Oxygenation in medetomidine-sedated dogs with and without 100% oxygen insufflation

Oxygenation status was evaluated in medetomidine-sedated dogs breathing room air (M) or 100 percent oxygen (MO2). Medetomidine (40 microg/kg IV) administration resulted in peripheral vasoconstriction and decreased venous saturation as measured by an increased oxygen extraction ratio in peripheral tissues. Providing 100 percent oxygen insufflation via face mask reduced desaturation by increasing oxygen content but did not prevent vasoconstriction or reduce the oxygen extraction ratio in peripheral tissues. Atipamezole (200 microg/kg IV) reversed medetomidine-induced vasoconstriction and increased oxygen supply to tissues as indicated by a lower tissue oxygen extraction ratio. The authors conclude that 100 percent oxygen insufflation via face mask during medetomidine sedation (40 micrograms/kg [corrected] IV) benefits tissue oxygenation in healthy dogs.     

Radiographic evaluation of acetabular component position in dogs

OBJECTIVE: To assess the usefulness of standard radiographic projections for determining acetabular cup position and to compare 2 radiographic methods for calculation of the angle of lateral opening of the acetabular cup. STUDY DESIGN: In vitro radiographic study. METHODS: Acetabular components were mounted on a custom-built inclinometer. The effect of varying the angles of lateral opening, inclination, version, and centering of the x-ray beam on the radiographic appearance of the cup was investigated. The angle of lateral opening was calculated trigonometrically after direct measurement and by means of computer-aided image analysis. RESULTS: Using a ventrodorsal radiograph, the computer-aided measurement of angle of lateral opening was accurate to within 5 degrees when the true angle of lateral opening was > or = 40 degrees. In the case of direct measurement, the calculated angle was accurate to within 5 degrees only when the true angle was > or = 60 degrees. An increasing angle of inclination was associated with reduced accuracy of calculation of the angles of lateral opening and version. Standard radiographic assessment of acetabular version and inclination was not found to be clinically useful. The displacement of the x-ray beam, which would cause significant error in the determination of lateral opening, is unlikely to be exceeded in practice. Cup size had no significant effect on the accuracy of the results. CONCLUSIONS: Computer-aided image analysis can be used to calculate angles of lateral opening to within 10 degrees throughout the range of acetabular positions seen in practice and is appropriate for postoperative documentation of cup position. The angles of inclination and version should be interpreted with caution.     

Radiographic evaluation of BFX acetabular component position in dogs

Objective: To assess the reliability of radiographic measurement of angle of lateral opening (ALO) and angle of version of BFX acetabular cups. Study Design: In vitro radiographic study. Sample Population: BFX cups (24, 28, and 32 mm). Methods: Total hip replacement constructs (cups, 17 mm femoral head and a #7 CFX stem) were mounted on an inclinometer. Ventrodorsal radiographs were obtained with ALO varying between 21° and 70° and inclination set at 0°, 10°, 20°, and 30°. Radiographs were randomized using a random sequence generator. Three observers blinded to the radiograph order assessed ALO using 3 methods: (1) an ellipse method based on trigonometry; (2) using a measurement from the center of the femoral head to the truncated surface of the cup; (3) by visual estimation using a reference chart. Version was measured by assessing the ventral edge of the truncated surface. Results: ALO methods 2 and 3 were accurate and precise to within 10° and were significantly more accurate and precise than method 1 (P<.001). All methods were significantly less accurate with increasing inclination. Version measurement was accurate and precise to within 7° with 0–20° of inclination, but significantly less accurate with 30° of inclination. Conclusions: Methods 2 and 3, but not method 1, were sufficiently accurate and precise to be clinically useful. Version measurement was clinically useful when inclination was ≤20°.     

Radiographic evaluation of nonanesthetized and nonsedated dogs for hip dysplasia

The use of chemical or gas restraint was unnecessary in most large breed dogs being evaluated radiographically for hip dysplasia. Of 100 large-breed dogs, 97 were successfully radiographed for hip dysplasia evaluation without the use of sedation or anesthesia.     

Radiographic bone surveys in the evaluation of primary bone tumors in dogs

Forty-two dogs with primary bone tumors underwent radiographic bone surveys. The use of radiographic bone surveys led to a higher yield in finding other nonclinically detectable neoplastic sites (7.1%) than did thoracic radiographs (4.7%). Multicentric bone tumors accounted for 9.5% of total cases. Bone infarcts were identified in 3 dogs (7.1%).     

Radiographic differentiation of mediastinal versus pulmonary masses in dogs and cats can be challenging

The ability to differentiate thoracic masses of mediastinal and pulmonary origins is often confounded by their complex spatial relationship. The objectives of this retrospective, observational cross‐sectional study were to assess radiographic differentiation of mediastinal versus pulmonary masses, and to determine if there are any correlations with specific radiographic findings. Thoracic radiographs of 75 dogs and cats with mediastinal and/or pulmonary masses identified on CT were reviewed. Radiographic studies were anonymized, randomized, and reviewed twice by three reviewers. Reviewers categorized the origin of each mass(es) as mediastinal, pulmonary, or both. On the second review, the presence or absence of 21 different radiographic findings was recorded for each mass. Agreement between the radiographic and CT categorization of mass origin, as well as inter‐ and intraobserver agreement, was calculated. Overall agreement between radiographs and CT was moderate for both mediastinal (68.6%) and pulmonary masses (63%). Overall, interobserver agreement was moderate (κ = 0.50‐0.74), with moderate to strong intraobserver agreement (κ = 0.58‐0.93). Masses within the mediastinum were significantly more likely to displace other mediastinal structures. Alternatively, masses lateral to midline and in the caudal thorax were found to be significantly positively correlated with a pulmonary origin. The results of this study highlight the limitations of radiography for differentiation of mediastinal and pulmonary masses, with mass location and displacement of other mediastinal structures potentially useful for radiographic findings that may help improve accuracy.     

Radiographic and computed tomographic evaluation of experimentally induced lung aspiration sites in dogs

This study was performed to radiographically examine the prevalence of aspiration sites and to evaluate their atomical correlation with the bronchial pattens. Ten healthy beagle dogs were repeatedly radiographed, at weekly intervals, in the left and right lateral, ventrodorsal (VD) and dorsoventral (DV) positions. Three mililiters of iohexol distilled with same volume of saline was infused into the tracheal inlet. Which lung lobe was aspirated was decided upon by the presence of a significant alveolar pattern due to the contrast medium. Alveolar patterns were identified at the left (100%) and right cranial lung lobes (77%) with the dogs in dependant lateral recumbency, at the right caudal lung lobe (71%) with the dogs in VD recumbency and at the right middle lung lobe (59%) with the dogs in DV recumbency, respectively. The anatomical correlation was evaluated by performing computed tomography. The right principal bronchus (165.8 ± 1.6°) was more straightly bifurcated than was the left principal bronchus (142.7 ± 1.8°, p < 0.01). In VD position, the right side lung had a greater opertunity to become aspirated. The ventrally positioned right middle lobar bronchial origin was more easily to be aspirated the other laterally positioned ones. We think that these anatomical characteristics can be one of the causes for aspiration pneumonia to occur more frequently in the right side lung.     

Conventional versus high-flow oxygen therapy in dogs with lower airway injury

Dogs with lower airway pathology that present in respiratory distress often receive oxygen therapy as the first line of treatment regardless of the underlying cause. Conventional “low-flow” systems deliver oxygen with a maximum flow rate of 15 L/minute. Traditionally, when an animal’s respiratory status does not improve with conventional oxygen therapy and treatments for underlying disease, options might be limited to either intubation and mechanical ventilation or humane euthanasia. High-flow oxygen therapy (HFOT) has been gaining popularity in veterinary medicine as an alternative route of oxygen supplementation for animals that require support beyond conventional therapy. High-flow oxygen therapy can supply a mixture of air and oxygen via a heated and humidified circuit. It is user friendly and can be used in an environment in which mechanical ventilation is unavailable.This review article is written for emergency doctors and general practitioners who lack access to mechanical ventilation. This article briefly reviews pertinent respiratory physiology, traditional oxygen supplementation techniques, the physiology of HFOT, and the limited evidence available in veterinary medicine regarding the use of HFOT, its applications, and limitations. Guidelines for the use of HFOT are suggested and HFOT is compared to conventional therapy.     

Pattern of breathing in brachycephalic dogs

The pattern of breathing was assessed in 19 brachycephalic dogs, using tidal breathing flow-volume loop (TBFVL) analysis. Fifteen dogs had TBFVL consistent with a fixed-type upper airway obstruction, whereas 4 dogs had a TBFVL indicative of a nonfixed upper airway obstruction. The dogs did not have a TBFVL shape the same as that considered normal for healthy nonbrachycephalic dogs. Tidal breathing flow-volume loops from brachycephalic dogs that were considered to have a normal respiratory tract (n = 11) were similar to those of dogs with clinical signs of upper airway obstruction (n = 8). Respiration was monitored continuously for short periods (20 to 50 minutes) in 3 brachycephalic dogs resting in a cage in a quiet, darkened laboratory; 2 of these dogs had periodic breathing patterns characterized by multiple episodes of alternating hypopnea and arousal. Brachycephalic dogs may be at risk for the development of disordered breathing during sleep.     

Radiographic assessment of liver volume in dogs

In a group of 65 dogs, radiographic liver length, the length of the axis from the most cranial part of the diaphragm to the apex of the liver tip, was correlated significantly (P less than 0.000001) with real liver volume. Within this group, radiographic liver length, compared with the length of the eleventh thoracic vertebra, was correlated with liver volume per kilogram of body weight. In a group of 30 dogs, with histologically normal liver, this measurement was not affected by thoracic conformation. These findings suggest that radiographic liver length is a reliable measurement for estimating liver volume in dogs and that it is not influenced by thoracic conformation. For 60 of the 65 dogs, a method of assessment of liver volume was formulated that required 2 measurements to be made on the lateral abdominal radiograph and 1 to be made on the dog itself.     

Comparison of abdominal computed tomography and abdominal ultrasound in sedated dogs

Abdominal ultrasound (US) is used frequently as a first-line screening tool for abdominal disease. Although computed tomography (CT) is superior to US in the diagnosis of some abdominal diseases, a major impediment is the requirement of general anesthesia to prevent motion and for safe restraint. With multidetector helical CT, faster examinations allow general anesthesia to be avoided, while producing diagnostic-quality images. Abdominal US and CT were compared for lesion detection in 27 sedated dogs, divided into three even groups based on body weight. Lesions were categorized further as to subjective clinical relevance. In dogs less than 25 kg, there is no significant difference in lesion detection between CT and US. In dogs weighing greater than 25 kg, more lesions were detected with CT than with US (P = 0.0001), including clinically relevant lesions (P = 0.0277). From these results, it appears that CT has an advantage in lesion detection in dogs greater than 25 kg, making it a better screening test for abdominal disease in these patients.     

Comparison of unilateral versus bilateral nasal catheters for oxygen administration in dogs

Objective: To determine the effect of bilateral nasal oxygen supplementation on tracheal airway and arterial blood gas parameters. Design: Original research. Setting: Research Laboratory. Animals: Eight normal dogs. Interventions: None. Measurements: Intra‐tracheal oxygen concentration and arterial oxygen partial pressure at three different oxygen flow rates given through either unilateral or bilateral nasal catheters. Main results: F_IO₂ and PaO₂ were significantly increased with higher total oxygen flow rates, but the increase was the same whether the higher flow was delivered through one nasal catheter or divided and administered though two nasal catheters. The use of bilateral nasal catheters allowed a tracheal F_IO₂ as high as 0.60 with minimal patient discomfort. Conclusions: The benefit of bilateral nasal catheters for oxygen supplementation is the ability to provide high total oxygen flows with decreased risk of patient discomfort. If the desired oxygen flow can be achieved with a unilateral nasal catheter, then the only benefit of bilateral catheters is increased patient comfort. The use of bilateral nasal oxygen catheters for oxygen supplementation can result in an F_IO₂ that is high enough to produce oxygen toxicity with prolonged administration.     

Radiographic evaluation of congenital vertebral anomalies in Korean raccoon dogs (Nyctereutes procyonoides koreensis)

BackgroundThe normal vertebral anatomy of Korean raccoon dogs and their variants require research attention as a prerequisite for identifying pathologies and anomalies.ObjectivesThis retrospective study aimed at describing the vertebral formula and congenital vertebral anomalies in Korean raccoon dogs (Nyctereutes procyonoides koreensis).MethodsRadiographs of 82 raccoon dogs (42 males, 40 females) acquired from May 2013 to June 2020 in the Gangwon Wildlife Medical Rescue Center were reviewed to evaluate the cervical, thoracic, and lumbar vertebrae of the spine.ResultsNormal morphology of all vertebrae was observed in 50 of the 82 raccoon dogs, and the vertebral formula was cervical 7, thoracic 13, and lumbar 7. Congenital vertebral anomalies were found in 32 raccoon dogs: transitional vertebrae (TV) in 31 and block vertebrae in 2. Two raccoon dogs had 2 types of vertebral anomalies: one had TV and block vertebra, and the other had 2 types of TV. Twenty-nine raccoon dogs had thoracolumbar TV (TTV) and 3 had lumbosacral TV. TTV was morphologically classified into 4 different types: unilateral extra-rib in 5 raccoon dogs, bilateral extra-ribs in 14, bilateral elongated transverse processes in 4, and an asymmetric mixed formation of extra-rib with elongated transverse process in 6.ConclusionsThis study showed that TTV is common in Korean raccoon dogs, and that the vertebral formula is relatively diverse. The bilateral extra-ribs type TTV is the most common variant, which is almost similar to normal rib to be confused the radiographic evaluation.     

Cardiopulmonary effects of fentanyl in conscious dogs and dogs sedated with a continuous rate infusion of medetomidine

OBJECTIVE: To determine the hemodynamic consequences of the coadministration of a continuous rate infusion (CRI) of medetomidine with a fentanyl bolus in dogs. ANIMALS: 12 healthy sexually intact male dogs weighing 30.3 -/+ 4.2 kg (mean +/- SD). PROCEDURE: Dogs received either fentanyl alone (15.0 microg/kg, i.v. bolus) or the same dose of fentanyl during an 11-hour CRI of medetomidine (1.5 microg/kg/h, i.v.). Prior to drug administration, dogs were instrumented for measurement of cardiac output, left atrial pressure, and systemic arterial blood pressures. Additionally, blood samples were collected from the pulmonary artery and left atrium for blood gas analysis. RESULTS: Medetomidine infusion reduced the cardiac index, heart rate, and O2, delivery while increasing left atrial pressure. Subsequent fentanyl administration further decreased the cardiac index. The Pao2 was not significantly different between the 2 treatment groups; however, fentanyl transiently decreased Pao2 from baseline values in dogs receiving a CRI of medetomidine. CONCLUSIONS AND CLINICAL RELEVANCE: Because of the prolonged hemodynamic changes associated with the CRI of medetomidine, its safety should be further evaluated before being clinically implemented in dogs.