Metabolic bone disease (MBD), while prevalent, is not commonly reported in the pet parrot literature. MBD is broadly defined as a diseases of the bone due to many causes- rather vague! African greys have certainly received most of the attention (especially from the European community). Regardless, MBD can occur in any species (above and beyond birds).

In my mind, there are several factors that contribute to the development of MBD in birds:

1.) Parents selectively feeding foods to their young that result calcium, phosphorous and other micronutrient imbalances. This can occur even if the parents are offered a balanced diet and with both experienced and inexperienced parents. Some birds are just not good parents and consume the high quality foods for themselves and manage to selectively regurgitate poorly food to their babies. This also appears to occur in the wild either because of poor parenting or the chick is not aggressive or healthy enough to get a complete diet.

2.) Poor (nutrient imbalanced) diets fed to birds. Poor diets (the classic all seed diet) is commonly blamed for MBD in birds, however I feel there are so many other factors than just the diet alone. Additionally, some birds like cockatiels and budgerigars are incredibly efficient at pulling nutrients out of a relatively poor diet. In fact, at least one study demonstrated how supplementing developing budgies with relatively small amounts of calcium could induce kidney disease.

3.) Lack of exposure to natural unfiltered sunshine. Over time, this has become a major concern of mine with birds kept entirely indoors. My travel and work schedules have me working in climate extremes from southern California (very warm and sunny) to the Great Lakes area of New York (cloudy and cold) and many places in between. While we are all hearing about the benefits of vitamin D and controlled exposure to sunshine, this issue struck me while working at a veterinary university in a colder climate. Upon reviewing radiographs (X-rays) of multiple animals (birds, reptiles, cats, dogs, etc), I noticed the bone mineral density was quite poor at this university location. The animals were not necessarily suffering from overt MBD, but they clearly had osteopenia (decreased bone density) compared to what I was used to seeing in Austin, Texas (warm and sunny). Also, the clinicians (including board certified radiologists) had not noticed these rather subtle changes. The further north (and towards more cloudy and colder climates) I work, the more dramatic the changes. What is ‘normal’ on radiographs for the animals of the area, is sometimes clearly abnormal to me.

Upon further evaluation, I could see differences in bone mineral density between those animals kept entirely indoors and those that were allowed unfiltered sunshine. The differences between the two classes of animals are most striking in the colder and cloudier climates. This may be because those living in colder climates either never take their animals outside or do so quite a bit when the weather is nice and sunny. The comparatively intense sun exposure during the summer months may be enough to make up that difference in bone mineral density for the rest of the year.

As a result, I very commonly recommend supervised unfiltered sunshine therapy. ‘Supervised’ because I don’t want the birds to get out (unless they are flight trained) and/or get harmed (eaten). ‘Unfiltered’ because even window glass can block beneficial UV radiation that would otherwise stimulate active vitamin D formation in a bird’s skin.

4.) Exposure to toxins or certain foods that competitively block the absorption of select nutrients (like calcium), cause increased elimination of calcium from the kidneys or that bind with calcium and other bone building nutrients in the diet (and subsequently prevent their absorption). The most common that comes to mind is excessive spinach consumption most frequently seen (by me) in pet doves. Of course oxalates are found in many plants and fruits but are particularly high in spinach and can result in either decreased absorption and/or urinary excretion of calcium (which is why they are sometimes associated with calcium oxalate kidney or urinary bladder stones). There are a number of toxins and mineral excesses that can also result in increased calcium absorption or secretion. However, there are other important bone component nutrients such as phosphorous, silicon and manganese that can have altered absorption and/or secretion with certain drugs and foods.

5.) Prolonged illness that results in decreased intestinal absorption of bone related nutrients. This can be something as simple as chronic diarrhea that decreases the amount of time foods have in the gut to be absorbed. More often, it is illnesses that affect the proventriculus/ventriculus (stomach) like proventriculuar dilatation syndrome or avian gastric yeast or various forms of liver and pancreatic disease that may prevent absorption of multiple nutrients. Primarily parathyroid diseases (which affect calcium and phosphorous balance) is considered rare in pet birds. However, we do commonly see secondary parathyroid disease as a result of MBD in pet birds.

6.) Disuse atrophy of the bones. This is better defined under ‘osteopenia’ where the exercise is limited (due to cage confinement, arthritis, etc) and bone strength is lost over time. Regardless, I feel that developing birds absolutely need exercise even before completely weaned. When observing weaning fledgling birds in the wild (from raptors to parrots to songbirds) I notice two consist factors that can affect bone health- young birds tend to sit out in the full or partially filtered (through tree leaves usually) sun and they practice stretching and flapping their wings in preparation for those first several flights. I feel that both activities are important to bone and muscle growth and development. Once a bird is fully weaned and eating on its own, I like to get those birds out foraging and playing with toys.

So my definition of MBD includes the obvious weak, soft and malleable bones we see in the most severe cases but also includes a collection of historical, physical exam labwork clues such as lack of exercise, poor (radiographic) bone density, poor or marginal diet, lack of sunshine exposure and more. MBD is not an exclusively dietary issue.

Dr Scott Echols

About africangrey

14 Responses to “Development of Metabolic Bone Disease in Birds”

  1. julianswilson

    The development of any kind of bone disease in birds is too difficult as we can’t have the conversation with them. Calcium, phosphorus are the main elements that result in the weakening the bones and results in pain. So, one should make sure to feed their pets with the sources rich in calcium.

    • spotdvm


      There are a number of diagnostics available to diagnose bone diseases in living birds including CT and biopsy (just to name 2). Just to be clear, diets naturally rich in calcium (such as dark leafy greens) are a good part of most parrot diets. However, adding supplemental calcium should be carefully done as some supplementation can result in disease (especially with the kidney).


      Scott Echols, DVM, Dipl ABVP (Avian)

  2. Brandy

    Is there a good system you or others have found that can increase density and such after poor nutrition and care of 12/13 week old eng Budgie? We rescued a little guy and took him to vet for X-rays and such- we’re hand feeding him much better food and keeping his cage 75-80F.

    • BirdDoctor


      Given that this budgie is young (under 6 months), you have a good chance to improve his bone density for lifelong health. Feed him an appropriate diet (not just a seed mix), provide unfiltered (supervised) sunshine therapy and lots of physical activity. You may want to also consider supplementing him with omega-3 fatty acids such as VetOmega.


      M. Scott Echols, DVM, Dipl ABVP (Avian Practice)

  3. Victoria Brun

    My questions is? Can you feed birds such as magpies, currawong, butcher birds, crows, ibis and bush turkeys minced meat. They all love it but here in Australia we have been told not to feed birds minced meat because of the fat content in the meat. they say use kangaroo meat because it is leaner. But these birds won’t eat kangaroo meat. So what is the hard and fast rule? And if they are wild birds and get plenty of sun and exercise what is the harm in feeding them minced meat?

    • BirdDoctor


      Good question! There are a couple issues with feeding wild birds minced meat. The first is that minced meat is generally only meat (muscle) and not the whole animal (especially the bones) which is a very unbalanced diet. This can lead to metabolic bone disease and more. Keep in mind that it is not just the adults eating the unbalanced diet, the same food is often fed to chicks which can have devastating nutritional consequences. During my last trip to Australia, I was surprised to see how many wild birds (included were magpies, butcher birds and more) were being treated at local hospitals for metabolic bone disease (and other conditions). The common issue was that these birds were found hanging around humans and eating our food! The second is that we risk introducing organisms (especially bacteria such as drug resistant E coli, Salmonella and more) that are not naturally encountered in the wild to these birds. There are other concerns, of which we don’t completely understand the effects, such as drug residues and other chemical exposures that are sometimes found in domestic meat. Another potential concern is that domestically reared meat tends to be more fatty than wild sourced meat. Again the effects of feeding these high fat diets to wild birds is not clear. The bottom line is that wild birds can suffer from eating these human sourced animal based foods. The safer alternative is to feed plant based foods to wild birds.


      M. Scott Echols, DVM, DABVP (Avian Practice)

  4. John grillo

    My cockatiel has metabolic bone disease she’s only six years old I’m wondering what I could do for her besides putting her in the sunlight keeping the special light on her UV a b. Better nutrition as best I can vegetables no spinach. Dr. Susan Clubb who is highly regarded in that field. Said there’s nothing much you can do just enjoy her time with you. I really don’t want to give up and start running to other bird that’s any suggestions ? thanks

    • BirdDoctor


      There are several things that can be done to work towards better bone density:
      1. Improved nutrition- sounds like you are working on this.
      2. Exposure to unfiltered (direct) sunlight. I always say ‘supervised sunshine therapy’. That is make sure you don’t cook, freeze or feed your bird to the local wildlife!
      3. Omega-3 fatty acid supplementation. When combined with exercise (see #4), omega-3 fatty acids have been shown to improve bone mineral density in birds.
      4. Physical exercise. Even with the proper diet, sunlight and omega-3’s, nothing will happen unless the bones are stressed with exercise. This includes flying and climbing. Foraging is a good means to get a bird to move and navigate its surroundings. Flying depends on your set up and safety of the bird.

      I hope this helps!

      M. Scott Echols, DVM, DABVP (Avian Practice)

  5. Carol

    Hi Dr. Echols!

    I was wondering in regard to bone health in smaller birds. How much sunlight exposure should my bird receive in the run of a day? Is there anything as too much exposure providing the right seasonal conditions? I live in a climate where our winters are cold and snow. Diet consists of pellets, nutriberries and avi-cakes that contain vitamin d3.
    Thank you!

    • BirdDoctor


      There is no right answer here. I always tell people, as much as you are comfortable with. If it is hot, don’t cook your bird. If it is cold, don’t freeze your bird. If you can get your bird out for 10-15 minutes a day- great! Somedays you may be able to do an hour or more- great!

      The second half of vitamin D and sunshine is that stress must be applied to the bones (in terms of weight bearing exercise) in order to strengthen bones. Think of sunlight and vitamin D as a gym membership. It only works if you go to the gym!

      I hope this helps,

      M. Scott Echols, DVM, DABVP (Avian Pracitce)

  6. Charise Mixa

    I’m wondering what the prognosis is for an elderly (41+ years) Amazon with MBD if diet is addressed, increased exercise is encouraged, and unfiltered sunlight is given regularly? Can MBD be reversed?

    • BirdDoctor


      We don’t have enough information to prove MBD reversal. Based on research in rodents and humans, metabolic bone diseases (such as osteoporosis) start in childhood and can affect bone structure and health for life. That is why it is so important to start with good bone health early in life!

      Regardless, anecdotal information supports that lifestyle changes (diet, exercise, sunlight) have a positive effect long term. I would not call this MBD ‘reversal’. However, I would say we do get improvement!

      Happy New Year!,

      M. Scott Echols, DVM, DABVP (Avian)

  7. Carol

    Dr. Echols.

    When feeding pellets, if it contains Omega 3 in the form of flax or chia seeds. Is there still a need to feed additional supplementation? How much is too much?

    • BirdDoctor


      This is a really good question. First, adding flax and chia into a parrot’s diet is a great means to increase dietary omega-3s. In most cases, adjusting the diet is all that is needed. If there is diagnosis or suspicion of kidney disease, arthritis or other problems that may benefit from omega-3 fatty acid supplementation, then I will often recommend the addition of more (as with VetOmega).

      Is there such thing as too much omega-3’s. Well… potentially. However, we don’t have strong research to support omega-3 ‘toxicity’. I believe in a balance of good quality fats which includes omega 3’s, 6’s and 9’s. It is best for the fats to come from a variety of food sources.

      I hope this helps,

      M. Scott Echols, DVM, DABVP (Avian)

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