JPC SYSTEMIC PATHOLOGY

RESPIRATORY SYSTEM

September 2017

P-P11

 

Signalment (JPC #1897187):  Adult male goat.

HISTORY:  Unknown. 

HISTOPATHOLOGIC DESCRIPTION:  Lung:  Multifocally, randomly, affecting approximately 1/3 of the section bronchi, bronchiole and alveolar lumina contain nematode eggs and larvae. Within alveoli there are fewer adult nematodes. Multifocally within both small and large airways, admixed with nematodes, there is abundant mucous and low numbers of macrophages, multinucleated giant cells and fewer neutrophils; additionally, alveolar lumina contain variable amounts of fibrin, hemorrhage and necrotic debris. Adult nematodes are 50-75 um in diameter, have a thin smooth hyaline cuticle, occasional cuticular ridges, polymyarian-coelomyarian musculature, lateral cords, a pseudocoelom containing an intestine lined by few multinucleate cells and tubular reproductive organs containing ova or spermatozoa.  Larvae measure 100 X 15 um and have a 1-2 um thick smooth eosinophilic cuticle and a thin posterior tip.  Embryonated eggs are ovoid, measure 40 X 60 um, have an indiscernible shell, and contain multiple 8 um diameter blastomeres.  Affected alveolar septa are infiltrated and thickened up to 5x normal by macrophages, fewer lymphocytes and plasma cells, occasional eosinophils, and small amounts of eosinophilic beaded or fibrillar material (fibrin) and edema. Areas of infiltration often coalesce to form more solid nodules which may contain nematodes.  Multifocally there is epithelial and goblet cell hyperplasia within bronchioles and bronchi, characterized by thickening of epithelium with loss of polarity of epithelial cells.  There is occasional peribronchiolar smooth muscle hypertrophy.  Rarely, within the alveoli or interstitium, there is basophilic granular mineral. There is peribronchiolar lymphoid hyperplasia.

MORPHOLOGIC DIAGNOSIS:  Lung:  Pneumonia, interstitial, granulomatous and eosinophilic, multifocal, moderate, with nematode adults, larvae, and eggs, etiology consistent with Muellerius capillaris, breed unspecified, caprine.

ETIOLOGIC DIAGNOSIS:  Pulmonary muelleriasis

CAUSEMuellerius capillaris

GENERAL DISCUSSION: 

PATHOGENESIS:

LIFE CYCLE

Indirect:  Eggs are deposited by adults within nodules in lung ->  L1 larvae emerge from nodules into airways and move via mucociliary escalator to pharynx-> swallowed and passed in feces -> L1 larvae penetrate the foot of the intermediate host (snail or slug) -> develop to L2, then to L3 in 2-3 weeks -> definitive host ingests intermediate host ->  L3 are freed by digestion and migrate to the lungs via the lymphatic system; larvae molt into adult worms -> break out into the alveolar spaces, and induce granulomatous nodules, particularly in subpleural locations

TYPICAL CLINICAL FINDINGS:

Non-specific: cough, moderate dyspnea, and loss of condition

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

ADDITIONAL DIAGNOSTIC TESTS:

Baerman apparatus for fecal examination (larvae in fresh feces) and post‑mortem

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY:
Lungworms of domestic species:

REFERENCES: 

  1. Bowman DD. Georgi’s Parasitology for Veterinarians. 10th ed. St. Louis, MO: Saunders; 2014:185, 296.
  2. Caswell JL, Williams KJ. The Respiratory System. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol. 2. 6th ed. Philadelphia, PA: Elsevier Saunders; 2016:565-566.
  3. Constable PD, Hinchcliff KW, Done SH, Grunberg W. Veterinary Medicine: A textbook of the diseases of cattle, horses, sheep, pigs, and goats. 11th ed. New York, NY: Saunders Elsevier; 2017:980-981.
  4. Ezenwa VO, Hines AM, Archie EA, et al. Muellerius capillaris dominates the lungworm community of bighorn sheep at the national bison ridge, Montana. Journal of Wildlife Diseases. 2010; 46(3): 988-993.
  5. Foreyt WJ, Jenkins EJ, Appleyard GD. Transmission of lungworms (Muellerius capillaris) from domestic goats to bighorn sheep on common pasture. Journal of Wildlife Diseases. 2009; 45(2): 272-278.
  6. Lopez A, Martinson SA. Respiratory System, Mediastinum and pleurae. In: McGavin MD, Zachary JF, eds. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO; 2016:539-540.
  7. Soulsby EJL. Helminths, Arthropods and Protozoa of Domesticated Animals. 7th ed. Philadelphia, PA: Lea & Febiger; 1982:262-283.
  8. Urquhart GM, Armour J, Duncan JL, Dunn AM, Jennings FW. Veterinary Parasitology. 2nd ed. Cambridge, MA: Blackwell Science Ltd; 1996:59-60.

 

Cudd 2017


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