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Mesenteric Volvulus 649

○ Azathioprine: q 1-2 weeks, then q 1-3 treatment are likely to do well, reaching the Avoid administration of procarbazine with
months median to higher range of survival. However, cyclosporine due to potential cytochrome
VetBooks.ir ○ Lomustine: 7-10 days after administration post-diagnostic period or first 2-3 months Technician Tips Diseases and Disorders
P450 interactions.
15%-33% of dogs die in the immediate
○ Mycophenolate: q 1-3 months
and before each treatment
of treatment.
○ Monitor for secondary infections (respira-
tory, urinary, dermatologic). • Potential negative prognostic indicators: • Cyclosporine concentrations are drawn in
multifocal disease, seizures, altered menta-
a purple-top tube; peak 2 hours after drug
• Gingival hyperplasia with chronic tion, MRI findings of herniation through administration, and trough just before the
cyclosporine administration the foramen magnum, decreased sulci depth next dosing.
• CNS depression and peripheral neuropathy of the cerebral cortex, or mass effect; partial • Blood should be collected from the jugular
with procarbazine instead of complete response to treatment vein of dogs being administered cytarabine,
• Secondary infection due to immune saving the peripheral veins for catheter
suppression PEARLS & CONSIDERATIONS placement.
Recommended Monitoring Comments Client Education
• Serial neurologic exams • If infectious disease titers are included in the Clients administering immunomodulatory/
• Repeat CSF ± MRI at 3 months; relapse is initial minimal database, referral should not chemotherapeutic agents at home should be
more likely if CSF remains abnormal after 3 be delayed while awaiting results. advised to wear gloves when handling the
months of treatment or treatment is stopped • Addition of a secondary immunomodula- medication or bodily fluids from their pet.
before resolution of MRI abnormalities. tory drug may allow more rapid taper of
• Owners should monitor closely for recurrence glucocorticoids and minimize associated side SUGGESTED READING
of clinical signs. Any relapse should be treated effects. Coates JR, et al: Perspectives on meningoencephalo-
aggressively because response to treatment ○ Procarbazine and radiation therapy are myelitis of unknown origin. J Vet Clin North Am
can decline. most expensive, followed by cyclosporine, Small Anim Pract 44:1157-1185, 2014.
mycophenolate, and lomustine. AUTHOR: Michaela J. Beasley, DVM, MS, DACVIM
PROGNOSIS & OUTCOME ○ Cytarabine and radiation therapy are EDITOR: Karen R. Muñana, DVM, MS, DACVIM
limited by availability of a practice capable
• Overall prognosis: fair to guarded (survival, of administration.
0-1834 days; median, 1-2 years). Breeds at • With resistant or recurrent disease, more
higher risk for NE (pugs) have a worse aggressive treatment can be initiated with a ter-
prognosis. tiary immunomodulatory medication. Cyta-
• Dogs that respond to treatment in the first rabine can be administered with cyclosporine,
24-72 hours and survive the first 3 months of procarbazine, azathioprine, or leflunomide.

Mesenteric Volvulus Client Education
Sheet

Clinical Presentation
BASIC INFORMATION • Endotoxins and bacteria translocate into the
HISTORY, CHIEF COMPLAINT abdomen through the damaged intestinal
Definition Acute-onset abdominal distention, pain, vomit- mucosa.
An uncommon disorder characterized by ing, and hematochezia • Patients eventually die from circulatory shock
twisting of the intestine around the root of and endotoxemia/sepsis.
the mesentery; this process can be rapidly fatal. PHYSICAL EXAM FINDINGS
• Physical findings consistent with hypovolemic DIAGNOSIS
Synonyms shock: tachycardia, weak pulses, pale mucous
Intestinal volvulus, mesenteric torsion membranes, prolonged capillary refill time, Diagnostic Overview
weakness or collapse The diagnosis is suggested by physical exam
Epidemiology • Abdominal distention, palpable gas-filled and appearance of abdominal radiographs.
SPECIES, AGE, SEX intestinal loops, abdominal pain Differential diagnoses must be ruled out to
Young adult male dogs are predisposed; also • ± Hematochezia on rectal palpation the extent possible (e.g., ileus due to parvoviral
reported in cats enteritis: testing as appropriate). Confirmation
Etiology and Pathophysiology of the diagnosis is made at the time of surgery.
GENETICS, BREED PREDISPOSITION • Twisting of intestine occurs around mesen-
Large-breed dogs, German shepherds, and teric axis or root, causing vascular occlusion Differential Diagnosis
English pointers to the intestines. Any condition associated with acute abdominal
• Thin-walled veins and lymphatics become pain or hematochezia and vomiting (p. 21):
ASSOCIATED DISORDERS obstructed, causing edema in the intestinal • GDV
Conditions that may be associated with mes- wall. • Cecocolic volvulus
enteric volvulus include exocrine pancreatic • Blood flow through cranial mesenteric artery • Intussusception
insufficiency, recent gastrointestinal (GI) and its branches is partially or completely • Splenic torsion
surgery, GI foreign bodies, enteritis, intestinal occluded due to twisting. • GI obstruction or rupture
neoplasia, blunt trauma, and gastric dilation/ • Ischemic necrosis of intestine occurs, and • Peritonitis
volvulus (GDV). blood is lost into the intestinal lumen. • Pancreatitis

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