Effect of spironolactone on diuresis and urine sodium and potassium excretion in healthy dogs

ObjectivesTo document the diuretic effect of different oral doses of spironolactone (SP) in healthy dogs.BackgroundSP is currently mentioned as a diuretic agent in the dog. However, the recommended doses were empirically defined and their corresponding diuretic effect has never been documented in dogs.Animals, materials and methodsEight adult Beagle dogs were used for two separate 2 * 2 cross-over designs. In the first cross-over, 4 dogs received SP orally for 8 days at 1 and 2 mg/kg per day. In the second cross-over the 4 other dogs received SP similarly, but at 4 and 8 mg/kg per day. Dogs were weighed on the first and last day of each period. Plasma SP and canrenone (the main active metabolite of SP) were assayed by high performance liquid chromatography (HPLC). Daily water consumption, urine weight, urine specific gravity, and urine excretion of sodium and potassium were measured during the SP treatment.ResultsTwo hours after SP administration, SP was metabolized into canrenone. A significant 14 and 22% decrease in urine potassium excretion was observed at 1 and 2 mg/kg, respectively, but not at the two other dose levels. Daily water consumption, urine weight, urine specific gravity, and urine excretion of sodium were not significantly altered by the SP treatment regardless of dose.ConclusionsRepeated oral administration of SP at 1, 2, 4 or 8 mg/kg for 8 days had no effect on water and sodium diuresis in healthy dogs.     

Weekly variability of plasma and serum NT-proBNP measurements in normal dogs

ObjectivesTo determine the weekly variability of serum and plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentrations in healthy dogs.Animals, materials and methodsFifty-three normal dogs were examined prospectively. Serum (n = 25) or plasma (n = 28) samples were obtained for NT-proBNP assay at one week interval for 3 consecutive weeks.ResultsMedian serum or plasma NT-proBNP concentration did not change over 3 consecutive weeks. Twenty-two of 53 dogs (42%) had at least one NT-proBNP value >500 pmol/L, including 14 dogs with at least one serum NT-proBNP concentration >500 pmol/L and 8 dogs with at least one plasma NT-proBNP concentration >500 pmol/L during the 3-week sampling period. The difference between the maximum and minimum NT-proBNP value obtained over the 3-week sampling period was <100 pmol/L in 40% of dogs, between 100 and 200 pmol/L in 40% of dogs, and >200 pmol/L in 20% of dogs. Of the 19 dogs with a value >500 pmol/L on either week 1 or 2, 11 dogs (58%) had a subsequent NT-proBNP value <500 pmol/L on either week 2 or 3.ConclusionsThere is a high degree of variability in weekly serum and plasma NT-proBNP values in healthy dogs. Individual variability should be considered when interpreting NT-proBNP results in dogs.     

Effect of azotemia on serum N-terminal proBNP concentration in dogs with normal cardiac function: A pilot study

ObjectivesTo evaluate amino-terminal pro-B type natriuretic peptide (NT-proBNP) concentration in dogs with renal dysfunction and normal cardiac structure and function.AnimalsEight dogs with renal disease, 23 healthy control dogs.MethodsSerum NT-proBNP concentration was measured in healthy dogs and dogs with renal disease using an ELISA validated for use in dogs. Affected dogs were eligible for inclusion if renal dysfunction was diagnosed based on urinalysis and serum chemistry, and if they were free of cardiovascular disease based on physical exam, systolic blood pressure, and echocardiography.ResultsThe geometric mean serum NT-proBNP concentration was significantly higher in dogs with renal disease (617 pmol/L; 95% CI, 260–1467 pmol/L) than in healthy control dogs (261 pmol/L; 95% CI, 225–303 pmol/L; P = 0.0014). There was a modest positive correlation between NT-proBNP and BUN and creatinine. Median NT-proBNP concentration was not significantly different between groups when indexed to BUN (median NT-proBNP:BUN ratio; renal, 14.2, IQR, 3.93–17.7 vs. control, 16.3, IQR, 9.94–21.2; P = 0.29) or creatinine (median NT-proBNP:creatinine ratio; renal, 204, IQR, 72.6–448 vs. control, 227, IQR, 179–308; P = 0.67).ConclusionDogs with renal disease had significantly higher mean serum concentration of NT-proBNP than control dogs. Renal function should be considered when interpreting NT-proBNP results as concentrations may be falsely elevated in dogs with renal dysfunction and normal cardiac function. The effect of renal disease was lessened by indexing NT-proBNP to BUN or creatinine. Future studies in dogs with both renal and heart disease are warranted.     

Radial strain and strain rate by two-dimensional speckle tracking echocardiography and the tissue velocity based technique in the dog

ObjectivesTwo-dimensional (2D) speckle tracking echocardiography (STE) is a new angle-independent ultrasound technique based on tracking of speckles within the myocardium on 2D grayscale images. The aims of this prospective study were as follows: (1) to assess the variability of left ventricular peak systolic radial strain (St) and strain rate (SR) in awake dogs using STE (Protocol 1); and (2) to quantify these variables in a healthy canine population and compare them with tissue Doppler imaging (TDI)-based St and SR values (Protocol 2).BackgroundSt and SR may be assessed using TDI, which is limited by angle dependency.Animals, materials and methodsThirty-six STE examinations were performed on 6 healthy dogs for Protocol 1 and 37 healthy dogs were recruited for Protocol 2. In both studies, STE measurements were obtained offline from the right parasternal short-axis view by the same trained observer using automatic frame-to-frame tracking of grayscale speckle patterns.ResultsAll within- and between-day coefficients of variation were <10% (Protocol 1). In Protocol 2, St (46.7 ± 12.2%) and SR (2.7 ± 0.6 s⁻¹) measured by STE were correlated with heart rate (p < 0.01), but not with the ratio of early mitral inflow velocity to early mitral annular velocity. There was a good correlation between STE and TDI for both St and SR values (p < 0.001).ConclusionsSTE is a repeatable and reproducible non-Doppler method for assessing radial St and SR. The combination of these indices with conventional echo-Doppler variables could provide a new approach for accurately quantifying canine systolic function.     

Quadricuspid aortic valve and associated abnormalities in the dog: Report of six cases

ObjectivesTo describe the clinical and echocardiographic findings in dogs with quadricuspid aortic valve (QAV).BackgroundQAV is a rare canine congenital heart disease which has been reported only three times in the young dog.Animals, materials and methodsSix dogs (0.3- to 13-year-old) with QAV diagnosed by two-dimensional echocardiography were retrospectively evaluated. Medical records, echocardiograms, and follow-ups were reviewed.ResultsAccording to aortic cusp morphology, QAV was classified as type A (n = 1), type B (n = 4) or type C (n = 1). QAV was associated with at least one other heart disease in all of the dogs including, ventricular septal defect (n = 1), enlarged left coronary ostium (n = 4), degenerative mitral valve disease (MVD, n = 1) and patent ductus arteriosus (PDA, n = 3). Mild to moderate aortic regurgitation was also detected in all dogs by continuous-wave and color-flow Doppler echocardiography. QAV was diagnosed in four asymptomatic dogs referred for evaluation of a heart murmur. The remaining two dogs had QAV and PDA with evidence of mild exercise intolerance and moderately retarded growth. The PDA was surgically corrected in both dogs and at the time of writing, 1–2.5 years after the initial diagnosis, none of the six animals shows evidence of clinical signs.ConclusionQAV is a cause of aortic insufficiency. It may incidentally be found by two-dimensional echocardiography in dogs of various ages in association with other congenital or acquired cardiac abnormalities.     

Plasma atrial natriuretic peptide concentration in warmblood horses with heart valve regurgitations

ObjectivesThis study measured plasma atrial natriuretic peptide (ANP) concentration in horses with heart valve regurgitations (HVR) with and without atrial and ventricular dilatation.BackgroundIn humans and small animals, plasma ANP concentration is increased in heart disease and correlates with the severity of clinical signs and heart enlargement.Animals, materials and methodsTen healthy horses (control) and 36 horses with HVR were evaluated by auscultation, electrocardiography, echocardiography, and determination of plasma ANP.ResultsControl horses demonstrated mean plasma ANP concentration of 21 ± 5.4 pg/mL. Of the 36 horses with HVR, 17 horses possessed normal echocardiographic heart size (group 1), 10 horses had a left atrial dilatation (group 2) and 9 horses had both left atrial and ventricular dilatation (group 3). Mean plasma ANP concentration of groups 1, 2 and 3 was 20.1 ± 5.6 pg/mL, 22.9 ± 11.0 pg/mL and 27.6 ± 17.4 pg/mL, respectively. The plasma ANP concentrations of HVR and control horses were not significantly different. The highest ANP concentrations were observed in horses with atrial and ventricular dilatation. No correlation between left atrial or ventricular size, weight, or sex and the plasma ANP concentration was found.ConclusionsNo significant differences in plasma ANP concentration was observed between groups. Further study, especially in horses with clinical signs of heart failure is needed.     

Evaluation of transformation growth factor beta1, interleukin-10, and interferon-gamma in male symptomatic and asymptomatic dogs naturally infected by Leishmania (Leishmania) chagasi

The aims of this study were to evaluate the immunomodulatory role of TGF-β₁, IL-10, and INF-γ in spleen and liver extracts and supernatant cultures of white spleen cells from male symptomatic and asymptomatic dogs, naturally infected by Leishmania (Leishmania) chagasi. Thirty dogs from Araçatuba, São Paulo, Brazil, an endemic leishmaniosis area, were selected by positive ELISA serological reaction for Leishmania sp. and divided into two groups: asymptomatic (n = 15) and symptomatic (n = 15) consisting of animals with at least three characteristic signs (fever, dermatitis, lymphoadenopathy, onychogryphosis, weight loss, cachexia, locomotion problems, conjunctivitis, epistaxis, hepatosplenomegaly, edema, and apathy). After euthanasia, spleen and liver fragments were collected for ex vivo quantification of TGF-β₁, IL-10, and INF-γ. Naturally active in vitro produced TGF-β₁ was also evaluated in spleen cell culture supernatant. Spleen and liver extract of asymptomatic dogs had higher mean TGF-β₁ levels than symptomatic dogs. High concentrations of IL-10 were found in spleen, and mainly in liver extract of both groups. Higher INF-γ concentrations were found in spleen extracts of symptomatic dogs, and in liver extracts of asymptomatic dogs. Extract of this cytokine was lower in spleen extract. Although INF-γ is being produced in canine infection, mean levels of TGF-β₁ and IL-10 from spleen and liver extracts were quantitatively much higher; suggesting that immune response in both asymptomatic and symptomatic dogs was predominantly type Th2.     

Improvements of immune status, intestinal integrity and gain performance in the early-weaned calves parenterally supplemented with L-alanyl-L-glutamine dipeptide

Glutamine (Gln) is an important substrate for the innate immune cells including lymphocytes and macrophages. In this report, the effects of alanyl-glutamine dipeptide (Ala-Gln) on the naïve immune system, intestinal integrity and gain performance of early-weaned calves were investigated. Early-weaned Chinese Holstein calves were intravenously administered different dosages of Ala-Gln. The effects of Ala-Gln administration were ascertained by evaluating the blood for naïve T lymphocyte subpopulations, the concentrations of serum IgG, serum IgA and intestinal mucosal secretory IgA (s-IgA), the intestinal integrity, as well as the gain performance. Results demonstrated that intravenous administration of Ala-Gln dipeptide (1.01 g/kg × d^?1) for 7 days had a positive effect on gain performance, intestinal integrity and the immune system. Calves administered doses of Ala-Gln displayed an improvement in gain performance and health status concurrent with increases in blood CD2⁺ and CD4⁺ lymphocytes, the ratio of CD4⁺/CD8⁺, serum IgA and IgG, intestinal mucosal s-IgA while decreasing the occurrence of diarrhea. Moreover, we found that animals given the effective dose (1.01 g/kg × d^?1) of Ala-Gln resulted in improved immune status and intestinal integrity relative to those given a lower (0.49 g/kg × d^?1) or higher dose (1.99 g/kg × d^?1) of Ala-Gln. These findings suggest that maintaining a certain concentration of plasma and/or tissue glutamine in the early stages of weaning is an effective alternative approach for improvement of growth performance in early-wean calves.     

Serum total thyroxine and thyroid stimulating hormone concentrations in dogs with behavior problems

The aim of this case controlled study was to determine whether dogs with behavioral problems have evidence of abnormal thyroid function on routine screening tests for hypothyroidism. The hypothesis of the study was that thyroid function, as assessed by serum total thyroxine (TT4) and serum thyroid stimulating hormone (thyrotropin) (TSH) concentrations, is normal in most dogs with behavioral problems. Concentrations of TT4 and TSH in 39 dogs with behavior problems presenting to a veterinary behavior referral clinic (abnormal behavior group), were compared with TT4 and TSH concentrations in 39 healthy control dogs without behavior problems presenting to 5 community veterinary practices (control group). Dogs in the control group were matched for age and breed with the abnormal behavior group. Dogs with behavioral problems had higher TT4 concentrations than dogs without behavioral problems (t-test: t = 2.77, N = 39, P = 0.009), however none of the TT4 values were outside the reference range. There was no significant difference in TSH concentration between the 2 groups. Two dogs with behavior problems and 1 dog without behavior problems had results suggestive of hypothyroidism. All other dogs were considered to be euthyroid. There was no evidence to support a diagnosis of hypothyroidism in the majority of dogs with behavior problems in this study. The higher concentration of TT4 in dogs with behavior problems suggests, however, that alteration in thyroid hormone production or metabolism may occur in some dogs with behavior problems. Further studies that include additional indicators of thyroid status such as serum total triiodothyronine, serum, free thyroxine, and anti-thyroid antibody concentrations are necessary to further evaluate the significance of this finding.     

Resting concentrations of cardiac troponin I in fit horses and effect of racing

ObjectivesTo determine normal resting values for cardiac troponin I (cTnI) in healthy Standardbred, Thoroughbred and Warmblood horses and investigate if racing has an influence on cTnI concentrations.BackgroundMeasuring cTnI concentrations in plasma is the gold standard for detecting myocardial injury in humans. Cardiac troponin I is highly conserved between species and has gained interest as a marker for cardiac injury in horses. Increased levels of cTnI have been reported in association with endurance and short-term strenuous exercise on a treadmill in horses. However, the effect of true racing conditions has not yet been reported.Animals, materials and methodsBlood samples for analysis of cTnI concentrations in plasma were collected from 67 Standardbred racehorses, 34 Thoroughbred racehorses and 35 Warmblood dressage horses at rest. Blood samples were also collected prior to and after racing in 22 Standardbred racehorses and 6 Thoroughbred racehorses.ResultsAll horses except one had resting plasma cTnI concentrations <0.022 μg/L. Mild increases in cTnI concentrations were seen in some horses 1–2 h after the race (1/17 Standardbreds and 2/6 Thoroughbreds) as well as 10–14 h after the race (4/21 Standardbreds and 1/6 Thoroughbreds).ConclusionsResting cTnI concentrations in horses are low but mildly elevated cTnI concentrations may be detected in some horses 1–14 h after racing. These findings could be of importance when evaluating horses with suspected cardiac disease that recently have performed hard exercise.     

Resveratrol decreases oxidative burst capacity and alters stimulated leukocyte cytokine production in vitro

IntroductionResveratrol, a naturally-occurring phytophenol, has been shown to bolster immune surveillance and reverse immunosenescence in a dose dependent manner in rodents and humans. Although safety and pharmacokinetic studies have been completed in dogs, the immunomodulatory effects of resveratrol in dogs has not yet been investigated. The objective of this study was to determine the effect of resveratrol on canine innate immune system function in vitro. The hypothesis was that similar to other species, low concentrations of resveratrol would stimulate while high concentrations would depress innate immune system function.MethodsWhole blood was collected from six healthy, adult, client-owned dogs and was incubated with resveratrol at final concentrations of 6000 ng ml⁻¹, 3000 ng ml⁻¹, 1000 ng ml⁻¹, or control solution for 4 h. Following incubation, phagocytosis and oxidative burst were evaluated using flow cytometry, and LPS-, lipoteichoic acid (LTA) – and peptidoglycan (PG)-stimulated leukocyte production of TNF, IL-6, and IL-10 were measured using a canine specific multiplex assay.ResultsPhagocytosis was not altered by resveratrol at any concentration compared to control. However, while the number of PMNs capable of performing oxidative burst did not change, the robustness of the reaction following stimulation with Escherichia coli and PMA was reduced in a dose dependent manner. In addition, LPS-, LTA-, PG, and PBS-stimulated TNF production was increased following incubation with all concentrations of resveratrol compared to control, and this effect was dose dependent. LTA-stimulated IL-6 was increased with resveratrol compared to control. Furthermore, LTA-stimulated IL-10 was decreased with 6000 ng ml⁻¹ and 3000 ng ml⁻¹ concentrations of resveratrol and PG-stimulated IL-10 production was decreased with all concentrations of resveratrol compared to control. The LPS-, LTA-, and PG-stimulated TNF:IL-10 ratio was increased with 6000 ng ml⁻¹ of resveratrol compared to control and lower resveratrol concentrations.ConclusionWhile resveratrol was sparing to PMN phagocytosis, it reduced the robustness of PMN oxidative burst. Resveratrol also increased pro-inflammatory and decreased anti-inflammatory leukocyte cytokine production capacity in vitro. These data suggest that resveratrol supplementation may depress oxidative burst reactions while promoting pro-inflammatory leukocyte cytokine production and decreasing anti-inflammatory cytokine production. Based on these findings, further in vivo study regarding the effects of resveratrol on PMN oxidative burst capability and leukocyte cytokine production capacity are indicated prior to routine supplementation.     

Canine heartworm (Dirofilaria immitis) in Fresno and Madera Counties, California: prevalence differences between foothill and valley habitats

The aim of this study was to assess the prevalence of heartworm in domestic dogs in Madera and Fresno Counties, California, dependent on habitat and other host and environmental factors. Dogs were screened for presence of heartworm antigen using the PetChek^® ELISA on blood samples (N = 519) collected at seven sites during April-July 2009. Eighteen dogs were heartworm antigen positive. Pearson Chi-square analyses were conducted testing the presence of heartworm antigen against the following independent variables: elevation range, percentage of time spent outdoors during the day, percentage of time spent outdoors during the night, pet coat length, weight class, prevention status, and sex. Dogs that spent at least 50% of their time outdoors during the day were significantly more likely to have heartworm that those who spent less time outside (N = 519, df = 1, p = 0.031). Overall prevalence (3.47%) was lower than expected, with Madera County having 3.8% positive samples and Fresno County 3.5%; this prevalence is lower than in many previous studies. The effect of time spent outdoors on heartworm prevalence was similar to previous studies. The impact of elevation on infection, though not significant, requires further investigation, as does the prevalence and viability of larval stages in mosquitoes.     

Contrast echocardiography in Boxer dogs with and without aortic stenosis

ObjectivesThe aim of this study was to investigate whether contrast echocardiography could enhance the subcostal Doppler signal for aortic flow measurements and achieve myocardial opacification, in Boxer dogs with and without AS.BackgroundIn evaluating dogs for aortic stenosis (AS) subcostal Doppler echocardiography was used for measurement of the aortic flow velocity, a measurement that can sometimes be difficult to perform in Boxer dogs.Animals, materials, and methodsCardiac auscultation, phonocardiographic and echocardiographic examinations, including a contrast study with Optison, were performed on 29 Boxer dogs selected based on previous examinations.ResultsThe initial subcostal Doppler signal was weak in 66% of the dogs and a marked improvement was seen in all dogs after contrast injection. The peak aortic flow velocity increased 5% from 2.58 ± 1.42 m/s before contrast to 2.71 ± 1.54 m/s after contrast (p = 0.003). This corresponds to a 2.8 mmHg increase in the pressure gradient from 26.6 mmHg before to 29.4 mmHg after contrast. A dose of 0.05–0.1 mL of Optison administered intravenously resulted in approximately 4 min of Doppler signal enhancement. With the present technique contrast echocardiography did not achieve myocardial opacification.ConclusionsSingle use of the contrast agent Optison can be recommended for enhancement of the subcostal Doppler signal in dogs, in which plain Doppler signals are difficult to obtain. Albeit statistically significant, the mild increase in peak aortic flow velocity after contrast was not considered biologically or clinically significant.     

Use of Fourier-transform infrared spectroscopy to quantify immunoglobulin G concentration and an analysis of the effect of signalment on levels in canine serum

Deficiency in immunoglobulin G (IgG) is associated with an increased susceptibility to infections in humans and animals, and changes in IgG levels occur in many disease states. In companion animals, failure of transfer of passive immunity is uncommonly diagnosed but mortality rates in puppies are high and more than 30% of these deaths are secondary to septicemia. Currently, radial immunodiffusion (RID) and enzyme-linked immunosorbent assays are the most commonly used methods for quantitative measurement of IgG in dogs. In this study, a Fourier-transform infrared spectroscopy (FTIR) assay for canine serum IgG was developed and compared to the RID assay as the reference standard. Basic signalment data and health status of the dogs were also analyzed to determine if they correlated with serum IgG concentrations based on RID results.Serum samples were collected from 207 dogs during routine hematological evaluation, and IgG concentrations determined by RID. The FTIR assay was developed using partial least squares regression analysis and its performance evaluated using RID assay as the reference test. The concordance correlation coefficient was 0.91 for the calibration model data set and 0.85 for the prediction set. A Bland–Altman plot showed a mean difference of −89 mg/dL and no systematic bias. The modified mean coefficient of variation (CV) for RID was 6.67%, and for FTIR was 18.76%.The mean serum IgG concentration using RID was 1943 ± 880 mg/dL based on the 193 dogs with complete signalment and health data. When age class, gender, breed size and disease status were analyzed by multivariable ANOVA, dogs <2 years of age (p = 0.0004) and those classified as diseased (p = 0.03) were found to have significantly lower IgG concentrations than older and healthy dogs, respectively.     

Fluoxetine combined with clorazepate dipotassium and behaviour modification for treatment of anxiety-related disorders in dogs

The effectiveness of clorazepate dipotassium combined with fluoxetine and a behaviour modification programme for the treatment of anxiety disorders in dogs was investigated. Forty dogs with anxiety disorders were initially enrolled and 36 dogs completed the trial. Dogs were classified into two behavioural categories (anxious dogs with aggression and anxious dogs without aggression) according to their presenting complaints, and were also subdivided into males, females, juveniles and adults. The dog owners were provided with a behaviour modification plan for their dogs to be commenced in the first week of therapy. Clorazepate dipotassium was administered PO at 1.0 mg/kg every 24 h for 4 weeks, and fluoxetine was administered PO at 1.0 mg/kg every 24 h for 10 weeks. Therapy with both drugs was initiated simultaneously. Improvement was reported in 25/36 dogs. Significant differences in treatment effects were observed between anxious dogs with aggression and anxious dogs without aggression (P < 0.05). Positive correlations between owner compliance with the treatment plan and reported improvement achieved during three periods of study were also noted.     

Assessment of the diagnostic accuracy of circulating natriuretic peptide concentrations to distinguish between cats with cardiac and non-cardiac causes of respiratory distress

ObjectivesTo determine if serum natriuretic peptide (NP) concentrations could distinguish cardiac from non-cardiac causes of respiratory distress (RD) in cats.AnimalsSeventy-four cats from 1 university hospital were used.MethodsSerum NP concentrations were measured in 41 cats with non-cardiac respiratory distress (RD-NC) and compared to 33 cats with RD due to congestive heart failure (RD + CHF) using sandwich enzyme immunoassays (ELISA).ResultsRD-NC cats had lower (P = 0.0001) median NT-proANP and NT-proBNP concentrations (614 and 45 fmol/mL, respectively) than RD + CHF cats (1690 and 523 fmol/mL, respectively). The area under the curve was 0.88 and 0.96 for the receiver operating curve analysis of the diagnostic accuracy of NT-proANP and NT-proBNP concentrations to discriminate RD + CHF from RD-NC cats (P = 0.036). An optimum cut-off concentration of 986 fmol/mL for NT-proANP and 220 fmol/mL for NT-proBNP accurately discriminated RD-NC from RC + CHF cats with a sensitivity of 93.8% and 93.9% and a specificity of 80.3% and 87.8%, respectively.ConclusionsSerum NP concentrations were different in RD + CHF cats compared to RD-NC cats. Evaluation of circulating NP concentrations may be helpful in the initial approach to cats presenting with respiratory distress, particularly if advances in ELISA technology result in a rapid cage-side test.     

Arrhythmogenic right ventricular cardiomyopathy in Boxer dogs is associated with calstabin2 deficiency

ObjectiveTo examine the presence and effect of calstabin2-deficiency in Boxer dogs with arrhythmogenic right ventricular cardiomyopathy (ARVC).AnimalsThirteen Boxer dogs with ARVC.Materials and methodsTissue samples were collected for histopathology, oligonucleotide microarray, PCR, immunoelectrophoresis, ryanodine channel immunoprecipitation and single-channel recordings, and calstabin2 DNA sequencing.ResultsIn cardiomyopathic Boxer dogs, myocardial calstabin2 mRNA and protein were significantly decreased as compared to healthy control dogs (calstabin2 protein normalized to tetrameric cardiac ryanodine receptor (RyR2) complex: affected, 0.51 ± 0.04; control, 3.81 ± 0.22; P < 0.0001). Calstabin2 deficiency in diseased dog hearts was associated with a significantly increased open probability of single RyR2 channels indicating intracellular Ca²⁺ leak. PCR-based sequencing of the promoter, exonic and splice site regions of the canine calstabin2 gene did not identify any causative mutations.ConclusionsCalstabin2 deficiency is a potential mechanism of Ca²⁺ leak-induced ventricular arrhythmias and heart disease in Boxer dogs with ARVC.     

The effect of maropitant on intraoperative isoflurane requirements and postoperative nausea and vomiting in dogs: a randomized clinical trial

ObjectiveTo establish if preoperative maropitant significantly reduced intraoperative isoflurane requirements and reduced clinical signs associated with postoperative nausea and vomiting (PONV) in dogs.Study designRandomized clinical trial.AnimalsTwenty-four healthy, client-owned dogs undergoing routine ovariohysterectomy.MethodsPremedication involved acepromazine (0.03 mg kg⁻¹) combined with methadone (0.3 mg kg⁻¹) intramuscularly 45 minutes before anaesthetic induction with intravenous (IV) propofol, dosed to effect. Meloxicam (0.2 mg kg⁻¹) was administered intravenously. Dogs were randomly assigned to administration of saline (group S; 0.1 mL kg⁻¹, n = 12) or maropitant (group M; 1 mg kg⁻¹, n = 12) subcutaneously at time of premedication. Methadone (0.1 mg kg⁻¹ IV) was repeated 4 hours later. Anaesthesia was maintained with isoflurane in oxygen, dosed to effect by an observer unaware of group allocation. The dogs were assessed hourly, starting 1 hour postoperatively, using the short form of the Glasgow Composite Pain Score (GCPS), and for ptyalism and signs attributable to PONV [score from 0 (none) to 3 (severe)] by blinded observers. Owners completed a questionnaire at the postoperative recheck.ResultsOverall mean ± standard deviation end-tidal isoflurane percentage was lower in group M (1.19 ± 0.26%) than group S (1.44 ± 0.23%) (p = 0.022), but was not significantly different between groups at specific noxious events (skin incision, ovarian pedicle clamp application, cervical clamp application, wound closure). Cardiorespiratory variables and postoperative GCPS were not significantly different between groups. Overall, 50% of dogs displayed signs attributable to PONV, with no difference in PONV scores between groups (p = 0.198). No difference in anaesthetic recovery was noted by owners between groups.ConclusionsMaropitant reduced overall intraoperative isoflurane requirements but did not affect the incidence of PONV.Clinical relevanceMaropitant provided no significant benefits to dogs undergoing ovariohysterectomy with this anaesthetic and analgesic protocol, although clinically significant reductions in isoflurane requirements were noted.     

Methods and normal values for echocardiography in adult dairy cattle

ObjectiveThe objective of the study was to report normal ultrasonographic appearance and intra-cardiac dimensions in two dairy breeds and to calculate cardiac output (CO) using echocardiography.BackgroundIntra-cardiac dimensions, time indices and CO estimation have not previously been reported in adult cattle.Animals, materials and methodsEchocardiograms were obtained from healthy adult dairy cows (10 Jersey (J) and 12 Holstein Friesians (HF)) in the body weight range of 400 to 700 kg. Standard echocardiographic images were obtained from the left and right hemithoraces. Velocity time integrals were obtained in order to calculate CO using pulsed wave Doppler of aortic flow in the J cows. Measurements obtained included pulmonary artery and aortic diameters, left and right ventricular diameters (and calculated fractional shortening and left ventricular ejection fraction), left atrial size and time indices assessing valve function.ResultsHF cows had significantly (p < 0.05) larger pulmonary artery and aortic diameters, larger left atrial diameters and left ventricular internal diameters during diastole, but these were not different when corrected for body weight. Left and right ventricular dimensions, adjusted for body weight, were significantly larger (p = 0.02 and p = 0.035 respectively) in J cows when compared to HF cows. No differences were noted in the time indices between the two groups. No significant differences were noted in intra-operator variability and the only significant difference in inter-operator variability was in measurement of the pulmonary artery (p = 0.03; ICC = 0.63).ConclusionsIt is possible to obtain repeatable, reliable echocardiograms in order that meaningful intra-cardiac dimensions can be obtained in adult dairy cattle.     

The role of vascular endothelial growth factor and its receptor Flk-1/KDR in promoting tumour angiogenesis in feline and canine mammary carcinomas: A preliminary study of autocrine and paracrine loops

Vascular Endothelial Growth Factor (VEGF) and its receptor KDR are involved in the regulation of angiogenesis and are up-regulated in a number of tumours in humans and in particular, breast cancer. We therefore evaluated the prognostic potential of the angiogenetic process in feline and canine mammary carcinomas by the immunohistochemical assessment of VEGF expression and micro vessel density (MVD) quantification and examined the interplay between VEGF and KDR. These variables were related to some relevant clinicopathological parameters and to overall survival (OS). VEGF and KDR expression were evaluated in epithelial, stromal and endothelial compartments in order to identify autocrine and/or paracrine loops. In dogs an increased VEGF expression did not show any statistical correlation with the clinicopathological parameters examined and was not correlated to a poorer prognosis. MVD was found to be significantly correlated to the histologic type (P = 0.04), tumour grading (P = 0.02), and to the OS (P = 0.01). In cats VEGF expression was significantly correlated to tumor grading (P = 0.01) and OS (P = 0.03), while no significant associations were found between MVD and the other parameters. VEGF and KDR were found to be detected on the epithelial, and/or endothelial and/or stromal cells of the carcinomas in both species, suggesting indications for some possible autocrine and paracrine loops. Our results encourage further studies on the possible prognostic role of VEGF and MVD in canine and feline mammary tumours and on the role of growth factors and their receptors in promoting tumour proliferation and an “angiogenetic shift”. The VEGF/KDR system may play a role in malignant transformation and tumor progression.