History
A 6-year-old 16.8-kg spayed female Golden Retriever–Poodle cross was initially seen 5.5 months prior to the time of imaging for excessive licking at the left paw and was treated empirically for allergies and a lick granuloma. The patient was seen again 1 month prior to time of imaging, for a toe-touching, left thoracic limb lameness, and continued licking of the left front paw. On physical examination at that visit, fluctuant swelling was identified on the dorsal aspect of the left metacarpus, which was draining clear serous fluid at the distal margin of the swelling. Strict cage rest for 2 weeks, a warm compress to encourage drainage, carprofen (2.2 mg/kg, PO, q 12 h for 7 days) to treat pain and inflammation, and an e-collar to prevent further licking were prescribed. Other diagnostic procedures were declined at that time by the owner.
One month later, the patient was returned for a recheck examination because of worsening lameness in the left thoracic limb. The prior fluctuant swelling of the left front paw had become a firm swelling at the dorsal and palmar aspects of the metacarpus. No fever had been present during previous examinations, and the patient’s rectal temperature was clinically normal (38.6 °C; reference range, 38.3 to 39.2 °C) at this recheck examination. The remaining findings on physical examination were clinically normal. Radiography of the carpus and manus of each forelimb was performed and submitted for teleradiological evaluation (Figure 1), and the dog was prescribed clindamycin (17.8 mg/kg, PO, q 12 h).
Lateral (A), dorsopalmar (B), and dorsolateral-palmaromedial oblique (C) radiographic views of the left manus of a 6-year-old 16.8-kg spayed female Golden Retriever–Poodle cross with 5.5 months’ history of excessive licking at the left front paw nonresponsive to empirical treatment for allergies and a lick granuloma.
Citation: Journal of the American Veterinary Medical Association 260, 12; 10.2460/javma.20.11.0632
Lateral (A), dorsopalmar (B), and dorsolateral-palmaromedial oblique (C) radiographic views of the left manus of a 6-year-old 16.8-kg spayed female Golden Retriever–Poodle cross with 5.5 months’ history of excessive licking at the left front paw nonresponsive to empirical treatment for allergies and a lick granuloma.
Citation: Journal of the American Veterinary Medical Association 260, 12; 10.2460/javma.20.11.0632
Lateral (A), dorsopalmar (B), and dorsolateral-palmaromedial oblique (C) radiographic views of the left manus of a 6-year-old 16.8-kg spayed female Golden Retriever–Poodle cross with 5.5 months’ history of excessive licking at the left front paw nonresponsive to empirical treatment for allergies and a lick granuloma.
Citation: Journal of the American Veterinary Medical Association 260, 12; 10.2460/javma.20.11.0632
Diagnostic Imaging Findings and Interpretation
Centered at the distomedial aspects of the diaphyses of the left second and fifth metacarpal bones on the dorsopalmar view, well-defined ovoid defects were present with a small well-defined mineral fragment in the defect of the fifth metacarpal bone (Figure 2). Based on the lateral and dorsolateral-palmaromedial oblique views, these bone defects were tubular in shape and extended from the dorsal to palmar cortices. At the margins of these bone defects was mild, well-defined periosteal bone formation. At the lateral margin of the left fourth metacarpal bone adjacent to this change, there was a well-defined concavity that interdigitated with the adjacent expansion of the fifth metacarpal bone. The overlying soft tissues, particularly at the dorsal and palmar aspect of the metacarpus, were moderately thickened and slightly irregular in margination. No mineral or metal opaque foreign material was evident; however, there was a questionable lucent band superimposed on the region of soft tissue swelling and at the level of the bone defects. Based on the radiographic findings, the diagnosis was a chronic embedded foreign body, such as a rubber band, with resultant pressure necrosis of the bone and associated cellulitis. The presence of the defects medially at the second and fifth metacarpal bones with complete lateral cortical margins was atypical and presumed secondary to chronic migration of the foreign body from outside the paw with subsequent healing of the lateral cortical margins. Ultrasonography and CT were recommended for further confirmation and treatment planning, with surgical exploration if additional imaging was not feasible.
Same images as in Figure 1. The soft tissues of the left metacarpus are thickened and irregular, particularly at the dorsal (asterisk) and palmar margins. On the dorsopalmar view (B), well-defined, ovoid bone defects (arrows) are within the mid to distomedial diaphyses of the second and fifth metacarpal bones. There is a small, mineral-density structure evident in the ovoid defect of the fifth metacarpal bone. On the lateral (A) and dorsolateral-palmaromedial oblique (C) views, these defects are tubular (arrowheads) and extend from the dorsal surface to the palmar surface of the affected bones. There is a small, mineral-density structure evident in the ovoid defect of the fifth metacarpal bone.
Citation: Journal of the American Veterinary Medical Association 260, 12; 10.2460/javma.20.11.0632
Same images as in Figure 1. The soft tissues of the left metacarpus are thickened and irregular, particularly at the dorsal (asterisk) and palmar margins. On the dorsopalmar view (B), well-defined, ovoid bone defects (arrows) are within the mid to distomedial diaphyses of the second and fifth metacarpal bones. There is a small, mineral-density structure evident in the ovoid defect of the fifth metacarpal bone. On the lateral (A) and dorsolateral-palmaromedial oblique (C) views, these defects are tubular (arrowheads) and extend from the dorsal surface to the palmar surface of the affected bones. There is a small, mineral-density structure evident in the ovoid defect of the fifth metacarpal bone.
Citation: Journal of the American Veterinary Medical Association 260, 12; 10.2460/javma.20.11.0632
Same images as in Figure 1. The soft tissues of the left metacarpus are thickened and irregular, particularly at the dorsal (asterisk) and palmar margins. On the dorsopalmar view (B), well-defined, ovoid bone defects (arrows) are within the mid to distomedial diaphyses of the second and fifth metacarpal bones. There is a small, mineral-density structure evident in the ovoid defect of the fifth metacarpal bone. On the lateral (A) and dorsolateral-palmaromedial oblique (C) views, these defects are tubular (arrowheads) and extend from the dorsal surface to the palmar surface of the affected bones. There is a small, mineral-density structure evident in the ovoid defect of the fifth metacarpal bone.
Citation: Journal of the American Veterinary Medical Association 260, 12; 10.2460/javma.20.11.0632
Ultrasonography of the left thoracic paw was performed by a separate radiologist, and heterogenous swelling of the metacarpal soft tissues and irregular margins of the second and fifth metacarpal bones (not shown) were identified. Small hyperechoic foci with distal shadowing (reverberation artifact) were also identified within the soft tissues and consistent with gas. No discrete foreign material was identified. Fistulography was recommended but declined by the owner. Clindamycin was continued, and treatment was initiated and expanded to also include ketoconazole (12 mg/kg, PO, q 24 h) and anti-interleukin 31 monoclonal antibody (2.4 mg/kg, SC, once). Clinical signs continued, and treatment with chloramphenicol (60 mg/kg, PO, q 8 h) was initiated due to concerns for a resistant infection. Repeated radiographic examination was performed 2 months later and submitted for evaluation, with similar findings.
Treatment and Outcome
The patient underwent general anesthesia and surgical exploration. An incision was made at the dorsal aspect of the left metacarpus at the level of the draining tract, which was debrided to the level of the second and fifth metacarpal bones, where an intact rubber band foreign body was identified passing through each bone. The rubber band (approx 0.1-cm-diameter wall X 2-cm flat length) was cut and removed, and the wound was debrided and lavaged. A palmar incision was made to debride the thickened soft tissues. The wounds were sutured closed, aside from a small portion of the center of each wound to allow drainage and healing by second intention. A bandage was placed, and treatment with chloramphenicol, carprofen, and an e-collar was continued. The owner identified the foreign body as a band from their child’s toy loom set.
At 1 month after surgery, the surgical site had healed with resolution of the lameness. Three months postoperatively, radiography was repeated and revealed reduced soft tissue swelling but persistence of the second and fifth metacarpal bone defects (Figure 3). The previously observed small mineral fragment within the defect of the fifth metacarpal bone was no longer present, presumed secondary to removal with the rubber band foreign body.
Lateral (A) and dorsopalmar (B) radiographic views of the left manus obtained 3 months following removal of a rubber band foreign body that was later identified by the owner as a rubber band from a children’s toy loom set. The tubular tracts (arrowheads) within the second and fifth metacarpal bones remain visible on the lateral view, as do the well-defined ovoid defects (arrows) on the dorsopalmar view. The small, mineral-density structure previously evident in the left fifth metacarpal bone tract is no longer present.
Citation: Journal of the American Veterinary Medical Association 260, 12; 10.2460/javma.20.11.0632
Lateral (A) and dorsopalmar (B) radiographic views of the left manus obtained 3 months following removal of a rubber band foreign body that was later identified by the owner as a rubber band from a children’s toy loom set. The tubular tracts (arrowheads) within the second and fifth metacarpal bones remain visible on the lateral view, as do the well-defined ovoid defects (arrows) on the dorsopalmar view. The small, mineral-density structure previously evident in the left fifth metacarpal bone tract is no longer present.
Citation: Journal of the American Veterinary Medical Association 260, 12; 10.2460/javma.20.11.0632
Lateral (A) and dorsopalmar (B) radiographic views of the left manus obtained 3 months following removal of a rubber band foreign body that was later identified by the owner as a rubber band from a children’s toy loom set. The tubular tracts (arrowheads) within the second and fifth metacarpal bones remain visible on the lateral view, as do the well-defined ovoid defects (arrows) on the dorsopalmar view. The small, mineral-density structure previously evident in the left fifth metacarpal bone tract is no longer present.
Citation: Journal of the American Veterinary Medical Association 260, 12; 10.2460/javma.20.11.0632
Comments
A circumferential constricting foreign body is sometimes referred to as rubber band syndrome (RBS) in human literature.1 In human medicine, RBS is associated with either unobserved (such as from being placed by a child in the home) or forgotten placement of an elastic band such as a hair tie or rubber band.1,2 The chronic pressure from the elastic foreign body results in migration through soft tissues and can also migrate through bone secondary to pressure resorption. This is important to differentiate from aggressive bone changes caused by neoplasia or osteomyelitis. Key features that indicated pressure resorption in this case included symmetric, well-defined, ovoid regions of bone loss with a short zone of transition to normal bone and the absence of an ill-defined or irregular periosteal bone reaction. Aggressive lysis, by comparison, would typically result in poorly defined margins of medullary and cortical lysis, a long and ill-defined zone of transition to normal bone, and an ill-defined periosteal bone reaction. Rubber band syndrome can result in chronic regional swelling (secondary to granulation tissue and cellulitis), draining tracts, neuropathy, scarring, constriction, and characteristic bone erosion consistent with pressure necrosis.3 Depending on the region constricted and the tightness of the band, signs of pain may not be present if the band is not causing complete ischemia. Although counterintuitive, the lack of signs of pain is likely due to numbness from chronic constriction and may aid in distinguishing RBS from other differential diagnoses, such as osteomyelitis or neoplasia.
To our knowledge, two prior veterinary cases of RBS have been reported: a cat with RBS of the left antebrachium with concave to ovoid bone defects of the radius and ulna4 and a dog with a band encircling the neck and right thoracic limb with a concave defect of the spine of the right scapula.5 Our findings differed from those of the previous reports4,5 in that bone had completely encircled and healed around and the foreign body in the dog of the present report. The foreign body in our patient had likely been present for 5.5 months prior to imaging, which allowed time for migration of the foreign body through the bones and healing of the outer migration tract. This bony healing of the tract likely made it more difficult to identify the foreign body on ultrasonography. This case highlights the importance of clipping the overlying haircoat of veterinary patients to allow close assessment for any embedded material. However, depending on the time of band placement, the wound or tract may not be visible if granulation tissue has developed. The removed foreign body was a band from a children’s toy set, highlighting that band placement by children during play is a potential route of pet exposure to RBS.
Radiography was diagnostic for identification of RBS and allowed for appropriate treatment recommendations for the dog of the present report. Ultrasonography can also be used to diagnose RBS but was not diagnostic in this case, possibly due to the small diameter of the wall of the rubber band, similar echogenicity to adjacent granulation tissue, or the migration through the bone with resultant partial encircling by the metacarpal bones. Cross-sectional imaging (CT or MRI) and fistulography may be needed for further investigation in some cases of RBS. However, the presence of well-defined symmetric concave or ovoid to tubular bone defects with short zones of transition, particularly at the outer margins of a distal limb, is supportive of a diagnosis of RBS. Although speculative from available literature, querying pet owners whether there are children in the household is recommended because unbeknownst to adult owners, children may place rubber band foreign bodies on their pets, and external signs may not be evident at time of presentation.
References
- 1. ↑
Aggarwal AN, Kini SG, Arora A, Singh AP, Gupta S, Gulati D. Rubber band syndrome–high accuracy of clinical diagnosis. J Pediatr Orthop. 2010;30(7):e1–e4. doi:10.1097/BPO.0b013e3181e0cb8a
- 2. ↑
Saour S, Mohanna PN, James M. An elastic band foreign body circumferentially around the proximal phalanx, detected 2 years post injury. J Plast Reconstr Aesthet Surg. 2010;63(2):e199–e200. doi:10.1016/j.bjps.2009.03.001
- 3. ↑
Armond CD, Niimura del Barrio MC, Rosati T, et al. Tracheal constriction in a growing dog. Vet Rec Case Rep. 2017;5(1):e000399. doi:10.1136/vetreccr-2016–000399
- 4. ↑
Brisson BA, Théoret MC. Osteolysis of the radius and ulna induced by a circumferential foreign body in a cat. J Am Vet Med Assoc. 2008;233(7):1117–1120.
- 5. ↑
Stelmach D, Sharma A, Rosselli D, Schmiedt C. Circumferential cervical rubber band foreign body diagnosis in a dog using computed tomography. Can Vet J. 2014;55(10):961–964.
