Respect the bones (Day -293)

Vet School Bones and Skeletons

Unfortunately today started badly with a me walking into a resus this morning, sadly the prognosis once an animals heart stops is very very poor. Even when we are able to get an animal back after their heart stops it is a low chance that the animal will leave the hospital alive.

However today is not about that – today is about something a lot more amazing. The bones of the body are probably one of the least understood yet most important parts of nature. There is a lot that can go wrong with bones and a lot of causes of diseases related to the bones.

Whilst there is well established procedures and techniques for dealing with things like fractures, and now even joint replacement. There is little to understanding the way bones grow.

We’ve got a new European Diplomat in Equine Surgery on staff at the vet school and today he gave a lecture looking at skeletal diseases in foals. Now when you consider that horses often have to grow to support 500kg of weight you realise just how important the skeleton is. However when growing, and in fact even during development within the womb bones develop sometimes in ways that will not be compatible with carrying that weight.

I know some of the equine surgical procedures, however I was amazed to learn that if done in the right place at the right time you can simply change the way a bone grows simply by sticking a needle into it. Whilst this is a crazy idea, it gets worse in that no one actually understands why it happens that way. Why does a needle stimulate bone to grow faster?

This is actually therapy used in foals when the leg is not straight to correct the angle the leg grows at because one side of the bone is growing faster than the other. And you would be right in thinking if we can speed up the growth on one side to fix the problem = what about slowing it down on the other side?

So to understand this you need to know that growing bones have two separate parts at every joint. There is the shaft of the bone which is the long bit, and at each end of this there is a separate part called the growth plate. Now the bone grows longer by growth between the shaft and the growth plate until the animal is mature and then these parts fuse together to form the normal end of the bone seen in adults.

Originally it was actually all about slowing down the growth on the side that grew too fast. Initially this was by using screws and wire to compress the growth plate. This worked however was not great to have things sticking out the side of the bone, so now is done using a single screw placed between the shaft of the bone and the growth plate.

Now doing this will slow down the speed of growth on that side of the bone – downside is that you need a second surgery to remove the screw. This is why it’s better to speed up growth of the other side.

This single lecture left me with so many questions… What else can we use to affect bone growth? Will laser affect it? Why does it speed up growth with needles? How do we know when this happens? Can this be used in animals other than horses?

The power of a muscle….

Dog skeleton with Tibia

Something that has always made me wonder ever since I started back in anatomy was how small the muscles of the lower legs are compared to the size of the body – yet these are responsible for keeping the body up as well as movement.

With motion a lot of it is based on the principle of them acting like springs and storing energy to release it again later. However to me they do look for small for such a purpose…

This fracture was in the tibia and fibula bones of the back leg. The type of fracture that this was, is known as a Salter Harris type II fracture, it involves the top of the bone however misses the growth plate. The

Today however I learnt that looks here are deceiving, assisting on a fracture repair where the surgery had been delayed – injury happened on Saturday and surgery was not until Wednesday – so there were already complications from the formation of fibrinous tissue and some bone remodelling. During the surgery we realised that we could not reduce and position the broken bones back together because of the muscle tension and so we detached the muscle that sits on the front of calf – the tibialis cranialis.

For such a small muscle, once it was detached the change in tension in the leg was remarkable. It allowed us to reposition the fractured part of the bone with good alignment. Once this was done it was possible to place screws into the bone to hold this in position.

Fixing the muscle back to its attachment was a lot quicker than I had expected, however to give it time to heal and regain basic strength we decided that the leg should be bandaged for a time after the surgery. The patient should recover uneventfully.

Animal Organ Donation, the facts behind being a Pet Donor! (Day 115)

Pet Donor - Animal Organ Donation

Todays diary entry is sponsored by YOUR BUSINESS HERE!

Someone asked me the other day about organ donation in animals, and then I just happened to attend a really cool lecture on pet donors so I’ve decided to share it with you today. When someone meantions organ donation most people tend to think about heart, lung and kidney transplants, however I think it is amazing that in humans the most commonly transplanted tissue is blood, followed by bone.

Pet Donor - Animal Organ Donation

Since April 2009 there has been a pet donor scheme in the UK, the scheme is run by the Veterinary Tissue Bank and is based on the human model however there are some big differences. First of all instead of giving consent themself, it is up to the owner to register the pet. Secondly only bone, tendon and ligament is currently used in transplant procedures. This is because organ transplantation is very complex both medically with the need to manage anti-rejection medication and logistically with getting organs to animals in need within hours of harvesting the organ from the donor.

Ethically as an animal is legally the “property” of the owner more complex organ transplantation scenarios are a ethical minefield as deciding that one animal should die so another can live is something that many vets would struggle with. To get a viable organ the body needs to be alive at the time of harvesting the organ, and many euthansia drugs have effects on different organs within the body. Currently bone, tendon and ligament can be harvested after the death of the animal, and are more robust and can in some cases with proper preparation have a shelf life up to 5 years.

Now its easy to wonder just how these are used to help other animals, this is suprisingly simple. After harvesting the tissues are processed to usable states and to allow them to be stored, when a vet has a patient which may benefit from this tissue they contact the VTB and order the tissue. With bone for example this may be in the form of bone chips for a animal that has been hit by a car and has a gap in the bone skeleton that needs to be filled. Previously this may have required the vet to harvest bone from another area of the animals body to use which causes more trauma (and in some cases is impossible as the animal is too small etc), and use it to fill the gap. In this case bone from a donor makes the surgery safer, decreases the pain the animal will experience, and speeds up recovery.

I know if I had a pet, I would consider adding them to Pet Donor register as if they needed surgery of this type I would want a donor graft. In addition the veterinary tissue bank also arranges for cremation of the remains and return of the ashes to you at no charge.

What are the steps of organ transplantation?

  1. The animal is registered as a Pet Donor at http://www.petdonor.co.uk
  2. Consent is collected and your vet is contacted to discuss this with you
  3. When the time comes for your pet to cross the rainbow bridge your vet examines and discusses the suitability of donation with the VTB – obviously some diseases may mean that your pet is not a suitable donor
  4. The VTB arranges collection of your pets body anywhere in the UK and transportation to their donor center where the tissue is harvested in a sterile and controlled environment
  5. The VTB arranges and pays for cremation of your pet and the return of the ashes to you
  6. The tissue collected is processed to be ready for use by veterinary surgeons across the country.