Many of us are familiar with the term, “OFA” and a few may have heard of “PennHIP”, but what exactly do these terms relate to? And exactly what is the difference between the two? Is one superior over the other? Are there any risks?
We are going to take a look at both procedures, see how they are similar and how they differ from one other, then you can be the judge. My goal is not to steer anyone in a specific direction but to provide a comparison of the procedure and the cost so owners can make an informed decision based on their individual needs and desires.
So, let’s start with OFA. The Orthopedic Foundation for Animals, or OFA, was founded in 1966. In its early days, The OFA screened only for hip dysplasia. Now, they provide a wide variety of health screening services which include evaluation of the shoulder, elbow and patella (knee), DNA testing for thyroid problems, heart defects and many other hereditary conditions. We are mainly going to focus on the screening method for hip dysplasia in this article, for the purpose of comparison.
The procedure for an OFA radiograph, or x-ray, can be performed with or without sedation. This is typically determined by the veterinarian and the clients’ individual wishes. Being on the receiving end myself and having to take multiple radiographs over due to sudden movement, I prefer to have my dogs sedated. However, I am well aware that many people are uncomfortable with the idea of sedation, so this is something you must discuss with your vet prior to the procedure.
In the OFA radiograph, the dog is positioned on its back with its rear legs fully extended and knees turned slightly inward, so a fully conscious dog can put up quite a bit of resistance. It is not a painful process, but can be overwhelming to a dog that is not accustomed to being handled by strangers. The radiograph is then sent to OFA either by mail or electronically if the veterinary clinic has digital radiography. After OFA receives the film(s), they are sent off to 3 different board certified radiologists for evaluation. The films are scored on a seven point grading system. “Excellent, good and fair” are all considered to be within normal limits. Then we move into descending levels of dysplasia: “borderline, mild, moderate and severe.” These films are graded on an average consensus between the three radiologists. For example, if two of them scored the hips as good, and the third scored the hips as fair, the final score would be good. Preliminary OFA radiographs can be submitted as early as four months of age, but in order to become “OFA Certified” the dog must be at least 24 months of age, or two years. Prelims are estimated to be 93% accurate of what the actual score will be at two years of age, so they can be a useful tool in screening a potential breeding animal.
The actual cost of OFA can vary a great deal between veterinarians. You can expect to pay anywhere from $170-$300 depending on how many films are needed. The cost of submitting these films to OFA is $35, plus postage if mailed. If you add shoulders or elbows to the evaluation, OFA charges only an additional $5-$10. They also offer a kennel rate or litter evaluation which is considerably cheaper, but again, the overall cost will increase with the number of films taken. Many veterinarians charge a set amount per x ray, so be sure and ask!
Now, let’s talk about the other alternative, PennHIP. PennHIP was first introduced in 1993 by the University of Pennsylvania. Unlike OFA, a PennHip evaluation does require full sedation in order to obtain the proper positioning that is required. In this process, the veterinarian will take 3 radiographs of the pelvis and surrounding structures. The first x ray is taken in a relaxed “frog leg” position with the dog lying on its back. The second image is obtained by applying steady consistent pressure to the pelvis in this same position, using the aid of a specially designed plate called a distractor. The third image is basically the same as the OFA view with the rear legs extended parallel, and knees rotated slightly inward. The x-rays are then sent off to a board certified veterinary radiologist, and comparative measurements are taken of the space between the ball and socket of the hip. This results in a number between 0-1. This number is called the distraction index, or DI. The closer this number is to 0, the tighter the hip joint, and the less chance of the dog developing osteoarthritis, or hip dysplasia. And likewise, the closer this number is to 1, the greater laxity in the hip joint and a higher likelihood of the dog developing hip dysplasia. There is no pass/fail score with the PennHIP method, but it is suggested that any dog with a DI of greater than 0.5 not be used for breeding purposes. In addition to the Distraction Index, the dog will receive a percentile score ranging from 1 to 99. This is a comparative score among all dogs within a specific breed or weight classification. For example, if your dog ranks in the 90th percentile, this means he scored higher than 90% of all other dogs within his breed or weight category. This number may change slightly as the number of dogs in a specific breed category are added to the database, but the original distraction index will never change.
The PennHIP procedure runs between $300- $400 and must be carried out by a specially trained veterinarian. PennHIP can be performed as early as 16 weeks, however, it is recommended that it be repeated closer to one year of age if done this early. Thus, it may be wise to compromise and wait until 6-9 months to avoid the extra cost. Neither of the two procedures have been shown to result in damage to the pelvis or surrounding structures.
I hope this article helps to clarify some of your questions surrounding the OFA and PennHIP method. Both are excellent tools for owners and breeders to employ in helping to identify hereditary conditions that can greatly reduce the quality or longevity of life. Although the initial cost may seem formidable, it is a small price to pay when compared to the thousands of dollars spent each year on surgery or anti-inflammatories to treat osteoarthritis and hip dysplasia.