What is Persistent Hyperplastic Primary Vitreous (PHPV)?
The simplest way to describe Persistent Hyperplastic Primary Vitreous ((PHPV) is a birth defect that affects the eyes in young puppies. This defect causes abnormalities in the lens of the eyes which often leads to the formation of cataracts and vision loss for those who are affected.
What causes PHPV in dogs?
PHPV occurs when the foetal blood vessels and structures in the eye that normally regress before birth persist. While the puppy foetus is developing in the womb, a structure called the primary vitreous has the important role of supplying nutrients to the lens. The primary vitreous is made up of major blood vessels of the eye that normally regresses during the third trimester of pregnancy. Growth factors and inhibitors released during pregnancy are involved in allowing these blood vessels to diminish as the foetus develops into a puppy. When these growth factors and inhibitors don’t coordinate well, or there is an abnormality present with the primary vitreous due to genetics, this can lead to PHPV.
Which dog breeds are most likely to get PHPV?
There are quite a few breeds that can be prone to this medical condition. Breeds that are predisposed include:
- Staffordshire Bull Terrier,
- Bouviers des Flandres,
- Airedale Terrier,
- German Shepherd,
- Alaskan Malamute,
- Siberian Husky,
- Miniature Poodle,
- Labrador Retriever,
- Irish Setter,
- Doberman Pinscher, and
- Irish Wolfhound.
What symptoms would suggest that a dog might have PHPV?
Since this disease affects the lens of the eye in young puppies, the most common symptom I would expect to see during my physical exam would be vision impairment. This may be made evident by the lack of response to visual cues, bumping into walls and objects, or limited to no response of the pupils to light. Also, a complete eye exam could reveal the appearance of cataracts or cloudiness in their lens.
How is PHPV clinically graded based on severity?
Grading of PHPV is determined by the amount of foetal tissue that retained in the eye and if there are any abnormalities associated with the lens. There are six grades of severity with Grade 1 being the lowest with minimal foetal tissue associated with the lens of the eye. The most severe are Grade 6, which is associated with a moderate amount of retention of foetal tissue and abnormally shaped lens.
How is PHPV diagnosed?
If I want to get a definitive diagnosis for PHPV, I refer the case to a veterinary ophthalmologist. The best ways to diagnose PHPV involves an eye ultrasound and a biopsy of excessive tissue performed by a veterinary specialist. An ultrasound typically reveals an abnormal shaped and sized lens, evidence of retained foetal tissue, and evidence of abnormal blood flow in the lens. A biopsy can be performed to confirm diagnosis at the time of surgical repair.
If an owner suspects PHPV, when would be the right time to consult an Expert or to take the dog to a Vet?
I would recommend any owner that has a puppy who is experiencing vision problems consult a veterinarian right away. This is especially important if the puppy is a breed predisposed to this condition. Depending on the severity of the disease, the earlier this disease is treated, the better the outcome will be.
How is PHPV treated?
Treatment of PHPV depends on the severity of the case. If I see a mild case of this condition, I may just treat it with an ophthalmic ointment to help with any inflammation and see how it responds. Otherwise, I would refer more severe cases to a veterinary ophthalmologist. Treatment of choice would likely be surgery which would involve removal of the affected lens and replace it with a prosthetic. Also, any retained foetal tissue could be surgically removed as well.
How much can PHPV treatment cost?
Treatment for PHPV can be costly. Since most of these cases will likely require a referral to a veterinary ophthalmologist, the cost of consultation, diagnostics, and treatment have to be considered. Costs can vary based on location. In Georgia where I practice, a consultation will cost anywhere from $90 -150. Diagnostics such as an ultrasound could cost as much as $500 and finally successful treatment which involves removal of the affected lens could cost as much as $1,200 per eye.
Anything to note about a dog’s recovery from PHPV?
My best advice for pet owners regarding recovery from PHPV is that early detection is likely to improve the prognosis. Also, it seems that in the majority of the cases surgery often can lead to a normal vision for these puppies.
Is there anything else dog owners need to know about PHPV?
My final advice regarding PHPV is since the disease is likely genetic, I wouldn’t recommend breeding any dog that has been diagnosed with this condition.
About the Author:
Dr Dwight Alleyne has been an Expert on JustAnswer since July 2015 with over 90 satisfied customers.
Dwight Alleyne is a small animal veterinarian that currently practices in Georgia. He has been practicing veterinary medicine for 10 years and graduated from Cornell Veterinary School in 2006. When he is not practicing veterinary medicine he enjoys sharing pet health information on his blog “The Animal Doctor Blog”.