Obesity is a nutritional disorder with a multifactorial origin, with excess energy storage as fat tissue, resulting in negative effects on the individual's longevity and health. The study aim was to evaluate cardiovascular function in obese dogs through a complete physical assessment, blood pressure (BP) measurements and electrocardiographic tests.

Sixty-nine obese dogs, with percent body fat (%BF)¹ >20%, were assessed from February 2002 to September 2003; 51 dogs were female (73.9%) and age ranged from 01 to 12 yrs old. Regarding breeds, there were 11 mixed breeds (15.9%), 10 labradors (14.5%), 8 cocker spaniels (11.5%), 6 poodles (8.7%), 5 dachshunds (7.2%), 5 pinschers (7.2%), 4 rottweilers (5.8%), 3 bichon frisés (4.3%), 3 beagles (4.3%), 2 alsatians (2.9%), and 1 (1.45%) of each: mastiff, collie, great dane, shar-pei, Weimaraner, border collie, and scotch terrier. Twenty-eight animals had been neutered.

The animals' mean systolic and diastolic blood pressure levels were 196 mmHg (SD±37 mmHg) and 127 mmHg (SD±32 mmHg), respectively. When blood pressure values were analyzed separately, 31 animals (44.9%) presented an increase in the systolic blood pressure, with values above 180 mmHg. Regarding cardiac frequency, the mean value was 119 bpm (SD±25 bpm). The electrocardiographic tracing showed a mean of 0.2 mV in relation to the P wave amplitude (SD±0.01mV). P wave duration showed a mean of 0.03s (SD±0.02s.). Regarding PR interval, there was a mean of 0.10s (SD±0.63s). As for the QRS complex, there was a mean of 1.5 mV for amplitude (SD± 0.02 mV). For the QRS complex duration, we obtained a mean of 0.04s (SD±0.03s). For the ST segment, we had a mean of 0.08s (SD±0.17s). T wave amplitude had a mean of 0.22 mV(SD±0.02), and its duration was 0.04s. The individual assessment of the electrocardiographic tracings of the 69 dogs showed that 50 (72.4%) presented alterations in the electrocardiographic findings: 35 animals presented ST segment alterations (50.7%), 15 (21.7%) presented descending R-branch fenestration, 12 (17.4%) presented cardiac axis deviation, 5 (7.2%) had QRS complex widening, suggestive of ventricular overload, 2 (0.3%) had atrium-ventricular dissociation (0.3%), 1 (0.15%) had ventricular tachycardia, and 1 (0.15%) had a possible overload of the right atrium (p pulmonale). The data analysis through logistic regression showed the influence of size, breed, gender, age and %BF was not statistically significant regarding BP alterations and electrocardiographic findings.

We conclude that the obesity, in many dogs in this series, caused significant alterations in blood pressure measurements and electrocardiographic tracings, suggestive of afterload increase and myocardial distress.

Reference

1.  Burkcholder, Small Animal Clinical Nutrition 4^th Edition, p. 401, 2000.