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	West Highland Terrier with Patella Luxation Q: I have a 4 years old male west highland terrier who has just been diagnosed with patella luxation in both his hind legs. The right hind leg being the more affected of the two, showing the knee slipping out and back fairly easily. When this happens he usually sits or lays down and it rights itself. Cosworth also has a problem with his right front leg which the vet thinks is a sprain. This happened when he suddenly jumped off the sofa in a state of panic when he heard the postman arriving, which has now resulted in Cosworth limping from that point on. Cosworth has and is being rested although I cannot stop him from being territorial! I consulted my vets and she gave him a course of "Rimadyl" anti-inflammatory tablets which are due to finish this Friday. Since he has had these tablets he has not limped. I will then have to leave him off the tablets for a few days to see if the front leg has healed i.e no limping. The problem with his front leg happened whilst we (myself and the vet)were deciding the best way forward for the patella luxation problem in his hind legs as she wanted to give him 3 weeks to see how the patella was before we decided on surgery. This has unfortunately put us back to square one at the moment as I cannot plan on Cosworth having surgery on his right hind leg if the front right leg cannot take the pressure and strain. I would appreciate any information you could tell me about patella luxation and what advice you or any of your readers / subscribers could give to me about this condition. If anyone has a dog that has this condition or has had surgery to correct this, then I would love to hear from you. Many Thanks Claire Evans

A: Dear Claire,

Sorry to hear about Cosworth's leg problems -it is typical that he injures a front leg just when you are trying to sort out his back legs ! You are right to leave everything until his front leg has completely healed. Surgery on the patella should only be carried out if he definitely needs it, and then he needs his 3 other legs to be in good shape while he recovers. It is not an emergency surgery, so you do have time to work out with your vet what is the best long-term treatment plan. It is a little bit unusual that he was 4 before it became obvious - often younger animals have problems and it can cause clinical signs in puppies. That may be an indication that it is not too severe a luxation, or that he was coping with it up to now, but arthritis or degenerative joint disease is developing. This is the long term problem - the patella slipping on and off the knee eventually damages the joint and it becomes comfortable and arthritic. Many little dogs live with a mildly luxating patella all their lives and never need surgery - but the more severe ones will benefit a lot from stabilisation of the patella.
Now to give you a bit more information about the condition. Luxation of the patella normally occurs because of congenital (present at birth) defects in the shape of the knee joint. but it can also occur because of trauma. The patella can luxate to the outside or inside of the joint - it is much more common to have it go to the inside. We are not sure why it happens in some animals and not others, but it is problems with the shape of the hip and knee as they develop which result in the patella being pulled to one side so that it occasionally pops off the groove it is meant to slide on. It is seen mostly in little dogs such as Cavaliers, Yorkies and Jack Russells, but can also occur in big dogs. Dogs are often brought to the vet because of it within their first year.
There are different grades of seriousness - some just have a shallower groove than normal and the patella will only occasionally slip off with difficulty.At the other end of the scale some dogs have no groove at all and the patella is out of place all the time. Cosworth sounds somewhere in the middle- your vet will be able to assess that.
There are different surgical techniques to improve the situation. In mild cases it may be possible to keep the patella in place using only soft tissue surgery - tightening up the tissue on the outside of the joint to pull the patella in that direction. but if there is actual skeletal deformity of the joint, then this will not be enough and bone surgery will be needed. The most commonly required surgery is to deepen the groove which the patella slides up and down in and so keep in it place. More severe cases need more drastic bone surgery. Many cases will have a combination of techniques performed. They normally do very well once they have recovered from the surgery. There is always a slight risk of the patella luxating again.

Good luck with Cosworth,


Maeve Moorcroft MVB MRCVS

(PetPlanet Vet)
It may also be worth using the chatgroup area to contact other owners with experience. Ed

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