a feral domestic shorthair cat was euthanized owing to acute onset and progression of neurological signs attributed to ethylene glycol toxicity . at post - mortem examination examination of the gastric nodules revealed an intact mucosal surface , each with multiple red slender nematodes extending through an individual central pore . histopathological evaluation of the nodules highlighted unique reactive fibroplasia , mimicking feline gastrointestinal eosinophilic sclerosing fibroplasia ( fgesf ) , encasing numerous nematodes with females possessing gravid uteri containing abundant larvated eggs . the latter findings were highly suggestive of the cylicospirura genus , further supported by an en face evaluation of the buccal cavity , highlighting a distinctive trifid tooth appearance . pcr for the cox-1 gene was unsuccessful on formalin - fixed specimens , attributed to nucleic acid and protein crosslinking . this represents the first documented case of cylicospirura species in a feral domestic shorthair cat in north america . identification of this case demonstrates the potential for feral cats to serve as reservoir hosts and ultimately support transmission of cylicospirura species into domesticated cat populations . gastric cylicospiruriasis may present clinically as a firm abdominal mass , potentially with a history of chronic vomiting . the latter emphasizes the importance of differentiating this condition from a neoplastic process such as alimentary lymphoma and adenocarcinoma . histologically , the unique thick anastomosing collagenous cords encasing nematodes represent a stereotypical response observed in a broad array of gastrointestinal inflammation in felines , including intralesional bacteria , fungal hyphae , foreign bodies and , in this case , gastric nematodes that closely resemble fgesf . additionally , these unique histological lesions have previously been misinterpreted as neoplastic conditions , including sclerosing mast cell tumor and extraosseous osteosarcoma . cylicospirura is within the family spiruroidea , which also includes physaloptera species , spirocerca lupi and cyathospirura species . these all are believed to have arthropod intermediate hosts with thick - shelled larvated eggs or a paratenic vertebrate host . owing to its unique histologic appearance , eckstrand et al proposed the term verminous alimentary sclerosing fibroplasia ( vasf ) for gastrointestinal cylicospiruriasis . unlike lupi , cylicospirura species nodules have not been shown to progress to neoplasms . in this particular case an adult neutered feral domestic shorthair feline of unknown age was humanely euthanized owing to the acute and progressive neurologic signs ultimately attributed to ethylene glycol toxicity , with gastric cylicospiruriasis representing an incidental finding . however , in wild felids , chronic vomiting , weight loss and intestinal perforation have been attributed to cylicospirura species infection . currently , no data have been published with regard to available efficacious anthelmintic treatments for cylicospirura species . the unique stromal reaction surrounding the gastric nematodes resembles feline gastrointestinal eosinophilic sclerosing fibroplasia ( fgesf ) , which , owing to the presence of large numbers of mast cells and the sclerotic appearance of collagen trabeculae , may be misdiagnosed as sclerosing mast cell tumors or extraosseous osteosarcoma , respectively . in contrast to our case , fgesf typically occurs as an ulcerated intramural mass within the pyloric sphincter , ileocecocolic junction or colon , with occasional regional lymph node involvement and common intralesional bacteria ( 56% of overall cases , n = 25 ) , or fungal hyphae associated with the characteristic collagenous cords , although bacteria were concurrently present in this lesion . interestingly , one case report of fgesf mimicked a metastatic neoplasm with multiple nodules involving the pylorus , colon , multiple mesenteric and mediastinal lymph nodes . fgesf cases typically fail to respond to antibiotic treatment ; however , the longest survival curves are seen in animals receiving corticosteroids or surgical excision . eosinophils require leukotriene d4 for initiation of transforming growth factor- production , a key fibrinogenic mediator , supporting the role of corticosteroids in medical management of these cases by inhibiting lipoxygenase and subsequent leukotriene production . similar histologic features characterized by an anastomosing fibrous network observed with both vasf and fgesf have also been observed in cougars ( puma concolor ) with intralesional intestinal porcupine quills . the fundus of the stomach contained two raised , well - circumscribed nodules measuring 2.5  1.5  1 cm and 2  2  1 cm , respectively ( figure 1 ) , each with a central mucosal pore containing several red slender nematodes , approximately 23 cm in length . on cut surface of the nodules , the wall of the stomach was transmurally expanded by a cavernous network of white - to - gray fibrous connective tissue surrounding numerous slender red nematodes ( figure 2 ) . the renal cortices displayed punctate fluorescence with the use of a wood s lamp , but were normal in size and cortical contour . tissues were routinely fixed in neutral - buffered 10% formalin , trimmed , embedded in paraffin and sectioned for microscopic examination . post - mortem photograph of one of the nodules present in the fundus of the stomach ; the raised nodule contains a central mucosal pore with multiple slender red nematodes extending onto the mucosal surface of the stomach . the inset highlights a larvated egg , observed upon fecal float examination ; mean measurements of 10 eggs were 40  30 m post - mortem cross - sectional photograph of one of the two stomach nodules displaying mural expansion of the submucosa by a labyrinth of white - to - gray fibrous connective tissue surrounding numerous red nematodes nodules within the gastric fundus were char - acterized by marked expansion of the submucosa by thick anastomosing cords of dense sclerotic collagen interlaced by loose aggregates of spindle cells , moderate numbers of lymphocytes and plasma cells , with lesser numbers of eosinophils and mast cells . the underlying muscularis and serosa were otherwise unaffected . within the confines of the dense connective tissue were numerous transverse and longitudinal sections of adult nematodes measuring approximately 250450 m in diameter , with an overlying mucosal pore . nematodes contained an 8-m - thick eosinophilic cuticle with fine serrated ridges , prominent compartmentalized lateral cords , coelomyarian musculature and a pseudocoelom containing amorphous basophilic material and occasional foci of yellow - to - brown granular pigment . the intestinal tract was lined by uninucleate columnar epithelium with long , fine apical projections . the vast majority of nematodes were female containing gravid uteri with large numbers of larvated eggs ( figure 3 , inset ) . wet mount microscopic examination of a dissected gravid female identified larvated eggs measuring 40  30 m ( mean measurement of 10 eggs ) . for identification , nematodes were mounted onto glass slides for en face examination of longitudinal ribs , identifying terminal trifid projections ( figure 4 ) . numerous transverse and longitudinal sections of nematodes ( indicated by arrows ) are surrounded by concentric anastomosing dense fibrous bands of sclerotic collagen ( indicated by stars ) . the inset highlights nematodes containing a thick eosinophilic cuticle and paired gravid uteri containing numerous larvated eggs ( hematoxylin and eosin ) photomicrograph of the buccal cavity en face displays a distinctive trifid appearance of the anterior segments of longitudinal ribs resembling a crown ( bar = 50 m ) renal tubules , most often within the cortex , contained abundant translucent , pale yellow , anisotropic , birefringent crystals arranged in sheaves and prisms ( calcium oxalate ) . tubular epithelial cells were frequently degenerate or necrotic , as evidenced by abundant vacuolated eosinophilic cytoplasm or hypereosinophilia and shrinkage with nuclear pyknosis , respectively . to the best of our knowledge this is the first case report of cylicospirura species in a feral domestic shorthair cat ( felis catus ) within north america , although this organism is frequently observed in multiple north american wild felids , including the bobcat ( lynx rufus ) , lynx ( lynx lynx ) and cougar ( p concolor ) . this species has been previously reported from domestic cats in asia , africa and australia . other species infecting domestic cats include cylicospirura subaequalis and cylicospirura ( petrowospirura ) barusi in asia , cylicospirura heydoni in australia , cylicospirura advena in new zealand and an unidentified cylicospirura species in italy . species can be differentiated based on morphological differences of tooth morphology within the buccal cavity , location of the vulva in comparison with the esophageal intestinal junction or dna sequence of the mitochondrial cytochrome c oxidase subunit 1 gene ( cox1 ) . in this particular case , specimens were identified as cylicospirura felineus based on the distinctive trifid morphology of the anterior portion of the longitudinal ribs ( figure 4 ) . there are three other species with distinct trifid dentation : cylicospirura crocutae from hyenas in africa , cylicospirura pardalis from leopards in africa and cylicospirura skrjabini from foxes in siberia . the shape of the cusps in teeth of c skrajabini are conical , whereas those in c pardalis are claw - like in appearance . both c crocutae and c felineus have rounded cusps , but c felineus has a 5070% shorter esophagus than c crocutae . we attempted multiple times to obtain the cox1 sequence from the several of the worms in the present study using the same primer sequences that amplify approximately 700 base pairs , but were unsuccessful . nevertheless , given the worm morphology , host and geographic location , we conclude that the infection presented here was caused by c felineus . this case represents the first documented report of cylicospirura species in a feral domestic shorthair cat in north america . this animal originated from a highly urban environment in new orleans , louisiana , where feral cats flourish . although a single isolated case such as this can not definitely support an established burden of gastric cylicospiruriasis in feral cats , animals such as this could serve as a reservoir for spillover into domestic cats , stressing the importance of monitoring feral cat populations . the lack of previous identification in domesticated cats within north america may suggest decreased consumption of intermediate and/or paratenic hosts . additionally , standard anthelmintic medications frequently administered to domesticated cats could potentially be highly efficacious against cylicospirura species . these findings continue to support a predictable fibrosing process within the gastrointestinal tract of felines in response to a variety of foreign objects , including nematodes , bacteria , fungal hyphae and foreign bodies ( porcupine needles ) . these unique stromal changes may be misdiagnosed as sclerosing mast cell tumors or extraosseous osteosarcomas . although uncommon , cylicospirura species can result in chronic vomiting when associated with the pyloric outflow tract .
case summarya feral domestic shorthair cat was euthanized owing to acute onset and progression of neurological signs attributed to ethylene glycol toxicity . at post - mortem examination 
 two nodules were identified within the fundus of the stomach . 
 examination of the gastric nodules revealed an intact mucosal surface , each with multiple red slender nematodes extending through an individual central pore . 
 histopathological evaluation of the nodules highlighted unique reactive fibroplasia , mimicking feline gastrointestinal eosinophilic sclerosing fibroplasia ( fgesf ) , encasing numerous nematodes with females possessing gravid uteri containing abundant larvated eggs . 
 the latter findings were highly suggestive of the cylicospirura genus , further supported by an en face evaluation of the buccal cavity , highlighting a distinctive trifid tooth appearance . 
 together , these findings are consistent with cylicospirura felineus . 
 pcr for the cox-1 gene was unsuccessful on formalin - fixed specimens , attributed to nucleic acid and protein crosslinking.relevance and novel informationthis represents the first documented case of cylicospirura species in a feral domestic shorthair cat in north america . 
 this particular cat lived in the highly urban environment of new orleans , louisiana . 
 identification of this case demonstrates the potential for feral cats to serve as reservoir hosts and ultimately support transmission of cylicospirura species into domesticated cat populations . 
 gastric cylicospiruriasis may present clinically as a firm abdominal mass , potentially with a history of chronic vomiting . 
 the latter emphasizes the importance of differentiating this condition from a neoplastic process such as alimentary lymphoma and adenocarcinoma . 
 histologically , the unique thick anastomosing collagenous cords encasing nematodes represent a stereotypical response observed in a broad array of gastrointestinal inflammation in felines , including intralesional bacteria , fungal hyphae , foreign bodies and , in this case , gastric nematodes that closely resemble fgesf . 
 additionally , these unique histological lesions have previously been misinterpreted as neoplastic conditions , including sclerosing mast cell tumor and extraosseous osteosarcoma .