Comparison of autogenous cancellous bone grafts obtained from the sternum and proximal portion of the tibia of llamas.

OBJECTIVE: To describe the anatomy of the sternum in llamas, define the surgical approach to the sternum for collection of cancellous bone graft tissue, and compare the histologic appearance of graft tissue obtained from the sternum with that obtained from the proximal portion of the tibia. DESIGN: Prospective study. ANIMALS: 12 llamas, 3 to 19 years old, that had been submitted for necropsy. PROCEDURE: Radiographs were taken of the sternum and left tibia of the llamas. Measurements of the sternum were determined from the radiographs and adjusted for magnification. Sternebrae volumes were estimated from these measurements. Anatomic dissections to the center of the fourth sternebra and the proximal portion of the tibia were made, and a surgical approach to the sternum was developed. Cancellous graft tissue was obtained from each site and submitted for histologic evaluation. RESULTS: Sternebrae 3, 4, and 5 were significantly larger in volume than the other sternebrae. The ventral aspect of the fourth sternebra was readily accessed for removal of graft tissue by making a 6-cm-long ventral midline incision centered 17 cm craniad to the xipnoid. Mean soft tissue thickness overlying the ventral aspect of the fourth sternebra was 3.1 cm. More tissue was obtained from the sternal (mean, 9.11 g) than from the tibial (mean, 5.16 g) sites. Sternal graft tissue consisted of trabecular bone spicules with predominantly hematopoietic marrow, whereas tibial tissue consisted of trabecular bone spicules with only fatty marrow. CONCLUSIONS AND CLINICAL RELEVANCE: The fourth sternebra in llamas is readily accessible for obtaining autogenous cancellous bone graft tissue that consists of predominantly hematopoietic marrow.     

Autogenous Cancellous Bone Grafts From the Sternum in Horses Comparison With Other Donor Sites and Results of Use in Orthopedic Surgery

Cancellous bone was collected from the fourth or fifth sternebra of six horses aged 12 to 36 months, and compared quantitatively and qualitatively with cancellous bone collected from the tuber coxa, proximal tibia, and rib at the time of necropsy, 28 to 49 days after surgery. Cancellous bone collected from the sternum was equivalent in amount and in microscopic appearance to that collected from the other three sites.
Cancellous bone also was collected from the sternum for use during clinical orthopedic surgery in 18 horses. Wound dehiscence occurring in two horses healed uneventfully by second intention. In each horse, an adequate amount of cancellous bone was obtained from one sternebra, with the exception of one horse where cancellous bone from two sternebra was used. Major complications with the donor sites were not encountered.     

Use of internal splinting to realign a noncompliant sternum in a cat with pectus excavatum

CASE DESCRIPTION: A 5.5-month-old female domestic longhair cat was examined because of dorsal deviation of the caudal aspect of the sternum and progressively worsening dyspnea during play activities. CLINICAL FINDINGS: A diagnosis of pectus excavatum was made clinically and confirmed radiographically. The cardiac silhouette was shifted into the right hemithorax. The vertebral index (VI) and frontosagittal index (FSI), which are radiographic indices used to grade the extent of the deformity, were 5.2 and 3.0, respectively. Minimum thoracic height was 13 mm at this time. TREATMENT AND OUTCOME: The sternal malposition was corrected during surgery; for stabilization, an internal splint was provided by use of a plate that was applied to the ventral side of the sternum. Radiographic indices improved until day 85; at that time, an increase in the distance between plate and sternum was detected, and plate removal was advised. The radiographic indices improved again after plate removal. At 310 days after surgery, VI was 9.6, FSI was 1.6, and minimum thoracic height was 34 mm. No dyspnea was evident during physical examination. CLINICAL RELEVANCE: Results of treatment suggest that this technique may be useful as an alternative surgical option for cats with pectus excavatum that have a noncompliant sternum.     

Comparative Structure and Morphology of the Goat Sternum in West African Dwarf and Danish Landrace Breeds

The structure and morphology of the sternum from 33 West African dwarf (WAD) and sixteen Danish Landrace breed goats were studied radiographically. In young kids of the Danish Landrace breed (DL), the number of sternal elements (Sternebrae) was six or seven with the fifth or the last but one being double in some animals due to bilateral bodies. All the sternal elements in the WAD breed appeared to have each a single locus of ossification and the number of sternal elements varied between 5, 6 or 7 at birth. In those goats with 5 or 6 sternal segments, bilateral indentations were observed on the left and right side on either the last or the last two segments. These indentations were considered to indicate a prenatal cranial coalescence of the last segments leading to the reduced number of sternebra. The structure and morphology of the sternum in neonatal kids for the two breeds appears to be basically different. 8 sternal and 5 asternal ribs were observed in animals of both breeds. The cartilaginous attachments of the ribs on the sternal segments were variable. A floating rib was also observed in one of the WAD goats. The comparative structure and morphology of other ruminant sternum is also discussed.     

Surgical correction of pectus excavatum in two cats

Two sexually intact male Bengal cats, one a 4-month-old weighing 2.8 kg and the other, a 3-month-old weighing 2.0 kg, were presented to the University of Missouri-Columbia Veterinary Teaching Hospital for evaluation of respiratory distress. On initial presentation, both cats were dyspneic, exercise intolerant, and had marked concave deformation of the caudal sternum. Surgical correction of pectus excavatum was performed using a cylindrical external splint and U-shaped external splint. Post-operative thoracic radiography revealed that there was decreased concavity of the sternum and increased thoracic height at the level of the caudal sternebrae in both cats.     

Pectus excavatum surgically repaired using sternum realignment and splint techniques in a young cat

Successful surgical repair of pectus excavatum deformities has so far only been reported in very young animals. This case report describes an alternative technique for repairing pectus excavatum in a young cat. The cat had shown moderate deformity with slight respiratory impairment when young and had experienced clinical problems with age. A sternum realignment technique involving a pin associated with an external splint was used. This alternative technique was a safe and efficient procedure in the five-month-old cat.     

Estudio Radiológico del Esternón del Ovino en Crecimiento

Radiological investigation of the sternum of the sheep A radiological investigation of the sternum of the sheep demonstrated distinct growth phases. Forty Merino sheep of mixed breeds were distributed into 4 age groups of 0, 45, 105 and 270 days. Each animal was radiographed in sternal and lateral recumbency. Measurements were made from the radiographs. The sternebra are rectangular in newborn and become concave in adult. The curvature of the sternum is 16 to 17° at day 0 and 27–28° at day 270. The nucleus of ossification was seen in all sternebrae at 45 days of age, they were present only in the most caudal sternebrae at 105 days.     

Optimisation of bone marrow aspiration from the equine sternum for the safe recovery of mesenchymal stem cells

Reasons for performing study: Mesenchymal stem cell (MSC) therapy for orthopaedic disease is being used with increasing frequency; there is a need to define a safe, reliable and effective technique for the recovery of MSCs from the sternum of the horse. Objectives: To describe an optimised safe technique for obtaining bone marrow‐derived MSCs from the sternum of the Thoroughbred horse. Methods: The anatomical relationship of the sternum with the heart and internal anatomy was demonstrated in cadavers. Sternal anatomy was evaluated ultrasonographically and after midline sectioning. Sternebrae were examined histologically after aspiration to determine the effect of needle insertion. The quality of the aspirate was evaluated as the number of colony‐forming units from sequential and separately aspirated 5 ml aliquots and assessed for their multipotency using trilineage differentiation. Results: The optimal safe location for the needle was the 5th sternebra because it had a safe dorsoventral thickness and was cranial to the apex of the heart. This sternebra could be reliably identified ultrasonographically. Aspirates could also be obtained from the 4th and 6th sternebrae, although the former is between the front limbs and the latter closer to the heart. Minimal disruption of the internal bony architecture was seen after needle insertion through the thin outer cortex and the first 5 ml aliquot contained the greatest number of colony‐forming units of mesenchymal stem cells with trilineage capabilities. Conclusions: Accurate placement of a Jamshidi needle into the medullary cavity of the 4th–6th individual sternebrae is facilitated by the use of ultrasonography and enables aspiration of bone marrow reliably with minimal damage to the sternum and risk to the horse. Potential clinical relevance: Sternal marrow aspiration as described is a safe and reliable technique to obtain MSCs for orthopaedic cell‐based therapies.     

Surgical correction of pectus excavatum, using external splintage in two dogs and a cat

Two 4-week-old pups and a 7-week-old kitten with respiratory distress and pectus excavatum were treated by external application of a coaptation splint to the ventral aspect of the thorax. Sutures were placed percutaneously around the sternum and through predrilled holes in a piece of moldable splint material that had been contoured to fit a normal-shaped thorax. Correction of the sternal deformity and alleviation of respiratory distress were achieved in all 3 animals. Frontosagittal index and vertebral index were assessed before and after surgery. In all 3 animals, both indices were abnormal before surgery, but were within the normal range after surgery.     

Sternal bone biopsy in standing horses

OBJECTIVE: To develop a technique for sternal bone biopsy in standing horses. STUDY DESIGN: Experimental study. ANIMALS: Five adult horses. METHODS: Horses were restrained in a standing stocks and sedated. The sternal biopsy site, identified by ultrasonographic examination, was clipped and prepared for aseptic surgery and infiltrated with local anesthetic. An electric bone biopsy drill (Osteocore; Institut Straumann AG, CH-4437, Waldenburg, Switzerland)), which yielded 4-mm-diameter bone specimens, was used to obtain sternal biopsies through a small skin incision. Sections (7 microm) of the bone specimens were stained with toluidine blue and Goldner's green trichrome and observed microscopically to determine suitability for histological and histomorphometric evaluation. RESULTS: The most suitable sternal biopsy site was at the 4th or 5th sternebra. The surgical procedure was easy to perform and well tolerated by the horses, and adequate samples were obtained on the first attempt. The only complications were incisional edema in all horses and wound drainage in 1 horse. CONCLUSIONS: Sternal bone biopsy may be successfully performed in standing horses, and the technique described in this report yields architecturally intact bone specimens. CLINICAL RELEVANCE: The sternum is an accessible site for cancellous bone biopsy specimens in standing horses.     

Imaging diagnosis--acquired pectus excavatum secondary to laryngeal paralysis in a dog

A 13-year-old neutered female Labrador retriever had inspiratory dyspnea secondary to bilateral laryngeal paralysis. Radiographically, there was pectus excavatum with a mediastinal shift to the right. Arytenoid lateralization was performed, relieving the upper respiratory obstruction, and the sternal deformity also resolved. Chronic upper respiratory obstruction should be considered in dogs with pectus excavatum. Furthermore, correction of upper respiratory obstruction has the potential to result in resolution of pectus excavatum.     

PRIMARY OSTEOSARCOMA OF THE STERNUM OF A DOG

Primary osteosarcoma of the fifth sternebra is reported in a 6-year-old male Great Dane. Presenting signs were suggestive of myocarditis and pulmonary congestion. Electrocardiography revealed R waves of low and variable amplitude and the plasma alpha-hydroxibutyrate dehydrogenase level was elevated. Radiography revealed neoplasia of the fifth sternebra with extensive bilaterial pulmonary metastases. Histologically the neoplasm showed typical osteosarcoma with plentiful osteoid production.     

Use of cancellous bone graft in treatment of navicular bone osteomyelitis in a foal

A 3-month-old Quarter Horse filly stepped on a fence staple and developed navicular bone osteomyelitis of the right hindfoot. A 1.5-cm spherical portion of medullary cavity containing purulent material was debrided and flushed with 0.9% NaCl solution. Cancellous bone was collected from a caudal sternebra and placed into the defect. The solar defect had filled with granulation tissue and was epithelialized 6 weeks after surgery. At 6-month follow-up evaluation, the navicular bone defect had healed and the foal was sound on the limb. Cancellous bone grafting may have merit for the treatment of navicular bone osteomyelitis in the horse.     

Dynamic right ventricular outflow tract (infundibular) stenosis and pectus excavatum in a dog

This is the first published report of a dog with dynamic right ventricular outflow tract (infundibular) stenosis, right ventricular hypertrophy, and pectus excavatum. A juvenile dog presented with a grade V/VI left base systolic heart murmur, tachycardia, and pectus excavatum. Diagnosis of the aforementioned conditions was based on radiography, electrocardiography, and echocardiography. At 9 1/2 wk of age the heart murmur was no longer audible and the right ventricular stenosis and hypertrophy had dissipated and regressed, respectively. Resolution may be associated with growth of the dog. A good prognosis is foreseen.     

Repair of pectus excavatum by percutaneous suturing and temporary external coaptation in a kitten

Severe pectus excavatum sternal deformity in a 3-month-old kitten was repaired by use of percutaneous circumcostal and circumsternal sutures to coapt the sternal deformity to an external splint made from thermoplastic material. One year after treatment, the kitten remained free of clinical signs of the disease or complications from the repair. The technique represents a conservative method of repair of pectus excavatum deformities in immature animals.     

Surgical management of a traumatic dislocation of the sternum in an English bulldog

A nine‐year‐old English bulldog presented with an acute history of dyspnoea, tachycardia and discomfort localising to the ventral thorax following a fall down the stairs that morning. After the dog was stabilised, thoracic radiographs revealed a luxation of the third and fourth sternebrae with dorsal displacement of the caudal segment. The sternum was reduced and stabilised with a contoured 12‐hole 3 · 5‐mm dynamic compression plate applied to the ventral surface of the sternum. The dog's initial recovery was rapid, cardiorespiratory parameters returning to normal in the first 24 hours. For 2 weeks postoperatively the dog exhibited difficulty in rising from a prone position. After this time there was a full recovery. Clinical examination at 8 months postoperatively did not reveal any abnormalities. Telephone follow‐up was performed at 18 months and no complications or cardiorespiratory compromise were reported. To the authors’ knowledge, this is the first reported case of a traumatic dislocation of the sternum and its management in the dog.     

Hypervitaminosis A in a cat.

A 10-year-old cat that was kept on a diet consisting largely of raw liver was evaluated because of lethargy, partial anorexia, and weight loss of several months' duration. The cat's head and neck were rigidly extended, and a hard mass was palpable in the ventral cervical region. Cervical and thoracic radiography revealed proliferative bony lesions of the cervical and thoracic vertebrae as well as of the sternum and costal cartilages. Serum vitamin A concentration was 4 times normal. For reasons unrelated to hypervitaminosis A, euthanasia and necropsy were performed 6 months after evaluation. The skull and the cervical and first few thoracic vertebrae were rigidly fused, and the vertebral architecture was altered by deposition of new bone. The sternum and costal cartilages were similarly affected. The historical, physical, radiographic, laboratory, and postmortem findings were consistent with the diagnosis of hypervitaminosis A. On the basis of findings in this cat, hypervitaminosis A should be suspected in any sick cat fed a diet consisting partly or completely of raw liver.     

Estimation in vivo of the body and carcass chemical composition of growing lambs by real-time ultrasonography

The relationship between ultrasound measurements and empty body and carcass chemical composition was investigated. A 500-V real-time ultrasound with a 7.5-MHz probe combined with image analysis was used to make in vivo measurements to predict the empty body and carcass chemical composition of 31 female lambs of two genotypes, ranging in BW from 18.2 to 48.9 kg. Eleven ultrasound measurements of s.c. fat, muscle, and tissue depth were taken at four different sites (over the 13th thoracic vertebra, between the 3rd and 4th lumbar vertebrae, at the 3rd sternebra of the sternum, and over the 11th rib, 16 cm from the dorsal midline). The single best predictor of empty body fat quantity and energy value was the s.c. fat depth over the 13th thoracic vertebra (r(2) = 0.904 and 0.912; P <0.01, respectively). Body weight was used with ultrasound measurements in multiple regression equations to establish the best independent variables combination for predicting chemical composition. Results showed that BW and two of the three ultrasound measurements (s.c. fat depth over the 13th thoracic vertebra, between the 3rd and 4th lumbar vertebrae, and tissue depth over the 11th rib, 16 cm from the dorsal midline), explained 94.7 to 98.7% (P < 0.01) of the quantity of water and fat and the energy value variation in the empty body and carcass. Body weight per se was the best predictor of the quantity of protein, accounting for 97.5 and 96.8% (P < 0.01) of the variation observed in the empty body and carcass, respectively. The results of this study suggest that BW and some ultrasound measurements combined with image analysis, particularly subcutaneous fat depth over the 13th thoracic vertebra, allow accurate prediction of empty body and carcass chemical composition in lambs.     

Pectus excavatum and left to right intracardiac shunt in a kitten

A six-week-old female kitten presented for severe pectus excavatum. Surgical correction was performed. One week later the kitten developed dyspnoea and a systolic murmur was detected on thoracic auscultation. Pulmonary oedema and cardiomegaly were identified radiographically, and a left to right intracardiac shunt was visualized using non-selective angiocardiography. Clinical signs resolved spontaneously one month later. The kitten has been asymptomatic for 24 months.