Health Articles

Comparison of Hip Certifications: OFA versus PennHIP

by Joanne Rubin, RN, MS, CCRN, CFRN

 
A responsible Bichon Frise breeder should be screening all breeding stock for hip dysplasia and certifying with at least one of the two main certifying organizations, OFA or PennHIP. These two options will be discussed in this article. It is the BFCA Health Committee's hope that PennHIP can be included in order to receive a CHIC number.

The "OFA" method of evaluating the hip joint uses an xray that shows the extended view of the pelvis. A preliminary evaluation can be attained before 24 months of age, or a permanent evaluation on or after 24 months of age. The dog is also recommended to have permanent identification (microchip or tattoo), which is noted in the published database results. OFA does recommend chemical restraint (either sedation or general anesthesia) but does not require it for evaluation.

So, in contrast, what is PennHIP? The acronym stands for the University of Pennsylvania Hip Improvement Program. This method involves evaluating the canine hip both qualitatively and quantitatively. The qualitative aspect involves assessing the hip joint conformation and any evidence of dysplastic changes, and the quantitative aspect involves measuring the joint itself for laxity. The University of Pennsylvania School of Veterinary Medicine developed this method in 1983. After conducting research and determining that the method was capable of estimating future susceptibility to developing hip dysplasia. The University of Pennsylvania established PennHIP as a public program in 1993. PennHIP is also a not-for-profit organization, and has an established database although individual scores are not currently published on the website.

The main components of both programs are using x-rays to examine the hips, procedures performed by trained Veterinarians, and a database containing the information. The goal is to reduce the occurrence and severity of hip dysplasia.

The main difference in the PennHIP procedure versus the OFA procedure is the (x-ray) technique. OFA uses one x-ray of the hips for certification. PennHIP uses three separate views of the hips in different positions. Their opinion is that the three views better measure hip slackness and fitting when compared to other techniques.

PennHIP has great value to any breeder based on the additional views, which show the laxity in more than one position. It is a more comprehensive and dynamic evaluation of the hips. The breed laxity statistics have been generated for August 2013. The statistics are available to all certified PennHIP veterinarians.

The PennHIP technique tends to cost more than the OFA. The reason for the increased charge is the added x-ray views and the additional training a Vet must have to be approved to perform the PennHIP technique. The PennHIP method can be performed on animals as young as 16 weeks of age, although many films are taken at one year or later. The films are submitted to the PennHIP analysis center that then processes the evaluation of the films and sends a report to the owner and veterinarian. The report includes information on the owner (name, address, etc.), information on the dog (breed, age, sex, microchip number, etc.), qualitative evaluation including evidence of dysplasia, etc. and quantitative measurements including distraction index (DI). There is also a line graph at the bottom of the report, which demonstrates where the dog's DI falls in a percentage comparison amongst other dogs of the same breed.

The line graph ranges from 0% to 100%, with 50% as the median. Dogs to the left of 50% have higher percentage "scores" and tighter hips. Dogs to the right of 50% have lower percentage "scores" and looser hips. For example, a dog with a 90% PennHIP rating has hips tighter than 90% of the rest of the population in the database for that breed. This would be an excellent dog to breed to if gaining tighter hips is the objective. Conversely, a dog with a 30% rating has hips tighter than only 30% of the rest of the population - in other words 70% of the population in the database for this breed has tighter hips than this individual. This dog would not be a good breeding individual if the goal is to produce tighter hips. It is recommended to breed dogs to the left of the median (in other words towards tighter hips) if the goal is to produce hips with less laxity and therefore less hip dysplasia. Pennhip suggests a DI of 0.5 as a "passing" score for Bichon Frises.

Some breeders only use and believe in one of the two techniques, PennHIP or OFA, and use that technique exclusively. Very few breeders screen all breeding stock using both techniques. To this point there is no rule about which is truly better. The bottom line is that all Bichon Frise breeding stock and the vast majority of at least 3 generations behind any individual dog should be certified with at least one of these organizations, or the governing organization in the dog's country of origin in the case of a foreign dog.

The other main controversy surrounding use of PennHIP is that it does not fail any hip as OFA does. PennHIP scores the hips based on a percentile rating as compared to other dogs in the breed. A truly bad hip is simply rated at a lower percentile. It is left up to the breeder to determine what percentile rating they feel comfortable with including in their breeding program. PennHIP does however require mandatory submission of all radiographs taken using their technique that should provide a better rounded picture of the problem within any particular breed. PennHIP also uses more scientific measurement techniques to arrive at their rating than OFA which is a much more subjective rating. In PennHIP the two hip joints are rated separately with their own score, but the percentile rating is based on the worse individual hip score.

PennHIP is more expensive than OFA, nevertheless, it is growing in popularity and the benefit- as breeders who have fully adopted PennHip have found- is a much reduced incidence of hip dysplasia in their lines and the knowledge that they are contributing to the overall health of a breed.

 

References:

Journal of the American Veterinary Medical Association September 1, 2010, Vol. 237, No. 5, Pages 532-541
Rooks DVM, R. (1997). Canine Orthopedics: Howell Book House
Character, B. (2005). Sports Medicine for the Retriever: Caring For the Hunting Retriever: Author House