Monday, December 16, 2013

Dogs reduce blood pressure

What's not soothing about the presence of this little guy?
The health benefits of pets are somewhat contested. One month a pro-pet group publishes on the benefits of pet ownership, the next month a bunch of killjoys publish a paper finding an absence of health benefits or even a detrimental effect. It pains me to say it but rarely is a field of scientific research so overtly biased.

The truth is, it’s complicated. I suspect people relate to their pets differently, integrating them into their respective lifestyles in very different ways, some of which are positive and others not so. Example: I’ve met clients who prefer not to leave their home because of their pet or pets. On the surface that seems terrible, but it depends on the individual circumstances. If your pet is your only companion and you won’t leave because of an unhealthy attachment, then I would suspect this could be detrimental to your health. But if your passion in life is to tend to your pet or menagerie, if that is where you draw your happiness, then you’re likely oodles better off than someone who doesn’t have that.

I also know from experience that our attachment and behaviour around companion animals changes over the lifespan of that animal and depends on the circumstances. For example, had a team of scientists arrived on my doorstep the week leading up to the removal of Phil’s retained tooth root, my blood pressure would have been sky-high (especially any time I cast my eyes on poor little Phil and the monster-boogers emerging from his right nostril) and they might well have concluded that it really was a detrimental attachment. Come the next week their findings would have been different. So I think we need to be careful about drawing blanket conclusions either way when it comes to these studies. The context has a huge impact which is very hard for scientists to factor in.

It’s also highly probable that writing about the health benefits of pets on this site is preaching to the converted. And as a veterinarian I have already laid my cards on the table – I believe that the relationship between humans and animals is important, is valuable, and is good for us and them.

All this by way of introduction to a study just published in Anthrozoos which found that dog ownership is associated with lower blood pressure. So why does that matter?

Untreated hypertension is associated with cardiovascular and kidney disease, and we’re going to see much more of that in an aging population with a sedentary lifestyle and questionable dietary choices. 

It is documented that ambulatory blood pressure is a better predictor of hypertension related morbidity (sickness) and mortality (death) than office blood pressure. [On a related note, a colleague of mine diagnosed himself with raging hypertension when he measured his blood pressure at work, only to find it was normal at the doctor. Apparently, the doc said, everyone is hypertensive at work!!!]

But seriously. If dog ownership is found to reduce morbidity and mortality, its a good argument for designing more pet-friendly retirement village and nursing homes. And another great reason (for those who needed one) to get a dog.

Bosca: do people really need a reason?
The latest study examined pet-owners aged 50 or older who lived independently and had mildly elevated blood pressure, for which most of them were taking medication. Participants wore a device which measured and reported on their blood pressure every 20 minutes – i.e. as they were going about their daily tasks – over there separate days across the three month study period.

The presence of a dog was associated with significantly lower systolic blood pressure (systole = when the heart muscle contracts) and diastolic blood pressure (diastole = when the heart muscle relaxes).

All good. Except when it came to cats. Cat owners had lower diastolic BP, but higher systolic BP when their cat was present. What does THAT mean? Well, it confused everyone as previous studies suggest that cat owners have lower stress and lower systolic and diastolic blood pressure.

The effect of cats on blood pressure is a little confusing.
According to spokesperson Jeanette Fielding, “We know changes in systolic blood pressure can be influenced by physical activity or arousal and further work on the nature of the interaction would be required to determine if this explained our current findings”.

The study, conducted at the University of Maryland, was partly funded by the Waltham Centre for Pet Nutrition, the scientific arm of Mars Petcare.

This is Hero, whom I caught lounging on top of the guinea pig enclosure. (He was removed just after this photo was taken). Its just one way he increases my blood pressure (probably also that of the guinea pigs). Look at that "I'm so busted" expression.