Prognosis for surgical intestinal resection in inflammatory bowel disease refractory to medical treatment in a dog

Abstract

A 14-year-old spayed female Maltese dog had been diagnosed with inflammatory bowel disease (IBD) via surgical biopsy and histopathologic findings. The dog had shown stable clinical control with prednisolone for 2 y but subsequently developed diarrhea, and serum albumin levels could not be adequately controlled. Despite titrating up the prednisolone dosage (1 mg/kg, PO, q12h), serum albumin concentration remained low and diarrhea persisted. Diagnostic imaging identified the underlying cause of the gastrointestinal signs as segmental eccentric small intestine wall thickening with homogenous hypoenhancement. A surgical resection of the affected segment was undertaken, primarily for histopathologic examination to identify the underlying cause rather than for therapeutic purposes. Postoperatively, medical management was continued, and the therapeutic response to medical therapy improved as the prednisolone was gradually tapered. Stable management was ultimately achieved at a prednisolone dosage of 0.25 mg/kg, PO, q24h, once.

Key clinical message:

In veterinary medicine, IBD is generally managed with medical therapy, and poor prognosis may occur if the clinical signs are not controlled. In certain cases, however, a surgical approach may offer benefits in the management of IBD. In the case reported herein, surgical resection was conducted on the segments of intestine with severe inflammation in a 14-year-old spayed female Maltese dog diagnosed with IBD that was not controlled by medical therapy. After surgery, the IBD was managed successfully with prednisolone.

In dogs, protein-losing enteropathy (PLE) often arises secondary to various pathophysiologic disruptions within the intestines. For example, obstructed lymphatic drainage in the intestinal tract may result in lymph leakage into the intestinal lumen, leading to loss of protein, predominantly serum albumin (1,2). Similarly, increased intestinal vascular permeability can cause plasma proteins, including albumin, to extravasate into the gut (1,2). In addition, PLE may develop in conjunction with chronic inflammatory diseases of the intestinal mucosa, of which inflammatory bowel disease (IBD) is one of the most prominent etiologies.

Inflammatory bowel disease is an idiopathic, immune-mediated condition that manifests chronic gastrointestinal signs such as persistent vomiting and recurrent diarrhea (2–4). The condition can be further classified based on anatomical location and histopathologic findings, with lesions confined to the small intestine or diffuse throughout the gastrointestinal tract (3). Histologically, the predominant pattern is lymphoplasmacytic enteritis, though eosinophilic or granulomatous inflammation may also occur (2). The clinical signs often include vomiting, diarrhea, or progressive weight loss. Hematochezia or melena may be present, depending on lesion location and severity (2,3). Appetite can vary according to disease severity, and chronic hypoalbuminemia secondary to PLE can lead to complications such as ascites (2).

Hematologic and biochemical profiles may not yield pathognomonic findings, but hypoalbuminemia, hypoglobulinemia, and hypocholesterolemia can result from impaired mucosal absorption (3). A definitive diagnosis requires histopathologic confirmation via intestinal biopsy (2).

Radiographic imaging may show nonspecific findings. However, abdominal ultrasonography often reveals focal or diffuse thickening of the intestinal wall, with characteristic striations indicative of concurrent lymphangiectasia (2,3,5).

Treatment is primarily medical, focusing on dietary modification, antibiotic therapy, and use of immunomodulatory agents (2,6,7). Mild cases can achieve remission with dietary therapy alone, whereas refractory cases necessitate immunosuppressive intervention (3,6,8). Corticosteroids, particularly prednisolone and prednisone, are the main immunomodulators in canine IBD, administered orally at an initial dosage of 1 to 2 mg/kg, q12h (3). Dosing is adjusted based on the clinical response and any adverse events, with gradual tapering to the lowest effective dose over 3 to 4 wk (3).

Adjunctive cytotoxic agents, such as azathioprine, cyclosporine, or mycophenolate mofetil, may be introduced in cases unresponsive to corticosteroids or in which effects are concerning, with close monitoring of therapeutic response and toxicity (3). Modulation of the gut microbiota using probiotics or prebiotics may provide adjunctive anti-inflammatory effects, and cobalamin supplementation is warranted in cases of documented hypocobalaminemia (2,3).

Although most cases are managed effectively through dietary and pharmacologic interventions, treatmentrefractory cases may exhibit a guarded prognosis (3). This case report evaluates the prognostic impact of a surgical resection of the affected intestinal segments in a dog with IBD refractory to medical therapy.

CASE DESCRIPTION

A 14-year-old spayed female Maltese dog weighing 2.2 kg that had been treated with prednisolone (0.25 mg/kg, q12h) for 2 y for the stable management of IBD, without notable adverse effects, suddenly developed diarrhea. Blood work revealed a progressive decline in serum albumin levels, which decreased from values > 2.0 mg/dL to as low as 1.5 mg/dL. The dog, which had previously shown no response to other immunosuppressive agents such as mycophenolate mofetil, was prescribed prednisolone at a dosage of 1 mg/kg, q12h. However, no significant clinical improvement was observed Serum albumin levels remained inadequately controlled. Abdominal ultrasonography was conducted to exclude other gastrointestinal causes and revealed a mass opacity in the small intestine (Figure 1). Further evaluation via computed tomography revealed the mass was localized to the small intestine (Figure 1). The mass measured 25 mm in length, 4.6 mm in height, and 4.3 mm in width.

FIGURE 1.

Diagnostic imaging in a dog. Abdominal radiographs (A, B), an ultrasound image visualizing the mass in the small intestine (C), and computed tomographic images of the mass (D, E). The yellow asterisks (C, D, and E) indicate the intestinal mass.

A surgical resection of the affected intestinal segment removed ~12 cm of the small intestine (Figure 2). Histopathologic examination after surgery revealed findings consistent with severe lymphangiectasia accompanied by lymphoplasmacytic nodules with central necrosis, along with mild lymphocytic and plasmacytic infiltration throughout the mucosa (Figure 2).

FIGURE 2.

Surgical and postsurgical histopathologic images. A — Before surgical resection. B and C — The intestine after resection. D and E — Histopathologic images obtained postsurgery. The histologic examination revealed lymphatic vessel dilation spanning the mucosal and serosal layers, along with lymphocyte infiltration. Staining: hematoxylin and eosin; scale bar: 100 μm (D, E).

Postoperative medical management included a single albumin transfusion. The serum albumin level, which had been 1.6 mg/dL before surgery, was increased to 2.8 mg/dL following the transfusion. The prednisolone dosage was tapered to 0.25 mg/kg, PO, q24h. During the 2-month follow-up, serum albumin levels remained stable compared to presurgical levels (Figure 3). The serum albumin concentration was measured using a Mindray Chemistry Analyzer BS-240Pro (MEDISTAR, Hamburg, Germany). Intermittent diarrhea was observed shortly after surgery, but stabilization of clinical signs, characterized by the resolution of diarrhea and soft stools, was achieved within 2 wk.

FIGURE 3.

Changes in prednisolone (PDS) dosage and albumin (ALB) concentration over time. The red asterisk indicates October 29, the date of the intestinal resection surgery.

DISCUSSION

Inflammatory bowel disease is an immune-mediated inflammatory disorder typically managed with medical treatments such as prednisolone or other immunosuppressive agents (7). Generally, IBD responds quite well to medical therapy and the prognosis is favorable, but the prognosis may be poor in rare cases for which these methods do not control the clinical signs. The lesions associated with IBD can affect the entire gastrointestinal tract or may be confined to the small intestine (3). Inflammation in the affected segments can worsen, sometimes accompanied by lymphangiectasia, if IBD is poorly managed. In such cases, hematologic findings, such as hypocholesterolemia due to lymphangiectasia and hypoalbuminemia caused by PLE, can be observed, along with gastrointestinal signs such as vomiting, diarrhea, and anorexia. In addition, due to hypoalbuminemia, the osmotic pressure of the body fluids decreases and can lead to the development of ascites.

In human medicine, surgical treatment of IBD is considered with medical treatment based on the patient’s condition (9–12). Surgery is generally indicated when the symptoms are not controlled by medical treatment or when complications arise (12). Specifically, surgery is considered when inflammation is so severe that signs cannot be controlled or when complications such as bleeding, perforation, or bowel obstruction occur (12). However, in dogs, IBD is managed primarily with dietary modification and medical therapy (1–3). In the case described herein, inflammatory lesions in a specific intestinal segment worsened. The primary goal of the surgical approach was not to control IBD by removing the inflammatory lesions, but rather to differentiate whether the lesions were neoplastic or inflammatory via histologic interpretation. Ultimately, the lesions were of an inflammatory origin, exacerbated by IBD, and the clinical signs were effectively controlled following surgical resection of the affected segment. Further, postoperative albumin levels were maintained within a stable range with the same dosage of prednisolone and were comparable to those observed before surgery.

In veterinary medicine, surgical resection of the affected bowel segment is generally not recommended for IBD. Although the surgery in the present case was conducted primarily for diagnostic purposes, to distinguish between neoplastic and inflammatory processes, the dog exhibited a notably favorable clinical response following the resection of the segment with particularly severe lesions. This positive outcome, including improvement of the clinical signs and hypoalbuminemia secondary to PLE, highlighted that, in cases with severe inflammatory lesions, surgical resection may provide therapeutic benefit in addition to its diagnostic value.

Nevertheless, the potential complications associated with surgical resection must be considered carefully (9). In particular, extensive bowel resection may lead to transient gastrointestinal signs caused by maldigestion and malabsorption (13). In addition, resection of a specific intestinal segment can result in impaired bile absorption, which may cause overaccumulation of bile salt in the intestine (14,15). In such cases, the passage of bile through the colon can disrupt the normal gut microbiota, compromising the integrity of the intestinal mucosa and potentially leading to chronic colonic diarrhea (14). Further, factors such as preoperative steroid use, poor nutritional status, intra-abdominal abscesses at the time of surgery, and recurrent flares of IBD signs are associated with an increased risk of septic complications in the context of intestinal perforation (16). Therefore, surgical resection should be approached with caution and be reserved for adjunctive purposes, such as obtaining tissue specimens for histopathologic examination aimed at forming differential diagnoses.

This condition is typically characterized by diffusely distributed lesions throughout the intestinal tract. Accordingly, segmental resection alone may have limited therapeutic value. Given the risks of postoperative leakage and septic peritonitis, surgical intervention should be reserved for use as a last resort when done with curative intent. Before considering surgical intervention due to lack of clinical improvement, clinicians must prioritize, or at least thoroughly consider, medical management, including antibiotics, immunosuppressants, biological formulations such as probiotics or prebiotics, and fecal microbial transplantation.

Funding Statement

This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2020R1F1A1073007); and by the Specialized Graduate Program for Training Wildlife Professionals through the National Institute of Wildlife Disease Control and Prevention, Ministry of Environment (20241104000003125600).