A clinically utilized intravenous continuous rate infusion of diltiazem does not significantly decrease systolic function in healthy dogs.

OBJECTIVE: To determine if left ventricular systolic function on echocardiography, systemic blood pressure, and electrocardiography change with a clinically accepted intravenous (IV) diltiazem constant rate infusion (CRI) compared to a control. ANIMALS: 10 healthy client-owned adult dogs. PROCEDURES: Prospective, masked, crossover study from May 27, 2021, to August 22, 2021. Dogs were randomized to receive diltiazem (loading dose of 240 µg/kg, IV followed by a CRI of 6 µg/kg/min for 300 minutes) or the same volume of 5% dextrose in water (D5W) administered IV followed by the opposite intervention after a 7-day washout. Blood pressure was monitored during each CRI, and echocardiographic and electrocardiographic studies were performed immediately before the CRI and during the last hour of the CRI. RESULTS: Postdiltiazem systolic time interval (STI) (median, 0.30; range, 0.16 to 0.34) was significantly lower than post-D5W STI (median, 0.32; range, 0.22 to 0.40; P = .046). All other echocardiographic parameters did not differ significantly between each of the groups after receiving diltiazem or D5W. Systemic blood pressure did not change significantly with either diltiazem (P = .450) or D5W (P = .940), and none of the dogs became hypotensive at any point in the study. Expectedly, negative dromotropy was observed with diltiazem. CLINICAL RELEVANCE: A significant decrease in left ventricular systolic function was not appreciated in healthy dogs receiving diltiazem at a clinically accepted intravenous infusion rate at this dosing regimen. Further studies are needed in dogs with cardiac disease.

Effects of an intravenous infusion of diltiazem on glomerular filtration rate, electrolyte excretion, and urine output in healthy dogs.

BACKGROUND: Acute kidney injury (AKI) in dogs has a high case fatality rate. Diltiazem might improve renal function, but effect of intravenous infusion has not been adequately studied in dogs. HYPOTHESIS/OBJECTIVES: To determine if an intravenous infusion of diltiazem improves renal function through changes in glomerular filtration rate (GFR), fractional excretion of sodium (FENa), and urine output (UOP) in healthy dogs. ANIMALS: Ten healthy adult dogs. METHODS: Prospective, unmasked, crossover study. Dogs were randomized to receive diltiazem (loading dose of 240 µg/kg followed by 6 µg/kg/min for 300 min) or the same volume of 5% dextrose in water (D5W). The opposite treatment was given after a 7-day washout period. GFR and FENa were obtained at baseline and after infusion. UOP was measured starting 1 hour before diltiazem administration. RESULTS: GFR did not significantly increase from baseline with diltiazem (before diltiazem median = 2.371 mL/min/kg, range = 1.605-4.359; after diltiazem median = 2.305 mL/min/kg, range = 1.629-4.387; median difference = 0.080 mL/min/kg, 95% confidence interval [CI] = -0.417 to 0.757; P = .85), and there was no difference in D5W GFR before and after diltiazem (median = 2.389 mL/min/kg, range = 1.600-3.557; median difference = 0.036 mL/min/kg, 95% CI = -0.241 to 1.112; P = .69). FENa did not increase from baseline after administration of diltiazem (median difference = 0%, 95% CI = -0.1 to 0.1; P = .81), and there was no difference in D5W FENa (median difference = 0.1%, 95% CI = -0.1 to 0.2; P = .26). UOP did not increase with diltiazem (P = .06). CONCLUSION AND CLINICAL IMPORTANCE: Intravenous administration of diltiazem does not improve markers of renal function in healthy dogs. Further studies are needed in dogs with AKI.

Unmasking of left heart dilation following treatment for precapillary pulmonary hypertension.

A 13-year-old spayed female dog was referred for a history of tachypnea and dyspnea. Severe pulmonary hypertension was diagnosed based on tricuspid regurgitation velocities and 2-dimensional echocardiography. Left atrial size was normal at the time of this diagnosis. However, following treatment with a selective phosphodiesterase inhibitor, echocardiography revealed unmasking of left heart dilation. Key clinical message: If phosphodiesterase inhibition therapy is deemed appropriate in patients with hemodynamically important myxomatous mitral valvular disease, using the lowest effective dosage and careful monitoring with echocardiography ± thoracic radiographs should be considered.

Découverte de dilatation cardiaque gauche après traitement d'hypertension pulmonaire précapillaire. Une chienne stérilisée de 13 ans a été référée pour une histoire de tachypnée et de dyspnée. Une hypertension pulmonaire sévère a été diagnostiquée sur la base des vitesses de régurgitation tricuspidienne et de l'échocardiographie bidimensionnelle. La taille de l'oreillette gauche était normale au moment de ce diagnostic. Cependant, après un traitement avec un inhibiteur sélectif de la phosphodiestérase, l'échocardiographie a révélé une dilatation du coeur gauche.Message clinique clé :Si un traitement par inhibition de la phosphodiestérase est jugé approprié chez les patients présentant une pathologie valvulaire mitrale myxomateuse évidente et hémodynamiquement significative, l'utilisation de la dose efficace la plus faible et une surveillance attentive par échocardiographie avec ou sans radiographies thoraciques doivent être envisagées.(Traduit par Dr Serge Messier).

Evaluation of a 3-dimensional ultrasound device for noninvasive measurement of urinary bladder volume in dogs.

BACKGROUND: The BladderScan Prime Plus (BPP; Verathon, Bothell, Washington) is an application-specific, three-dimensional ultrasound device used for human, point-of-care volumetry of the urinary bladder. OBJECTIVE: To estimate the BPP's accuracy, repeatability, and optimized settings for assessing urinary bladder volumes in dogs, a variable utilized in assessing micturition disorders. ANIMALS: Twenty-four, client-owned, healthy, male dogs presenting for routine examination. METHODS: Prospective examinations were conducted by an experienced ultrasonographer and a novice, selecting the BPP's "man" or "child" setting, and were compared to urine volume obtained by catheterization. RESULTS: Mean urine volume significantly varied by operator (P = .05), device setting (P < .001), and weight (P = .01); the "man" setting produced mean volumes nearer to catheterized volumes. The mean difference between BPP's "man" setting and catheterized volume was 0.88 mL, with maximal positive and negative disagreement of +23.2 mL to -55.3 mL (SD 19.0). Percent disagreement between BPP and catheterized volumes demonstrated a mean of -4.5%, with maximal positive and negative disagreement of +58.1% to -74.1% (SD 34.9). The experienced operator recorded volumes significantly (P = .05) higher than the novice, with difference in means of 3.2 mL. In dogs weighing >5.5 kg (n = 18/24), mean difference between BPP's "man" setting and catheterized measurements, regardless of operator, was not significant. CONCLUSIONS: Although small magnitude interuser variability is present in BPP examinations, the device provides accurate, though imprecise quantification of bladder volume in canids weighing >5.5 kg.

Comparison of the effects of a dexmedetomidine-ketamine-midazolam anesthetic protocol versus isoflurane inhalation anesthesia on echocardiography variables and plasma cardiac troponin I concentration in black-tailed prairie dogs (Cynomys ludovicianus).

OBJECTIVE: To compare the effects of a dexmedetomidine-ketamine-midazolam (DKM) anesthetic protocol versus isoflurane inhalation anesthesia on echocardiographic variables and plasma cardiac troponin 1 (cTnI) concentration in black-tailed prairie dogs (BTPDs; Cynomys ludovicianus). ANIMALS: Nine 6-month-old sexually intact male captive BTPDs. PROCEDURES: Each BTPD was randomly assigned to be anesthetized by IM administration of dexmedetomidine (0.25 mg/kg), ketamine (40 mg/kg), and midazolam (1.5 mg/kg) or via inhalation of isoflurane and oxygen. Three days later, each BTPD underwent the alternative anesthetic protocol. Echocardiographic data and a blood sample were collected within 5 minutes after initiation and just prior to cessation of each 45-minute-long anesthetic episode. RESULTS: Time or anesthetic protocol had no significant effect on echocardiographic variables. For either protocol, plasma cTnI concentration did not differ with time. When administered as the first treatment, neither anesthetic protocol significantly affected plasma cTnI concentration. However, with regard to findings for the second treatments, plasma cTnI concentrations in isoflurane-treated BTPDs (n = 4; data for 1 animal were not analyzed because of procedural problems) were higher than values in DKM-treated BTPDs (4), which was suspected to be a carryover effect from prior DKM treatment. CONCLUSIONS AND CLINICAL RELEVANCE: The DKM and isoflurane anesthetic protocols did not have any significant effect on echocardiographic measurements in the BTPDs. Increases in plasma cTnI concentration during the second anesthetic episode were evident when BTPDs underwent the DKM anesthetic protocol as the first of the 2 treatments, suggestive of potential myocardial injury associated with that anesthetic protocol. Clinicians should consider these findings, especially when evaluating BTPDs with known or suspected cardiac disease.

Effect of ractopamine hydrochloride and zilpaterol hydrochloride on cardiac electrophysiologic and hematologic variables in finishing steers.

OBJECTIVE To investigate the effects of dietary supplementation with the ß-adrenoceptor agonists ractopamine hydrochloride and zilpaterol hydrochloride on ECG and clinicopathologic variables of finishing beef steers. DESIGN Randomized controlled trial. ANIMALS 30 Angus steers. PROCEDURES Steers were grouped by body weight and randomly assigned to receive 1 of 3 diets for 23 days: a diet containing no additive (control diet) or a diet containing ractopamine hydrochloride (300 mg/steer/d) or zilpaterol hydrochloride (8.3 mg/kg [3.8 mg/lb] of feed on a dry-matter basis), beginning on day 0. Steers were instrumented with an ambulatory ECG monitor on days -2, 6, 13, and 23, and continuous recordings were obtained for 72, 24, 24, and 96 hours, respectively. At the time of instrumentation, blood samples were obtained for CBC and serum biochemical and blood lactate analysis. Electrocardiographic recordings were evaluated for mean heart rate and arrhythmia rates. RESULTS Steers fed zilpaterol or ractopamine had greater mean heart rates than those fed the control diet. Mean heart rates were within reference limits for all steers, with the exception of those in the ractopamine group on day 14, in which mean heart rate was high. No differences in arrhythmia rates were identified among the groups, nor were any differences identified when arrhythmias were classified as single, paired, or multiple (> 2) beats. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that dietary supplementation of cattle with ractopamine or zilpaterol at FDA-approved doses had no effect on arrhythmia rates but caused an increase in heart rate that remained within reference limits.

Survival of 4 dogs with persistent atrial standstill treated by pacemaker implantation.

Pacemakers were implanted in 4 client-owned female dogs which had persistent atrial standstill. Three dogs were alive after 14 to 39 months and 1 dog was euthanized after 10.5 years. This report demonstrates that some dogs with persistent atrial standstill can survive for extended time periods.

Survie de 4 chiennes atteintes de paralysie auriculaire persistante traitées à l'aide de l'implantation d'un cardiostimulateur. Des cardiostimulateurs ont été implantés chez 4 chiennes, appartenant à des propriétaires, atteintes de paralysie auriculaire persistante. Trois chiennes étaient vivantes après 14 à 39 mois et 1 chienne a été euthanasiée après 10,5 ans. Ce rapport démontre que certains chiens atteints de paralysie auriculaire persistante peuvent survivre pendant des périodes de temps prolongées.(Traduit par Isabelle Vallières).

CARDIAC ASSESSMENT OF ZOO-KEPT, BLACK-TAILED PRAIRIE DOGS (CYNOMYS LUDOVICIANUS) ANESTHETIZED WITH ISOFLURANE.

Cardiomyopathy is suggested to be a relatively common disease condition in prairie dogs; however, there are no reports of normal cardiac echosonography and radiology in the prairie dog ( Cynomys spp.). The objective of this study was to report the ultrasonographic and radiographic measurements of the heart, and plasma troponin concentration in captive healthy anesthetized black-tailed prairie dogs ( Cynomys ludovicianus ). Zoo-kept prairie dogs with no signs of cardiac disease (n = 17) were evaluated. Each animal was anesthetized with isoflurane via face mask and a complete clinical assessment was performed, including complete blood cell count and plasma biochemistry, urinalysis, blood gasses, plasma troponin concentration, three-view whole body radiography, and echocardiogram. Standard measurements were taken. Few trivial findings were identified on echocardiographic evaluation. Further research with a larger sample size is needed to determine if these variations are normal, or represent early or mild cardiac disease. The data presented here can aid, with the necessary caution, in evaluating prairie dogs with possible cardiac disease, potentially resulting in earlier diagnosis and more successful treatment.

The static electrocardiogram in clinically healthy, anesthetized, zoo-kept black-tailed prairie dogs (Cynomys ludovicianus).

OBJECTIVES: The goal of this study was to evaluate the static electrocardiograms of clinically healthy black-tailed prairie dogs (Cynomys ludovicianus), and suggest normal values. ANIMALS: Thirteen clinically healthy black-tailed prairie dogs were included in the study. They were anesthetized for physical examination, and complete laboratory data including troponin I concentration, thoracic radiographs, echocardiograms, and static ECG were recorded. MATERIAL AND METHODS: Static electrocardiograms were recorded using standard, six-limb leads from each of the 13 apparently healthy prairie dogs. Each prairie dog was anesthetized with isoflurane via facemask. Electrocardiograms were recorded in right lateral recumbency. The data were retrospectively analyzed. Lead II was used for waveform analysis. RESULTS: The median heart rate was 250 bpm (range 147-320). Median P-wave amplitude was 0.05 mV (range 0.01-0.06) and P-wave duration was 0.03 s (range 0.02-0.03). The PR interval was 0.06 s (range 0.04-0.06). The R-wave amplitude was 0.5 mV (range 0.1-1.15) and the QRS duration was 0.02 s (range 0.02-0.03). The QT interval was 0.12 s (range 0.1-0.14). Sixty-two percent of the QRS complexes were of Rs configuration. CONCLUSIONS: Static electrocardiograms can be performed and evaluated in anesthetized prairie dogs. This report provided normal values in clinically healthy black-tailed prairie dogs.

Pulmonary edema secondary to a cardiac schwannoma in a dog.

A 4-year-old castrated labrador retriever presented for cardiac evaluation to determine the etiology of cardiogenic pulmonary edema diagnosed 1 month prior. A large pedunculated mass involving the ventral aspect of the mural mitral valve leaflet and the endocardial surface of the left ventricular free wall, resulting in severe mitral regurgitation, was identified on echocardiogram. Histopathology and immunohistochemistry of this mass and other endocardial masses identified at necropsy for S-100 protein were consistent with a diagnosis of schwannoma. To the authors' knowledge, this is the first case of a benign intracardiac schwannoma described in the left heart of a dog.

Doppler echocardiographic diagnosis and surgical therapy of constrictive pericarditis in a cat.

A 4-year-old Ragdoll cat presented for dyspnea secondary to chylous pleural effusion to the University of Georgia Veterinary Teaching Hospital. Physical examination, complete blood count, serum chemistries, urinalysis, thoracic radiographs, abdominal radiographs, and thoracic fluid cytology and culture failed to identify an etiology for the chylous effusion. The patient tested negative for feline leukemia virus, feline immunodeficiency virus and heartworm disease. Respiration phasic influences on early diastolic trans-mitral, trans-tricuspid and pulmonary vein blood flow velocities during Doppler echocardiography were consistent with constrictive pericarditis. The cat underwent subtotal pericardectomy. The patient recovered without complication and is overtly healthy without radiographic or echocardiographic abnormalities 6-months post-surgery. Constrictive pericarditis should be considered in cats with idiopathic pleural effusion, with or without ascites, in which standard echocardiographic assessment is not suggestive of structural heart disease. If constrictive pericarditis is present, the Doppler characteristics outlined here may allow for this diagnosis to be made. Pericardectomy may be highly rewarding, although the specific etiology of the constrictive pericarditis may remain unknown.