Hips, elbows and patella

Hips

Everything I write in this section is based on the course “Understanding Hip and Elbow Dysplasia” which I attended at the Institute of Canine Biology in the Winter of 2017. In the course, we went through all the research in English that is available on HD and ED.

Background: The Orthopedic Foundation for Animals (OFA) has collected hip joint data from all dog breeds since 1966 (ofa.org). In their statistics they have HD data from 784 Pugs and 71 % of them had hip dysplasia (HD) (data collected 220119). Furthermore, bad hips are probably underreported since the willingness to report often decreases if the dog has health problems. Pugs’ hip joint status is thus an important issue in breeding.

Many countries have tried to deal with HD in affected breeds for decades by X-raying of dogs and then only the dogs that have top hips are picked out for breeding. However, this has not yielded the desired result; two parents with good hips can give puppies with bad hips and vice versa. It has not been possible to improve the hip joint status at all through such X-ray programs. Recently, it has been found that the reason for this is that HD to 60-80% is determined by the environment, and thus only to 20-40% of genetics.

The causes in the environment that the researchers have found to be important are the following:

– Heavily built breeds, both small and large, have much greater problems with HD

– Slippery substrates for the puppies during the first eight weeks can give worse hip joints (the first eight weeks are most important for the dog to get good hips)

– “Over-feeding” of the puppy from 8 weeks up to about 20 weeks. (During this time, the cartilage of the joints continues to ossify, and at 20 weeks most of the bone is completed)

– Large puppies are at greater risk for HD than small puppies (which means that it is desirable that there are not too few puppies in the litters, which in turn has to do with fertility)

– The puppies are allowed to climb stairs before the age of 12 weeks

– Letting the puppy run after sticks and balls increases the risk of HD

– The risk increases if the puppy can only walk on flat surfaces, e.g. in urban environments, while the risk decreases if the puppy gets to play freely in hilly terrain

Goal: The Pug shall have well-functioning hip joints, free of osteoarthritis, that allow full mobility and a free life.

Strategy: We as breeders have a great responsibility for ensuring that our puppies develop good hips. We need to make sure that our breeding animals are not too heavily built; The Pug should be bred towards a slimmer type, since it is the robust dog breeds that mainly suffer from HD.

Elena vom Möhnetal, “Leni”
Leni has great hips.

We also need to make sure that we have fertile bitches in breeding that get a decent number of puppies. (See further under “Fertility” below.) Then we need to keep in mind that the puppies have a good substrate where they get a “foothold” both when they crawl and when they walk. When the puppies can start to go outdoors, they should be allowed to play and move e.g. on grass and in slightly hilly terrain. We breeders also need to inform the puppy buyers about what is beneficial for good hip joints; not to give the puppies too much food, not to let them climb stairs the first month in their new home, not to let them run after sticks and balls, but to let them play freely in hilly terrain.

Regarding the genetic part of the hips, one can use the “Estimated Breeding Value”. To be able to do this you need a database with the HD status of several of the relatives of the dogs you want to evaluate in terms of suitability for breeding. If you do not have access to such a database, you will still get better results if you work with the environmental factors than you will if you work with the X-ray results.

Sources and further reading:

Beuchat, Carol. 2017. “Understanding Hip and Elbow Dysplasia”. Course at the Institute of Canine Biology.

www.ofa.org/diseases/breed-statistics

Elbows

Background: In the OFA statistics of Pugs’ diseases, 216 Pugs have been tested for ED. Of these 40,7% had ED (data collected 220119). We can count on an underreporting of ED as well. The statistics indicate that the problem with ED is far too large in the breed, which makes this an important issue in breeding.

Goal: The Pug shall have well-functioning elbow joints without osteoarthritis that allow full mobility and a free life.

Strategy: For the elbow joints, the same applies as for HD, i.e. low heritability, while the environment is the main cause for good or bad elbow joints. Therefore, the strategy for elbow dysplasia (ED) is to work in the same way as with HD.

Sources and further reading:

Beuchat, Carol. 2017. “Understanding Hip and Elbow Dysplasia”. Course at the Institute of Canine Biology.

www.ofa.org/diseases/breed-statistics

Patella

Background: In the OFA statistics 904 Pugs were tested for patellar luxation and only 5,4 % had the diagnose (data collected 220119).

Goal: The statistics look good and there are possibilities to get it even better. Therefore, the goal is that no Pugs shall suffer from patellar luxation (PL).

Strategy: Because patellar luxation is caused by too straight, i.e. poorly angled hind legs, only dogs with well angled hind legs should be used in breeding. A dog that has PL I according to the table below can have other properties that are considered valuable for the breeding and then it can be combined with a dog that is free of PL.

Degree	State	”Grade”	Breeding restrictions
0 PL-free	The patella cannot luxate	Very good	None
I	The patella luxates but returns in right position of itself	Sufficient	The partner must have as above
II	The patella luxates but can be returned in right position mechanically	Insufficient	Prohibition for breeding
III	The patella luxates and remains luxated	Completely insufficient	Prohibition for breeding

Sources and further reading:

www.ofa.org/diseases/breed-statistics

Chapters in Strategies for the breeding of Healthy Pugs