One possibility would be a UTI. Common symptoms of a urinary tract infection are frequent urination, dribbling urine, blood in the urine, squatting frequently to urinate, strong odor to the urine, inappropriate urination and straining to urinate as well as an increase in fluid intake. The constant licking of the vulva and urethra can lead to swelling of the vulva.
A dog with a UTI does not always show all the symptoms and typically displays 2 or 3. I believe you need to have your Vet check your dog out so it can get medication for the problem IF your dog is displaying 2 or more of the above symptoms.. If you believe it is a uti, two antibiotics that are commonly used are cephalexin (Keflex) and Enrofloxacin (Baytril.
You can read about Keflex and dosages here:
You can read about Baytril and dosages here:
This site discusses UTI’s and various medications used for treatments.
You should have your dog seen by a Vet for any UTI and should not administer any prescription medication without notifying your vet first.
Holistic approach to uti treatment can be found here:
Now it might also be a condition called vaginitis or a skin dermatitis of the fold of the vulva. Usually with vaginitis there is a discharge, but she may be licking it so much, that it isn't noticeable. You can read about vaginitis here:
If this is a skin fold dermatitis, You will want to keep the area clean and dry. Benzoyl Peroxide wipes are also effective for cleaning the folds as well and to keep bacteria in the area down. You should apply miconazole cream to help clear the dermatitis if it is yeast type dermatitis. You may also want to have your vet prescribe an antibiotic to help clear this infection up. Once the infection itself is cleared, keeping the area dry and free of bacteria with the wipes should help keep it cleared. You can read about skin fold dermatitis here:
If your girl is overweight, getting your dog's weight down will also help as being overweight does contribute to the amount of skin folds in the area.
Both vaginitis and skin fold dermatitis can cause the vulva to become swollen due to the irritation. If she doesn't have symptoms of a uti then try the wipes and miconazole cream until you can have her seen by your vet.
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