Arthroscopic removal of a solitary osteochondroma interfering with the podotrochlear apparatus in a foal.

OBJECTIVE: To report the diagnostics, surgical treatment, and outcome of a juvenile foal with solitary osteochondroma (SO) interfering with the podotrochlear apparatus. STUDY DESIGN: Case report ANIMAL: One 36-day-old Arabian colt. METHODS: Clinical, radiographic, ultrasonographic, computed tomographic, and histopathologic examinations were required to characterize and treat an SO located at the palmar aspect of the diaphysis of the second phalanx of the left forelimb. This SO caused severe distal interphalangeal joint (DIPJ) inflammation, marked interference with the podotrochlear apparatus, and associated lameness. RESULTS: Despite the small size of the foal's foot, complete resection of the SO was possible via palmar DIPJ arthroscopy by using motorized equipment. Full resolution of the lameness was achieved within 3 months of surgery. CONCLUSION: Atypical SO located on the palmar aspect of the second phalanx can cause marked nonseptic inflammation of the DIPJ and interference with the podotrochlear apparatus and should be considered among the differential diagnoses for severe lameness in juvenile foals. Arthroscopic resection of the SO led to an excellent outcome.

Arthroscopic approach and intra-articular anatomy of the equine atlanto-occipital joint.

OBJECTIVE: To develop arthroscopic approaches to the atlanto-occipital (A-O) and describe associated arthroscopic anatomy. STUDY DESIGN: Experimental ex vivo study and clinical case report. ANIMALS: Ten equine cadaver joints and 1 clinical case. METHODS: CT arthrograms of 8 A-O joints were performed to determine the placement of an arthroscopic portal. Arthroscopy was performed via dorsal and/or ventral approaches (dorsal or ventral to the longissimus capitis tendon) in 10 cadaveric A-O joints and the A-O joint of a 2-week-old foal with septic arthritis. Accessible cartilage was debrided in 3 cadaver joints. Accessibility and risks were assessed by review of arthroscopic images, postoperative necropsy, and computed tomography (CT). RESULTS: Dorsal and ventral outpouchings of the A-O joint were identified with CT. Arthroscopy of the dorsal pouch provided access to 50% of the dorsocranial occipital condyle and 15% of the dorsocranial atlas articular surfaces. Joint distension caused displacement of the dura. Dura perforation occurred with a blind dorsal approach in 2 of 5 joints. Dura perforation did not occur after ultrasonography-guided approaches. Arthroscopic debridement of septic arthritis and osteomyelitis was successful in 1 clinical case. CONCLUSION: Approaches to the A-O joint were determined from CT examinations. The cranial aspect of the dorsal pouch of the A-O joint was accessed via arthroscopic triangulation in all horses of this study. Ultrasound-guided joint access prevented perforation of vital structures, including the spinal canal. CLINICAL SIGNIFICANCE: Advanced imaging improves the diagnosis of A-O joint pathology. Descriptions of arthroscopic anatomy and accessibility provide important information for surgical intervention.

PROSPECTIVE COMPARISON OF TUMOR STAGING USING COMPUTED TOMOGRAPHY VERSUS MAGNETIC RESONANCE IMAGING FINDINGS IN DOGS WITH NASAL NEOPLASIA: A PILOT STUDY.

Identification of nasal neoplasia extension and tumor staging in dogs is most commonly performed using computed tomography (CT), however magnetic resonance imaging (MRI) is routinely used in human medicine. A prospective pilot study enrolling six dogs with nasal neoplasia was performed with CT and MRI studies acquired under the same anesthetic episode. Interobserver comparison and comparison between the two imaging modalities with regard to bidimensional measurements of the nasal tumors, tumor staging using historical schemes, and assignment of an ordinal scale of tumor margin clarity at the tumor-soft tissue interface were performed. The hypotheses included that MRI would have greater tumor measurements, result in higher tumor staging, and more clearly define the tumor soft tissue interface when compared to CT. Evaluation of bone involvement of the nasal cavity and head showed a high level of agreement between CT and MRI. Estimation of tumor volume using bidimensional measurements was higher on MRI imaging in 5/6 dogs, and resulted in a median tumor volume which was 18.4% higher than CT imaging. Disagreement between CT and MRI was noted with meningeal enhancement, in which two dogs were positive for meningeal enhancement on MRI and negative on CT. One of six dogs had a higher tumor stage on MRI compared to CT, while the remaining five agreed. Magnetic resonance imaging resulted in larger bidimensional measurements and tumor volume estimates, along with a higher likelihood of identifying meningeal enhancement when compared to CT imaging. Magnetic resonance imaging may provide integral information for tumor staging, prognosis, and treatment planning.

Multiple intravenous injections of allogeneic equine mesenchymal stem cells do not induce a systemic inflammatory response but do alter lymphocyte subsets in healthy horses.

INTRODUCTION: Intravenous (IV) injection of mesenchymal stem cells (MSCs) is used to treat systemic human diseases and disorders but is not routinely used in equine therapy. In horses, MSCs are isolated primarily from adipose tissue (AT) or bone marrow (BM) and used for treatment of orthopedic injuries through one or more local injections. The objective of this study was to determine the safety and lymphocyte response to multiple allogeneic IV injections of either AT-derived MSCs (AT-MSCs) or BM-derived MSCs (BM-MSCs) to healthy horses. METHODS: We injected three doses of 25 × 10(6) allogeneic MSCs from either AT or BM (a total of 75 × 10(6) MSCs per horse) into five and five, respectively, healthy horses. Horses were followed up for 35 days after the first MSC infusion. We evaluated host inflammatory and immune response, including total leukocyte numbers, serum cytokine concentration, and splenic lymphocyte subsets. RESULTS: Repeated injection of allogeneic AT-MSCs or BM-MSCs did not elicit any clinical adverse effects. Repeated BM-MSC injection resulted in increased blood CD8(+) T-cell numbers. Multiple BM-MSC injections also increased splenic regulatory T cell numbers compared with AT-MSC-injected horses but not controls. CONCLUSIONS: These data demonstrate that multiple IV injections of allogeneic MSCs are well tolerated by healthy horses. No clinical signs or clinico-pathologic measurements of organ toxicity or systemic inflammatory response were recorded. Increased numbers of circulating CD8(+) T cells after multiple IV injections of allogeneic BM-MSCs may indicate a mild allo-antigen-directed cytotoxic response. Safety and efficacy of allogeneic MSC IV infusions in sick horses remain to be determined.

Extraoral surgical correction of lingual entrapment in a Chinese goose (Anser cygnoides).

An adult female Chinese goose (Anser cygnoides) presented with a ventral displacement of the hyoid apparatus, associated with distension of the intermandibular sublingual space and of the gular skin, causing difficulties with prehension and deglutition of food and water. Physical examination revealed that the tongue was able to move normally and could be replaced into a normal anatomical position by external compression of the distended ventral intermandibular region. A mild hypoalbuminemia was the only remarkable finding of the biochemistry panel. Radiographs and computed tomography scan of the head and neck regions confirmed a normal hyoid apparatus. An extraoral surgical reconstruction of the distended intermandibular skin was performed: the excess skin was incised and resected and the margins of the incision were sutured with appropriate tissue tension to obtain a good apposition and prevent ventral displacement of the hyoid apparatus. Postoperative complication included airway obstruction by a large amount of respiratory secretions, which were successfully aspirated from the trachea. A supportive elastic bandage was placed at the level of the beak commissure during the following 24 hours in order to reduce downward pressure on the suture line and minimize the risk of dehiscence of the suture. The goose resumed eating within 4 hours following the surgery and oxygen supplementation was discontinued after 24 hours. Respiration was assessed as normal and the tongue remained permanently in normal position. The lingual entrapment did not recur during the following 18 months.

Clinical and scintigraphic findings in horses with a bone fragility disorder: 16 cases (1980-2006).

OBJECTIVE: To describe clinical and scintigraphic abnormalities in horses with a bone fragility disorder. DESIGN: Retrospective case series. ANIMALS: 16 horses with scintigraphic evidence of multiple sites of increased radiopharmaceutical uptake (IRU). Procedures-Medical records were reviewed for information on signalment; history; clinical, clinicopathologic, and diagnostic imaging findings; and treatment. Follow-up information was obtained through telephone interviews with owners. RESULTS: Horses ranged from 4 to 22 years old; there were 8 castrated males and 8 females. Foci of IRU most commonly involved the scapulae, ribs, sternebrae, sacral tubers, ilia, and cervical vertebrae. Most horses were examined because of chronic intermittent (n = 10) or acute (6) lameness involving a single (10) or multiple (6) limbs that could not be localized by means of regional anesthesia. Cervical stiffness (n = 3), scapular bowing (3), swayback (3), and ataxia (1) were also seen in more advanced cases. Signs of respiratory tract disease and exercise intolerance were evident in 4 horses. Ultrasonographic or radiographic evidence of bone remodeling or degeneration was seen in 19 of 33 affected bones. Histologic examination of bone biopsy specimens revealed reactive bone. Improvement was initially seen with conservative treatment in some horses, but the condition worsened in all horses, and 11 horses were euthanized within 7 years. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that horses may develop a bone fragility disorder characterized clinically by an unlocalizable lameness and scintigraphically by multiple sites of IRU involving the axial skeleton and proximal portion of the appendicular skeleton.

Evaluation of continuous infusion of lidocaine on gastrointestinal tract function in normal horses.

OBJECTIVE: To determine the effect of continuous infusion of lidocaine on fecal transit time in normal horses. STUDY DESIGN: Experimental randomized cross-over study. ANIMALS: Healthy horses (n=6). METHODS: Barium-filled microspheres were administered to horses by nasogastric intubation and feces were collected every 2 hours for 4 days. A bolus of 2% lidocaine (1.3 mg/kg) was administered randomly, followed by a continuous infusion of lidocaine (0.05 mg/kg/min) for 3 days or an equivalent volume of saline. The washout period was 10 days. Variables assessed included defecation frequency, weight of feces produced, intestinal transit time (number of microspheres observed on radiographs), fecal moisture content, borborygmus score, heart and respiratory rate, and signs of lidocaine toxicity (e.g., ataxia, CNS depression). RESULTS: During the first 24 hours of lidocaine administration, mean (+/-SD) fecal output (10.8+/-6.9 kg) was decreased compared with controls (15+/-4.9 kg). Mean (+/-SEM) time for passing 50% of the barium-filled microspheres was shorter in controls (42+/-1.13 hours) compared with the lidocaine group (50+/-1.32 hours). CONCLUSIONS: Continuous infusion of lidocaine increases the transit time of feces in normal horses. CLINICAL RELEVANCE: Clinicians need to be aware of the effects of using a continuous infusion of lidocaine on the transit time of feces in normal horses, with a potential for exacerbating those effects when combined with drugs that decrease motility and in horses with medical colic (e.g., impaction) or where a diagnosis has not been made.

Skeletal lesions of histiocytic sarcoma in nineteen dogs.

The purpose of this study was to describe the clinical and radiographic findings in dogs with bone lesions secondary to histiocytic sarcoma. Nineteen dogs with radiographically identified bone lesions that were histologically diagnosed as histiocytic sarcoma were assessed. The medical records, all available radiographs and histologic sections were reviewed retrospectively. Dogs were subcategorized into localized or disseminated histiocytic sarcoma groups. Golden Retrievers or Rottweilers greater than 5 years of age, with a history of lameness or neurologic deficits localized to the spinal cord was the most common presentation. Fifteen of 19 dogs had a radiographically detectable soft tissue mass associated with bone destruction. The bone lesions had aggressive characteristics and the sites of involvement included periarticular bones (n = 11), vertebrae (n = 6), proximal humerus (n = 5), and rib (n = 2). Fifteen of 19 dogs had disseminated histiocytic sarcoma, and four had localized histiocytic sarcoma. All Rottweilers had disseminated histiocytic sarcoma. Histiocytic sarcoma should be considered as a differential diagnosis for aggressive periarticular, vertebral, or proximal humeral bone lesions identified on radiographs. The index of suspicion should be increased in greater than 5-year-old Golden Retrievers and Rottweilers when a soft tissue mass is associated with the bone lesion on radiographs or myelography. Bone involvement with histiocytic sarcoma, and the Rottweiler breed, was associated with the disseminated form of the disease.