What Is Your Diagnosis?

Benjamin Perry Department of Small Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843.

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Tige Witsberger Department of Small Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843.

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Benjamin Young Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843.

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Lisa Howe Department of Small Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843.

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 DVM, PhD, DACVS

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History

A 9-year-old spayed female Jack Russell Terrier was evaluated because of a chronic draining axillary wound. The owners reported that 3 months earlier, the patient had been chasing a squirrel when the dog received a puncture wound to the left axilla by a tree root. Repeated wound debridement, surgical closure, and antimicrobial treatment initiated by the referring veterinarian had failed to resolve the wound, which continually had a reddish-brown fluid discharge.

On physical examination, an approximately 5-mm draining wound was noted in the left axillary region. The surrounding soft tissue was erythematous, and a small amount of red-brown exudate was present. Mild lameness associated with the left forelimb was also noted during examination. A CBC was performed, and all values were within reference limits. Serum biochemical analysis was performed and revealed the following abnormalities: hypernatremia (149 mmol/L; reference range, 139 to 147 mmol/L) and hypermagnesemia (2.3 mg/dL; reference range, 1.7 to 2.1 mg/dL). Thoracic radiographs were obtained (Figure 1).

Figure 1—
Figure 1—

Right lateral and ventrodorsal radiographic views of a 9-year-old spayed female Jack Russell Terrier evaluated because of a chronic draining wound of the left axillary region of 3 months' duration.

Citation: Journal of the American Veterinary Medical Association 241, 4; 10.2460/javma.241.4.429

Determine whether additional imaging studies are required, or make your diagnosis from Figure 1then turn the page

Diagnostic Imaging Findings and Interpretation

A large concave defect is evident on the medial aspect of the left scapular body measuring nearly 2 cm in diameter. Margins of the defect are smooth and surrounded by a sclerotic rim. No gas is observable in the subcutaneous tissues. No reaction of the adjacent ribs and no pleural effusion are evident. Structures within the thoracic cavity appear radiographically normal (Figure 2). Differential diagnoses for a chronic wound with these clinical and radiographic signs included abscess, penetrating radiolucent foreign body with associated reaction, and fungal granulomatosis. Less likely differential diagnoses included bone sequestrum, osteomyelitis, and neoplasia.1,2

Figure 2—
Figure 2—

Same radiographic images as in Figure 1. Notice the concave defect in the medial aspect of the left scapula with associated sclerosis from the caudal to dorsal margins of the bone (arrows).

Citation: Journal of the American Veterinary Medical Association 241, 4; 10.2460/javma.241.4.429

Positive-contrast sinography was then performed with fluoroscopy by injection of iohexol (240 mg/mL diluted 2:1 with sterile water) into the draining tract in the left axilla.a Contrast medium immediately coursed dorsally and pooled in the region of the left scapular defect. A large, tubular filling defect within the contrast media was noted, measuring approximately 4.8 cm in length by 1.1 cm in diameter. Given these findings and an absence of opacity detection on survey radiographs, a chronic wooden foreign body was suspected (Figure 3).

Figure 3—
Figure 3—

Positive-contrast right lateral sinographic image of the left axillary region of the same dog as in Figure 1. Notice the filling defect, measuring approximately 4.8 × 1.1 cm, caused by a foreign body (arrows).

Citation: Journal of the American Veterinary Medical Association 241, 4; 10.2460/javma.241.4.429

Comments

Surgical exploration of the draining wound produced a wooden stick that had penetrated the left axillary region and lodged in the craniomedial aspect of the scapula. Continued presence of the foreign material led to cutaneous abscess formation and pressure remodeling of the scapula. Escherichia coli, Klebsiella pneumoniae, Enterococcus spp, Bacillus cereus, and Clostridium spp were isolated from the sinus. The wound was flushed, the draining tract excised, and antimicrobial treatment initiated. The patient was discharged from the hospital 2 days after surgery, and the wound was completely resolved with no evidence of lameness 25 days later at follow-up examination.

Potential imaging methods for diagnosis of penetrating foreign bodies include radiography, positive-contrast sinography, fistulography, ultrasonography, CT, and MRI. Common findings on radiographs include gas opacity between fascial planes or within subcutaneous tissues as well as soft tissue swelling. The soft tissue changes and fluid accumulation associated with a penetrating wound may make identification of foreign bodies of similar radiographic opacity a challenge. Contrast studies such as sinography are often helpful in delineating those foreign objects that are not sufficiently radiopaque; contrast studies do not require special equipment, making the procedure an accessible technique for any practitioner. Sinography also allows for identification of the foreign body, the number of cavities present, and whether the sinus communicates with underlying bone or viscera.1 The terms fistulography and sinography are often used interchangeably, but a fistula is a draining tract that communicates with a mucosal surface, whereas a sinus drains through a cutaneous opening. Ultrasonography can be helpful for identification of foreign bodies. Grass awns, thorns, and splinters generally appear as hyperechoic structures with distal acoustic shadowing.3 Ultrasonography may also provide the opportunity to evaluate vascularity via Doppler imaging. Computed tomography and MRI also have been useful in evaluating wooden foreign bodies but were ultimately deemed unnecessary in this case on the basis of the results of sinography.4,5

a.

Omnipaque, GE Healthcare, Little Chalfont, Buckinghamshire, England.

  • 1 Lamb CR, White RN, McEvoy FJ. Sinography in the investigation of draining tracts in small animals: retrospective review of 25 cases. Vet Surg 1994; 23:129134.

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  • 2 Ettinger SJ, Feldman EC. Hematology and immunology. In: Textbook of veterinary medicine: diseases of the dog and cat. 6th ed. Vol 2. St Louis: Elsevier Saunders, 2005;19891991.

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  • 3 Kealy JK, McAllister H. Soft tissues. In: Diagnostic radiology and ultrasonography of the dog and cat. 4th ed. St Louis: Elsevier Saunders, 2005;486487.

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  • 4 Young B, Klopp L, Albrecht M, et al. Imaging diagnosis: magnetic resonance imaging of a cervical wooden foreign body in a dog. Vet Radiol Ultrasound 2004; 45:538541.

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  • 5 Ober CP, Jones JC, Larson MM, et al. Comparison of ultrasound, computed tomography, and magnetic resonance imaging in detection of acute wooden foreign bodies in the canine manus. Vet Radiol Ultrasound 2008; 49:411418.

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