SOME things in life are pretty obvious.

Scotland is wet. Tuesday follows Monday. Newspaper editors get stick from everyone. Veterinary nurses talk too much. Vets are more intelligent than lawyers and accountants and, the real no-brainer, smoking cigarettes is bad for you.

And here’s even worse news. It is bad for your pet too. Very bad. And I can prove it.

Up until now, there have been no studies which investigated the effects of passive smoking on the lung function of dogs that already had chronic coughs. Sure, there was plenty of anecdotal evidence. Many smokers recognised that their dog coughed less if it was kept in fresher air. It seems entirely logical that breathing clean air is healthier than smoke but, as I keep telling the ‘feed bones and raw food’ brigade, anecdotal evidence is just not admissible and hard, compelling scientific fact is required, so that veterinary surgeons can give informed advice.

But now that has changed. Investigators Yamaya, Sugiya and Watari, working at Nihon University, Kanagawa, Japan, looked at whether passive smoking exacerbated coughing in dogs who already had some form of respiratory disease.

The study group included dogs affected by interstitial lung disease, lung tumours, chronic bronchitis, bronchiectasis and bronchopneumonia. The kind of stuff we see each and every day. The dogs were split into two groups and classified as either exposed to tobacco smoke or not exposed, based, not on what owners said, but on serum cotinine levels. Nicotine can only be measured for a short time in blood but cotinine is a metabolite of nicotine that has a half-life of 24 hours, so it can be detected for up to two weeks after tobacco smoke is inhaled. Life insurance companies use the same cotinine test to see if humans are fibbing about whether or not they smoke or use nicotine gum or patches.

Anyway, back to the dogs.

After separating them into ‘smoking’ and ‘non-smoking’ groups, lung function was assessed using the rather grand sounding plethysmography. Regrettably, I cannot say this word in Japanese, but then the editor can’t even pronounce it in English, which makes me feel a lot better

Plethysmography has all to do with volume and pressure. And guess what? Indexes of airway limitation were significantly higher in exposed dogs than in unexposed dogs. Which I think is the Japanese way of saying passive smoking makes dogs’ lungs worse. For definite.

Two probable causes have been identified. First, nicotine seems to trigger the nervous system to cause contraction of the bronchi and bronchioles, the little tubes through which air should whistle happily on its way to the oxygen exchanging areas of the lung. And second, compounds in tobacco smoke contribute to the development of increased sputum secretion. In west of Scotland technical parlance, what we are left with is a wheezy chest filled with grot. And that combination is not good for your general ability to breathe.

So there you have it. We might have had to wait a while for the Japanese to discover it, but passive smoking, without doubt, no use arguing, it’s in black and white, is bad for dogs. And I am guessing cats too.