Respiratory System

September 2017



Signalment (AFIP #1639870): Dogs, age and breed unspecified

HISTORY: Tissue taken from two dogs with chronic coughs


Slide P14a: Lung: 

Diffusely throughout the section bronchi, bronchiolar and alveolar lumina contain tangential and cross-sections of adult nematodes that are characterized by: 100 um diameter, thin cuticle, coelomyarian musculature, a large intestine lined by a few multinucleated cells and that often contains golden-brown granules and reproductive tracts with developing larvae or sperm. Airway lumina are also filled with plasma cells, lymphocytes, eosinophils, macrophages, including multinucleated cells (foreign body or Langhans type) and hemosiderin laden macrophages, and neutrophils admixed with small amounts of fibrin, hemorrhage and karyorrhectic and cellular debris (necrosis) and rare nematode larvae that are 20-30 um in diameter, eosinophilic with many basophilic nuclei and a tapered end.  Alveolar septa are mildly expanded by lymphocytes, macrophages, fibrin and edema.   

MORPHOLOGIC DIAGNOSIS: Lung: Pneumonia, pyogranulomatous and eosinophilic, diffuse, severe with intraalveolar, intrabronchiolar, and intrabronchial adult and larval metastrongyle nematodes etiology consistent with Andersonstrongylus milksi, breed not specified, canine

Signalment (AFIP #1371567): A dog, age and breed unspecified



Slide P14b: Trachea and peritracheal tissue.

Diffusely infiltrating the tracheal submucosa, forming nodules in peritracheal tissue and extending into adjacent adipose tissue and skeletal muscle are eosinophils, lymphocytes, plasma cells, with fewer histiocytes and neutrophils, admixed with fibrin, edema, and hemorrhage which are multifocally centered on tangential and cross sections of adult nematodes.  Nematodes are present within lymphatics and characterized by:  a 4um thick cuticle, coelomyarian musculature, a pseudocoelom, an intestinal tract lined by few multinucleated cells, and a reproductive tract that either contains developing larvae or sperm.  There is multifocal attenuation, erosion and ulceration of the tracheal epithelium. 

Tracheobronchial lymph node: The subcapsular and medullary sinuses contain few to moderate numbers of eosinophils and few neutrophils and histiocytes with fibrin, hemorrhage and erythrophagocytosis.

MORPHOLOGIC DIAGNOSIS: 1. Trachea: Tracheitis and peritracheitis, lymphoplasmacytic and eosinophilic, diffuse, moderate, with submucosal and peritracheal, intralymphatic adult nematodes etiology consistent with Oslerus osleri, and tracheal ulceration, breed not specified, canine

1. Lymph node, tracheobronchial: Draining eosinophilic inflammation and sinus hemorrhage, acute, diffuse.

Signalment:  Adult female red panda

HISTORY:  A captive-born panda presented for evaluation of dyspnea and thin body condition.  She arrested while being anesthetized for radiographs. 


Slide P14c:  Lung

Multifocally bronchiolar and bronchi lumina contain cross and tangential sections of adult nematodes characterized by: 350 - 400 um diameter, a thin cuticle, coelomyarian musculature, a prominent digestive tract lined by a few multinucleated cells, a reproductive tract containing larvae or clusters of eosinophilic sperm.  Larvae (10-15 um in length, eosinophilic with a basophilic granular interior) are rarely noted within airway lumina.  Multifocally, the lumina of bronchi and bronchioles are filled with a dense cellular exudate composed of degenerate and non-degenerate neutrophils, eosinophils, macrophages and fewer numbers of plasma cells and lymphocytes admixed with necrotic karyorrhectic and cellular debris, fibrin (eosinophilic fibrillar material), scattered foci of mineralization, a few sloughed epithelial cells and hemorrhage.  The peri-bronchiolar and peri-bronchiole connective tissue is moderately expanded by the previously described inflammatory cells, fibrin and edema; the respiratory epithelium is moderately hyperplastic. Multifocally, alveolar lumina contain hemorrhage and fibrin; rare aggregates of pigment laden macrophages (hemosiderin, anthracosilicosis). Alveolar septa are multifocally discontinuous, suggestive of emphysema. There is perivascular edema.

MORPHOLOGIC DIAGNOSIS:  1. Lung:  Bronchitis and bronchiolitis, eosinophilic and pyogranulomatous, chronic, multifocal, severe with epithelial hyperplasia, emphysema, hemorrhage and numerous intraluminal nematodes consistent with Crenosoma spp.

ETIOLOGIC DIAGNOSES: Metastrongylid pneumonia, bronchitis and tracheitis

CAUSE:  Lung (dog): Andersonstrongylus milksi (aka, Angiostrongylus milksi, Filaroides milksi); Trachea (dog): Oslerus osleri (previously Filaroides osleri)

Lung (red panda):  Crenosoma vulpis





Gray-tan or black-green, 1-5 mm diameter nodules scattered widely in subpleural regions of the lung; may have clear cystic center or be white and firm

Single or multiple 1-10 mm diameter, firm, gray-pink, sessile submucosal nodules in trachea and bronchi, tracheal bifurcation; coiled worms are visible through the intact overlying mucosa

Grey consolidation of caudaldorsal lung; adult worms live in bronchioles and small bronchi.




  1. Lung parasites
  1. Tracheal parasites of dogs


COMPARATIVE PATHOLOGY (not comprehensive):



 Site of adult


Eucoleus aerophila, Spirocerca lupi

Trachea, bronchi


Eucoleus (capillaria) boehmi

Nasal cavity - rare


Angiostrongylus vasorum

Pulmonary arteries


Oslerus osleri

Trachea, bronchi


Dirofilaria immitis (filarid)

Pulmonary artery


Filaroides hirthi, Andersonstrongylus milksi

Bronchi, bronchioles, alveoli


Linguatula serrata (pentastome)

Nasal passages


Crenosoma vulpis

Bronchi and bronchioles


Eucoleus aerophila, Filaroides rostratus

Trachea, bronchi


Aelurostrongylus abstrussus

Bronchioles, alveolar ducts


Paragonamus kellicoti (fluke)

 In inflammatory cavitations


Dictyocaulus viviparous

Large bronchi

Sheep, Goat

Dictyocaulus filaria

Bronchi, bronchioles


Protostrongylus rufescens



Muellerius capillaris



Cystocaulus ocreatus

Alveoli & small bronchioles


Oestrus ovis (bot)

Nasal cavity

Horse, Donkey

Dictyocaulus arnfieldi

Bronchi, bronchioles


Metastrongylus apri; M. salmi,

Bronchi, bronchioles


Filaroides and Filariopsis

Bronchioles à alveoli


Syngamus trachea




  1. Caswell JL, Williams KJ. Respiratory system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. 6th ed. St. Louis, MO; Elsevier; 2016:585-587.
  2. Gardiner CH, Poynton SL. An Atlas of Metazoan Parasites in Animal Tissues. Washington, DC: Armed Forces Institute of Pathology; 2006:27.
  3. Lopez A, Martinson SA. Respiratory System, Mediastinum, and Pleurae. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017:548.
  4. Strait K, Else J, Eberhard ML. Parasitic disease of nonhuman primates. In: Abee CR, Mansfield K, Tardiff S, Morris T, eds.  Nonhuman primates in biomedical research: Diseases.  Waltham, MA: Academic Press, 2012: 224-229.
  5. Kollias GV, Fernandez-Moran J. Mustelidae. In: Miller RE, Fowler ME, eds.  Fowler’s Zoo and Wild Animal Medicine.St. Louis, MO: Elsevier, 2015: 486. 



Click the slide to view.

Click on image for diagnostic series.

Back | Home | Contact Us | Links | Help |