Spontaneous regression of osteosarcoma in four dogs.

Spontaneous regression of primary malignant bone tumors is rare but has been reported in the human literature. To the authors' knowledge, spontaneous regression of primary bone tumors in dogs or cats has not been reported. Osteosarcoma (OSA) is the most common primary bone tumor in humans, and it has been reported that the incidence of OSA is 40 to 50 times greater in dogs than humans. In this report, high-grade OSA was diagnosed in biopsy specimens obtained from 4 dogs that subsequently underwent spontaneous regression without tumor-specific treatment. Osteosarcoma in dogs has characteristics similar to that of OSA in humans.

Use of pyloroplasty (Y-U) to treat presumed delayed gastric emptying in a cheetah (Acinonyx jubatus).

A 4-yr-old cheetah (Acinonyx jubatus) with a 2-yr history of chronic intermittent vomiting and spiral bacteria-associated gastritis presented with dramatically increased vomiting frequency and marked intermittent abdominal distention. Physical examination revealed loss of muscle mass and poor fur coat quality. Contrast radiography was consistent with delayed gastric emptying due to presumed gastric outlet obstruction. Both Y-U pyloroplasty and incisional gastropexy were performed, and no subsequent vomiting has been observed for 3 yr with the exception of three episodes during the immediate postoperative period. The cause of delayed gastric emptying was not determined, although a gastric motility disorder associated with gastric bacterial infection and elevated gastrin levels was suspected.

Omentum-enhanced reconstruction of chronic nonhealing wounds in cats: techniques and clinical use.

The greater omentum was used to aid in the reconstruction of nonhealing wounds in five cats. In each cat the cause of the nonhealing wound could not be determined. A vascular omental pedicle was created at laparotomy by dividing the dorsal leaf of the omentum at it pancreatic attachments (four cats) or by dividing the ventral leaf at its gastric attachments (one cat). The pedicle was then passed through either the ventral or lateral body wall into the nonhealing wound via a subcutaneous tunnel. The wounds were closed over the omentum after local tissue mobilization. All the wounds healed uneventfully and have remained healed with a mean follow-up period of 2.5 years. Complications included intestinal herniation through a ventral midline exit hole (one cat), presumed abdominal fat herniation through a ventral abdominal exit hole (one cat) and seroma formation (one cat). All of the complications were treated successfully. The omentum should be considered a useful adjunct in the treatment of nonhealing wounds in cats.

The effects of plate type, angle of ilial osteotomy, and degree of axial rotation on the structural anatomy of the pelvis.

Unilateral triple pelvic osteotomy was performed with three variations in technique on canine cadaver pelves. The following variables were studied: the angle of the ilial osteotomy (perpendicular to the long axis of the ilium and 10 degrees, 20 degrees, and 30 degrees off perpendicular); the degree of axial rotation (20 degrees, 30 degrees, and 45 degrees); and the type of fixation (canine pelvic osteotomy plate [CPOP] or a 2.7-mm dynamic compression plate [DCP]). Structural changes measured were the pelvic inlet and acetabular area, interischiatic tuberosity distance, and degree of acetabular version. Means and standard error of the means were determined for all pelvic measurements and were analyzed by three-way analysis of variance (P < .05). As the axial rotation increased from 20 degrees to 45 degrees an ilial osteotomy angled 10 degrees, 20 degrees, or 30 degrees resulted in a significantly greater decrease in the pelvic inlet area and significantly less deviation of the interischiatic tuberosity distance and degree of acetabular version from normal than an osteotomy directed perpendicular to the long axis of the ilium. Compared with the CPOP, as the axial rotation increased from 20 degrees to 45 degrees, the DCP resulted in a significantly greater decrease in the pelvic inlet area, an increase in the interischiatic tuberosity distance and degree of acetabular version, and less of an increase in the acetabular area. The results of this study suggest that to maximize dorsal acetabular coverage, while minimizing disruption of normal pelvic architecture, a CPOP and an ilial osteotomy angled 10 degrees to 30 degrees are preferred for all degrees of axial rotation.

Effect of total ablation of the external acoustic meatus and bulla osteotomy on auditory function in dogs.

Seven dogs with end-stage bilateral otitis externa were evaluated for auditory function before and after bilateral total ear canal ablation and lateral bulla osteotomy. Evaluations were performed by owner questionnaire and by recording brainstem auditory-evoked responses. Prior to surgery, all dogs could hear a loud voice or noise, however, only 3 dogs responded to a voice spoken at a normal level. Of the 14 ears tested electrodiagnostically, only 1 did not have a response, using air-conducted or bone-conducted stimuli. After surgery, 2 dogs responded to a normal voice, but all 7 responded to loud voices or noise. Three ears that had recordable brainstem auditory-evoked responses to air-conducted stimulation prior to surgery, failed to respond after surgery. Ears that responded to bone-conducted stimulation prior to surgery also responded after surgery.

Evaluation of an omental pedicle extension technique in the dog.

A two-step omental pedicle extension technique was performed on 10 dogs. Step 1 of the pedicle extension involved release of the dorsal leaf of the omentum from its pancreatic attachment, whereas step 2 consisted of an inverse L-shaped incision to double the length of the pedicle. The pedicle dimensions were measured and the distance reached when extended toward the hind limb, forelimb, and the muzzle recorded after each stage of the procedure. The vascular patency of the pedicle was determined by intravenous injection of fluorescein dye after the second stage of omental extension. Mean pedicle lengths were 44.5 cm with the first stage of extension and 82.0 cm after full extension. The mean width at the caudal extent of the pedicles after dorsal and full extension was 30.4 cm and 17.2 cm, respectively. Eight of the 10 pedicles were patent after full extension. The fully extended omental pedicles reached and, in most cases, extended beyond the distal extremities and the muzzle. The findings in this study suggest that the canine omentum can be extended to any part of the body without being detached from its vascular supply.

Biomechanical evaluation of acrylic external skeletal fixation in dogs and cats.

Acrylic external skeletal fixators (ESF) were compared with Kirschner ESF in biomechanical tests. A 2-cm unilateral acrylic ESF was found to be superior to medium Kirschner ESF in compression and shear loads. Acrylic ESF performed as well as Kirschner ESF in torsion loads. Acrylic ESF were used on 11 dogs and cats for repair of long bone fractures, for arthrodesis, or for immobilization of joints following ligament or tendon surgery. There were no complications associated with the use of acrylic ESF. Acrylic ESF offers the advantage of reduced cost, improved versatility, and simplified application technique when compared with Kirschner ESF.

Primary jejunal osteosarcoma associated with a surgical sponge in a dog.

Primary jejunal osteosarcoma was diagnosed in association with a surgical sponge in a dog. The tumor was biologically aggressive, resulting in widespread metastasis throughout the abdomen within 2 months of surgical resection. Microscopic examination of the resected osteosarcoma revealed strands of gauze material throughout the tumor mass. It was theorized that the presence of a sponge foreign body may have resulted in malignant transformation of adjacent tissues similar to what has been reported to occur after internal fixation of some long-bone fractures.

Transcatheter thoracic duct embolization in the dog. An experimental study.

Thoracic duct embolization was created by injecting an isobutyl 2-cyanoacrylate/iophendylate (IBCA) mixture through a cannulated mesenteric lymphatic vessel in eight normal dogs. Aqueous contrast lymphangiography was repeated at minute 10 and week 6. Six dogs were euthanatized at week 6 and two dogs at month 6. Embolization with 1.5 to 3.9 ml of the mixture resulted in complete obstruction of the thoracic duct in all eight dogs. Results of lymphangiography in six dogs at week 6 showed a persistent, complete obstruction of the thoracic duct in six dogs and alternate lymphaticovenous anastomoses in four dogs. Histologically, there were a sclerosing granulomatous response surrounding the lymphatic embolus, mild congestive changes in the mesenteric lymph nodes, and mild lacteal dilatation in the jejunum. The procedure was well tolerated with only a few complications. One dog suffered partial thrombosis of the cranial vena cava by the injected material with later dislodgement and embolization of a pulmonary artery branch. Modifications have been made in the injection procedure to avoid this complication. This technique for occlusion of the thoracic duct shows potential for clinical use in the management of canine chylothorax. The obstruction appears to be complete and permanent, and surgical/anesthetic time is decreased greatly from previously described procedures.

ATP requirement for mg chelatase in developing chloroplasts.

The synthesis of Mg-protoporphyrin-IX from exogenous protoporphyrin-IX, in a crude plastid pellet extracted from greening cucumber cotyledons was found to require l-glutamate as a cofactor. It has now been shown that glutamate acts in the presence of contaminating mitochondria to provide an ATP regenerating system. With purified plastids, Mg chelatase is not stimulated by glutamate; instead, it requires a high concentration of ATP and is greatly stimulated by added phosphoenolpyruvate and pyruvate kinase. GTP, UTP, CTP, and ITP will not substitute for ATP. ADP in the absence of an ATP generating system is completely ineffective, whereas it is slightly inhibitory in the presence of 10 mm ATP. AMP is strongly inhibitory in the reaction; 50% inhibition is obtained at approximately 3.5 mm AMP in the presence of 10 mm ATP.