Ontogenetic change of the weight support pattern in growing dogs

Abstract

Weight support patterns vary widely among mammals. Differences in how much of the body weight is supported by the fore- versus the hind-limbs are well documented among and within species. Intraindividual variation due to ontogenetic processes has been studied in several hindlimb-dominated species and consistently showed a caudal shift in the limbs' support roles. We hypothesized that forelimb-dominated species exhibit a cranial shift in their support pattern and tested this hypothesis by examining the vertical ground reaction forces in growing dogs. Six male Beagle siblings were studied from 9 to 51 postnatal weeks (PW) of age while they trotted on an instrumented treadmill. Ontogenetic shifting in fore-to-hind support was evaluated using vertical force ratios (i.e., peak and impulse) as well as the stance time ratio of the fore- and the hind-limbs. Because morphological and kinematic characteristics influence weight support patterns, changes in body shape (i.e., trunk shape), and average limb position were determined. As in adult dogs, the forelimbs carried a greater proportion of the body weight than the hindlimbs at all ages. When the dogs were younger, peak vertical force occurred earlier during stance in the hindlimbs but not the forelimbs. Both the increasing ratio of the vertical force and the increasing ratio of the stance times indicate an increasing weight support by the forelimbs (i.e., 59% at PW9 vs. 63% at PW51). The observed ontogenetic changes in trunk shape and average limb angle were consistent with this cranial shift in weight support.

Comparative kinematic gait analysis in young and old Beagle dogs

“…Kinematic recordings were performed in the gait analysis laboratory of the Small Animal Clinic in a manner similar to those in previous kinematic studies in this laboratory [ 10 16 21 24 25 ]. An instrumented four-belt treadmill (TM-07-B; Bertec, USA) was used.…”

“…Most previous kinematic studies have analyzed the gait of healthy adult dogs at different ages [ 13 28 ] or of dogs with various orthopedic diseases [ 4 8 ], focusing in particular on investigation of different therapeutic treatments [ 10 16 ]. In one case, alterations of limb angles in growing puppies were analyzed [ 25 ], but not the effects associated with aging. For the present pilot study, we hypothesized that joint mobility is restricted and that consequently joint ROM is decreased in elderly dogs.…”

An individually adjusted endurance test reveals differences in physical fitness between young and old Beagles

“…Previous studies already investigated the ground reaction forces of, for example, growing Beagle dogs [22], healthy adult dogs [23], different types of diseases, e. g. lameness [10][11] or amputation [12][24]. However, no comparison of the ground reaction forces between young and old dogs has been carried out, so far.…”

Growing Beagles and Foxhound-Boxer-Ingelheim Labrador Retriever mixed breeds show a forelimb-dominated gait and a cranial shift in weight support over time during a kinetic gait analysis

“…Dogs are a forelimb-dominated species and carry about 60% of their BW on the thoracic limbs and 40% on the pelvic limbs. 1,5,13 Therefore, the PVF, VI, and BWD values of the thoracic limb are higher than those of the pelvic limb. Slight differences in BWD between dogs of different breeds have been reported.…”

“…To the best of our knowledge, there have been only 2 studies evaluating kinetic and kinematic parameters of the gait cycle in growing dogs. 13,19 One study 13 investigated the change of the weight support pattern in Beagles from 9 to 51 postnatal weeks by determining the PVF, VI, ST, and TOO during trotting but not during walking gait. The PVF of the thoracic limb increased from 59% at postnatal week 9 to 63% at postnatal week 51, and the VI of the thoracic limb increased from 62% at postnatal week 9 to 67% at postnatal week 51, showing that the thoracic limb carried an increasing portion of the body as a dog grows.…”