Four-paw grip strength was measured following the manufacturer's instructions.
In a first step, animals were monitored in vivo by 4-paw grip strength measurements and wire hanging tests.
The analysis of 1.5-year-old WT, HET, and HOM animals revealed a statistically significant reduction in the 4-paw grip strength in HOM mice as compared to WT mice (Fig. 7a).
When placed upside-down under the wire mesh, animals were required to grip onto the wire grid with front and hind paws, and grip strength is required to support their body weight.
We treated hTNFtg mice, as animal model for RA, with YopM and recorded clinical parameters (weight, grip strength and paw swelling).
In addition, grip strength of each paw was analyzed by semiquantitatively evaluating the force needed to detach the paw from a wire 3 mm in diameter using a score from 0 to –3 (0, normal grip strength; –1 mildly reduced grip strength; –2 moderately reduced grip strength; –3, severely reduced grip strength).
The results were measured using three different methods: the dogs walking at a consistent speed on a special platform that recorded the strength of each paw; a special electronic collar that recorded the dogs' daily activities; and owner evaluations of their dog's behavior.
Additionally, grip strength decreased and paw swelling increased during the progression of the disease, again displaying no differences between the two genotypes.
In addition, the grip strength of each paw was analysed on a wire 3 mm in diameter, using a score from 0 to -4 (0, normal grip strength; -1, mildly reduced grip strength; -2, moderately reduced grip strength; -3, severely reduced grip strength; -4, no grip strength at all).
The same animals showed similar grip strength of the hind paw, as compared to IT NaCl animals at 5 days after IT injection (figure 1A).
