Dogs don't usually grow masses or lumps very quickly unless they got injured some how and this injury has turned into an infection. If a dog gets scratched by a cat or another animal, it can easily and quickly become infected. As it was mention before, you need to use warm compresses to try to get this lump to drain. I have cats who fight with one another and often begin growing small lumps. These lumps will keep growing because it is puss under the skin. I inspect my pets on a daily basis for this type of problem. The sooner you treat the better off the animal is. I first look for an entry wound, a dot or scratch to which may have opened the skin to cause this infection. I then get a warm, wet compress, as hot as my hands can stand it and apply it to the wound. I hold it there as long as the animal will let me prior to it getting cold. Even if it is a slight bit warm, I keep holding it as not only is it bringing the infection to a head but the moisture is softening up the scab. When the compress gets cooled down, I will look again to see if draining has started. If there is no drainage, I will scrap off the scab myself to purposely get it to drain. As mentioned before, I will press or squeeze the area to try to drain it as much as possible. Once I have done this, I will apply antibiotic ointment. I used to try to pour peroxide on the wound but this can also hurt the animal, especially if it is near the ears or eyes. Peroxide also causes the wound to heal, you don't want this to heal, you want all the infection to come out. You need to repeat this at least twice a day but 3 times would be better if you can. The antibiotic ointment will keep the scap soft and allow for the wound to continue to drain. It will also help to get rid of the infection as it has antibiotics in it. You can't use this on small animals but dogs and cat are ok to do this. Within 24 hours you should notice that the lump is smaller and you should see drainage. The drainage may or may not have an odor and may also include blood but this is alright as long as it drains. You also want to keep this wound draining until it is totally cleaned inside because you don't want this to heal from the outside as this will only cause more problems. If you keep re-opening the wound, you are making it heal from the inside out and heal properly. It may take a week-week and a half before you can begin allowing it to heal on its own so be prepared to do this for a while. Continue to watch it for a week or two after you think it is healed to insure it won't flare up again. If you don't notice any improvement within the first 24 hours, this may not be the cause of your problem and a vet should be contacted ASAP as it may be something more serious. The care I am explaining is basic first aid for infection and wound healing and nothing more then that.
