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What is Fibrous Osteodystrophy? 

Doctors have found that humans need calcium to strengthen their bones, but did you know that guinea pigs do as well? 

Fibrous osteodystrophy, also known as Satin Syndrome, a condition caused by hyperparathyroidism, is seen in virtually every species, from dogs and cats to reptiles and birds, including guinea pigs and other small mammals. 

Hyperparathyroidism means the body is making too much of the parathyroid hormone (PTH). The parathyroid gland produces this hormone and is responsible for managing calcium storage in the body. When there is too much PTH, calcium is pulled out of the bones and teeth to be available to circulate throughout the body. This can cause fibrous osteodystrophy, also known as metabolic bone disease. This metabolic issue creates a lack of calcium, leaving bones and teeth more flexible and fragile.  

Fibrous osteodystrophy is most common in animals under two years old and can be seen equally in both males and females. Satin guinea pigs may be more likely to develop this condition than other breeds.  

Signs 

Metabolic issues like fibrous osteodystrophy can be difficult to detect, but if your guinea pig is suffering from this condition, there are a few abnormal signs you may notice.  

Your guinea pig may seem lethargic, weak, and less interested in eating. You may notice that they prefer softer foods and toys, meaning that chewing is painful.

Diagnosis 

• Biochemistry profile: Your veterinarian may take a sample of your guinea pig’s blood to examine their calcium levels. Changes to liver and kidney enzyme measurements on this panel may also indicate hyperparathyroidism. 

• Radiographs: In cases of fibrous osteodystrophy, radiographs can show signs of decreased bone density and joint swelling, which can support a diagnosis. However, 30-50% of bone density must be lost before this can be seen on radiographs, so this may be helpful only in cases of advanced disease. 

• Biopsy/Histopathology: A sample of the parathyroid gland can be examined under a microscope. In cases of hyperparathyroidism, the tissue may become hyperplastic (thickened), which may take a few months to occur. 

Treatment and Prognosis 

Guinea pigs should be fed a diet of timothy hay, pelleted ration, and a variety of dark leafy green vegetables to ensure they are eating the correct amounts of all essential nutrients.  

Calcium may be given orally until calcium levels in the blood are normal. It also corrects the calcium and phosphorous ratio in the diet. If the cause of the disease is nutritional, hyperparathyroidism is reversible once the diet is corrected.  

If the cause of the disease is not treated, this could create irreversible changes to your guinea pig’s parathyroid glands, requiring surgical removal of these glands.  

Healthy guinea pigs have a lifespan of about five years, whereas guinea pigs with advanced fibrous osteodystrophy are often euthanized at a younger age due to concerns about discomfort and quality of life. This means that early detection and treatment of fibrous osteodystrophy may allow your guinea pig to have a longer and fuller life. 

Please consult with your veterinarian to choose the best treatment plan for your guinea pig.