Variation of canine and feline frontal-plane QRS axes with lead choice and augmentation ratio

The intraindividual variability in mean electric axis referable to choice of ECG leads and augmentation ratio was investigated by means of a digital computer program. Although, in theory, the choice of leads for determining the QRS axis should make no difference, the maximum intraindividual variation in axis angle was about 50 degrees for canine and feline subjects. The angle conputed for the lead combinations I and III and I and aVF will usually fall within 5 to 10 degrees of the mean of all lead combinations, but larger variations are seen at time. The application of an "augmentation ratio" for the augmented unipolar leads was most helpful when it was individually computed. Further methods of lead-vector improvement are discussed.     

Effects of intravenous sodium bicarbonate and sodium acetate on equine acid-base status

Changes in blood gases, pH, and plasma electrolyte concentrations in response to intravenously infused sodium bicarbonate (NaHCO₃) and sodium acetate (NaCH₃CO₂) solutions (1.34 mEq/mL) in 5 light breed mares were investigated. Jugular venous blood samples were collected before and after completion of the infusions in 20-minute intervals for 200 minutes. Infusion of sodium bicarbonate and sodium acetate caused significant (P < .00l) increases in blood pH and bicarbonate ion concentration that persisted throughout the collection period. The elevation in blood pH and bicarbonate ion concentrations was greater (P < .01) for sodium bicarbonate than for sodium acetate immediately after the completion of the infusions but was not different (P > .05) thereafter. There were significant reductions (P < .01) in plasma-ionized calcium and potassium after infusion of both sodium bicarbonate and sodium acetate. This study found that significant metabolic alkalosis in horses and corresponding shifts in electrolyte concentrations can be induced by intravenous infusion of solutions of either sodium bicarbonate or sodium acetate, and they persist for at least 3 hours. These data show that the short-term elevation in pH and bicarbonate ion concentration is momentarily higher after infusion of sodium bicarbonate. This is likely due to the direct infusion of bicarbonate ions in the sodium bicarbonate treatment, such that further metabolism is not required to be effective. However, the longer-term alkalosis did not differ between isomolar solutions of sodium bicarbonate and sodium acetate.     

Computed tomography dacryocystography evaluation of the nasolacrimal apparatus

Computed tomography-dacryocystography (CT-DCG) was used to evaluate the nasolacrimal system in four patients (three dogs and one horse) that were admitted for evaluation of chronic epiphora, facial swelling, or facial trauma. The four patients are reviewed and the technique for performing CT-DCG is described. Additionally, the indications for this procedure are discussed. CT-DCG is advantageous because cross-sectional imaging provides superior resolution of the nasolacrimal apparatus and the relatively long, small-diameter, bony nasolacrimal canal in most veterinary patients.     

Comparison of Seven Digital Cameras for Digitizing Radiographs

The purpose of this study was to evaluate seven digital cameras for their ability to adequately capture quality radiographic images and their relative cost effectiveness. Radiographs of line pair (LP) phantoms (ranging from 0.6 to 16.6 LP/mm) and a 20-step contrast phantom were photographed at a near distance of 30.0 cm and a far distance (determined for each camera) at which a full 14 x 17 in film filled the viewfinder. Of the seven cameras tested, the Canon EOS-D30 consistently performed the best in LP/mm resolved (7.7 at close distance, 1.4 at far distance) and in contrast latitude (all 20 steps at both close and far distances). The Canon EOS-D30, determined to be the best camera used in this study for photographing radiographic images, is also the most expensive camera that was used. Two cameras, the Nikon Coolpix 995 and the Sony DSC-F707, were very close to the Canon in performance at considerably less cost. Certain inexpensive cameras may not be acceptable choices for teleradiology.