Holding the dog is risking its life and yours and AGAINST THE LAW IN THE UK according to the UK highway code.
Here is some basic physics that have to do with the impact force generated by an object thrown forward in a collision.
A 15lb dog (eg a very small cavalier) in a 30 mph minor collision if unrestrained has a collision force of UP TO 300LBS. A 50lb dog (eg border collie or small lab) would be thrown forward at that speed with HALF A TON OF FORCE!
The basic formula is the force generated by a body is up to 20 times the mass (weight) of the body being thrown in a collision. If the dog is on your lap even in a residential street collision at this relatively slow speed, it will likely go straight into and possibly right through the window, the dashboard, the back set, and most likely have its skull crushed and neck snapped.
If your cavalier is sitting on a lap in the back seat or loose inthe back seat, it is likely to be catapulted into an airborne missile. If a dog of 15 lbs hits the head of the driver or passenger with even 50 lbs of collision force, it will break any human neck or potentially, at 300lbs of force, even decapitate you.
This is why it is no longer legal in most countries to carry children unrestrained. And in many it is illegal to carry dogs unrestrained.
Every motor safety organisation says: seatbelt the dog or crate it. Please do NOT leave a dog loose in a car or on a lap.
Please read:
http://www.parkvets.com/petsandvets-seatbelts.html
from this article from a UK vets:
Few commercially available harnesses have been independently tested. The ultimate endorsement must be to establish whether the harness you are considering has been subjected to similar crash testing as used for human seat belts and proven to be effective.
That means booster seat type seats with attached harnesses are most likely not safety tested (and to me have always looked potentially risky as they raise the dog even higher putting human passengers at risk if the restraint system fails). MOST dog restraint systems sold in the US, UK and Ireland are untested as well.
The article states:
Various reviews of the canine safety harnesses have been undertaken some of which can be found on the Internet. There appears to be two clear leaders in the field that fulfil all the above criteria.
Ruff Rider Roadie - This harness has been tested in the States and exceeded the standards for human seatbelts. Some users suggest that it is slightly harder to put on than other systems. Available in the UK from Company of Animals (
www.companyofanimals.co.uk). The manufacturer's web site is
www.ruffrider.com.
Champion Canine Seat Belt System - A tested harness system that receives consistently good press. The official distributor in Europe can be contacted at (
www.caninesafety.co.uk). The manufacturers web site is
www.CanineAuto.com .
A crate that is the right size for the dog (eg not too large, in particular, and seatbleted into place) is also a safe form of transport.
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