PennHip is another method for screening for hip dysplasia, however it is different from the method used by the Orthopedic Foundation for Animals (OFA). Both OFA and PennHip are recognized as approved methods for screening Cavalier King Charles Spaniels so whichever method a breeder might choose to use is their choice.

One advantage to PennHip screening versus OFA is the age they can be first screened. PennHip can be screened at 16 weeks of age. OFA will do a preliminary screening at 6 months of age, but strongly view 2 years as the norm. PennHip studies have shown that the laxity number at 16 weeks is only off by a few points at 2 years, but testing done in between 16 weeks and 2 years will have a tendency towards a higher laxity number due to the growth process.

PennHip is a scientific measurement from 3 separate x-rays of different views. OFA is an opinion of certified Orthopedics from the view of one x-ray.

Hip Dysplasia (HD) is a disorder found in numerous breeds and has been studied for decades. The genes that attribute to HD have yet to be discovered because they are polygenic and multifactoral. Since Cavalier King Charles Spaniels are a toy breed most Cavaliers that are found to have mild dysplasia with an OFA reading can be screened with PennHip and have a high laxity, but with PennHip's extra x-ray views they can further indicate if Degenerative Joint Disease (DJD) is present or not. Therefore, a dog can be found to have mild dysplasia with OFA and a second opinion through PennHip can indicate no dysplasia present, but the high laxity gives the dog the predisposition to the disorder.

Polygenic traits are controlled by unknown numbers of genes. The gene expression is also influenced by a variety of factors, such as gender (females seem to be more prone to the disorder than males), environment, development, etc. Heritability varies from breed to breed as well as within different dogs within a breed. It is difficult to control disorders with a polygenic mode of inheritance as the exact genes which cause such a disease and the non-genetic factors which will influence expression are unknown.

I have read numerous articles and information pertaining to hip dysplasia. One study showed a German Shepherd with excellent hips at 2 years of age and another German Shepherd with mild hip dysplasia at 2 years of age. At 10 years of age the German Shepherd with excellent hips had debilitating hip dysplasia and was exhibiting clinical signs of pain and discomfort. The other German Shepherd with mild dysplasia still had mild dysplasia at 10 years of age without any clinical signs of pain or discomfort. I believe somewhere in each dog's DNA sequence there is a trigger and once they reach a certain age they trigger the regression to begin. I personally do not think that a dog passing at 2 years of age should be considered clear for the rest of their life. I also do not feel that a dog with mild dysplasia should be eliminated from the gene pool if DJD is not present.

The above chart shows the date, breed count, and medium Distraction Index (DI) for Cavalier King Charles Spaniels. When the PennHip method is used for testing it must be sent in unlike veterinarians across the country that might take an x-ray for OFA and then give the breeder their opinion and if the diagnosis is not passing as far as the vet is concerned the breeder does not send the x-ray to OFA. This lack of reporting hurts the breed overall.

When reading a PennHip diagnosis the dog will be given a number for their left hip and their right hip somewhere between "0" and "1". By using the above mean it is best to always breed dogs that are higher than the mean with dogs that are lower than the mean to improve the breed. It is common for each hip to have a different number outcome and averages are taken from the hip with the highest number when comparing against the breed, so when a breeder is making a decision about pairing their dogs together they need to go by whichever hip has the highest number. PennHip is not a pass/fail screening like OFA is. When new breeds come out it is very common to have a very high laxity in the hips giving a high number and if using only the OFA method a new breed could be eliminated instantly if all the dogs were eliminated from the gene pool from a failed OFA reading. PennHip is a constantly changing mean number since the mean is adjusted within each breed semi-annually, but as a whole a dog should be scored against its own breed norm versus the norm of all breeds put together I think. If the PennHip comes back with a higher number than the mean on both legs they will also tell you if degenerate joint disease is present or not. If it is NOT present then breeding to a mate below the mean is the quickest way to achieve improvement. If degenerate joint disease is present then that dog should be eliminated from your breeding stock.

PennHip does not share its database at this time for Cavalier King Charles Spaniels, but when I filled out the paperwork for the screening on each of my dogs I gave approval for my results to be posted if they resulted in the top 40% for the Cavalier King Charles Spaniel breed. I believe eventually they will post a database for Cavalier breeders to resource, but there may be a certain number of Cavaliers that must be tested before they can accurately report the top 40%. Once I receive my PennHip report screening back on my Cavalier I can then pay $25 to the Canine Health Information Center (CHIC) and they will publish the screening results to OFA. Most Cavalier breeders believe that a CHIC certified dog must be over the age of 2 years, but using the PennHip method a dog can become CHIC certified after 12 months if they have obtained their heart, eye, patella, and PennHip clearance. While I do not endorse breeding at 12 months of age, I do believe that knowledge about a dog's ability to pass all of its testing is very important before tacking on the high expenses of showing a dog to their championship title.