JPC SYSTEMIC PATHOLOGY
Signalment (JPC# 2019292): 9-week-old crossbred female cat
HISTORY: This cat presented with a nasal discharge, cough, and labored respiration
Trachea: Diffusely and circumferentially, the submucosa is thickened up to 700um by moderate numbers of macrophages, lymphocytes, plasma cells, fewer eosinophils, neutrophils and edema. Multifocally the epithelium piles up to 8-10 cell layers deep (hyperplasia), or is attenuated and eroded, often lacks cilia, and is infiltrated by numerous neutrophils, lymphocytes and plasma cells, admixed with necrotic debris and sloughed epithelial cells. There is multifocal squamous metaplasia. Within the superficial epithelium there are several cross and tangential sections of adult nematode parasites, up to 80 um in diameter with a 2 um thick, eosinophilic cuticle; a pseudocoelom with coelomyrian-polymyarian musculature; bacillary bands; a stichosome (basophilic stichocytes surrounding the esophagus); and a reproductive tract. Submucosal glands are often ectatic, lined by attenuated epithelial cells and contain small amounts of mucin.
Lung: Multifocally, up to 60% of this section is affected with bronchi and bronchioles that have an epithelium that is hyperplastic, piled up to 6 layers deep, forming folds into the lumen, which is variably filled with sloughed epithelial cells, an exudate composed of abundant mucin, eosinophils, degenerate and nondegenerate neutrophils, macrophages, fewer lymphocytes, necrotic cellular debris, and multifocally, few previously described adult nematodes. The inflammatory cell population penetrates through the smooth muscle surrounding the airways and surrounds the peribronchial and peribronchiolar glands which are hyperplastic. Multifocally in the adjacent pulmonary parenchyma, effacing alveolar septa and filling alveolar lumina, are numerous neutrophils and macrophages admixed with necrotic cellular debris, colonies of 2um coccobacilli, fibrin, hemorrhage, and edema. Less affected alveoli are filled with eosinophilic fluid (edema) and septa are thickend up to three times normal with congestion, macrophages, lymphocytes, and plasma cells. There is marked perivascular edema and mild hemorrhage with increased clear space and dilated lymphatics.
- Trachea: Tracheitis, proliferative, pyogranulomatous and eosinophilic, diffuse, moderate, with squamous metaplasia, submucosal gland ectasia, and aphasmid nematodes, mixed breed, feline.
- Lung: Bronchitis and bronchiolitis, pyogranulomatous and eosinophilic, chronic, multifocal, moderate, with respiratory and glandular epithelial hyperplasia, and intraluminal and interepithelial aphasmid nematodes.
- Lung: Pneumonia, necrosuppurative, acute, multifocal, moderate, with edema, hemorrhage and numerous colonies of cocci.
1.Tracheal and bronchial/bronchiolar eucoliasis
2. Bacterial pneumonia
1. Eucoleus aerophilus (previously Capillaria aerophila)
2. Unknown bacteria (not cultured)
- Capillaria spp genera divided into: Eucoleus (airways), Aonchotheca (intestine) and Pearsonema (urinary bladder)
- Capillaria has wide variety of hosts: Canids (dogs, foxes, coyotes, wolves), cats, birds, frogs, fish, rabbits
- Eucoleus aerophilus are nematodes in Trichuridae family (stichosome esophagus), subclass Aphasmid
- Aphasmids differ from phasmid nematodes because they:
- One of the most characteristic features is a row of basophilic esophageal gland cells (stichocytes) that form a stichosome and surround the esophagus
- Lack a tiny pair of sensory papillae (phasmids) on their caudal end (not readily identifiable histologically) and lack lateral cords
- Have bacillary bands (hypodermal bands with associated nuclei)
- Adult females have only one genital tract (most phasmids have two)
- Aphasmids differ from phasmid nematodes because they:
- E. aerophilus parasitizes trachea and bronchi of wild canids, domestic dogs, and cats
- The body mounts an inflammatory response against developing adults in epithelium (bronchitis, bronchiolitis) > pneumonia can result if secondary bacterial infection occurs because of decreased mucociliary clearance
- Life cycle can be either direct or indirect
- Earthworms are facultative intermediate (paratenic) hosts
- Host ingests infective egg or earthworm containing infective larvae > infective larvae penetrates intestinal wall > goes to lungs (via blood) > develops into adult in mucosa of trachea and bronchi > eggs laid in lumen, coughed up, swallowed, passed out with feces, become infective in 5 to 7 weeks
- Prepatent period: 6 weeks
TYPICAL CLINICAL FINDINGS
- Dogs and cats are usually asymptomatic
- Wheezing, chronic cough, weight loss
TYPICAL GROSS FINDINGS
- Adult worms are 2-3cm long and embedded in mucosa of trachea and bronchi
TYPICAL LIGHT MICROSCOPIC FINDINGS
- aerophilus adult stage is characterized by reduced polymyarian-coelomyarian musculature, two bacillary bands (hypodermal bands with associated nuclei), a stichosome esophagus (deeply basophilic esophageal gland cells [stichocytes] that surround the esophagus), a spiny sheath, and oval, sometimes embryonated, bioperculate eggs (approximately 70 um x 35 um) within airways
- Subacute to chronic mild tracheobronchitis
ADDITIONAL DIAGNOSTIC TESTS
- Fecal float, tracheal wash
- Common lungworms in cats: Aelurostrongylus abstrusus (metastrongyle; most common nematode parasite in domestic cats), Troglostrongylus subcrenatus, Filaroides rostratus
- Bioperculate eggs: feliscati, C. putorii, Trichuris spp., Pearsonema plica
- Birds – aerophilus (fatal pneumonia in peregrine falcons), Capillaria annulata and C. contorta (crop, esophagus in poultry), C. caudinflata and C. bursata (small intestine of gallinaceous birds), C. obsignata (poultry, pigeons, quail), C. anatis (cecum of poultry and waterfowl), C. philippinesis (intestines of piscivorous birds)
- Fish - Numerous species in the GI tract and liver, including catenata and C. eupomotis, intermediate host for C. philippinesis
- Frogs – Pseudocapillaroides (Capillaria) xenopi (skin)
- Urinary - Pearsonema plica, P. feliscati (cats), C. micronata (mink), papillosa, Trichosomoides crassicauda (urothelium of rats)
- Respiratory - aerophilus, E. boehmi (pitted shell on flotation, nasal mucosa of dogs), C. didelphis (opossums), Anatrichosoma sp. (nasal mucosa of nonhuman primates and buccal mucosa of American oppossum)
- Skin – Anatrichosoma cutaneum in SQ around joints and palms/soles of monkeys
- Esophagus - Gongylonema (ruminants and nonhuman primates)
- Intestinal - Aonchotheca putorii (cats), C. entomelas, C. bovis, erinacea, C. philippinesis
- Hepatic - Calodium hepatica (rats and NHPs), Capillaria intestinalis, Capillaria gastrica
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