JPC SYSTEMIC PATHOLOGY
Signalment (JPC #3048313): A pigeon
HISTOPATHOLOGIC DESCRIPTION: Proventriculus: Multifocally, compound tubular glands are markedly dilated, lined by attenuated epithelium and contain many cross sections of adult female nematodes, which compress adjacent atrophic glands (compression atrophy) and elevate the overlying mucosa. Nematodes are approximately 1.5 mm in diameter, have a 3 um cuticle and a pseudocoelom containing abundant homogenous brightly eosinophilic material; polymyarian/coelomyarian musculature; a digestive tract lined by many uninucleate cuboidal cells with a brush border containing abundant brown pigment; uteri containing numerous 25 x 50um, oval, thick shelled, embryonated eggs, and variably sized ovaries with ova. Occasionally, embryos within ova have visible polar filaments. Multifocally within the lamina propria of the primary ducts are several small aggregates of lymphocytes and rare heterophils. There is increased mucous production in the superficial mucosa.
Heart; esophagus; ventriculus; great vessel; and lung: Essentially normal tissue.
MORPHOLOGIC DIAGNOSIS: Proventriculus, tubular glands and lumen: Duct ectasia, multifocal, moderate, with compression atrophy and intraductal and intraluminal adult nematodes, etiology consistent with Tetrameres sp., pigeon (Columba livia), avian.
ETIOLOGIC DIAGNOSIS: Proventricular tetrameriasis
CAUSE: Tetrameres sp. (T. americana or T. fissispina)
- Proventricular spirurid of chickens, turkeys, many types of water fowl, grouse, pigeons, and quail
- These parasites have marked sexual dimorphism; males are small, white and filiform; females are large, blood red, and either spherical (globular in tissue section ‑ Tetrameres) or coiled (lobate in tissue section ‑ Microtetrameres)
- Females suck blood and cause moderate to severe irritation/inflammation in the proventriculus of some avian hosts
- Necrosis and degeneration of proventricular mucosa, edema, leukocytosis and extensive blood loss may occur
- Females live in the proventricular glands. Males live free in the lumen or on the mucosal surface and enter the glands only temporarily to copulate
- Tetrameres require an intermediate host (water crustaceans or insects (grasshopper, earthworms or cockroach))
- Embryonated eggs pass in feces > develop in intermediate host (grasshopper, cockroach) > eaten by a bird > infective larvae mature in the proventriculus
TYPICAL CLINICAL FINDINGS:
- Vary from no clinical signs to anemia, diarrhea, emaciation, and death depending on severity of infection and susceptibility of the host species
- Tetrameres americana causes no signs in bobwhite quail but can cause death in pigeons
TYPICAL GROSS FINDINGS:
- Bright red female worms are embedded in the proventricular glands and can be observed through the wall of the unopened gland
- Hyperplasia of the proventricular wall that can obliterate the lumen may occur in some hosts
TYPICAL LIGHT MICROSCOPIC FINDINGS:
- Distension of glands by female nematodes with compression of adjacent tissue
- Mucosal thickening with heavy infestation
- americana is usually associated with mild inflammation, while T. fissispina produces degeneration, edema and extensive leukocyte infiltration
- Nematode characteristics: Polymyarian/coelomyarian musculature; large stalked lateral cords; esophagus divided into anterior muscular and posterior glandular portions; large intestine lined by many uninucleate columnar to cuboidal cells with a prominent (long) microvillar border; distinguishing eosinophilic fluid in the pseudocoelom (feature of most Spirurids); and small thick-shelled embryonated eggs (characteristic of Spirurids)
ADDITIONAL DIAGNOSTIC TESTS:
- Demonstration on histology
- Fecal examination
For nematodes in proventriculus:
- Tetrameres sp.: Fat, spherical, blood-red worms in the wall of the proventriculus and that distend glands
- Microtetrameres sp.: Lobate, wide, coiled, blood red worms in the wall of the proventriculus ( helix: Russian and North American crows and pigeons)
- Cyrnea sp.: Spirurids, but lack the marked sexual dimorphism of the Tetramitidae; nonpathogenic; do not suck blood; do not attach to mucosa or live in glands
- pileata: Bobwhite quail
- colini: Various North American gallinaceous birds
- Dispharynx nasuta: Lives on the mucosa of the proventriculus, esophagus, and rarely intestines of various species of pigeons, chickens, turkeys, and guinea fowl worldwide; can cause severe ulceration with chronic diffuse fibrosis; most severe in young birds and the main cause of grouse disease in USA
- Echinuria uncinata: In esophagus, proventriculus, gizzard, and small intestine of the duck, goose, swan; penetrate deep into the mucosa forming large nodules with caseous centers, which can obstruct the passage of food
- Gongylonema ingluvicola: mucosa of the crop and sometimes the esophagus and proventriculus of chicken, turkey, partridge, pheasant and quail; burrows in the mucosa, which appear as white convoluted tracks
- Tetrameres americana: Chicken, quail, turkey, guinea fowl, pigeons, ducks, and geese; mainly USA and South Africa
- fissispina: Most common in ducks and geese; rare in pigeons, chickens, turkeys, and other birds; worldwide distribution
- crami: North American ducks
- pattersoni: Only in bobwhite quail
- Gardiner CH, Poynton SL. In: An atlas of metazoan parasites in animal tissues. Washington DC: Armed Forces Institute of Pathology; 1999:34.
- McDougald LR. In: Swayne DE, ed. Diseases of Poultry. 13th ed. Ames, IA: John Wiley & Sons; 2013:1131-1132.
- Schmidt GD, Roberts LS. In: Foundations of Parasitology. St. Louis, MO: Mosby; 1981: 501-511.
- Urquhart GM, Armour J, Duncan JL, Dunn AM, Jennings FW. In: Veterinary Parasitology. 2nd ed. Oxford, UK: Blackwell Science Limited; 1996:85.