In this month’s column is all about jumping problems. In this month’s issue I am going to look at the biomechanics of jumping and where problems arise. Some are due to physical issues and some are down to training issues. In next month’s issue I will talk a bit more in depth about the physical problems, how to identify, treat and prevent. I will be jointed by Lauren Langman of Devon Dogs to talk about the training problems of jumping.
By David Prydie BVMS, CertSAO, CCRT, MRCVS
Jumping is an extremely complicated sequence of events that a dog must learn in order to take off and land without injury and without knocking over the pole. A dog has to be at a canter or a gallop to jump. These are the only two gaits that have a lead leg. There is no lead leg at a walk or a trot. I will deal with gaits in a later column.
In the basic sequence of events the head goes up, the front legs leave the ground at the calculated distance from the jump; the more angulation the higher the lift. The tail goes down. The back legs then provide thrust forwards (Fig.1). The combination of these actions results in the trajectory. After passing the apex of the jump the head goes down and the tail goes up with the body rotating forwards and downwards (Fig.2). The dog then prepares for landing (Figs.3).
The trajectory is also controlled by speed at take off. A flat trajectory will require greater speed than a round trajectory to clear the same height jump. The flat trajectory will also cover more ground (Fig.4). The rate of descent is down to gravity at 9.8m/sec.2 The higher the dog jumps the faster it will be travelling when it hits the ground.
There are several different jumping styles. Border Collies tend to jump at full stretch. Smaller breeds such as Shelties and Poodles often jump in a half stretch. Larger breeds such as the German Shepherd Dog and Rottweiler often jump with the rear legs tucked up. Some dogs dangle legs when jumping. This is particularly seen in Labradors. Over jumping is common in small breeds. None of these styles are right or wrong. They are just the style the dog has adopted.
Injury or physical problems occur or become apparent during one or more of the three phases of the jump:
1. The take off phase; 2. The floating phase and 3. The landing phase. In part 2 next month’s I will go into the details of common injuries that manifest themselves in each phase. Lauren will go through training issues that arise during the jump sequence.
The Fourth Height
I am in favour of a fourth height. I have had the impression for a number of years that dogs that just fall into the large category are seen more often at my clinic. Rather than rely on my impression, in the last 2 weeks I have started a study of new agility cases presented at my clinic. So far dogs measuring between 43-50cm are over represented. In next months issue I will give more details of the study and how other clinics can pool data.
The argument that classes would be bigger and take longer is irrelevant, as dog welfare must come first. Again it has been suggested that the higher jump allows the handler a chance to catch up to their dog. Again this is putting competition before welfare. The stride of a racing greyhound is similar in length to that of a thoroughbred horse. A racehorse is never asked to jump one and a half times its own height at the withers. As most readers will be aware, the RSPCA are calling for jump heights in horse racing to be reduced. I think sooner or later that the attentions of the RSPCA will fall on canine sports such as agility.
Another argument against a fourth height is that in international competition the heights would then be different. Jumping heights already vary in many countries. I believe this is another opportunity for the Kennel Club to lead the world and be proactive towards dog welfare, just as it has lead the way in breeding reform.