More about OD
Source:
www.oginet.com/Cavies/satin.htmOSTEODYSTROPHY IN SATIN CAVIES by Desiree Riemersma-Soentjens
Osteodystrophy (OD) is a metabolic disease that affects the bones. In 1999 a study was conducted at the University of Berlin, researching this disease in relation to satin cavies. The results of the study showed that a great number of satin cavies suffered from OD.
In a healthy animal calcium is being withdrawn from the bones and carried back. This interaction is regulated by hormones.
The parathyroid glands secrete a hormone called parathormone (PTH). This hormone regulates the withdrawal of calcium from the bones. Calcitonin is a hormone produced by the thyroid gland and this hormone promotes the absorption of calcium into the bones. In a healthy animal there is a balance in this interaction of tyhroid gland and parathyroid gland hormones.
When there's a reduction of calcium in the bones, the parathyroid glands will react by secreting more PTH. A hormone producing tumour of the parathyroid glands can be a cause for this reduction of calcium in the bones. Another cause can be calcium deficiency in the blood. When the latter is the case, the parathyroid will react by secreting even more PTH, thus trying to regulate calcium levels in the blood. The bones are used as it were, as a calcium depot for the blood.
When there is a constant calcium deficiency, the bones will decalcify (osteoporosis) and fibrous tissue will form (osteitis fibrosa). This will lead to a weak and instable skeleton, causing a lot of pain. It's name: Osteodystrophy (OD)
a healthy cavy with well defined bone structure
Satin with osteodystrophy, femurs and pelvic region are severely affected, bone structure is not well defined.
Constant calcium deficiency can have several causes:
Poor ratio of calcium and phosphorus in food (phosphor high/calcium low)
Deficient resorption of calcium from the bowel. This can be caused by a chronic bowel disease, or vitamin D3 deficiency. Vitamin D3 plays a major role in the resorption of calcium from the bowel into the blood. Lack of sunlight and chronic liver- and kidney diseases can also lead to vitamin D3 deficiency.
During the study in Berlin all foods that were given to the cavies were analysed for poor calcium/phosphor ratio's, none were found.
Administering calcium to the affected satins gave no positive results, it did not slow down the disease.
Bad housing with lack of sunlight, would affect non satins living in the same conditions, the same way as satin cavies. This was not the case though.
Blood analysis and pathology research excluded liver- and kidney diseases. At post mortem no tumours of the parathyroid glands were found and also no changes in bowels were found that could indicate a chronic bowel disease.
Possibly we are dealing with a genetic defect in the metabolism of the satin cavy. In what part of the metabolism the defect is located is as yet not clear. There are suspicions that the absorption of calcium in the bowels is disturbed. This suspicion can be justified by the fact that administering calcium has no effect on the disease.
To confirm this suspicion, DNA research is needed, but this is very costly. Material costs alone would be around 17000 GBP. As to this day, no funding could be found for this research.
(source: Dr. Ewringmann)
The study in Berlin was some years ago and the final results have not yet been published. Not much has been done with the results that were made public. There has been some discussion about it, but a lot of people ignored the study or said it was nonsense. Proof that it was nonsense, was never produced though…
I run a rescue for old and sick cavies and over the years a lot of satin cavies came to our rescue. Most of them were smaller than an average non satin and quite a few of them had dental problems. Having dental work done however, did not make it any better, the animals still couldn't process any food. Others did not move around a lot and when they did they seemed a bit stiff in the hind legs. A lot of these cavies had to be put to sleep for, at that point, unclear reasons.
When my vet, Krista Caers, and I heard about the results of the Berlin study, everything fell into place.
Since that time all satins that come into our rescue are X-rayed and the results were quite shocking, at least to my vet and me. We have X-rayed numerous satin cavies and 'till this day have found only 2 that do not have OD. As a control group we also X-rayed quite a few non satins and 2 satin carriers. In them we found no signs of OD. The offspring of the 2 carriers however are positive for OD. Post mortems on deceased satins showed no abnormalities in parathyroid glands, bowels or liver and kidneys. A few weeks ago we sent bones of a deceased satin off to a pathology lab for histology research. We have yet to get the results, but the symptoms and the X-rays already gave a clear outcome: OD. **
SYMPTOMS
Initially a gradual weight loss is observed, the appetite of the animal stays the same. After some time there will be significant weight loss and the cavy will have difficulty processing hard food, like pellets. People are often under the impression that the cavy is still eating well, because it's standing with it's front paws on the food bowl, dipping it's nose into it. When observed closely, they see the cavy has a hard time picking up the food and eating it.
The cavy prefers soft foods and this change in the eating pattern can lead to dental problems. Having dental work done on a cavy with OD, will not make things better. The instability and weakness (and pain) of the jaw prevents the cavy from eating. When this is the case, euthanasia is the only option.
People who own a satin cavy that is having dental problems, should always be aware of the fact that there is a good possibility the cavy has OD. X-rays can verify this. When you examine the jaw, you can often feel that it is thicker.
Often the hind legs of satin cavies with OD are affected. The animal has an unsteady and wobbly gait and it looks like it hops like a rabbit. When standing, they will alternate their weight from one leg to the other. When lying down, the legs are spread out in an unnatural way.
When the disease progresses, the animal can barely eat or walk and X-rays will show a competely decalcified skeleton.
Things should not go as far as that and the animal should be put to sleep before it reaches this stage in the disease. In my opinion however, I don't think an animal should be put to sleep upon being diagnosed and the symptoms are mild. When the cavy can still process it's food and is happy and alert, owners can still give it a happy life. Pain medication can be necessarry and the cavy should be closely monitored for any change in symptoms. We have quite a few satins living in our rescue, that were diagnosed with OD some time ago, but are still eating properly and are still begging for greens etc.
When the symptoms progress and the animal is in a lot of pain, it should be put to sleep.
There will be people that disagree on this, but when for example a dog is diagnosed with Hypdisplasia most owners also do their best to give the dog a happy life.
Symptoms of OD usually occur at the age of 12 to 18 months. But there can be exceptions, we found OD in a 4 month old cavy.
Usually the long bones are affected: Femur, Tibia, Humerus, Radius/Ulna. The pelvic bones and the jaw can also be affected. In the end the whole skeleton is affected.
X-rays can be made without aneasthetic, much the same way as a dog is X-rayed for Hipdysplasia. (this is the case in the Netherlands)
Research of blood will give changes in calcium, phosphorus and alkaline phosphates, but this is not typical for OD, but also for a number of other bone diseases.
Pathological research is valuble to exlude other things and verify the OD diagnoses.
Most important are the X-rays though, they will give a clear diagnosis of OD.
PROBLEMS IN BREEDING SATIN CAVIES
I have heard from many satin breeders that there are numerous problems in breeding satin cavies. A heavy loss of offspring and sows. This might be explained because of the low bloodcalcium levels a satin sow will have due to a genetic defect in the metabolism in the absorption of calcium.
Calcium is necesarry for the formation of bone and teeth. It is commonly known that a pregnant sow needs more calcium and a lot of breeders give their pregnant sows milk and bread. However, when the calcium is not properly absorbed in the system (as test in Berlin have showed), the body will withdraw more calcium from the mother's body. This will lead to hypocaelcemia, a fall in the level of bloodcalcium. Hypocalcaemia can lead to paralysis of the hindquarters, convulsions etc. It severely affects the nervous system and muscles. Eclampsia is associated with hypocalcaemia.
Depending on the bloodcalcium level, a satin sow may give birth to a litter. Mother's milk contains calcium, which is withdrawn from the mother's body. The parathyroid glands react to this by secreting more PTH and will withdraw more calcium from the bones. Thus causing a further fall in the bloodcalcium level leading to hypocalcaemia. Administering calcium has no effect, because it is very likely it won't be absorbed. This could explain why satin sows die a few days after giving birth.
When calcium levels in the mother's milk are too low, this will lead to hypocalcaemia in the baby satins.
Satins are most of the time smaller than non satins. Growing requires calcium for the bones. When there is not sufficient calcium , growth is impaired.
Of course there are always exceptions to the rule.
The perceived wisdom of using a satin carrier sow instead of a satin sow has validity then. Since OD was not found in satin carriers (at least so far), the problems caused by hypocalcaemia are much less likely to occur.
However there will be satin cavies in the offspring of satin carriers and a high percentage of these satins will have OD. So the use of carriers will prevent high losses in breeding, but it does not solve the OD problems.
People have said, let's exclude satins that are OD positive from breeding. That will be difficult with sows, since they will have to bred for the first time before they are 1 year old. OD symptoms are most likely to show at 12 to 18 months, so I think everyone can see the problem there.
THE NEED FOR MORE RESEARCH
It is very likely that there are satins that do not have OD. Hopefully some healthy strains can be found. Up util now however most satins seem to have OD. I will keep on searching for answers and the only way to do that is by observing, making X-rays, pathological research etc. We will do that by taking in satins. Research takes time and patience is required. There is also o lot of money involved. Hopefully, by doing this, a University might get interested and take up the study and may even get funding fo DNA research.
I hope the public and rescues in the UK will take in satins as well. As I said before, it is not necessarry to perform euthanasia as soon as OD is diagnosed. By observing the animals, taking X-rays, blood samples etc. we might learn a lot more. The animal should be put to sleep though, when it can't lead a fairly normal life anymore and the pain gets too much. We will work closely together with Reading Guinea Pig Rescue by exchanging information etc.
It is important to inform the public and vets about the satin problem. People that have a satin cavy as a pet have to know that their pet might suffer from OD. Vets should be informed because they will treat satins with , for example dental problems. When they know about the disease they will look further and hopefully X-ray the cavy.
Reports have come in from satin owners from Australia, New Zealand, the UK and the US, all stating there are problems with the satin cavy.
Some satin breeders in the UK have shown a keen interest in doing a study themselves. This will involve X-rays etc. My vet has offered to look at the X-rays for free. Of course there's is a lot of money involved in X-raying the cavies. Hopefully, this money can be found. The study is not only important for diagnosing OD in satins, it might also lead to finding some healthy strains.
To the question why satin mice etc. do not seem to suffer from OD, I have no concrete answers. If the disease causing OD in satin cavies is genetic, then that might be an answer, because mice do not have the same genetic build up as cavies.
It is not my intention to cause an uproar in the satin breeder's community. There will be breeders that say nothing is wrong with the satin breed and that is Ok, but proof would be nice. It shouldn't be a question of "two sides fighting each other". Better to make it a joined effort to ensure the well being of satin cavies. I have lost satin cavies to OD and for them I will continue, so their lives and deaths will not be in vain.
©Desiree Riemersma-Soentjens
Rusthuis@knoevel.nlOther contacts:
UK. Karen Lecras: Karen Lecras
www.readingguineapigrescue.co.ukFor Finland:
kkivipur@mappi.helsinki.fiSource:
www.oginet.com/Cavies/satin.htm
