Hypertrophic cardiomyopathy in a dog: a systematic diagnostic approach

Possible sinoatrial node dysfunction in a 6-month-old domestic shorthair cat

Case summary

A 6-month-old male entire domestic shorthair cat was presented to the ophthalmology department for nasolacrimal duct cannulation and flushing, and castration under general anaesthesia. On pre-anaesthetic assessment, the cat had a heart rate of 90 beats/min (bpm). Clinical examination was unremarkable, although the cat appeared stressed. The echocardiogram was within normal limits. An ambulatory electrocardiogram (ECG) monitor was fitted overnight, and analysis of the ECG revealed a sinus rhythm with a lower than normal heart rate. The mean 1 min rate was 98 bpm. There was a slower than normal sinus rhythm and frequent ventricular escape beats. Differential diagnoses included increased vagal tone and sinoatrial node dysfunction (SND). The latter was suspected as the cat demonstrated signs of stress although an atropine response test was not performed.

Relevant and novel information

SND is relatively common in dogs but extremely rare in cats. To the authors' knowledge, there is only one affected cat mentioned in the literature. In both dogs and humans, most cases described are in middle-aged and elderly patients. Although the condition is recognised in human infants and fetuses, it has not been reported in dogs under 2 years of age. This case is unusual because SND was suspected in an immature cat. On analysis of the ECG, the heart rate was considerably lower than those previously reported in hospitalised cats; however, findings on physical examination were subtle, highlighting the importance of pre-anaesthetic examination in identifying unexpected abnormalities.

Myocardial injury in dogs: a retrospective analysis on etiological, echocardiographic, electrocardiographic, therapeutic, and outcome findings in 102 cases

INTRODUCTION

In dogs, myocardial injury (MI) is a poorly characterized clinical entity; therefore, this study aimed to provide a detailed description of dogs affected by this condition.

ANIMALS, MATERIALS, AND METHODS

Dogs diagnosed with MI according to the concentration of cardiac troponin I (cTnI) were retrospectively searched. Signalment, diagnostic, therapeutic, and outcome data were retrieved. Dogs were divided into six echocardiographic (dilated cardiomyopathy phenotype; hypertrophic cardiomyopathy phenotype; hypertrophic cardiomyopathy phenotype with systolic dysfunction; abnormal echogenicity only; endocarditis; and no echocardiographic abnormalities suggestive of MI), four electrocardiographic (abnormalities of impulse formation; abnormalities of impulse conduction; abnormalities of ventricular repolarization; and no electrocardiographic abnormalities suggestive of MI), and nine etiological (infective; inflammatory; neoplastic; metabolic; toxic; nutritional; immune-mediated; traumatic/mechanical; and unknown) categories. Statistical analysis was performed to compare cTnI values among different categories and analyze survival.

RESULTS

One hundred two dogs were included. The median cTnI value was 3.71 ng/mL (0.2-180 ng/mL). Echocardiographic and electrocardiographic abnormalities were documented in 86 of 102 and 89 of 102 dogs, respectively. Among echocardiographic and electrocardiographic categories, the dilated cardiomyopathy phenotype (n = 52) and abnormalities of impulse formation (n = 67) were overrepresented, respectively. Among dogs in which a suspected etiological trigger was identified (68/102), the infective category was overrepresented (n = 20). Among dogs belonging to different echocardiographic, electrocardiographic, and etiological categories, cTnI did not differ significantly. The median survival time was 603 days; only eight of 102 dogs died due to MI.

CONCLUSIONS

Dogs with MI often have an identifiable suspected trigger, show various echocardiographic and electrocardiographic abnormalities, and frequently survive to MI-related complications.