Elizabeth A. Riedesel

The use of intraluminal stents for tracheal collapse in two horses: Case management and long-term treatment

Summary Tracheal collapse is an uncommon clinical disorder in horses but when present can be difficult to correct. Various medical and surgical procedures to correct tracheal collapse have been described in horses with variable success. Recently, the use of an intraluminal stent has been described as a treatment for tracheal collapse in a miniature horse. The long-term management, utilising intraluminal stents, in 2 miniature horses with tracheal collapse is presented here. In particular, various complications as a result of intraluminal stent placement are described, the most persistent being the formation of granulation tissue at various regions of the stents. Multiple methods of combating granulation tissue in this situation also are discussed.

A Vascular Hamartoma Arising from the Cervical Spine of a Cat

A 15-month-old cat presented for evaluation of worsening generalized proprioceptive ataxia. Computed tomography of the cervical spine revealed the presence of a compressive extradural bony mass involving the dorsal aspect of C1. Surgical exploration and debulking of the mass was performed. Histological evaluation of the mass revealed fibrovascular tissue consistent with a vascular hamartoma. This mass was deemed to be originating from the soft tissue associated with the C1 vertebra with subsequent bony proliferation. Surgical debulking of the mass resulted in complete resolution of clinical signs with no evidence of recurrence 2 years after surgery.

Computed tomographic appearance of canine thyroid tumours.

OBJECTIVES To describe the computed tomography features of canine thyroid tumours. METHODS Retrospective study of records of dogs with a thyroid tumour and neck computed tomography. Neck computed tomographies were evaluated for tumour characteristics. Thoracic radiographs and computed tomographies were evaluated for lung nodules. RESULTS Of 19 identified cases, 17 were carcinomas and 2 were adenomas; 12 had mineralisation, 16 had heterogeneous attenuation and 16 were unilateral. Tumours were located from the temporomandibular joint to C5. Sixteen had well-defined margins postcontrast. Tumours were ovoid and mean volume was 57·4 cm(3) . By computed tomography, eight had definitive or possible invasion into surrounding structures; all eight were histopathologically invasive carcinomas. Five histopathologically non-invasive tumours and two adenomas had no computed tomography invasion into surrounding structures. Four had complete palpable mobility (two adenomas and two histopathologically invasive carcinomas); one had computed tomography evidence of possible invasion. The sensitivity of palpable mass mobility to determine histopathological invasion was 71% with 0% specificity. The sensitivity of computed tomography invasion to determine histopathological invasion was 70% with 100% specificity. CLINICAL SIGNIFICANCE Computed tomography scans revealed several common features. Palpable mass mobility was not definitive for lack of histopathological invasion. Computed tomography invasion was specific but not very sensitive for histopathological invasion.

Successful medical treatment of an orbital osteoma in a dog

A 6-year-old neutered male German Shepherd-mixed breed with a 2-month history of bilateral conjunctival hyperemia, epiphora, and a firm, slowly progressive swelling of the medial canthal region of the left eye (OS) was examined. Ophthalmic examination OS revealed a firm and smooth mass, extending from the medial canthus toward the medial orbital wall. Indirect ophthalmoscopy revealed indentation of the nasal part OS, which corresponded to the position of the orbital mass. Orbital neoplastic diseases were the main differential considerations. Computerized tomography revealed a bony smooth orbital mass without bone destructive features. Biopsy was performed, and histologic features were suggestive of osteoma. Systemic nonsteroidal anti-inflammatory (NSAID) drugs resulted in complete mass regression and absence of clinical signs for 5 years following initial diagnosis. This report describes the first case of canine orbital osteoma, which was responsive to NSAIDs.

SINGLE-SHOT TURBO SPIN ECHO PULSE SEQUENCE FINDINGS IN DOGS WITH AND WITHOUT PROGRESSIVE MYELOMALACIA

Progressive myelomalacia is an uncommon type of ischemic, hemorrhagic spinal cord infarction. Diagnosis can be difficult, but prompt recognition is important. We hypothesized that cerebrospinal fluid signal attenuation on magnetic resonance (MR) images would be more extensive in dogs that developed progressive myelomalacia vs. control dogs. A retrospective analytic cohort study was designed. Dogs were included if they presented for acute paraplegia and loss of deep pain perception and had undergone MR imaging using both sagittal single-shot turbo spin echo (SSTSE) and standard sagittal T2-weighted fast spin echo (T2W) pulse sequences. Dogs were divided into progressive myelomalacia and control groups for comparisons. All MR examinations were evaluated by three reviewers blinded to patient outcome. Length of cerebrospinal fluid attenuation was recorded as a ratio to the length of the L2 vertebral body in SSTSE and T2W sequences (CSF:L2SSTSE and CSF:L2T2 , respectively). Length of intramedullary spinal cord hyperintensity was recorded as a ratio to the length of the L2 vertebral body in T2W sequences. A total of 21 dogs were included (five in the progressive myelomalacia group and 16 in the control group). The mean CSF:L2SSTSE attenuation value was significantly higher in dogs that developed progressive myelomalacia (CSF:L2SSTSE = 10.7) compared to controls (CSF:L2SSTSE = 5.4; P = 0.015). A cut off ratio of attenuation >7.4 provided optimal differentiation between groups in this study. Findings supported the conclusion that dogs with CSF:L2SSTSE ≤ 7.4 are unlikely to develop progressive myelomalacia while dogs with CSF:L2SSTSE > 7.4 are indeterminate for progressive myelomalacia.

COMPARISON OF FLUOROSCOPY AND COMPUTED TOMOGRAPHY FOR TRACHEAL LUMEN DIAMETER MEASUREMENT AND DETERMINATION OF INTRALUMINAL STENT SIZE IN HEALTHY DOGS

Tracheal collapse is a progressive airway disease that can ultimately result in complete airway obstruction. Intraluminal tracheal stents are a minimally invasive and viable treatment for tracheal collapse once the disease becomes refractory to medical management. Intraluminal stent size is chosen based on the maximum measured tracheal diameter during maximum inflation. The purpose of this prospective, cross-sectional study was to compare tracheal lumen diameter measurements and subsequent selected stent size using both fluoroscopy and CT and to evaluate inter- and intraobserver variability of the measurements. Seventeen healthy Beagles were anesthetized and imaged with fluoroscopy and CT with positive pressure ventilation to 20 cm H2 O. Fluoroscopic and CT maximum tracheal diameters were measured by three readers. Three individual measurements were made at eight predetermined tracheal sites for dorsoventral (height) and laterolateral (width) dimensions. Tracheal diameters and stent sizes (based on the maximum tracheal diameter + 10%) were analyzed using a linear mixed model. CT tracheal lumen diameters were larger compared to fluoroscopy at all locations (P-value < 0.0001). When comparing modalities, fluoroscopic and CT stent sizes were statistically different. Greater overall variation in tracheal diameter measurement (height or width) existed for fluoroscopy compared to CT, both within and among observers. The greater tracheal diameter measured with CT and lower measurement variability has clinical significance, as this may be the imaging modality of choice for appropriate stent selection to minimize complications in veterinary patients.

IATROGENIC MICROCHIP ARTERIAL EMBOLISM IN A CHILEAN FLAMINGO (PHOENICOPTERUS CHILENSIS)

Abstract Aberrant microchip migration has been reported in domestic animal species, but in most cases, this migration is atraumatic to the patient. Reports of microchip-associated trauma and sarcoma development also have been reported in a variety of mammal species. This report describes accidental arterial microchip insertion causing obstruction of the iliac artery in a Chilean flamingo (Phoenicopterus chilensis). Diagnostic imaging included digital radiography and pre- and post-contrast computed tomography to determine the location of the microchip. Surgical removal of the microchip was attempted; however, the flamingo died intraoperatively. Postmortem evaluation found trauma to the epicardium, without penetration of the ventricle. The descending aorta was found traumatized and identified as the most likely insertion point leading to the embolism.