A Technique for Elective Splenectomy of Equidae Using a Transthoracic Approach

Splenectomy was performed electively on 80 ponies, horses, and donkeys for preparation in collecting Babesia antigens. Access to the abdomen was by resection of the sixteenth left rib and incision of the diaphragm. The technique afforded good exposure of the splenic vessels and attachments. Closure was facilitated by preservation of the periosteum of the resected rib. Difficulty was encountered both in surgical technique and postoperative complications in obese animals. The transthoracic approach was found to be a useful technique for equine splenectomy.     

Controlled Cross Circulation in Dogs: Effects on Donor Hemodynamics

Controlled cross circulation (CCC) was performed in six pairs of dogs for 45 minutes with aortic cross clamping and cardioplegia. Data were collected in donor dogs at 10 minute intervals three times before, three times during, and three times after CCC and included arterial blood pressure, pulmonary capillary wedge pressure (PCWP), central venous pressure (CVP), cardiac index (CI), heart rate (HR), blood gas analysis, temperature, maximum rate of rise of left ventricular pressure dP/dt max/End diastolic volume (EDV), blood volume (BV), complete blood count (CBC) and activated clotting times (ACT). Pulse pressure (PP), systemic vascular resistance (SVR), oxygen delivery (Do₂), and left ventricular cardiac work (LVCW) were calculated. Arterial blood pressure, CVP, blood gas analysis, temperature, BV, CBC, and ACT were measured in recipient dogs. During CCC, donor hemodynamic changes resembled those observed in models of acute onset arteriovenous fistulas. Insidious BV shifts can occur despite the use of occlusive roller pumps. After CCC, donor hemodynamics resembled acute blood loss, characterized by decreases in mean arterial pressure (MAP), CVP, PCWP, and CI, and increases in SVR and dP/dt max/EDV. These changes were probably caused by pump imbalance and BV shift to the recipient dog.     

Correlation of Clinical, Radiographic, and Surgical Localization of Intervertebral Disc Extrusion in Small-Breed Dogs: A Prospective Study of 50 Cases

Objective —To compare prospectively clinical, radiographic, and surgical findings of intervertebral disc extrusion (IDE) localization in small-breed dogs and to determine the best means of lesion localization for the purpose of hemilaminectomy. Study Design —Clinical, radiographic, and surgical findings of small-breed dogs with thoracolumbar IDE were prospectively compared for agreement on lesion localization. Sample Population—50 small-breed dogs with IDE treated at the three participating veterinary hospitals were included in the study if no other confounding diseases were identified and if the owner gave permission for diagnostic tests and surgery. Methods —Clinical and surgical findings were recorded by the surgeon assigned to the case. Radiographic studies were evaluated independently by two radiologists blinded as to the clinical and surgical findings. values and 95% confidence intervals were calculated for agreement on lesion localization by clinical, radiographic, and surgical means and for agreement between radiologists. Results —K values for agreement of lesion localization were as follows: clinical versus surgical, 0.595; radiologist A versus radiologist B, 0.81; radiologist A versus surgical findings, 0.60; radiologist B versus surgical findings, 0.71. Both radiologists' interpretation of IDE localization agreed with surgical localization in 60% of cases. Conclusions —Clinical lateralization of IDE was found to be the least reliable factor of those studied for determining on which side the hemilaminectomy should be performed. Results of this study differ from those of previous studies examining the reliability of myelography to localize the site of IDE accurately. The results of this study further suggest that surgery may not be an absolute standard for determination of the localization of IDE in small-breed dogs. Clinical Relevance —Intervertebral disc extrusion in small-breed dogs frequently results in bilateral distribution of extruded material. Computed tomography or magnetic resonance imaging may be necessary to delineate completely the distribution of extruded disc material in IDE.     

COMPARATIVE PERFORMANCE OF RADIOGRAPHY AND COMPUTED TOMOGRAPHY IN THE DIAGNOSIS OF MIDDLE EAR DISEASE IN 31 DOGS

The purpose of this study was to compare computed tomography (CT) and radiography for diagnosing the presence and severity of middle ear disease in dogs with a history of chronic otitis externa. Thirty-one dogs undergoing a total ear canal ablation and bulla osteotomy were studied. Three normal dogs served as controls. All dogs were examined using radiography and CT. Three radiologists independently evaluated imaging studies in random order. A visual analog scale method was used for scoring certainty and severity of middle ear disease. Surgical findings were recorded intra-operatively. Bulla lining samples were submitted for histopathologic evaluation and scored by a single pathologist who also used a visual analog scale system. Findings from both imaging modalities agreed more closely with surgical findings than with histopathologic findings. With either surgical or histopathologic findings as the gold standard, CT was more sensitive than and as specific as radiographs for predicting presence and severity of middle ear disease. Observer performance with CT was more consistent than the performance with radiographs in the detection of changes that occur with middle ear disease. Both radiography and CT were more accurate for predicting the severity of the disease than its presence. Findings indicate that CT is more accurate and reliable than radiography in diagnosing middle ear disease for dogs having concurrent otitis externa, but only when severity of disease is moderate or high. With low severity of disease, diagnostic certainty for both modalities becomes more variable.     

Surgical Correction of Congenital Bilateral Choanal Atresia in a Foal

Congenital bilateral choanal atresia was corrected surgically in a neonatal foal. Presenting clinical signs included complete obstruction of the upper airway, which had been relieved by tracheotomy. The diagnosis was confirmed by endoscopic examination and contrast radiography. Bilateral nasal flaps were used to gain access to the caudal nasal cavity, allowing removal of obstructive tissue and restoration of normal respiration. Malocclusion developed secondary to surgical intervention and resultant damage to suture lines of developing flat bones of the skull. Nine months postoperatively, the asynchronous growth of the mandible and maxilla had not resulted in difficulty during mastication. Respiration, although audible during periods of exercise, was acceptable to the owners.     

The incidence of thoracic trauma in dogs with skeletal injury

One hundred dogs with skeletal injury were evaluated for co-existing thoracic abnormalities. Parameters used to assess thoracic trauma were physical examination, thoracic radiographs, electrocardiograms and arterial blood gas PaO₂. Thoracic abnormalities were found in 57 per cent of the dogs. Within this group, 77 per cent had abnormal thoracic radiographs, 44 per cent had abnormal low PaO₂, and 30 per cent had cardiac arrhythmias. No clinical signs suggestive of thoracic injury were found on physical examination in 79 per cent of the dogs with thoracic lesions.     

Muscle Flap Closure of a Frontocutaneous Fistula in a Horse

A frontal sinus fistula was corrected surgically using a temporalis muscle flap and split thickness skin graft in a horse. The operative approach for temporalis muscle transposition is described. Application of the temporalis muscle flap allowed restoration of a functional covering and excellent final appearance.     

QUANTITATIVE PERTECHNETATE THYROID SCINTIGRAPHY AND THE ULTRASONOGRAPHIC APPEARANCE OF THE THYROID GLAND IN CLINICALLY NORMAL HORSES

We characterized the scintigraphic and sonographic appearance of the thyroid gland in clinically normal horses to establish the value of these modalities for assessment of the thyroid gland in this species. Horses were divided into two age groups. One group consisted of eight horses between 3 and 10 years of age and the other of seven horses between 11 and 20 years of age. Total T₄ concentrations were within the laboratory reference interval in all horses. Thyroid to salivary (T/S) ratio, percent dose uptake of pertechnetate (Na^99mTcO₄) and thyroid lobe volume were calculated. The echogenicity of thyroid lobes and presence of nodules was documented. The two groups were compared using appropriate parametric and nonparametric statistics. Mean total T₄ concentration was lower in older horses. Sixty minute mean±standard deviation (SD) T/S ratios for old vs. young horses were 5.8±3.0 and 5.3±2.2, respectively. Sixty‐minute median and interquartile ranges for percent dose uptake of pertechnetate for old vs. young horses were 3.64% (1.5–3.98%) and 2.55% (2.33–2.90%), respectively. Mean±SD thyroid lobe volume for old vs. young horses were 18.93±5.16 cm ³ and 13.55±3.56 cm³, respectively. Differences between groups were not significant. Most thyroid lobes were hyper or isoechoic to the sternocephalicus muscle. Prevalence of thyroid nodules did not differ between groups. Further study is needed to determine if thyroidal percent dose uptake is significantly different in horses with thyroid dysfunction and if it is clinically useful.     

Corticocancellous Bone Biopsy from the 12th Rib of Standing Horses

Unicortical corticocancellous bone biopsy specimens 4.5 mm and 6.5 mm in diameter were obtained without long-term complications from the 12th rib in eight standing horses. However, the bone specimens were unsuitable for histologic or histomorphometric evaluation. In in vitro comparisons of biopsy specimens 6.5 mm and 12 mm in diameter, and of unicortical and transcortical biopsy specimens, 12 mm transcortical specimens yielded the most cancellous bone. Transcortical bone biopsy specimens 12 mm in diameter were obtained from eight horses by using power-assisted trephination. The surgical procedure was well tolerated, but some degree of pneumothorax in all horses was treated by aspiration of air from the thorax. Long-term complications were not observed.