Canine Intussusception Study Guide

NAVLE Study Guide

Gastrointestinal and Digestive System | Species: Canine

Estimated Read Time: 30-35 minutes | Last Updated: December 2024

Overview and Clinical Importance

Intussusception is the invagination (or telescoping) of one segment of the gastrointestinal tract into the lumen of an adjacent segment. The invaginated segment is termed the intussusceptum, while the enveloping outer segment is called the intussuscipiens. This condition represents a surgical emergency in veterinary medicine because it leads to intestinal obstruction, compromised blood supply, tissue necrosis, and potentially life-threatening peritonitis if left untreated.

Intussusception is a common cause of bowel obstruction in small animals and is most frequently encountered in young dogs (less than 1 year of age). The condition requires rapid recognition and surgical intervention for optimal patient outcomes. Understanding the etiology, clinical presentation, diagnostic approach, and surgical management is essential for NAVLE success.

Figure 1. Diagram illustrating the anatomy of intussusception showing the intussusceptum (invaginated segment) telescoping into the intussuscipiens (enveloping segment), with the apex and neck clearly labeled.

Learning Objectives

• Define intussusception and understand the anatomical terminology (intussusceptum, intussuscipiens, apex, neck)
• Identify predisposing factors and underlying causes of intussusception in dogs
• Recognize clinical signs associated with acute and chronic intussusception
• Describe diagnostic imaging findings, particularly the pathognomonic ultrasound target sign
• Understand surgical treatment options including manual reduction, resection and anastomosis, and enteroplication
• Discuss prognosis, complications, and recurrence prevention strategies

Etiology and Pathophysiology

Mechanism of Intussusception

Intussusception occurs when there is abnormal intestinal motility characterized by a segment of hypermotile bowel adjacent to a segment with decreased motility (ileus). The hypermotile segment telescopes into the adjacent relaxed segment, typically in the direction of normal peristalsis (normograde or direct intussusception). Retrograde intussusception can occur but is less common.

The pathophysiology progresses as follows: initial invagination causes partial obstruction, which may progress to complete obstruction. The mesentery becomes trapped between the intussusceptum and intussuscipiens, leading to venous congestion and edema of the invaginated segment. Progressive constriction eventually compromises arterial blood flow, causing ischemia and necrosis. Fibrinous adhesions form between serosal surfaces, and if left untreated, bowel perforation and peritonitis develop.

Predisposing Factors and Underlying Causes

Any condition causing intestinal inflammation (enteritis) or altered motility can predispose to intussusception. In approximately 67% of cases, no identifiable cause is found (idiopathic). The most common predisposing factors include:

High-Yield Note: Canine parvovirus is a major predisposing factor for intussusception. If a dog with parvoviral enteritis shows sudden clinical deterioration, persistent vomiting despite antiemetics, or a palpable abdominal mass, always consider intussusception as a complication!

Signalment and Breed Predispositions

Approximately 75% of dogs with intussusception are less than 1 year of age. Large breed dogs may be more commonly affected, although intussusception can occur in any breed. German Shepherds are particularly predisposed to gastroesophageal intussusception. When intussusception occurs in older dogs (greater than 3-4 years), neoplasia should be suspected as an underlying cause.

Types and Anatomical Locations

The most common location for intussusception in dogs is the ileocolic junction (ileum into colon/cecum), accounting for approximately 43-50% of cases. Jejunojejunal intussusception is the second most common type.

Board Tip: Remember "I-C-E" for the most common intussusception location: Ileum into Cecum/colon (Enterocolic). The severity of clinical signs generally increases the more proximal the obstruction - jejunojejunal intussusceptions typically cause more severe signs than ileocolic intussusceptions.

Clinical Signs and Presentation

Clinical signs vary based on the location of intussusception, degree of obstruction (partial vs. complete), duration, and presence of vascular compromise. Signs may be acute or chronic/intermittent.

Acute Presentation

• Vomiting - often persistent; may be bilious or contain blood
• Diarrhea - frequently bloody (hematochezia) or mucoid; "currant jelly" appearance
• Abdominal pain - may present as hunched posture, reluctance to move
• Depression and lethargy
• Anorexia
• Dehydration - tachycardia, prolonged CRT, pale mucous membranes

Chronic Presentation

• Intermittent, intractable diarrhea
• Weight loss and emaciation
• Hypoalbuminemia - intussusception is one of the two major causes of protein-losing enteropathy in dogs less than 12 months of age (along with parasites)
• Intermittent episodes of obstruction that spontaneously resolve

Physical Examination Findings

• Palpable abdominal mass - reported in approximately 53% of cases; firm, tubular, "sausage-shaped" structure
• Abdominal distension
• Tenesmus (especially with ileocolic intussusception)
• Rectal prolapse of intussuscepted segment - distinguish from true rectal prolapse by attempting to pass a probe alongside the prolapsed tissue (impossible with intussusception, possible with rectal prolapse)
• Signs of shock in severe cases: tachycardia, weak pulses, prolonged CRT, hypothermia

High-Yield Note: Clinical signs may be INTERMITTENT! The intussusception can spontaneously reduce and then reform. Do not be falsely reassured by temporary improvement - surgical intervention is still typically required to prevent recurrence.

Diagnosis

Laboratory Findings

Laboratory abnormalities are often nonspecific and reflect the underlying cause and degree of illness:

• CBC: Leukocytosis or leukopenia (if concurrent parvovirus), stress leukogram, hemoconcentration from dehydration
• Serum biochemistry: Electrolyte abnormalities (hypokalemia, hypochloremia), azotemia (prerenal), hypoalbuminemia in chronic cases, elevated lactate
• Fecal examination: To rule out parasites as underlying cause; parvovirus ELISA testing

Diagnostic Imaging

Abdominal Radiography

Plain radiographs have limited sensitivity (approximately 48%) for detecting intussusception. Findings may include:

• Signs of intestinal obstruction: dilated, gas/fluid-filled intestinal loops
• Soft tissue density mass effect in abdomen
• Decreased serosal detail (if peritonitis present)
• "Gravel sign" - granular appearance from trapped ingesta

Contrast (barium) studies may show a "coiled spring" appearance as contrast outlines the intussusception, but have largely been replaced by ultrasound.

Abdominal Ultrasonography - Gold Standard

Figure 2. Transverse ultrasound view showing the pathognomonic target sign (also called bull's eye sign or doughnut sign) of intussusception, demonstrating concentric alternating hyperechoic and hypoechoic rings representing the layers of invaginated bowel.

Figure 3. Longitudinal ultrasound view of intussusception showing multiple parallel hyperechoic and hypoechoic layers within the lumen of the intussuscipiens.

Board Tip - Memory Aid: "TARGET your diagnosis with ultrasound!" The TARGET SIGN is pathognomonic for intussusception. Think of it like looking at a dartboard (target) from above - you see concentric rings. On longitudinal view, you see "stacked pancakes" or parallel lines.

Doppler Ultrasound for Reducibility Prediction

Color Doppler assessment of blood flow to the intussusceptum can help predict reducibility and bowel viability. Absence of blood flow suggests non-viability and the need for resection rather than manual reduction.

Treatment

Preoperative Stabilization

Intussusception is a surgical emergency. However, patient stabilization prior to anesthesia is essential:

• IV fluid therapy: Correct dehydration and electrolyte imbalances (crystalloids; colloids if hypoalbuminemic)
• Broad-spectrum antibiotics: For bacterial translocation risk (ampicillin/sulbactam, or cefazolin plus metronidazole)
• Analgesia: Opioids (methadone, hydromorphone) - also help slow intestinal motility
• Address underlying cause: Continue parvovirus treatment if applicable

Surgical Options

Figure 4. Intraoperative photograph showing an intussusception at exploratory laparotomy, demonstrating the telescoped segment of bowel prior to surgical correction.

Surgical Decision Making

Assessment of bowel viability is critical. Signs of viable bowel include: pink color, presence of peristalsis, pulsatile mesenteric vessels, and return of color after decompression. Non-viable bowel appears dark purple/black, lacks peristalsis, and has no mesenteric pulses - these segments require resection.

High-Yield Note: Enteroplication is controversial! While it may prevent recurrence (recurrence rate 0% with enteroplication vs. up to 28% without in some studies), it can cause serious complications including intestinal obstruction from vegetative material and strangulation of enteroplicated loops. The decision to perform enteroplication should be weighed against these risks. Consider it for: recurrent intussusception, visible hyperperistalsis at surgery, spontaneous reduction cases, and idiopathic cases in young dogs.

Postoperative Care

• Continued IV fluid therapy: Until eating normally
• Analgesia: Opioids (also provide GI motility benefits)
• Antiemetics: As needed
• Antibiotics: Depending on contamination level
• Early enteral nutrition: Small, frequent meals of highly digestible food within 12-24 hours if tolerated
• Treat underlying cause: Deworming, continue parvovirus treatment, address dietary issues
• Monitor for recurrence: Most recurrences occur within 72 hours to 3 weeks postoperatively

Prognosis and Complications

Prognosis

With appropriate surgical treatment, prognosis is generally good. Survival rates with surgical correction range from 70-90% depending on underlying cause and timing of intervention. Factors affecting prognosis include:

• Duration of intussusception (better if treated early)
• Underlying cause (parvovirus carries higher mortality)
• Presence/absence of peritonitis
• Amount of bowel resected
• Prevention of recurrence

Complications

Board Tip - Recurrence Prevention: "TRAP" prevents recurrence: Treat the underlying cause (deworm, treat enteritis) Resect non-viable bowel (don't just reduce if damaged) Assess for enteroplication (selective cases) Prevent parasites/parvovirus with routine preventive care

Differential Diagnosis

When a young dog presents with vomiting, bloody diarrhea, and abdominal pain, consider:

• Parvoviral enteritis - can be concurrent with intussusception
• Intestinal foreign body obstruction
• Hemorrhagic gastroenteritis (HGE)
• Intestinal volvulus/mesenteric torsion
• Severe parasitism
• Intestinal neoplasia (especially in older dogs)
• Rectal prolapse - distinguish from prolapsed intussusception

Summary - Key Takeaways

• Definition: Invagination of one intestinal segment (intussusceptum) into an adjacent segment (intussuscipiens)
• Most common location: Ileocolic junction
• Signalment: 75% of cases occur in dogs less than 1 year of age
• Major predisposing factor: Any cause of enteritis, especially canine parvovirus and parasites
• Classic clinical signs: Vomiting, bloody diarrhea, palpable abdominal mass, abdominal pain
• Diagnostic gold standard: Abdominal ultrasound showing TARGET SIGN (pathognomonic)
• Treatment: SURGICAL - resection and anastomosis in most cases (84%); consider enteroplication for recurrence prevention
• Recurrence rate: 3-25% without enteroplication, usually within 72 hours to 3 weeks
• Prognosis: Good with early surgical intervention (70-90% survival)

Practice Question

Correct Answer: B

Explanation

Option B is correct. The ultrasound findings of concentric rings (target sign) are pathognomonic for intussusception. Combined with the clinical presentation (young, unvaccinated dog with vomiting, bloody diarrhea, palpable abdominal mass), this confirms the diagnosis. Intussusception is a surgical emergency. The patient should be stabilized with IV fluid therapy to correct dehydration and electrolyte abnormalities, and then proceed to exploratory laparotomy for surgical correction. Delays increase the risk of bowel necrosis and peritonitis.

Option A (barium contrast) is incorrect because the diagnosis has already been made with ultrasound. Barium contrast would delay definitive treatment and is unnecessary. Additionally, barium is contraindicated if perforation is suspected.

Option C (metoclopramide and monitoring) is incorrect because intussusception requires surgical intervention. Prokinetic agents and conservative management will not resolve the problem and delays worsen prognosis.

Option D (colonoscopy) is incorrect because colonoscopy is not standard for diagnosing or treating intussusception in dogs. The diagnosis is already confirmed with ultrasound.

Option E (hydrostatic reduction) is incorrect. While hydrostatic reduction is commonly used in pediatric human medicine, it is not standard of care in veterinary patients. In veterinary medicine, surgical exploration allows assessment of bowel viability and treatment of underlying causes.

High-Yield Note: When you see a young, unvaccinated dog with acute GI signs and a TARGET SIGN on ultrasound, think intussusception and proceed to surgery after stabilization. Remember this puppy is also at high risk for parvovirus given the signalment and shelter origin - test for parvovirus and provide appropriate supportive care, but do not delay surgery for the intussusception. The intussusception may have developed as a complication of parvoviral enteritis.

Image Sources

Figure 2 - Ultrasound triple circle/target sign (transverse and longitudinal views, double intussusception, Case 1): Aprea F et al. (2012). "Ultrasonographic diagnosis and surgical management of double intestinal intussusception in 3 dogs." Can Vet J. Figure 2. PMC3398523. URL: https://pmc.ncbi.nlm.nih.gov/articles/PMC3398523/ - Open Access.

Figure 3 - Lateral radiograph showing gas-distended intestinal loops (Case 2, double intussusception): Aprea F et al. (2012). Can Vet J. Figure 1. PMC3398523. URL: https://pmc.ncbi.nlm.nih.gov/articles/PMC3398523/ - Open Access.

Figure 4 - Intraoperative photograph of double jejunoileal intussusception through ileocolic orifice prior to surgical correction (Case 1): Aprea F et al. (2012). Can Vet J. Figure 3. PMC3398523. URL: https://pmc.ncbi.nlm.nih.gov/articles/PMC3398523/ - Open Access.

References

• American College of Veterinary Surgeons. Intussusception. Available at: https://www.acvs.org/small-animal/intussusception/
• Applewhite AA, Hawthorne JC, Cornell KK. Complications of enteroplication for the prevention of intussusception recurrence in dogs: 35 cases (1989-1999). J Am Vet Med Assoc. 2001;219:1415-1418.
• Chagnon Larose P, et al. Clinical findings and outcomes of 153 dogs surgically treated for intestinal intussusceptions. Vet Surg. 2020;49:858-867.
• Levitt L, Bauer MS. Intussusception in dogs and cats: A review of 36 cases. Can Vet J. 1992;33:660-664.
• Merck Veterinary Manual. Canine Parvovirus Infection. Available at: https://www.msdvetmanual.com/digestive-system/
• Oakes MG, Lewis DD, Hosgood G, Beale BS. Enteroplication for the prevention of intussusception recurrence in dogs: 31 cases (1978-1992). J Am Vet Med Assoc. 1994;205:72-75.
• Patsikas MN, et al. Acute enteritis or gastroenteritis in young dogs as a predisposing factor for intestinal intussusception: a retrospective study. J Vet Med A. 2003;50:416-420.
• Patsikas MN, Papazoglou LG. Current Views in the Diagnosis and Treatment of Intestinal Intussusception. Topics in Companion Animal Medicine. 2019;35:28-35.
• VCA Animal Hospitals. Intussusception in Dogs. Available at: https://vcahospitals.com/know-your-pet/intussusception-in-dogs
• WSAVA 2008 Congress. Intussusception: Diagnosis and Treatment. Available at: https://www.vin.com/