I'm unfamiliar with Spear Grass. But...if you want to remove practically anything....you can soak a piece of bread in milk and hold onto the area. You have to be VERY careful and monitor.....as it will suck out everything...including flesh. But it will pull out anything stuck.
To comfortably remove the foxtail from the paw, have your dog lie down. If your dog is sitting or standing, it will be extremely difficult to locate and remove the seeds as it will be easy for the dog to pull its paw away from you.
Use a standard human hair comb, or another comb with small teeth. Gently hold the paw in your hand, and with the other hand, softly comb the fur around the foxtail to loosen the hold the seeds have on the fur.
Once the fur is untangled from the foxtail, apply an antiseptic liquid to the wound to prevent any infection from spreading.
Using standard tweezers gently grasp the foxtail. Do not attempt to violently pull the spikes out of the paw as this will cause the removal of the skin around the spikes, resulting in bleeding. With the tweezers, move the foxtail back and forth in small motions. After a few moments you will feel the foxtail releasing its hold in the paw, and it will smoothly pull out.
Treat the wound with more antiseptic and wrap the paw in a bandage. You can use gauze and a tensor bandage for this. Be sure to not wrap the bandage to tight as it will cause a loss of circulation in the paw.
Tips & Warnings
Use a nonalcoholic antiseptic if possible to ease the dogs pain. If an alcoholic antiseptic is used, the pain caused from the liquid may result in the dog attempting to stand or run away, and you'll have to start the process all over again.
Foxtails that are embedded for some time in paws may require removal from a veterinarian. If you are unsure of when the foxtail became lodged in your dogs paw, consult your veterinarian before attempting to remove it yourself.