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Lung Parasites 595

Lung Parasites
VetBooks.ir Diseases and Disorders

parenchymal diseases as well as in normal
BASIC INFORMATION
dogs. compatible radiographic findings. Confirmation
requires detecting the parasite and/or its egg in
Definition • Thoracic auscultation is usually unremarkable. specialized fecal exam or in respiratory samples.
Infestation of major airways or pulmonary ○ Wheezes or crackles can be heard in
parenchyma with parasites, including Oslerus severely affected animals. Differential Diagnosis
osleri, Paragonimus kellicotti, Eucoleus aerophilus, • Chronic bronchitis (p. 136)
Filaroides hirthi, Crenosoma vulpis, and Aelu- Etiology and Pathophysiology • Infectious tracheobronchitis
rostrongylus abstrusus • Parasitic pulmonary disease may be caused • Asthma
by LW and other parasites. • Pulmonary edema
Synonyms • Parasites of the pulmonary vasculature • Bacterial or fungal pneumonia
Lungworms (LWs), Oslerus osleri (formerly (Dirofilaria immitis [pp. 415 and 481]) and • Pulmonary metastatic disease
Filaroides osleri), Eucoleus aerophilus (formerly Angiostrongylus vasorum) cause pulmonary • Pneumothorax
Capillaria aerophila) pathology. • Pulmonary granulomatosis
• Intestinal worms Toxocara sp and Ancylostoma • Eosinophilic bronchopneumopathy (pulmo-
Epidemiology sp undergo pulmonary migration and with nary infiltrates with eosinophils, eosinophilic
SPECIES, AGE, SEX a large worm burden may cause verminous bronchitis)
• Dogs and cats pneumonia.
○ Dogs: O. osleri, E. aerophilus, P. kellicotti, • For LWs, the final destination is the respira- Initial Database
C. vulpis, and F. hirthi/milksi tory tract. Thoracic radiographic abnormalities reflect the
○ Cats: P. kellicotti, E. aerophilus, and A. O. osleri: causative organism:
abstrusus • Transmission: direct transmission (ingestion) • O. osleri: tracheal and bronchial nodules
• Clinical signs are most common in younger of larvae in regurgitated food, feces, or saliva • P. kellicotti
animals but can be seen in animals of any • Adults live in carina and mainstem bronchi ○ Solid or cavitary mass lesion, most com-
age. and cause local nodular inflammation and monly in the right caudal lobe
fibrosis. ○ ± Bulla
RISK FACTORS P. kellicotti: ○ Pneumothorax
• Dogs clinically affected by F. hirthi often are • Transmission: ingestion of crayfish intermedi- ○ Bronchial or interstitial lung pattern on
immunocompromised. ate host or paratenic host such as rodents radiographs
• Free-roaming animals and those not receiving • Adult flukes live in a subpleural cyst that • E. aerophilus: normal, or bronchial to
regular preventatives are at increased risk. communicates with a bronchus. bronchointerstitial pattern
• Ingestion of paratenic or intermediate hosts ○ Rupture of cyst/bulla in patients with P. • A. abstrusus: bronchial to diffuse miliary or
kellicotti can cause pneumothorax. nodular interstitial pattern most common
GEOGRAPHY AND SEASONALITY E. aerophilus: early; generalized alveolar pattern in severely
Geographic distribution and seasonality are • Transmission: direct transmission (ingestion) affected animals
parasite specific. P. kellicotti is most often of eggs in respiratory secretions or feces or • F. hirthi: nodular interstitial pattern or
found in the Southeast, Midwest, and Great by ingestion of earthworm intermediate host alveolar infiltrates
Lakes regions of the United States (snail and • Adults live in bronchial mucosa. • C. vulpis: normal to mild-moderate bronchial
crayfish are intermediate hosts). C. vulpis is F. hirthi, F. milksi: or interstitial pattern
highly prevalent in Atlantic Canada (red fox • Transmission: ingestion of larvae in feces CBC/serum biochemistry panel/urinalysis:
reservoir). • Adult worms live in lung parenchyma (alveoli typically unremarkable
and terminal airways) • Occasional eosinophilia, representing non-
ASSOCIATED DISORDERS • Severe infection most likely in young, small- specific parasitic infection or inflammation
• Eosinophilic pneumonia breed dogs, immunosuppressed dogs, or those from other causes
• Pneumothorax with superinfections.
• Cavitary lung disease A. abstrusus: Advanced or Confirmatory Testing
• Hemoptysis • Transmission: ingestion of snail or slug • Transtracheal/bronchial washes may demon-
• Bleeding diathesis intermediate host or paratenic host such as strate larvae or eggs (pp. 1073 and 1074).
• Respiratory distress (p. 879) birds and rodents • Bronchoscopy to identify nodules of O. osleri
• Adults live in terminal bronchioles, alveolar • Fecal exam may show eggs or larvae (insensi-
Clinical Presentation ducts, and alveoli. tive due to intermittent shedding)
HISTORY, CHIEF COMPLAINT • Important differential for asthma in endemic ○ Zinc sulfate flotation or Baermann tech-
• Can be an incidental finding areas (p. 84) nique is recommended for identification
• Cough C. vulpis: of ova or larvae, respectively, of O. osleri,
• Wheeze • Transmission: ingestion of snail or slug A. abstrusus, C. vulpis, and F. hirthi.
• Exercise intolerance intermediate host ○ Fecal flotations can identify E. aerophilus
• Respiratory distress may be noted with • Adults live in bronchi. ova.
pneumothorax or verminous pneumonia. ○ High-density fecal flotation or fecal sedi-
DIAGNOSIS mentation is preferred for identification
PHYSICAL EXAM FINDINGS of P. kellicotti ova.
• Cough elicited on tracheal palpation Diagnostic Overview • Use of nested polymerase chain reaction
(nonspecific finding): tracheal palpation Diagnosis is suspected based on age (typically (PCR) has been studied and may prove
may also elicit coughing in patients with young animals), signs of respiratory disease, helpful for diagnosis of A. abstrusus in cats
other tracheal, bronchial, or pulmonary exposure to paratenic or intermediate host, and (not routinely available).

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