monia in dogs. ● Heartworm antigen test
Canine infectious respiratory disease complex – Bordetella Fecal Baermann and flotation
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bronchiseptica, canine influenza, Mycoplasma, etc. ● NT pro‐BNP
Congestive heart failure
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Fungal pneumonia – histoplasmosis, blastomycosis,
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and coccidiomycosis. reverse sneezing or other upper airway noises that may
Interstitial lung disease. be mistaken for a cough. Whether a cough can or cannot
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Parasitic pneumonia – Aelurostrongylus sp., Capillaria be produced during physical examination, a descriptive
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aerophila, Crenosomavulpis, Filaroides hirthi, and history should be gathered from the owners – is it dry or
Paragonimus kellicotti. Oslerus osleri can result in productive, paroxysmal or intermittent, is there a rela-
coughing, but is found in the trachea rather than the tion to eating or certain activities, does it occur at spe-
lower airways. Dirofilaria immitis (heartworm disease) cific times during the day/night, has there been any voice
also results in cough. change or reluctance to bark? Some dogs may have syn-
Pleural effusion. copal events associated with coughing. This is known as
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Protozoal infections – Neospora caninum and the cough‐drop syndrome, which is most likely associ-
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Toxoplasma gondii. ated with high vagal tone.
Pulmonary neoplasia.
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Tracheal collapse.
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Upper airway dysfunction (laryngeal paralysis). Diagnosis
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Diagnostic evaluation should be tailored to the individ-
attention should be focused on investigating their ual patient, and prioritized with regard to clinical assess-
systemic illness. Questions about weight loss, anorexia, ment and history.
lethargy, and other behavior changes could lead to the Recommended laboratory tests can be found in
detection of a systemic illness. A clinical history should Box 31.2. These diagnostic evaluations are typically nor-
also include questions that discuss potential exposure to mal in patients with CCB but they assist with the general
passive (second‐hand) smoke, the presence of excessive assessment of the patient’s health. A CBC may be sugges-
environmental odors/perfumes, and prior prescriptions tive of an infectious component to the cough, while
or home remedies and their clinical effect on the cough. appropriate fecal evaluation may lead to the identifica-
Physical examination of most patients with CCB is rela- tion of lungworm larva or eggs, and a NT‐proBNP has
tively unremarkable. Patients tend to be systemically well, been shown to be useful in the identification of left atrial
with the only major clinical sign being coughing. Patients enlargement/congestive heart failure.
are often seen due to an acute exacerbation in their cough- Thoracic radiographs are essential in the evaluation of
ing secondary to exposure to environmental irritants or a coughing dog. In patients where diagnostic testing is
allergens, secondary development of a bacterial infection, limited, thoracic radiographs have been shown to be the
or the unveiling of an unrelated concurrent disease. Some most useful test. Patients with CCB may show findings
dogs will present with tachypnea or increased expiratory consistent with bronchial thickening, evidenced by
effort (labored breathing). Physical examination should increased “donuts and tramlines” (Figure 31.1). Additional
focus on the cardiopulmonary system and signs of sys- findings consistent with CCB include hyperinflation
temic illness (weight loss or gain, anorexia, lethargy, etc.). and bronchiectasis. Although radiographs are relatively
Careful auscultation of the lungs can provide clues to lower insensitive for the diagnosis of CCB, they provide the
airway disease, and the presence or absence of a murmur benefit of assisting with the exclusion of other conditions
should be noted. Although heart disease and CCB can co‐ that result in coughing, such as cardiomegaly, lung
exist, the presence of a sinus arrhythmia supports the air- masses, pleural effusion, and interstitial lung disease. It is
way/pulmonary system as the primary cause of coughing. important to remember that normal chest radiographs do
Sometimes a cough can be elicited with palpation of not exclude a diagnosis of CCB.
the trachea due to nonspecific inflammation of the air- Fluoroscopy may be useful in evaluation for tracheal
ways. This may assist with characterization of the cough and bronchial collapse, but does not typically provide
by the clinician and exclude other conditions such as benefit for evaluation of chronic cough unless concurrent