Monday, August 18, 2014

Hip Dysplasia

LiLo was my very first "puppy". I think I got her when she was about 16 weeks old. Not knowing what I know now I wanted her spayed as soon as possible because I didn't want to worry about her going into heat. At the time we also thought she would be much larger than she turned out to be and if she was going to have bad hips my vet was going to perform a JPS surgery. We took PennHip xrays and my vet who is very orthopedically educated looked at them and said that her hips were fine. I didn't send the xrays in and we went ahead with spaying her. A few years post spay she was dysplastic. Her DI numbers for pennhip were .63 and .61 putting her in the high risk category. At the time we xrayed she had no djd or any obvious flaws that we could see. While spaying her early did not cause her hip dysplasia, it is a concern.

In this study:

"Specifically, early neutering was associated with an increase in the occurrence of hip dysplasia, cranial cruciate ligament tear and lymphosarcoma in males and of cranial cruciate ligament tear in females. Late neutering was associated with the subsequent occurrence of mast cell tumors and hemangiosarcoma in females.

In most areas, the findings of this study were consistent with earlier studies, suggesting similar increases in disease risks. The new study, however, was the first to specifically report an increased risk of late neutering for mast cell tumors and hemangiosarcoma.

Furthermore, the new study showed a surprising 100 percent increase, or doubling, of the incidence of hip dysplasia among early-neutered males."

Another study:

" For example, if the femur has achieved its genetically determined normal length at 8 months when a dog gets spayed or neutered, but the tibia, which normally stops growing at 12 to 14 months of age continues to grow, then an abnormal angle may develop at the stifle. In addition, with the extra growth, the lower leg below the stifle becomes heavier (because it is longer), causing increased stresses on the cranial cruciate ligament. These structural alterations may be the reason why at least one recent study has shown that spayed and neutered dogs have a higher incidence of CCL rupture.(3) Another recent study showed that dogs spayed or neutered before 5 1/2 months had a significantly higher incidence of hip dysplasia than those spayed or neutered after 5 1/2 months of age."


It was fun to send LiLo's xrays in and it doesn't change anything. I expected that she was dysplastic and we just missed it. To the naked eye her xrays did look very clean, of course she was too young/they weren't bad enough to have arthritis or signs of DJD at that point. I still think it's important to let your dog grow before spaying and neutering. I doubt it would have changed anything for LiLo - but I am sure it didn't help things either.

I would also like to take a moment to plug pennhip. I always thought that OFA was better because your dog has to be 2yrs old to have xrays taken [you can take early preliminaries but the permanent ones are after 24mos]. However, reading the pennhip website I think it is a far more accurate testing method and it doesn't matter what age you take the xrays, you can take them as young as 16weeks and the outcome will be the same. Here is some "fast facts" directly from their website:

1.   The Distraction Index (DI) as determined by the PennHIP method is the most reliable indicator of future hip osteoarthritis.

In a study comparing factors such as age, breed, weight, gender, distraction index and Norberg angle (another method of measuring hip laxity based on the conventional OFA-type x-ray), it was found that the distraction index was the most significantly correlated with future development of osteoarthritis irrespective of age at the time of PennHIP evaluation.
Smith GK, Popovitch CA, Gregor TP. Evaluation of risk factors for degenerative joint disease associated with dysplasia in dogs, J Am Vet Med Assoc, 1995; 206: 642-647.

2.   The distraction index does not change significantly over time.  

A study of large breed dogs showed that the distraction index stayed the same over time (within acceptable statistical limits) and was much more reliable over time than other methods such as the Norberg angle and the OFA scoring method.
Smith GK, Gregor TP, Rhodes WH and Biery D. Coxofemoral joint laxity from distraction radiography and its contemporaneous and prospective correlation with laxity, subjective score and evidence of degenerative joint disease from conventional hip-extended radiography, Am J Vet Res, 1993; 54: 1021-1042.

3.   Keeping your dog at a lean weight throughout life delays the onset of hip osteoarthritis related to hip dysplasia.

Restricted feeding to maintain a lean body condition delayed or prevented development of radiographic (x-ray) signs of hip joint osteoarthritis in a group of 48 Labrador Retrievers followed throughout life. Lifetime maintenance of 25% diet restriction delayed onset and reduced severity of hip joint osteoarthritis, thus favorably affecting both length and quality of life. This study also showed that hip osteoarthritis can develop at anytime throughout a dog’s life.
Smith GK, Paster ER, Powers MY, Lawler DF, Biery DN, Shofer FS, McKelvie PJ, Kealy RD. Lifelong diet restriction and radiographic evidence of osteoarthritis in the hip joints of dogs. J Am Vet Med Assoc. 2006 Sep 1; 229 (5); 690-3.

4.   The PennHIP method can be reliably performed on a dog as young as 16 weeks old. 

PennHIP has studied the efficacy of this method from eight weeks up to three years of age. For the present, it is recommended that dogs should not be evaluated before 16 weeks of age and that follow-up radiography at 6 months or 1 year of age is encouraged. However, the decision to have the method performed again is always that of the owner.
Smith GK , Gregor TP, Rhodes WH and Biery DN. Coxofemoral joint laxity from distraction radiography and its contemporaneous and prospective correlation with laxity, subjective score and evidence of degenerative joint disease from conventional hip-extended radiography, Am J Vet Res, 1993;54:1021-1042.
Smith GK , Hill C, Gregor TP, Olsson K. Reliability of the hip distraction index in two-month-old German Shepherd dogs. J Am Vet Med Assoc, 1998;212:1560-1563.

5.   80% of dogs evaluated as “normal” by the OFA were found to have hip laxity by PennHIP testing that predisposed them to developing hip osteoarthritis in the future.

Dogs judged as normal by the OFA harbored clinically important passive hip joint laxity as determined via the PennHIP distraction index. Results suggested that OFA scoring radiographs (x-rays) underestimated susceptibility to osteoarthritis in dogs. The presence of these “normal” dogs in the breeding pool may slow the progress of decreasing hip dysplasia prevalence.
Powers MY, Karbe GT, Gregor TP, McKelvie PJ, Culp WT, Fordyce HH, Smith GK. Evaluation of the relationship between Orthopedic Foundation for Animals’ hip joint scores and PennHIP distraction index values in dogs. J Am Vet Med Assoc 2010; 237: 532-541.

6.   PennHIP Biomechanics

Biomechanical testing determined the optimal patient position for measuring hip laxity. Hip laxity was found to be maximal in the non weight-bearing position used in the PennHIP method and is actually masked in the conventional hip-extended position. 
Smith GK , Biery DN and Gregor TP. New concepts of coxofemoral joint stability and development of a clinical stress-radiographic method for quantitating hip joint laxity in the dog, J Am Vet Med Assoc. 1990;196:59-70.
Heyman J, Smith GK and Cofone MA. A biomechanical study of the effect of coxofemoral positioning on passive hip joint laxity in the dog. Am J Vet Res, 1993;54:210-215.

7.   PennHIP continues to research inherent differences among breeds.

The breeds with the tightest hips as measured by DI have the lowest susceptibility to showing hip osteoarthritis. Within each of the 8 breeds (American bulldog, Bernese Mountain Dog, German Shepherd dog, Golden Retriever, Labrador Retriever, Newfoundland, Rottweiler, and Standard Poodle) studied thus far, the looser the hips, the greater the likelihood of showing hip osteoarthritis. 
Runge JJ, Kelly SP, Gregor TP, Kotwal S, Smith GK.  Distraction index as a risk factor for osteoarthritis associated with hip dysplasia in four large dog breeds.  Journal of Small Animal Practice 2010;51:264-269.
Smith GK , Mayhew PD, Kapatkin AS, Shofer FS, Gregor TP. Evaluation of risk factors for degenerative joint disease associated with canine hip dysplasia in German Shepherd dogs, golden retrievers, Labrador retrievers, and Rottweilers. J Am Vet Med Assoc, 2001;219:1719-1724.

8.   Hormonal effects on hip dysplasia

Contrary to popular belief, estrus (being in heat) is of no consequence to hip scoring; the study performed showed definitively that estrus does not adversely affect the distraction index or any other hip scoring method. The hormone relaxin, however, remains present up to 8 weeks post whelping (although it varies by breed). We know of no study describing whether relaxin has any effect on DI or any other hip scoring method but to be on the safe side, we advise waiting 8 weeks post-lactation or 16 weeks post-whelping. 
Hassinger KA, Smith GK, Conzemius HM, Hill CM and Gregor TP. Effect of estrus cycle on coxofemoral joint laxity, Vet Comp Ortho Traum, 1997;10:69-74.

9.   Within and Between Examiner Repeatability

Studies have shown that the PennHIP method has a very high degree of reproducibility between examiners. In other words, your dog should have similar distraction scores no matter which PennHIP certified veterinarian performs the radiographs. This high degree of consistency is attributable to the inherent biomechanics of the canine hip joint and to the quality-assurance training that all PennHIP network veterinarians must successfully complete.
Smith GK , LaFond E, Heyman SJ, Cofone MA and Gregor TP. Biomechanical characterization of passive laxity of the canine coxofemoral joint, Am J Vet Res, 1997;58:1078-1082.
Smith GK , LaFond E and Gregor TP. Within-and between-examiner repeatability of distraction indices of the hip joints in dogs, Am J Vet Res, 1997;58:1076-1077.

10.               Cats and Hip Dysplasia

Did you know cats can get hip dysplasia? As in dogs, the distraction index is correlated with osteoarthritis; the greater the distraction index, the more likely a cat will develop osteoarthritis. However, further studies need be conducted to determine how well cats tolerate laxity. As of June 2011, 131 cats are listed in the PennHIP database.
Langenbach A,Giger U, Green P, Rhodes H, Gregor T, LaFond E, and Smith G. Relationship of degenerative joint disease and laxity in the coxofemoral joint by use of distraction index and Norberg angle measuement in a group of cats. J Am Vet Med Assoc 1998;213:1439-1443.
Murphy TP, Biery DN, Fordyce HH, Gregor TP, Shofer FS, and Smith GK. Radiographic prevalence of hip dysplasia in 121 Maine Coon Cats, Proc 27th An Conf Vet Ortho Soc, Val dIsere, France, 2000:p. 53. 


I've mentioned this in the past I think but I manage LiLo's hip dysplasia and arthritis with monthly adequan injections - all three of my dogs get adequan and they also get flax & fish oil. I keep LiLo active and she can bike 4miles and keep up with the boys, but she does have her sore days. If she is sore I will give her an NSAID or some tramadol. I also keep her at a lean weight as to not add more stress to her compromised joints.

Just as a side note, LiLo has lost most of the muscle mass on her hindquarters, as well as along her spine. She also has pretty severe muscle wasting in her skull. I saw a rottweiler last week with the same pattern of muscle loss and I can only think it's related to her crappy hips. Although she can still jump around and do some running she obviously compensates a lot with her front end.


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