Introduction: Five-minute heart-rate variability (HRV) measurement is a useful tool for assessing the autonomic nervous system (ANS) balance in humans, but there are no studies on healthy dogs. The aim of the study was, therefore, to provide the reference ranges in small and medium-sized breeds for short-term HRV time and frequency domain (TFD) analyses. Material and Methods: A total of 79 healthy dogs were included in the study between 2015 and 2019. Grouping by age with the breakpoint at six years and subgrouping by reproductive status and sex was imposed. All the dogs were included after physical and cardiological examinations and blood analyses. The TFD of HRV were analysed from a five-minute-long digital ECG recording after removal of non-sinus complexes. Results: There were no statistically significant differences in any TFD parameters between age, reproductive status or sex groups. A mild increase in all time domain parameters and the high-frequency (HF) band was observed in older dogs, and the low frequency (LF):HF ratio decreased in these dogs. In males, the time domain parameters and HF band increased slightly. Conclusion: The normal ranges for HRV derived from short-term ECG recording in the usual clinical environment now have proposed reference ranges. Our findings suggest that accommodation time, age, sex, or reproductive status do not influence the results derived from these recordings, indicating that this method is reliable for assessing the ANS function in small and medium-sized dog breeds.

Radiology plays an important role in veterinary cardiology, along with other methods, such as electrocardiography, echocardiography, and biomarkers, in the diagnosis of cardiac diseases. Particularly, thoracic radiography is often used to assess heart size and for confirmation of left-sided congestive heart failure by the presence of pulmonary edema. Many cardiac diseases in dogs are associated with a heart size increase, especially in more advanced stages, and cardiac size assessment has been of great interest for a long time for both clinicians and researchers. A substantial number of methods for heart size measurement has been described; however, two methods, the vertebral heart score and the vertebral left atrial size are currently widely used in dogs. Therefore, the literature provides an abundant number of research articles for using these measurements in both healthy dogs and dogs with cardiac and extra-cardiac pathologic conditions. This review article aims to cover the current use of two radiographic measurements of the heart in healthy and diseased dogs, based on the available literature.

Acute canine idiopathic polyradiculoneuritis (ACIP) is one of the most common generalised neuromuscular diseases affecting dogs. In this report, we describe a 5-year-old, 25-kg, male, intact, Siberian Husky dog with ACIP with secondary induced arterial hypertension {systolic blood pressure [mean (m) ± standard deviation (sd)], 214 ± 19 mmHg; mean blood pressure (m ± sd), 164 ± 6.36 mmHg; and diastolic blood pressure (m ± sd), 137 ± 0.7 mmHg} and sinus tachycardia. Heart rate variability analysis indicated decreased vagal activity (low root-mean-square values of successive RR interval differences and percentages of the RR intervals differing by more than 50 ms in the entire recording) and predominance of sympathetic activity. Arterial hypertension was treated with amlodipine but remained greater than the upper limit for 51 days until the dog recovered ambulation. This is the first case report of ACIP and secondary arterial hypertension in a dog. Routine blood pressure measurements should be included in the monitoring of patients with ACIP if arterial hypertension might interfere with patient prognosis.

In both humans and animals, cardiac fibrosarcoma is rare among primary cardiac malignant neoplasia. The overall prevalence of cardiac neoplasia in dogs is low, reported to be between 0.17% and 0.19% of hospital admissions. The aim of this report is to describe the clinical and pathological findings of a dog presenting signs of right sided congestive heart failure due to an intracardiac and venous obstructing mass, diagnosed by histopathology as cardiac fibrosarcoma with myxoid features. A 7 years old male mix breed Husky weighing 23 kg was presented to our Veterinary Teaching Hospital the owner reporting weight loss, inappetence and exercise intolerance and on presentation exhibited breathlessness and an enlarged abdomen. A 5 minutes six leads electrocardiogram and cardiac ultrasonography were performed using standard, established techniques. Complete blood count, serum liver enzyme activities and renal parameters were assessed. Shortly after the cardiologic examination, the dog died and necropsy examination of the cardiovascular system revealed an elongated and branched mass attached dorsally to the endocardial insertion of the septal tricuspid valve leaflet. This mass extended retrogradely into the lumen of the cervical veins, obstructing the venous flow. Histological diagnosis of the mass was cardiac fibrosarcoma with myxoid features. Multiple metastases were found inside the lungs only. This is the first report describing a right cardiac fibrosarcoma with myxoid features and venous obstruction in a dog. Cardiac fibrosarcoma is a rare finding, however should be considered when an intracardiac mass is diagnosed.