A true case of an inverted vulva is not something that would be considered common to a specific breed, but it is something that does occur from time to time in any breed, as well as in mixed breeds. It's probably more common than some people believe, but it is still less common than under/overbites or cryptorchid males (males who retain one or both testicles in the abdomen).

As to the genetic component of the problem, it all depends on who you are talking to.  There have not been any specific studies on the trait and there is litter research on the subject.  In turn, there are some veterinarians who are of the belief that the trait is a recessive gene passed on through the bloodline while others believe it has to do with development and is not hereditary.  There is at least one study, however, that indicated fetal female exposure to androgens can result in an underdeveloped vulva. This has nothing to do with the dam, a similar situation occurs in cattle, when a heifer calf is twinned with a bull calf--the bull calf will be reproductively normal, but 90% or better of their twin sisters will have underdeveloped vulvas, and will be sterile as well. Because the trigger is likely to have been exposure to hormonal influence in the utero, and not a genetic predisposition, it isn't likely that breeding a female with this condition will perpetuate it in her offspring.

Breeding a female with an inverted/recessed vulva is possible although it can be difficult in some cases.  Because there is no actual evidence as to if this is genetic or developmental.  So, if you breed your female, there is a CHANCE that she could pass it on to her offspring.

An Inverted/Recessed Vulva and Urinary Tract Infections (UTI)

Many veterinarians believe that an inverted or recessed vulva can be one cause of Urinary Tract Infections in puppies.  With an inverted/recessed vulva, the “bulb” of the vulva is folded inward.  This can allow bacteria to lie in the fold causing the frequent infections from bacterial growth.

With some urinary tract infections, some females will develop inflammation of the vulva, which will result in pain upon urination; these females will typically stop urinating before they actually clear their bladder due to the pain.    Retained urine in the urethra and bladder also increases risk for bacterial overgrowth. Until the primary condition (the inverted/recessed vulva) resolves or is treated, it can be expected that the female will continue to be at risk for recurrent UTIs. In the interim, keeping the area clean between urinations and treating any existing inflammation can discourage bacterial growth and reduce risks of recurrence. In some individuals where the risk is high for recurrence after initial treatment or in cases of low-grade persistent infection, your vet may prescribe a maintenance (long term, low dose) antibiotic to control the infection.

A veterinary reproduction specialist by name of Mary C. Wakeman, D.V.M. , when talking about puppy UTI’s states:

“The so called inverted vulva is usually not a problem. Yes, zillions of bitches have a vulva that is surrounded by a fold of skin. Very seldom is this condition a problem unless basic hygiene is ignored by the owner. If your puppy is exhibiting signs of cystitis or vaginitis, and the area of skin around the vulva and vulvar fold is irritated, pay attention to the situation and clean inside this fold of skin. It is dead simple to do this – just pull on the hair of the vulva to bring it down and straighten out the fold. Then gently wash, rinse and dry the area, and apply a coating of bag balm or Desitin on the skin of the vulva and in and around the fold, to prevent further urine scalding. Way easier than surgery!!! Of the zillions of bitches with this conformation of the vulva, 99.9% have no problem. It is hygiene, not the conformation itself, that is responsible for the irritation and skin inflammation.”

Care and Therapy

If your puppy has an inverted/recessed vulva and has problems with urinary tract infections, there are some steps you can take to help prevent the urinary tract infections and/or inflammation.

1.      As stated above, you should clean the puppy’s vulva after she urinates.  At first, you might need help while doing this.  Have your pup lay down.  Roll her over on her back and rub her belly, then pull on the hair on the vulva to straighten out the fold.  Wipe the area with an unscented baby wipe.  Then apply bag balm or desitin on the skin surrounding the vulva and around the fold.  Do not apply the salve inside the vulva itself.  If you cannot wash your pup every time she urinates, make sure you wash her a couple times daily. 

2.      You can help reduce any inflammation by apply a warm wet wash cloth to her vulva a couple of times a day.  Make sure that the cloth is warm and not hot.  Apply the compress a couple of times in a sitting (re-warming it every time) for about one minute at a time and allowing a 1 minute tummy rub between each application.

3.     Some of the information on this subject says that the holistic treatment of this trait is very helpful.  To help reduce the chance of UTI’s it is recommended that your puppy/dog that is over 10 lbs be started on 2100 mg of cranberry capsules once daily.  If your pup is less than 10 lbs, I would ½ the dosage.  The recommendation is that the capsules are given every day until after the pup has completely gone through her first heat cycle. 

4.     It is also recommended that you check your pup’s urine PH at home.  You can easily purchase urine ph strips.  It is best to check the ph once a week.  Normal ph for a dog is 5.5 – 7.  If the ph is elevated or the pup has a UTI, double the dosage of cranberry capsules by giving the dosage of 2100 mg twice daily instead of once daily for 1 week.  Check the ph again after 7 days of double dose treatment check the ph again.  If it is still elevated, double the dose for one more week.  If the ph is normal after 1 week, resume the normal dosage.  If after 2 weeks the ph has not returned to normal, I would take a urine sample to the vet because antibiotics may be necessary.  

5.  Add water or beef broth to their food to help keep the system flushed.

6.  Give an additional 500 - 1000mg of Vitamin C (not Ester C) at least until 4 weeks after the first heat. Dosing depends on if you already supplement your dog with a supplement mixture that contains Vitamin C or Ester C.

Puppies that get frequent bladder infections and have an inverted/recessed vulva should NOT be spayed before their first heat. When a female goes into season that vulva gets larger and pops out of the skin folds. When this happens, the inverted/recessed vulva usually “fixes” itself.  Once they're out of season (heat), wait 4  - 8 weeks afterwards to have them spayed. If you do not choose to wait and instead spay your female early, there is a high risk of her suffering from UTI’s for the rest of her life.