Distribution of vertical forces in the pads of Greyhounds and Labrador Retrievers during walking

Objective-To document peak vertical force (PVF) and vertical impulse (VI) in the pads of Greyhounds and Labrador Retrievers. Animals-8 Greyhounds and 8 Labrador Retrievers. Procedure-Velocity and acceleration were restricted to ranges of 0.9 to 1.1 m/s and -0.1 to 0.1 m/s(2), respectively. The PVF and VI measurements were collected from digital pad (DP)-2, -3, -4, and -5 and the metacarpal pad (McP) or metatarsal pad (MtP) of each limb in each dog. Results-We found no significant differences between the left and right forelimbs or hind limbs for any pad in either breed. Vertical forces in the forelimb were always greater than those in the hind limb. The PVF in the forelimbs of Greyhounds was greatest in DP-3, -4, and -5 and DP-3, DP-4, and the MtP in the hind limbs. The VI in Greyhound forelimbs was greatest in DP-3, -4, and -5 but greatest in DP-4 in the hind limbs. The PVF in the forelimbs of Labrador Retrievers was greatest in the McP whereas in the hind limbs it was greatest in DP-4. The VI in Labrador Retriever forelimbs was greatest in DP-3, DP-4, and the McP but greatest in DP-3 and -4 in the hind limbs. Significant differences were detected in load distribution between the breeds. Conclusions and Clinical Relevance-This study confirms that DP-3 and DP-4 are major weight-bearing pads in dogs. However, loads were fairly evenly distributed, and DP-5 and the McP or MtP bear a substantial amount of load in both breeds.