Dog Claws & Grout
The grout is dislodged and appears to be falling out [Photo 1]. Usually there is evidence of associated oils, fats and animal hairs around the damaged areas.
Technical reasons for dog claw damage in grout joints
Morgan advises that there may be multiple causes for the damage of grout by dog claws.
In a few cases, the dog genuinely has very tough claws and gauges out the grout as it moves off its resting area.
This cause can be exacerbated by grout that has been prematurely dried out and not completely hydrated. Refer to soft & powdery grout.
Recommended procedure for repairing dog claw damage in grout joints
It is important to determine the cause of the failure first.
Grouts that have been mixed with too much water will usually shrink back into the grout joint and support a white efflorescence layer at the surface. Grouts that have been mixed with too much water therefore need to be removed completely and the entire tile installation needs to be re-grouted.
Grouts installations that have been dehydrated before curing generally are flush with the tile joints but are weak and friable. These types of faulty installations can usually be hydrated using a damp curing method. Good results can generally be obtained with clean water and a mop & bucket. Any areas of grout missing should be thoroughly cleaned out and then re-grouted.