2 yr old male castrated Cape porcupine (Hystrix africaeaustralis)

Findings:

• Marked gastric distension with presumed ingesta, fluid, gas, and trace granular opaque material.  Gastric margins extend to L3.  
• Extensive gas distension of intestinal loops ranging from mild to marked distention. 
• Caudal displacement of intestines, likely secondary to gastric dilation
• Subjective reduction in cecal contents
• Generalized loss of serosal detail
• Mild esophageal gas, no other thoracic abnormalities

Diagnosis:

• Marked gastric distension and multifocal dilation of small intestines. Given the challenge inherent in interpreting gastrointestinal dilation in rodents, both severe functional and mechanical ileus were considered. Given the risks inherent in an elective laparotomy, abdominal CT was recommended to help differentiate between a surgical and non-surgical lesion.
• Normal limited thoracic evaluation

Imaging Findings:

• As seen on radiographs, there is persistent gastric distension with ingesta, gas, fluid, and trace granular mineral attenuating material.
• There is variable distension of small intestinal loops with the duodenum being the most severely dilated. The duodenum is also markedly distended in post-contrast images.
• Compared to radiographs, there is passage of some gastric contents into the duodenum
• On pre contrast images, there is poor serosal detail due to both suspected fluid and scant peritoneal fat, limiting the ability to delineate segments of small intestine.
• There is a mixed gas and soft tissue attenuating ovoid structure within a segment that is thought to be small intestine at the pelvic inlet, ventral to the colon (measures 1.7 cm x 1.8 cm x 2.4 cm).  Fluid dilation of the intestinal loops are present only at one side of the structure.
• Formed feces in the colon
• There is trace granular mineral attenuating material in the bladder
• Asymmetric ureteral dilation with contrast material, of unknown signficance

Imaging Diagnosis:

• Segmental small intestinal dilation consistent with mechanical ileus
• Intraluminal ovoid material may be aggregated fibrous food material given mixed attenuation
• Scant peritoneal effusion
• Trace mineral cystic debris

Based on the CT findings, an exploratory ventral midline laparotomy was performed. Gas distended loops of bowel were noted and decompression was initiated to improve visualization. There was a small volume of clear, yellow peritoneal fluid.  The stomach was markedly enlarged and firm, extending to the to mid-abdomen. A firm, non-mobile obstruction was palpated in the jejunum with minimal intestinal contents aborad to the obstruction. An enterotomy was performed and a firm concretion of hay material was removed. Gastrotomy was performed to decompress the stomach of excessive hay material. Cytology of peritoneal fluid was consistent with neutrophilic and histiocytic inflammation with foreign material and reactive mesothelial cells. Cultures of abdominal fluid were negative for aerobic and anaerobic organisms. The patient was treated both intra-operatively and post-operatively with IV fluids, broad-spectrum antibiotics, gastroprotectants, and analgesics. Metoclopramide was started post-operatively to improve GI motility. Fecal eliminations resumed 72 hours post-operatively.

Distinguishing between obstructive and non-obstructive ileus was challenging in this case, but was greatly assisted by CT imaging which helped identify and localize the obstruction to direct surgical exploration.  Post-contrast CT imaging was vital to the case as it allowed for improved delineation of bowel walls, particularly in the face of scant peritoneal fat and ascites. Differential diagnoses for acute GI distension in rodents include: foreign body obstruction, gastroliths, ileus, acute gastroenteritis, and dysbiosis. Like rabbits, porcupines are monogastric hind-gut fermenters and may be prone to functional ileus and GI obstruction. Obstruction secondary to gastroliths has been documented in prehensile-tailed porcupines (a New World species), but has not been previously reported in an Old World porcupine species (such as in this case) to the authors’ knowledge.  Like rabbits, clinical signs of GI obstruction in porcupines can include acute anorexia, lack of defecation, signs of abdominal pain, and abdominal distension.  Whether medically or surgically managed, supportive care in the form of fluid therapy, analgesia, pro-kinetics, and early return to feeding and defecating are crucial for positive outcomes.

• Hagen, K. B., Hammer, S., Frei, S., Ortmann, S., Głogowski, R., & Kreuzer, M. (2019). Digestive physiology, resting metabolism and methane production of captive Indian crested porcupine (Hystrix indica). Journal of Animal and Feed Sciences, 28, 69-77.
• Spriggs, M., Thompson, K. A., Barton, D., Talley, J., Volle, K., Stasiak, I., … & Hagey, L. R. (2014). Gastrolithiasis in prehensile-tailed porcupines (Coendou prehensilis): Nine cases and pathogenesis of stone formation. Journal of Zoo and Wildlife Medicine, 45(4), 883-891.
• Van Jaarsveld, A. S. (1983). Aspects of the digestion in the Cape porcupine. South African Journal of Animal Science, 13(1), 31-33.