QUANTITATIVE VIDEOFLUOROSCOPIC EVALUATION OF PHARYNGEAL FUNCTION IN THE DOG

Videofluoroscopic evaluation of both liquid barium and barium soaked kibble was performed in 11 adult, clinically normal dogs of varying breeds. Each examination was digitized and evaluated frame by frame to establish the normal timing sequence of the pharyngeal phase of swallowing. Closure of the epiglottis was considered the onset of swallowing. The time to each of the following events was recorded: (1) Maximum pharyngeal contraction, (2) Opening of the epiglottis, (3) Opening of the cranial esophageal sphincter, and (4) Closure of the cranial esophageal sphincter. These values were found to be consistent both intra and interpatient. Retrospective analysis of 3 videofluoroscopic examinations from dogs that met the subjective criteria defining cricopharyngeal achalasia was then performed. A statistically significant delay in the time to opening and closure of the cranial esophageal sphincter was found employing both liquid barium and barium soaked kibble in the dogs with cricopharyngeal achalasia.     

EFFECT OF BOLUS SIZE ON DEGLUTITION AND ESOPHAGEAL TRANSIT IN HEALTHY DOGS

Contrast videofluoroscopy is the gold standard procedure for evaluating dysphagia in humans, but quantitative measures vary depending on bolus size and consistency. We hypothesized that quantitative measures made during videofluoroscopy of swallowing in dogs would differ between bolus sizes and consistencies. Ten healthy adult dogs were enrolled a prospective, crossover experimental study and underwent contrast videofluoroscopy while swallowing liquid (5, 10, and 15 ml) and canned food (3, 8, and 12 g) boluses. Maximum pharyngeal contraction occurred significantly later with medium solid boluses than with medium liquid boluses, with a mean difference of 0.021 s (adjusted P = 0.042). Upper esophageal sphincter opening occurred significantly earlier with large solid boluses than with medium solid boluses, with a mean difference of 0.018 s (adjusted P = 0.025). Thoracic esophageal transit time was significantly longer with small solid boluses than with small liquid boluses, with a mean difference of 0.68 s (adjusted P = 0.004). Odds of primary esophageal peristalsis occurring were significantly (18.5 times) higher with large solid vs. large liquid boluses (adjusted P = 0.031). No other statistical comparisons reached significance. Based on these results, we recommend a standardized approach to videofluoscopy in dogs with determination of quantitative measures using medium liquid and soft food boluses to minimize effects of size. Furthermore, we conclude that measurements made on liquid swallows should not be directly compared to measurements made on soft food boluses.     

INFLUENCE Of PATIENT POSITIONING ON THE L5–L6 MID-LAMINAR DISTANCE

The aim of this project was to determine the effect of patient position on the L5-L6 mid-laminar distance (MLD). The lumbar area of 22 recently euthanatized dogs of various breeds was radiographed in three positions: lateral recumbency with the spine in neutral position, lateral recumbency with the spine flexed in a kyphotic position, and sternal recumbency with the spine flexed in a kyphotic position. Digital images of the radiographs were analyzed using a computer program that allowed measurement of the MLD between L5-L6 in the three positions. The L5 and L6 MLD was significantly larger in sternal recumbency with the spine flexed (142.3 units) than both in lateral recumbency with the spine flexed (138.7 units; P= 0.001) and lateral recumbency with the spine in the neutral position (135.8 units; P < or = 0.001). The MLD in lateral recumbency with the spine flexed was significantly larger than in lateral recumbency with the spine in neutral position (P = 0.005). Positioning a dog in sternal recumbency with the spine flexed produces a significantly larger MLD than in lateral recumbency with the spine flexed; this should simplify needle placement when performing a lumbar puncture.     

Alfaxalone in cyclodextrin for induction and maintenance of anaesthesia in ponies undergoing field castration

Objective  To evaluate the induction and maintenance of anaesthesia using alfaxalone following pre-anaesthetic medication with romifidine and butorphanol in ponies undergoing castration in the field.
Study design  Prospective clinical study.
Animals  Seventeen male ponies weighing 169 ± 29 kg.
Methods  The ponies were sedated with romifidine and butorphanol intravenously (IV). Induction time was recorded following administration of alfaxalone 1 mg kg⁻¹ and diazepam 0.02 mg kg⁻¹ IV. If movement during surgery occurred, alfaxalone 0.2 mg kg⁻¹ was administered IV. The quality of anaesthetic induction, and recovery were scored on a subjective scale of 1 (good) to 5 (poor). The number of attempts to attain sternal recumbency and standing, quality of recovery and times from induction to end of surgery, first head lift, sternal recumbency and standing were recorded.
Results  Induction quality was good [median score (range) 1 (1–3)] with a mean ± SD time of 29 ± 6 seconds taken to achieve lateral recumbency. Ten ponies required incremental doses of alfaxalone during surgery. Mean times to the end of surgery, first head lift, sternal recumbency and standing were 26 ± 9 minutes, 31 ± 9 minutes, 33 ± 9 minutes and 34 ± 9 minutes respectively. The number of attempts to attain sternal recumbency was 1(1–1) and to attain standing was 1(1–2). Quality of recovery was good, with a recovery score of 1(1–2).
Conclusions and clinical relevance  Alfaxalone provided smooth induction and recovery characteristics and was considered suitable for maintenance of anaesthesia for castration in ponies.     

GASTRIC EMPTYING IN THE NORMAL DOG A Contrast Radiographic Technique

A total of 22 radiographic studies was made to determine comparative gastric emptying times of two different solid test meals (intact kibble food and ground kibble food mixed with barium sulfate suspension) in four mature (15-26 months) normal Beagle dogs under controlled conditions. Complete gastric emptying times of the intact kibble and ground kibble meals of a given dose (8 g/kg of dog food plus 5-7 ml/kg of the contrast agent) ranged from five to ten hours (7.6 ± 1.98 hours with intact kibble meal and 7.0 ± 1.86 hours with ground kibble meal). Feeding a halfdose of ground kibble meal (4 g/kg of dog food plus 3.5 ml/kg of the contrast agent) resulted in complete gastric emptying times of four to six hours (4.7 ± 0.67 hours). Individual dogs had repeatable gastric emptying times although the times varied among different dogs.     

Anaesthetic potency of isoflurane in cattle: determination of the minimum alveolar concentration

Objective To determine the minimum alveolar concentration (MAC) of isoflurane in cattle.
Study design Prospective study.
Animals Sixteen healthy adult female Holstein-Friesian cattle weighing 612 ± 17 kg (× ± SEM) and aged 5.7 ± 0.9 years old.
Methods The unsedated cattle were restrained in right lateral recumbency using a rope harness technique. Anaesthesia was induced with isoflurane (ISO) in oxygen via a face mask connected to a large-animal, semiclosed anaesthetic circle system. Each cow was intubated with a cuffed orotracheal tube (25 mm ID). Inspired and end-tidal ISO were monitored using a calibrated infra red analyser with a methane filter. The MAC of ISO that prevented gross purposeful movement in response to a tail and dewclaw clamp was determined. The time from the start of ISO administration to intubation, the time interval between discontinuance of ISO and the time the animal regained sternal recumbency, were recorded. Time to standing and quality of recovery were also recorded.
Results The time from the start of ISO administration to tracheal intubation was 18.68 ± 2.77 minutes. The MAC of ISO in these cattle was 1.27 ± 0.03% (1.14 ± 0.01% corrected to sea level). Time to sternal recumbency after 90 ± 16 minutes of anaesthesia from intubation was 4.60 ± 0.58 minutes and time to standing was 6.70 ± 1.02 minutes. All cattle were extubated when they regained sternal recumbency.
Conclusion The MAC of isoflurane in these cattle was 1.27 ± 0.03% (1.14 ± 0.01% corrected to sea level). ISO provided a smooth induction to, and rapid recovery from, anaesthesia.
Clinical relevance Knowledge of the MAC of ISO in cattle will facilitate its appropriate clinical use.     

The effect of body position on the 'hanging drop' method for identifying the extradural space in anaesthetized dogs

ObjectivesTo assess the accuracy of the ‘hanging drop method’ for identifying the extradural space in anaesthetized dogs positioned in sternal or lateral recumbency.Study designProspective randomized-experimental study.AnimalsSeventeen clinically healthy adult dogs, 10 females and seven males weighing 8.4–26.2 kg.MethodsDogs were positioned in either sternal (n = 8) or lateral (n = 9) recumbency under general anaesthesia. A 20 SWG spinal needle pre-filled with 0.9% saline was advanced through the skin into the lumbosacral extradural space and the response of the saline drop recorded, i.e. whether it: 1) was aspirated from the hub into the needle; 2) remained within the hub, or 3) moved synchronously with i) spontaneous respiration, ii) heart beat or iii) manual lung inflation. The position of the needle tip was ultimately determined by positive contrast radiography.ResultsOne dog positioned in lateral recumbency was excluded from the study because bleeding occurred from the needle hub. Saline was aspirated into the needle in seven of eight dogs held in sternal recumbency but in none of the dogs positioned in lateral recumbency. Accurate needle tip placement in the extradural space was confirmed by positive contrast radiography in all dogs.Conclusion and clinical relevanceThe ‘hanging drop’ method, when performed with a spinal needle, appears to be a useful technique for identifying the location of the extradural space in anaesthetized medium-sized dogs positioned in sternal, but not in lateral recumbency. The technique may yield ‘false negative’ results when performed in dogs positioned in sternal recumbency.     

Anesthetic Potency of Desflurane in the Horse: Determination of the Minimum Alveolar Concentration

Objective — To determine the minimum alveolar concentration (MAC) of desflurane (DES) in the horse.
Study Design — Prospective study.
Animals — Six healthy adult horses (three males and three females) weighing 370 ±16 kg and aged 9 ±2 years old.
Methods — Anesthesia was induced with DES vaporized in oxygen via a face mask connected to a large-animal, semiclosed anesthetic circle system. The horses were endotracheally intubated and positioned in right lateral recumbency. Inspired and end-tidal DES were monitored using a calibrated Ohmeda RGM 5250 multigas analyzer (Ohmeda-BOC, Spain). The MAC of desflurane that prevented gross purposeful movement in response to 60 seconds of noxious electrical stimulation of oral mucous membranes was determined.
Results — The time from the start of DES administration to lateral recumbency was 6.1 ±0.9 min. The MAC of DES in these horses was 7.6 ±0.4%. Time required for the animal to regain sternal recumbency after 98 ±4 minutes of anesthesia was 6.6 ±0.5 minutes and the time to standing was 14.3 ±2.7 minutes.
Conclusions — The MAC of desflurane in these horses was 7.6 ±0.4%. DES provided a rapid induction to, and recovery from, anesthesia.
Clinical Relevance — Desflurane offers the potential for more precise control during anesthesia, and may allow a faster and uneventful recovery. It is important to know the MAC of an inhalant to use it clinically.     

Diagnostic outcome of contrast videofluoroscopic swallowing studies in 216 dysphagic dogs

Determining the anatomic and functional origin for dysphagia is critical for development of an appropriate therapeutic plan and determination of the prognosis. The purpose of this retrospective study was to report the quantitative and qualitative outcome of contrast videofluoroscopic swallowing studies in a large cohort of dysphagic dogs presenting to a tertiary veterinary care hospital. The videofluoroscopic swallowing studies were reviewed to generate values for pharyngeal constriction ratio, timing of swallowing events (maximum pharyngeal contraction, opening of upper esophageal sphincter, closing of upper esophageal sphincter, and reopening of epiglottis), type of esophageal peristalsis generated, and esophageal transit time. One or more anatomic locations for origin of dysphagia were assigned (pharyngeal, cricopharyngeal, esophageal (primary motility disorder), other esophageal (stricture, vascular ring anomaly, mass), lower esophageal sphincter/hiatus. Sixty‐one of 216 studies (28%) were deemed unremarkable. Twenty‐seven of 216 dogs (13%) had pharyngeal dysphagia, 17/216 dogs (8%) had cricopharyngeal dysphagia, 98/216 dogs (45%) had dysphagia secondary to esophageal dysmotility, 19/216 dogs (9%) had dysphagia secondary to focal esophageal disorders, and 97/216 dogs (45%) had dysphagia of lower esophageal sphincter/hiatus origin. Multiple abnormalities were present in 82/216 (38%) dogs. Elevated pharyngeal constriction ratio was associated with pharyngeal, cricopharyngeal, and esophageal motility disorders, delayed upper esophageal sphincter opening was associated with cricopharyngeal disorders, a lower percentage of primary esophageal peristaltic waves was associated with cricopharyngeal, pharyngeal, or primary esophageal motility disorders. In conclusion, videofluoroscopic swallowing studies was pivotal in the diagnosis of dysphagia with 155/216 (72%) dogs receiving a final diagnosis.     

Evaluation of six-lead electrocardiograms obtained from dogs in a sitting position or sternal recumbency

OBJECTIVE: To compare 6-lead ECG traces in clinically normal conscious dogs in a sitting position and sternal recumbency to that of right lateral recumbency. ANIMALS: 31 healthy dogs with no history of cardiac disease. PROCEDURE: Six-lead ECGs were recorded for dogs in right lateral recumbency, a sitting position, and sternal recumbency. Q-, R-, and S-wave amplitudes as well as QRS-complex duration were measured in all leads. Additionally, P-wave amplitude and duration, PR interval, ST-segment elevation or depression, and OT interval were measured in lead II. RESULTS: Compared with measurements in right lateral recumbency, the sitting position resulted in increased Q-wave amplitude (lead III), increased R-wave amplitude (leads I and aVL), decreased R-wave amplitude (leads III and aVF), increased S-wave amplitude (lead aVR), decreased S-wave amplitude (lead aVL), increased P-wave amplitude (lead II), and a leftward shift in the mean electrical axis. Compared with measurements in right lateral recumbency, sternal recumbency resulted in decreased Q-wave amplitude (leads I, II, and aVF), increased R-wave amplitude (leads 11, III, and aVF), decreased R-wave amplitude (lead aVR), increased S-wave amplitude (lead aVR), increased P-wave amplitude (lead II), and decreased ST-segment depression (lead II). Compared with right lateral recumbency, the sitting position or sternal recumbency did not result in significant differences in PR interval, QT interval, or QRS-complex duration. CONCLUSIONS AND CLINICAL RELEVANCE: Significant changes are found in ECG measurements in the sitting position and sternal recumbency, compared with right lateral recumbency. In dogs, many ECG reference range values for right lateral recumbency are not valid for ECGs obtained in the sitting position or sternal recumbency.     

Normal Swallowing in the Dog: A Cineradiographic Study

Normal dog swallowing dynamics were analyzed and correlated with specific structures. There were oropharyngeal, esophageal, and gastroesophageal phases. The oropharyngeal phase was characterized by food prehension and bolus formation (oral stage), reflex pharyngeal peristalsis (pharyngeal stage), and reflex cricopharyngeal sphincter relaxation (cricopharyngeal stage). The esophageal phase was characterized by primary peristalsis initiated by the oropharyngeal phase and secondary peristalsis which occurred in response to mechanical stimuli from a bolus in the esophagus. There was a post-peristalsis refractory period during which new peristalsis would not occur. Repeated rapid swallowing would, therefore, result in accumulation of ingesta in the esophagus. The gastroesophageal phase occurred when a bolus passed through the gastroesophageal junction, an area which serves as a lower esophageal sphincter. Gastroesophageal reflux was observed as a normal, infrequent event followed by rapid esophageal clearance. Low doses of tranquilizers had no significant influence on swallowing function. The differences observed between sternal and lateral recumbent postures related only to the rate of food consumption which, in turn, influenced esophageal motor response and inhibited gastroesophageal closure. These differences did not adversely affect the autonomous phases of swallowing.     

Upper gastrointestinal examinations: a radiographic study of clinically normal beagle puppies

A total of 24 upper gastrointestinal examinations were performed on four weanling beagle puppies over six weeks, using liquid barium (10 ml/kg bodyweight of 60 per cent w/v barium sulphate suspension] and barium food (8 g/kg of crushed kibble dog food and 7 ml/kg bodyweight of 60 per cent w/v barium sulphate suspension) as contrast media. The radiographic appearance was similar to that noted in adult dogs except for the consistent location of the pylorus on or near the midline. Duodenal pseudoulcers were seen more often with liquid barium and the caecal shadows were identified more often with the longer examination time with barium food. The stomach of the puppies appeared to have discriminatory emptying function; that is, semi-solid food was emptied from the stomach at a slower rate (210 to 450 minutes) than liquid (60 to 90 minutes). Solid meals emptied faster in puppies than in adult dogs. Dosages of 13 to 15 mg/kg bodyweight for the liquid barium examination and 14 g of ground kibble and 16 ml of barium sulphate suspension per m² of body surface area for the barium food examination are suggested as more appropriate for contrast studies in puppies.     

CONTRAST VIDEOFLUOROSCOPIC ASSESSMENT OF DYSPHAGIC CATS

The diagnostic utility of contrast‐enhanced videofluoroscopic esophagography in dysphagic cats has been rarely studied relative to dogs. Current literature regarding feline dysphagia typically consists of individual case reports or small case series. This retrospective study analyzed the imaging findings in 11 cats undergoing 15 videofluoroscopic swallow studies. Hiatal hernia (n = 5), esophageal stricture (n = 3), and esophageal dysmotility (n = 7) were the most common diagnoses (some cats having more than 1 diagnosis) in dysphagic cats that underwent videofluoroscopic swallow studies. Esophageal dysmotility appeared to be associated with a higher percentage of swallows from which no peristaltic waves were generated. Oropharyngeal and cricopharyngeal causes of dysphagia were not identified in any cat and quantitative assessment of the swallowing reflex (pharyngeal constriction ratio = 0.17 ± 0.09; time to maximum pharyngeal contraction = 0.13 ± 0.02 s; time to proximal esophageal sphincter opening = 0.07 ± 0.02 s; time to proximal esophageal sphincter closed = 0.23 ± 0.05 s; time to opening of the epiglottis = 0.27 ± 0.04 s) was similar to quantitative swallowing parameters previously reported in healthy dogs. In conclusion, videofluoroscopy is a diagnostic tool that can identify esophageal abnormalities that are not readily apparent on survey radiographs. Limitations include the potential need for multiple studies, and the possibility of poor compliance in the feline patient. Results of this study are intended to help veterinarians define a prioritized differential diagnosis list for dysphagic cats.     

Effect of body position on the arterial partial pressures of oxygen and carbon dioxide in spontaneously breathing,conscious dogs in an intensive care unit

Objective – To evaluate the effect of body position on the arterial partial pressures of oxygen and carbon dioxide (PaO₂, PaCO₂), and the efficiency of pulmonary oxygen uptake as estimated by alveolar‐arterial oxygen difference (A‐a difference). Design – Prospective, randomized, crossover study. Setting – University teaching hospital, intensive care unit. Animals – Twenty‐one spontaneously breathing, conscious, canine patients with arterial catheters placed as part of their management strategy. Interventions – Patients were placed randomly into lateral or sternal recumbency. PaO₂ and PaCO₂ were measured after 15 minutes in this position. Patients were then repositioned into the opposite position and after 15 minutes the parameters were remeasured. Measurements and Main Results – Results presented as median (interquartile range). PaO₂ was significantly higher (P=0.001) when patients were positioned in sternal, 91.2 mm Hg (86.0–96.1 mm Hg), compared with lateral recumbency, 86.4 mm Hg (73.9–90.9 mm Hg). The median change was 5.4 mm Hg (1.1–17.9 mm Hg). All 7 dogs with a PaO₂<80 mm Hg in lateral recumbency had improved arterial oxygenation in sternal recumbency, median increase 17.4 mm Hg with a range of 3.8–29.7 mm Hg. PaCO₂ levels when patients were in sternal recumbency, 30.5 mm Hg (27.3–32.7 mm Hg) were not significantly different from those in lateral recumbency, 32.2 mm Hg (28.3–36.0 mm Hg) (P=0.07). The median change was ?1.9 mm Hg (?3.6–0.77 mm Hg). A‐a differences were significantly lower (P=0.005) when patients were positioned in sternal recumbency, 21.7 mm Hg (17.3–27.7 mm Hg), compared with lateral recumbency, 24.6 mm Hg (20.4–36.3 mm Hg). The median change was ?3.1 mm Hg (?14.6–0.9 mm Hg). Conclusions – PaO₂ was significantly higher when animals were positioned in sternal recumbency compared with lateral recumbency, predominantly due to improved pulmonary oxygen uptake (decreased A‐a difference) rather than increased alveolar ventilation (decreased PaCO₂). Patients with hypoxemia (defined as PaO₂<80 mm Hg) in lateral recumbency may benefit from being placed in sternal recumbency. Sternal recumbency is recommended to improve oxygenation in hypoxemic patients.     

Effect of Experimental Hypothyroidism on Glomerular Filtration Rate and Plasma Creatinine Concentration in Dogs

Background: Hypothyroidism affects renal function in a manner opposite the effects of hyperthyroidism.
Objective: To evaluate the effects of experimentally induced hypothyroidism on glomerular filtration rate (GFR) and basal plasma creatinine concentration in dogs.
Animals: Sixteen anestrous, female dogs.
Methods: Hypothyroidism was induced by administration of ¹³¹I in 8 dogs, and 8 healthy euthyroid dogs acted as controls. Exogenous plasma creatinine clearance (an estimate of GFR) was measured in all dogs before (control period) and 43–50 weeks after induction of hypothyroidism (posttreatment period). Other pharmacokinetic parameters of creatinine were also determined.
Results: No significant difference was observed for basal plasma creatinine concentration and creatinine clearance between control and hypothyroid dogs in the control period. In the posttreatment period, mean ± SD creatinine clearance in the hypothyroid group (2.13 ± 0.48 mL/min/kg) was lower ( P < .001) than that of the control group (3.20 ± 0.42 mL/kg/min). Nevertheless, basal plasma creatinine concentrations were not significantly different between the hypothyroid and control groups (0.74 ± 0.18 versus 0.70 ± 0.08 mg/dL, respectively) because endogenous production of creatinine was decreased in hypothyroid dogs (22 ± 3 versus 32 ± 5 mg/kg/d, P =.001).
Conclusion and Clinical Importance: Hypothyroidism causes a substantial decrease in GFR without altering plasma creatinine concentrations, indicating that GFR evaluation is needed to identify renal dysfunction in such patients.     

Effect of Thyroxine Supplementation on Glomerular Filtration Rate in Hypothyroid Dogs

Background: Glomerular filtration rate (GFR) is decreased in humans with hypothyroidism, but information about kidney function in dogs with hypothyroidism is lacking.
Hypothesis: Hypothyroidism influences GFR in dogs. The objective of this study was to assess GFR in hypothyroid dogs before implementation of thyroxine supplementation and after re-establishing euthyroidism.
Animals: Fourteen hypothyroid dogs without abnormalities on renal ultrasound examination or urinalysis.
Methods: Blood pressure and GFR (measured by exogenous creatinine clearance) were measured before treatment (T0, n = 14) and at 1 month (T1, n = 14) and at 6 months (T6, n = 11) after beginning levothyroxine supplementation therapy (20 μg/kg/d, PO). The response to therapy was monitored at T1 by measuring serum total thyroxine and thyroid stimulating hormone concentrations. If needed, levothyroxine dosage was adjusted and reassessed after 1 month. Statistical analysis was performed using a general linear model. Results are expressed as mean ± standard deviation.
Results: At T0, the average age of dogs in the study group was 6.3 ± 1.4 years. Their average body weight decreased from 35 ± 18 kg at T0 to 27 ± 14 kg at T6 ( P < .05). All dogs remained normotensive throughout the study. GFR increased significantly with levothyroxine supplementation; the corresponding results were 1.6 ± 0.4 mL/min/kg at T0, 2.1 ± 0.4 at T1, and 2.0 ± 0.4 at T6 ( P < .01).
Conclusion: GFR was <2 mL/min/kg in untreated hypothyroid dogs. Re-establishment of a euthyroid state increased GFR significantly.     

Effect of body position on cranial migration of epidurally injected methylene blue in recumbent dogs

OBJECTIVE: To determine the relationship between different body positions during recumbency on the cranial migration of epidurally injected methylene blue in canine cadavers. SAMPLE POPULATION: 21 fresh cadavers of clinically normal adult female mixed-breed dogs. PROCEDURE: Dogs were randomly assigned to the following 3 groups: dogs remaining in right lateral recumbency (n = 7), dogs rotated from left to right lateral recumbency (7), and dogs rotated from dorsal to right lateral recumbency (7). Each dog received an epidural injection of 0.05% methylene blue (0.1 mL/kg) at the lumbosacral space. A dorsal laminectomy of the vertebral column was made, and cranial extent of methylene blue in 4 quadrants (right lateral, left lateral, ventral, and dorsal) was determined by examining dura mater staining. RESULTS: No significant difference was found among groups in regard to body weight or body condition score. Epidural cranial migration of methylene blue in the right lateral quadrant was significantly greater in dogs that remained in right lateral recumbency than in dogs that were rotated from left to right lateral recumbency. No significant difference was found within groups for epidural cranial migration of methylene blue between each quadrant. No significant relationship was found between body weight or body condition score and epidural cranial migration of methylene blue. CONCLUSIONS AND CLINICAL RELEVANCE: Body positioning and amount of recumbency time influence cranial migration of epidurally injected methylene blue. If greater cranial migration of an epidurally administered drug is desired, placing the patient in lateral recumbency with the surgical site on the dependent side may precede surgery.     

Thoracoscopic Thoracic Duct Ligation and Thoracoscopic Pericardectomy for Treatment of Chylothorax in Dogs

Objective— To report the use of thoracoscopic thoracic duct ligation (TDL) and pericardectomy for treatment of chylothorax.
Study Design— Case series.
Animals— Dogs with chylothorax (n=12).
Methods— Dogs with secondary or idiopathic chylothorax had thoracoscopy performed in sternal recumbency through 3 portals in the caudal right hemithorax for TDL and were then repositioned in dorsal recumbency for pericardectomy. Portals were placed in the 5th and 7th intercostal spaces of the right hemithorax with 1 transdiaphragmatic portal in the right paraxiphoid position. Follow-up was performed by recheck examination or telephone interview to determine outcome.
Results— Seven dogs (58%) had idiopathic chylothorax; 6 dogs (85.7%) had complete resolution of their effusion, whereas only 2 of the 5 nonidiopathic dogs (40%) had complete resolution.
Conclusions— Thoracoscopy is minimally invasive, provides excellent observation, and allows for ligation of the thoracic duct in the caudal thorax. Patients with idiopathic chylothorax may have a better prognosis after TDL and pericardectomy than dogs with nonidiopathic chylothorax.
Clinical Relevance— Thoracoscopy for ligation of the thoracic duct and pericardectomy is an acceptable surgical technique for treatment of chylothorax.     

Effect of Pimobendan on Echocardiographic Values in Dogs with Asymptomatic Mitral Valve Disease

Background: Pimobendan (PIMO) is a novel inodilator that has shown promising results in the treatment of advanced mitral valve disease (MVD), but little is known about its hemodynamic effects, especially regarding the mitral regurgitant volume in naturally occurring MVD.
Hypothesis: The addition of pimobendan to treatment decreases the regurgitant fraction (RF) in dogs with asymptomatic MVD.
Animals: Twenty-four client-owned dogs affected by International Small Animal Cardiac Health Council class Ib MVD.
Methods: Prospective, blinded, and controlled clinical trial. Dogs were assigned to a PIMO treatment group (n = 19) (0.2–0.3 mg/kg q12h) or a control group (n = 5). Echocardiographic evaluations were performed over a 6-month period.
Results: The addition of PIMO to treatment did not decrease the RF of dogs affected by asymptomatic class 1b MVD over the study period ( P = .85). There was a significant increase in the ejection fraction of the PIMO treated dogs at 30 days (80.8 ± 1.42 versus 69.0 ± 2.76, corrected P = .0064), and a decrease in systolic left ventricular diameter (corrected P = .011) within the PIMO group compared with baseline. However, this improvement in systolic function was not sustained over the 6-month trial period.
Conclusion and Clinical Importance: This study did not identify beneficial long-term changes in the severity of mitral regurgitation after addition of PIMO to angiotensin converting enzyme inhibitor treatment of dogs with asymptomatic MVD.     

Effect of body position on intraocular pressure in dogs without glaucoma

OBJECTIVE: To determine the effects of body position on intraocular pressure (IOP) in dogs without glaucoma. ANIMALS: 24 healthy dogs with no evidence of glaucoma. PROCEDURES: Dogs underwent ophthalmic examinations to ensure that no IOP-affecting ocular diseases were present. Each dog was sequentially placed in dorsal recumbency, sternal recumbency, and sitting position. For each of the 3 positions, IOP in the right eye was measured by use of an applanation tonometer immediately after positioning (0 minutes) and after 3 and 5 minutes had elapsed. The initial body position was randomly assigned; each position followed the other positions an equal number of times, and IOP measurements were initiated immediately after moving from one body position to the next. Proparacaine hydrochloride (0.5%) was applied to the right eye immediately prior to IOP measurements. RESULTS: Intraocular pressure was affected by body position. During the 5-minute examination, IOP decreased significantly in dogs that were dorsally recumbent or sitting but did not change significantly in dogs that were sternally recumbent. For the 3 positions, overall mean IOP differed significantly at each time point (0, 3, and 5 minutes). Mean IOP in dorsal recumbency was significantly higher than that in sternal recumbency at 0 and at 3 minutes; although the former was also higher than that in sitting position at 3 minutes, that difference was not significant. CONCLUSIONS AND CLINICAL RELEVANCE: Body position affects IOP in dogs. When IOP is measured in dogs, body position should be recorded and consistent among repeat evaluations.