Signalment: (JPC#2456580): Adult castrated male pig.

HISTORY: Clusters of bubbles along a 20 cm length of distal small intestine were present at necropsy.

HISTOPATHOLOGICAL DESCRIPTION: Small intestine: Markedly expanding the submucosa up to 3 mm, to a lesser extent multifocally expanding the lamina propria, tunica muscularis, and serosa, and elevating the overlying mucosa are numerous dilated lymphatics, up to 2 mm in diameter, that have a well demarcated central clear space (emphysema). These dilated, emphysematous lymphatics are separated by submucosal connective tissue bands that measure up to 200 µm thick and are infiltrated and/or expanded by scant to moderate hemorrhage, fibrin, edema, moderate numbers of multinucleated giant cells, and fewer epithelioid macrophages, eosinophils, lymphocytes, and plasma cells that occasionally extend into the adjacent tunica muscularis and serosa.

MORPHOLOGIC DIAGNOSIS: Small intestine: Emphysema, intralymphatic and submucosal to transmural, multifocal to coalescing, marked, with multifocal granulomatous and eosinophilic submucosal enteritis, breed not specified, porcine.

CONDITION: Emphysema intestinalis; intestinal emphysema; pneumatosis cystoides intestinalis; pneumotosis cystica of the intestine

CAUSE: Unknown

GENERAL DISCUSSION:

Gas-filled cystic lymphatics in the lamina propria, submucosa, tunica muscularis, subserosa, mesentery, and mesenteric lymph nodes
Infrequent, incidental finding in weaned pigs found at time of slaughter; also reported in rabbits

PATHOGENESIS:

Unknown
Gas producing bacteria have been implicated

TYPICAL CLINICAL FINDINGS:

None

TYPICAL GROSS FINDINGS:

Thin walled, gas filled cystic structures in intestine wall and on serosal surface
Numerous cystic lymphatics ranging from less than 1 mm to several cm in diameter; primarily in submucosa; seen grossly in the tunica serosa
1. Occurs most often in the wall of the small intestine; large intestine, mesentery, and mesenteric lymph nodes may be also involved

TYPICAL MICROSCOPIC FINDINGS:

Gas-filled, dilated lymphatics of the lamina propria, submucosa, tunica muscularis, subserosa, mesentery or mesenteric lymph nodes
A granulomatous to mixed inflammatory reaction may be present in surrounding submucosa

ADDITIONAL DIAGNOSTIC TESTS:

None

DIFFERENTIAL DIAGNOSIS:

Fluid-filled lymphatics (edema or lymphatic obstruction)
Empty parasitic cysts
Congenital anomalies (remnant cysts of reproductive origins)

COMPARATIVE PATHOLOGY:

Prosimians: Similar gross and histologic findings in the gastric wall of white ruffed lemurs, red-ruffed lemurs, and a slow loris (gastric pneumatosis; emphysematous gastritis; pneumatosis cystoides intestinalis)
Sirenia (manatees): Reported as a possible sequala to enterocolitis due to intestinal tract compromise from an artificial diet and immunosuppression; isolated bacteria include Pseudomonas aeruginosa, Salmonella spp., and Clostridium difficile
Loggerhead sea turtle: Iatrogenic gas emboli, including emphysema of the intestine, as well as gas emboli throughout the subcutis, heart and vasculature, and brain, reported after hyperbaric oxygen therapy (HBOT) to treat pneumocoelom

REFERENCES:

McAloose D, Stalis IH. Prosimians. In: Terio KA, McAloose D, St. Leger J, eds. Pathology of Wildlife and Zoo Animals. London: Elsevier/Academic Press; 2018: 330-1.
Owen H, Flint M, de Wilt M. Sirenia. In: Terio KA, McAloose D, St. Leger J, eds. Pathology of Wildlife and Zoo Animals. London, UK: Academic Press; 2018:601.
Spagnoli ST, Gelberg HB. Alimentary System and the Peritoneum, Omentum, Mesentery, and Peritoneal Cavity. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 7th ed. St. Louis, MO: Elsevier; 2022:479.
Suárez-Pérez A, Orós J. Iatrogenic gas embolism in a juvenile loggerhead sea turtle (Caretta caretta). J Comp Pathol. 2024;208:50-53.
Uzal FA, Plattner BL, Hostetter JM. Alimentary system. In: Maxie MG, ed. Jubb, Kennedy and Palmer’s Pathology of Domestic Animals. Vol 2. 6th ed. Philadelphia, PA: Elsevier Saunders; 2016:87.