Ventricular bigeminy associated with myocardial ischemia in a dog with a colonic torsion: a case report

BACKGROUND

Ventricular bigeminy due to myocardial ischemia has been reported in humans as well as in canine patients with obstructive gastrointestinal diseases. This is the first case report of ventricular bigeminy in a dog with a colonic torsion that resolved after fluid resuscitation and restoration of myocardial perfusion.

CASE PRESENTATION

An 11-year-old, male neutered mixed breed dog presented with a one day history of vomiting, tenesmus, and lethargy. Physical examination identified an irregular heart rhythm and intermittent pulse deficits. A ventricular arrhythmia represented by ventricular premature complexes (VPCs) organized in bigeminy, was appreciated on a 3-lead electrocardiogram (ECG) with a single lead (II) view. Abdominal radiographs confirmed a colonic torsion. Prior to anesthetic induction, ventricular bigeminy was non responsive to fentanyl or lidocaine. The patient was anesthetized and intravascular volume deficit was identified by dampened plethysmographic wave amplitude (plethysomographic variability), audible softening of the Doppler sound, and more pronounced pulse deficits. Fluid resuscitation was achieved with a combination of intravenous crystalloid and colloid fluid therapy comprising 7.2% hypertonic saline and 6% hetastarch. The patient's cardiac rhythm converted to normal sinus after fluid resuscitation. The colonic torsion was surgically corrected. The patient recovered well from anesthesia and was ultimately discharged from the hospital 5 days later.

CONCLUSIONS

The present case report highlights that myocardial ischemia can lead to ventricular arrythmias, such as ventricular bigeminy. This is the first documented case of ventricular bigeminy in the canine patient with a colonic torsion. Assessment of patient volume status and appropriate fluid resuscitation along with continuous electrocardiogram (ECG) monitoring are vital to patient stability under general anesthesia.

Training vs. racing: A comparison of arrhythmias and the repeatability of findings in Thoroughbred Chuckwagon racehorses

Arrhythmias are commonly reported in exercising horses, however due to regulatory constraints electrocardiograms (ECGs) are acquired during training but not competition, raising questions about the repeatability of findings. The aims were (1) compare training and competition arrhythmias and (2) describe the repeatability of arrhythmias during maximal-intensity exercise. A convenience sample of 52 healthy Thoroughbreds (aged 8.7 ± 2.5 years) competing in the World Professional Chuckwagon Association were obtained, totaling 152 training or competition ECGs (2-7 ECGs/horse). Speed, heart rate (HR) and arrhythmias (supraventricular premature complex, SVPC; ventricular premature complex, VPC) were examined. Pre- and post-recovery (approximately 6 min) blood samples measured lactate and high-sensitivity troponin-T. Training and competition arrythmias were compared (Friedman's test) and reliability of repeated ECGs assessed (intraclass correlation; P < 0.05). Training vs. competition: Forty horses had clean tracing from training and competition (n = 80 ECGs); the number and type of arrhythmias were not different. In training, VPCs were present in 7/40 horses (median [interquartile range, IQR]/ECG; range; 0 [0,0]; 0-4) and 9/40 horses (0 [0,0]; 0-5) in active-recovery. In competition, VPCs were present in 7/40 horses (0 [0,0]; 0-8) and 8/40 horses (0 [0,0]; 0-5) in active-recovery. Arrhythmias were primarily single premature complexes. Training and competition speed, HR, lactate and troponin-T did not differ however, sampling was too early for peak serum Troponin-T levels. Repeatability: total arrhythmias between serial ECGs did not differ. The reliability to detect SVPCs and VPCs was poor to moderate, and poor, respectively. Overall, the total number of arrhythmias was repeatable, but the reliability of arrhythmia type was poor to moderate.

Evaluation of a new smartphone-based digital stethoscope featuring phonocardiography and electrocardiography in dogs and cats

This study assessed a new smartphone-based digital stethoscope (DS) featuring simultaneous phonocardiographic and one-lead electrocardiogram (ECG) recording in dogs and cats. The audio files and ECG traces obtained by the device were compared with conventional auscultation and standard ECG. A total of 99 dogs and nine cats were prospectively included. All cases underwent conventional auscultation using an acoustic stethoscope, standard six-lead ECG, standard echocardiography and recordings with the DS. All the audio recordings, phonocardiographic files and ECG traces were then blind reviewed by an expert operator. The agreement between methods was assessed using Cohen's kappa and the Bland-Altman test. Audio recordings were considered interpretable in 90% animals. Substantial agreement was found in the diagnosis of heart murmur (κ = 0.691) and gallop sound (k = 0.740). In nine animals with an echocardiographic diagnosis of heart disease, only the DS detected a heart murmur or gallop sound. ECG traces recorded with the new device were deemed interpretable in 88 % animals. Diagnosis of heart rhythm showed moderate agreement in the identification of atrial fibrillation (k = 0.596). The detection of ventricular premature complexes and bundle branch blocks revealed an almost perfect agreement (k = 1). Overall, the DS showed a good diagnostic accuracy in detecting heart murmurs, gallop sounds, ventricular premature complexes and bundle branch blocks. A clinically relevant overdiagnosis of atrial fibrillation was found but without evidence of false negatives. The DS could represent a useful screening tool for heart sound abnormalities and cardiac arrhythmias..

Assessment of heart rate turbulence in dogs with myxomatous mitral valve disease

Background:

Myxomatous mitral valve degeneration (MMVD) is the most common heart disease affecting small dogs, it reduces cardiac output resulting in compensatory adaptation of the autonomic nervous system. Chronically, it leads to reduced heart rate variability (HRV) which is an accurate marker for autonomic balance. More than two decades ago in human medicine an indicator of autonomic balance that happens after a premature ventricular beat, it was described as heart rate turbulence (HRT). In humans with ischemic heart disease, the absence of HRT has proven to be a more accurate and an independent indicator of mortality than known HRV parameters. Currently, there are very few studies of HRT in dogs and it is still not tested in small dogs within different stages of myxomatous mitral valve disease.

Aim:

The aim of this study was to assess the HRT indicators, onset and slope, in small dogs with myxomatous mitral valve disease and to statistically test it.

Methods:

Dogs under 25 kg had electrocardiogram and echocardiography performed and, in some patients, holter monitoring was carried out. Data were divided into groups B1, B2, C, and D for mean comparison with analysis of variance and Tukey test. In addition, receiver operating characteristic (ROC) curve for differentiating among symptomatic and asymptomatic dogs and for differentiating between remodeled and non-remodeled hearts. The Pearson was executed after correlations of turbulence onset (TO) and turbulence slope (TS) with commonly used echocardiographic parameters.

Results:

Variance analyses held significant differences in TO and TS between stages B1 from stages C and D, while B2 held similarity to the other groups. In the receiver operating curve was found a very good area under the curve for differentiating among symptomatic and asymptomatic dogs and remodeled and non-remodeled dogs. Few echocardiography parameters held weak correlation with TO while others held weak to moderate correlation with TS.

Conclusion:

In dogs with MMVD and without other diseases, HRT is a feasible indicator for autonomic balance. Our result suggests HRT changes as the MMVD progresses and congestive heart failure is present. More studies with HRT are needed. The number of ventricular premature contractions (VPCs) may be the strongest limitation for the technique.

Arrhythmogenic right ventricular cardiomyopathy in Boxer dogs: the diagnosis as a link to the human disease

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a myocardial disease with an increased risk for ventricular arrhythmias. The condition, which occurs in Boxer dogs, shares phenotypic features with the human disease arrhythmogenic cardiomyopathy (ACM) suggesting its potential as a natural animal model. However, there are currently no universally accepted clinical criteria to diagnose ARVC in Boxer dogs. We aimed to identify diagnostic criteria for ARVC in Boxer dogs defining a more uniform and consistent phenotype.

METHODS AND RESULTS

Clinical records from 264 Boxer dogs from a referral veterinary hospital were retrospectively analysed. ARVC was initially diagnosed according to the number of ventricular premature complexes (VPCs) in the 24-hour-Holter-ECG in the absence of another obvious cause. Dogs diagnosed this way had more VPCs, polymorphic VPCs, couplets, triplets, VTs and R-on-T-phenomenon and syncope, decreased right ventricular function and dilatation in comparison to a control group of all other Boxer dogs seen by the Cardiology Service over the same period. Presence of couplets and R-on-T-phenomenon on a 24h-ECG were identified as independent predictors of the diagnosis. A diagnosis based on ≥100 VPCs in 24 hours, presence of couplets and R-on-T phenomenon on a 24h-ECG was able to select Boxer dogs with a phenotype most similar to human ACM.

CONCLUSION

We suggest the diagnosis of ARVC in Boxer dogs requires two out of the three following criteria: presence of ≥ 100 VPCs, presence of couplets or R-on-T-phenomenon on a 24 h-ECG. This results in a uniform phenotype similar to that described in human ACM and may result in the adoption of the term ACM for this analogous condition in Boxer dogs.

Use of an Implantable Loop Recorder in a Chimpanzee (Pan troglodytes) to Monitor Cardiac Arrhythmias and Assess the Effects of Acupuncture and Laser Therapy

Cardiovascular disease is a leading cause of death in captive chimpanzees and is often associated with myocardial fibrosis, which increases the risk of cardiac arrhythmias. In this case report, we present a 36-y-old male chimpanzee (Pan troglodytes) diagnosed with frequent ventricular premature complexes (VPC). We placed a subcutaneous implantable loop recorder for continual ECG monitoring to assess his arrhythmias without the confounding effects of anesthetics. During his initial treatment with the antiarrhythmia medication amiodarone, he developed thrombocytopenia, and the drug was discontinued. After reviewing other potential therapies for the treatment of cardiac arrhythmias, we elected to try acupuncture and laser therapy in view of the positive results and the lack of adverse side effects reported in humans. We used 2 well-known cardiac acupuncture sites on the wrist, PC6 (pericardium 6) and HT7 (heart 7), and evaluated the results of the therapy by using the ECG recordings from the implantable loop recorder. Although periodic increases in the animal's excitement level introduced confounding variables that caused some variation in the data, acupuncture and laser therapy appeared to decrease the mean number of VPC/min in this chimpanzee.

Assessment of heart rate variability in Boxers with arrhythmogenic right ventricular cardiomyopathy

OBJECTIVE

To assess heart rate variability (HRV) in Boxers with arrhythmogenic right ventricular cardiomyopathy (ARVC), assess the ability of HRV analysis to identify differences in Boxers on the basis of severity of their arrhythmia, and evaluate the use of HRV to determine whether persistently high sympathetic tone is present in these dogs.

DESIGN

Prospective study.

ANIMALS

24 Boxers with ARVC and 10 clinically normal non-Boxer dogs.

PROCEDURE

Boxers were categorized as dogs with congestive heart failure (CHF), dogs with < or = 2 ventricular premature complexes (VPCs)/24 h (designated unaffected), or dogs with > 1,000 VPCs/24 h (designated affected). Ambulatory electrocardiography (24 hours) was performed in each dog. Recordings were analyzed for HRV variables at a commercial laboratory; differences in HRV variables among groups were compared with 1-way ANOVA.

RESULTS

Compared with control non-Boxer dogs and Boxers without CHF (affected and unaffected Boxers), HRV was reduced in Boxers with CHF. No differences in HRV variables were detected between affected and unaffected Boxers. Inconsistent differences were identified between the control dogs and Boxers without CHF that had various degrees of arrhythmias.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that persistently high sympathetic tone is not a consistent feature of ARVC. Differences in some HRV variables between Boxers without CHF and control dogs suggest that Boxers may have different autonomic control of heart rate, compared with that of clinically normal non-Boxer dogs. The usefulness of HRV analysis appears limited to Boxers with ARVC that have systolic dysfunction and CHF.

The relationship of resting S-T segment depression to the severity of subvalvular aortic stenosis and the presence of ventricular premature complexes in the dog

Electrocardiograms (ECG) from 35 dogs with subvalvular aortic stenosis (SAS) with a left ventricular outflow tract pressure gradient (PG) of > or =50 mm Hg were retrospectively evaluated for S-T segment depression (STD, > or =0.2 mV in lead II). Pressure gradient, age, heart rate (HR), and number of ventricular premature complexes (VPCs) on a 24-hour ambulatory ECG for dogs with STD were not significantly different from those for dogs without STD. The S-T segment deviation did not correlate significantly with PG, age, HR, or VPCs. The significance of STD in the dog with SAS remains uncertain. Long-term prospective studies are needed to fully understand this observation.

Ventriculo-atrial conduction in the ovine heart, caused by premature ventricular complexes

In humans, and certain animals, the atrioventricular conduction system is capable of bidirectional conduction. Depolarization impulses, originating in the ventricle itself, may thus be conducted in a retrograde direction towards the atria. Two common causes for this phenomenon of ventriculo-atrial (retrograde) conduction are premature ventricular complexes and ventricular pacing. The surface electrocardiogram can be used for the detection of such retrogradely conducted beats. The purpose of this study was to investigate the possibility of ventriculo-atrial conduction in Dorper sheep. Premature ventricular complexes in eight healthy Dorper wethers were induced and it was possible to document retrogradely conducted beats on the surface electrocardiogram in all of them. It is concluded that the Dorper sheep heart is capable of ventriculo-atrial conduction.

Comparison of the effects of four antiarrhythmic treatments for familial ventricular arrhythmias in Boxers

OBJECTIVE

To evaluate the effect of 4 antiarrhythmic treatment protocols on number of ventricular premature complexes (VPC), severity of arrhythmia, heart rate (HR), and number of syncopal episodes in Boxers with ventricular tachyarrhythmias.

DESIGN

Randomized controlled clinical trial.

ANIMALS

49 Boxers.

PROCEDURE

Dogs with > 500 VPC/24 h via 24-hour ambulatory ECG (AECG) were treated with atenolol (n = 11), procainamide (11), sotalol (16), or mexiletine and atenolol (11) for 21 to 28 days. Results of pre- and posttreatment AECG were compared with regard to number of VPC/24 h; maximum, mean, and minimum HR; severity of arrhythmia; and occurrence of syncope.

RESULTS

Significant differences between pre- and posttreatment number of VPC, severity of arrhythmia, HR variables, or occurrence of syncope were not observed in dogs treated with atenolol or procainamide. Significant reductions in number of VPC, severity of arrythmia, and maximum and mean HR were observed in dogs treated with mexiletine-atenolol or sotalol; occurrence of syncope was not significantly different between these 2 treatment groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Treatment with sotalol or mexiletine-atenolol was well tolerated and efficacious. Treatment with procainamide or atenolol was not effective.

Results of ambulatory electrocardiography in overtly healthy Doberman Pinschers with equivocal echocardiographic evidence of dilated cardiomyopathy

OBJECTIVE

To determine results of ambulatory electrocardiography in and outcome of overtly healthy Doberman Pinschers with equivocal echocardiographic evidence of dilated cardiomyopathy.

DESIGN

Case series.

ANIMALS

44 overtly healthy (25 male, 19 female) Doberman Pinschers.

PROCEDURE

24-hour ambulatory electrocardiographic (Holter) recordings with > 90% scan quality obtained the same day that echocardiography was performed were reviewed.

RESULTS

Holter recordings from 42 of 44 (95%) dogs contained ventricular premature complexes (VPC). Fifteen of 44 (34%) dogs had > 100 VPC, 9 (20%) had > 500 VPC, and 5 (11%) had > 1,000 VPC. Nonsustained (< 30 seconds) ventricular tachycardia was detected in 4 dogs. Eighteen of 27 (67%) dogs with > 100 VPC, any couplets or triplets of VPC, or ventricular tachycardia developed dilated cardiomyopathy within 1 year, compared with 8 of 17 (47%) dogs with < 100 VPC, no couplets or triplets of VPC, and no ventricular tachycardia. Of the 18 dogs that did not develop dilated cardiomyopathy within 1 year, 11 (61%) did so within 3 years.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that a high percentage of Doberman Pinschers with equivocal echocardiographic evidence of dilated cardiomyopathy will be found to have VPC during 24-hour ambulatory electrocardiography and that most will develop echocardiographic abnormalities indicative of cardiomyopathy.

Use of ambulatory electrocardiography for detection of ventricular premature complexes in healthy dogs

OBJECTIVE

To evaluate the use of 24-hour ambulatory electrocardiography (AECG) for the detection of ventricular premature complexes (VPC) in healthy dogs.

DESIGN

Case series.

ANIMALS

50 healthy mature dogs.

PROCEDURE

A 24-hour AECG was performed on each dog and evaluated for the presence of VPC.

RESULTS

Fifty dogs weighing between 18.2 to 40.9 kg (40 and 90 lb) representing 13 breeds were evaluated; there were 4 sexually intact females, 21 spayed females, 4 sexually intact males, and 21 castrated males. Ages ranged from 1 to 12 years. Thirty-four dogs had no VPC; 16 dogs had between 1 and 24 VPC. The grade of arrhythmia ranged from 1 to 4, with 4 dogs having an arrhythmia with a grade > 1. Significant differences were not detected between the group of dogs with VPC and those without VPC with regard to sex, age, and minimum, maximum, or mean heart rate.

CONCLUSIONS AND CLINICAL RELEVANCE

We conclude that healthy mature dogs have infrequent VPC, as detected by use of 24-hour AECG. The presence of numerous or sequential VPC may be suggestive of cardiac or systemic disease and may indicate the need for thorough clinical evaluation.

Electrocardiographic findings in dogs with motor vehicle-related trauma

Motor vehicle-related injury is the most common form of trauma incurred by dogs, and cardiac arrhythmias are a well-recognized complication. Although posttraumatic arrhythmias are often observed, little is known regarding their frequency. This study utilized continuous ambulatory electrocardiography (i.e., Holter monitoring) to describe the cardiac rhythm disturbances in 30 dogs sustaining trauma in motor vehicle accidents. Ventricular ectopy was identified by Holter monitoring in 29 of 30 dogs, although the initial electrocardiogram (EKG) only documented ventricular ectopic complexes (VECs) in four dogs. Ventricular ectopy was infrequent in most dogs (i.e., 62% of the dogs had less than 100 VECs per day for the entire study), but 16% developed frequent arrhythmias (greater than 4,000 VECs per day). In all cases, the VECs were observed within 24 hours of injury. Forty-three percent of dogs had at least one episode of ventricular tachycardia, including several dogs that had an overall infrequent rate of VECs (i.e., less than 100 or 100 to 1,000 VECs per day). Although baseline EKGs are useful in identifying arrhythmias in most dogs, the length of the recording should be increased to improve the likelihood of observing an abnormal EKG event. Most importantly, additional EKGs should be obtained or continuous EKG monitoring should be performed in dogs that display clinical signs that could be attributed to ventricular arrhythmias.

Association between results of ambulatory electrocardiography and development of cardiomyopathy during long-term follow-up of Doberman pinschers

OBJECTIVE

To characterize ambulatory electrocardiographic results of overtly healthy Doberman Pinschers and determine associations between those results and development of dilated cardiomyopathy.

DESIGN

Cohort study.

ANIMALS

114 (58 male, 56 female) overtly healthy Doberman Pinschers without echocardiographic evidence of cardiac disease on initial examination.

PROCEDURE

Echocardiograms and 24-hour ambulatory electrocardiograms (Holter recordings) were obtained initially and at variable intervals. The status (live vs dead) of all dogs was known at least 2 years and as long as 10 years after initial examination (mean [+/- SD] follow-up time, 4.33 +/- 1.84 years). Associations between development of dilated cardiomyopathy and number of ventricular premature contractions (VPC), age, and sex were determined.

RESULTS

55 dogs (48%) did not have VPC on initial Holter recordings, and only 8 dogs had > 50 VPC/24 hours. The likelihood that a dog would have VPC was associated with increasing age and being male. At least 1 VPC/24 hours, and in particular, > 50 VPC/24 hours or > or = 1 couplet or triplet of VPC/24 hours, were predictive of subsequent development of dilated cardiomyopathy. Fifty-four dogs (47%) developed dilated cardiomyopathy; 12 were still alive at the end of the study, and 42 had died. Twenty-five of these 42 dogs died after the onset of congestive heart failure (CHF), 15 died suddenly before the onset of overt CHF, and 2 died of noncardiac causes. More males developed dilated cardiomyopathy than females, and dogs that died suddenly were approximately 1 year younger than those that developed CHF.

CONCLUSIONS AND CLINICAL RELEVANCE

Results of high-quality Holter recordings may be used to identify overtly healthy Doberman Pinschers that are at a high risk for dilated cardiomyopathy.

Familial ventricular arrhythmias in boxers

The purposes of this study were to evaluate families of Boxers with ventricular arrhythmias to determine whether this disorder is a familial trait and, if so, to determine the mode of inheritance. Eighty-two Boxers were evaluated by physical examination, electrocardiogram, echocardiogram, and 24-hour ambulatory electrocardiogram. Dogs were considered affected if at least 50 premature ventricular complexes (PVCs) were observed during a 24-hour period. All dogs were at least 6 years of age at evaluation. Complete cardiovascular examinations were performed on dogs from 6 extended families. The 2 most complete pedigrees were used to determine the pattern of inheritance. The number of PVCs observed during a 24-hour period in affected dogs ranged from 112 to 4,894 (mean +/- SD, median; 1,309 +/- 2,609, 1,017). The number of PVCs observed during a 24-hour period in the unaffected dogs ranged from 0 to 16 (7 +/- 10, 12). Pedigree evaluation was performed to determine pattern of inheritance. An autosomal dominant pattern was determined to be most likely because a sex predisposition was not observed, affected individuals were observed in every generation, and 2 affected individuals produced unaffected offspring. We conclude that familial ventricular arrhythmias is inherited as an autosomal dominant trait in some Boxers.

Clinical and pathologic findings in Doberman pinschers with occult cardiomyopathy that died suddenly or developed congestive heart failure: 54 cases (1984-1991)

OBJECTIVE

To determine echocardiographic, electrocardiographic, and histologic abnormalities in Doberman Pinschers with occult cardiomyopathy that died suddenly and to compare findings with those of Doberman Pinschers with cardiomyopathy that died of congestive heart failure.

DESIGN

Retrospective study.

ANIMALS

14 Doberman Pinschers with occult cardiomyopathy that died suddenly (group 1) and 40 Doberman Pinschers with cardiomyopathy and congestive heart failure (group 2).

PROCEDURE

Serial echocardiography and continuous, ambulatory electrocardiographic (Holter) monitoring were performed. Hearts of dogs that died suddenly were examined histologically.

RESULTS

Group-2 dogs died at a significantly older age than did group-1 dogs. All dogs had echocardiographic abnormalities, but changes were more severe in group-2 than in group-1 dogs. Ventricular tachyarrhythmias were documented in all dogs. Group-1 dogs were more likely to have episodes of sustained ventricular tachycardia than were group-2 dogs. Multifocal interstitial fibrosis and replacement of muscle fibers with collagen and fat were consistently observed in hearts from dogs that died suddenly. Ten group-1 dogs had received antiarrhythmic treatment prior to death.

CLINICAL IMPLICATIONS

Occult cardiomyopathy can be identified by means of echocardiography and Holter monitoring in Doberman Pinschers. Doberman Pinschers with cardiomyopathy that had episodes of sustained (> 30 seconds) ventricular tachycardia were at risk of dying suddenly.

Evaluation of a hypertonic saline-dextran solution for treatment of dogs with shock induced by gastric dilatation-volvulus

OBJECTIVE

To test the hypothesis that small volumes of hypertonic saline-dextran (HSD) solution can be used to effectively resuscitate dogs in shock induced by gastric dilatation-volvulus (GDV), and, compared with administration of large volumes of lactated Ringer's solution (LRS), can be used to limit the overall volume of fluid needed for resuscitation.

DESIGN

Prospective, clinical study.

ANIMALS

15 dogs with GDV-induced shock.

PROCEDURE

Initially, HSD solution (5 ml/kg of body weight) or LRS (60 to 90 ml/kg) was administered. All dogs then received a maintenance administration (20 ml/kg/h) of LRS. Cardiorespiratory, blood gas, and serum biochemical analyses were performed over a 4-hour period after initiation of treatment.

RESULTS

Systolic arterial and central venous pressures and plasma volume increased more rapidly in dogs in the HSD + LRS group. The cumulative dose of fluids administered to dogs in the HSD + LRS group was significantly less than that administered to dogs in the LRS group. Serum sodium and chloride concentrations and osmolality increased significantly in dogs in the HSD + LRS group, but not in dogs in the LRS group. Ventricular arrhythmias were detected in both groups of dogs, but did not appear to be induced by either form of fluid therapy.

CLINICAL IMPLICATIONS

Administration of HSD rapidly restored cardiorespiratory function and induced resuscitation equivalent to administration of large volumes of LRS. Use of HSD solutions to treat dogs in GDV-induced shock may be more efficient than use of isotonic fluids. Administration of HSD solution was not associated with noticeable complications.

Electrocardiographic observation on spontaneously occurring arrhythmias in chickens

In order to clarify the spontaneous occurrence of arrhythmias in chickens, electrocardiograms using standard bipolar limb leads were recorded for 461 chickens of 7 breeds, including 3 pure breeds: Rhode Island Red (RIR, n = 125), Japanese Game (JG, n = 101), and White Leghorn (WL, n = 52); and 4 crossbreeds of RIR: the first filial generation (F1) obtained by mating RIR with JG (RIR x JG, n = 44), the backcross obtained by mating the Fl of RIR x JG with the parental JG ((RIR x JG) x JG, n = 10), the F1 obtained by mating RIR with WL (RIR x WL, n = 73), and the F1 obtained by mating RIR with the commercial hybrid chicken, Dekalb Amber Link (DAL)(RIR x DAL, n = 56). Nine types of arrhythmias were observed in 107 chickens (23.2%, 107/461): 66 had sinus arrhythmia, 19 had atrial premature contraction, 9 had ventricular preexcitation syndrome, 7 had ventricular premature contraction, 2 had second-degree atrioventricular block. 1 had atrial fibrillation, I had aberrant ventricular conduction. I had intraventricular conduction disturbance, and 1 had ventricular electrical alternans. Except for sinus arrhythmia, the incidence of other arrhythmias in RIR was significantly high, compared with that in pure breeds other than RIR (p < 0.001) and that in crossbreeds of RIR (p < 0.01). Arrhythmias other than ventricular premature contraction and sinus arrhythmia will be the first to be described as spontaneously occurring arrhythmias in chicken. Although the reason for both the highest incidence of sinus arrhythmia in WL and the predominance of other arrhythmias in RIR were obscure, the present results suggest the possibility of using chickens, especially RIR which shows a high incidence of arrhythmias, as a relevant animal for studying arrhythmias.