Atherosclerosis: The Hidden Killer

Atherosclerosis is a common disease in companion parrots – one we must all take seriously. If you have ever heard of an older parrot who died suddenly, without apparent cause, there is a good chance that this progressive disease was a primary factor in the demise.

What is Atherosclerosis?

Atherosclerosis is one type of arteriosclerosis.  The word atherosclerosis derives from the Greek words athero, which means “gruel or porridge,” and sclerosis, which means “hardness.” This is a fairly descriptive term for the disease itself, in which cholesterol is deposited onto the sides of arteries, creating hard plaques. Once build-up is great enough, plaques can dislodge; these cause blockages, which lead to heart attack.

It is primarily a disease of inflammation. The more inflammation, the greater the risk of atherosclerosis.Blue and Gold by Engin Akyurt

Birds are more susceptible to atherosclerosis than any mammal, with the exception of humans. “The reported incidence rates in avian species range widely from 1.9% to 91.9%.”(Powers, 2015)

A Confusion of Information

While much is known about atherosclerosis in humans, this information cannot be readily transferred with reliability to birds. Reading through scientific papers about the disease causes consternation and befuddlement. Undeniable conclusions are lacking, although more recent research does point to strong correlations.

Much of the research has been done on bird species other than parrots, such as quail, waterfowl, and chickens. Diagnosis on parrot species who have succumbed to this illness has been conducted on a very mixed population, particularly those kept previously in zoos, who have been maintained under a variety of conditions and fed a mix of diets.

Moreover, the studies that are being done on risk factors that exist for parrots are being performed on the known risk factors for humans and other mammals. There may, however, be other risk factors specific to avian species that may take longer to uncover, such as individual species’ genetics.

Thus, I will warn you that what I write today may well be something I will edit extensively in another five years.  The danger is significant and real for our parrots, so an examination now of what we know is important. However, I have every expectation that some of what you read below may be proved wrong in the future, while additional details will in turn come to light.

Which Parrots Are At Risk?

While we have a very good understanding of risk factors in mammals, this is not so with parrots. But, a few things we do know.


It is currently agreed that Amazon parrots, African Grey parrots, quaker parakeets, and cockatiels appear to be at greatest risk. While the disease has been seen in cockatoos and macaws, they are not believed to be quite as susceptible. Many avian species, though not all, have been found to develop atherosclerosis in captivity.


Increased age is a significant risk factor. However, while more common in older parrots, Nemeth states that atherosclerosis has been found in birds aged 1 to 42 years. (Nemeth at al, 2016) It is most common in companion parrots over the age of 10.


Female parrots have been proven statistically to be at greater risk. Female birds in reproductive mode generally have elevated levels of cholesterol, triglycerides and lipoproteins, as well as calcium, creating greater susceptibility.

Diet and Nutrition

“The inclusion of cholesterol in the diet of birds that consume non-animal protein, even as low as 0.25% of the diet, dramatically increases plasma and serum cholesterol levels.” (Petzinger and Bauer, 2013).

Petzinger also mentions a 2003 paper by Bavelaar and Beynen that found that African grey parrots fed a high-fat diet containing palm kernel oil (saturated fatty acids) had increased cholesterol levels.cockatiel-1213758__340

Petzinger also reports on the findings of yet another study from 2012. In this research, a total of 47 cockatiels who were supplemented with fish oil had lower plasma cholesterol than cockatiels fed flaxseed oil. The conclusion? “Thus, dietary fish oil (and possibly dried algae products) may be more beneficial than oils high in A-linolenic acid on reducing risk factors and prevalence of atherosclerosis in avian species.” (Petzinger and Bauer, 2013)

Another nutrient capable of lowering cholesterol levels in birds is pectin. Pectin is the soluble fiber contained in fruit and some vegetables.

The overall amount of food eaten may also contribute to the development of atherosclerosis. Overeating and obesity are proven risk factors for mammals. This correlation has been studied in birds with varying conclusions.

Physical Inactivity

Every research paper I read reported a presumed link between inactivity and the development of atherosclerosis. However, I could find no evidence that any link between exercise and this illness had actually been researched in avian species.Conure2

Since such a strong link exists between the two in mammals, including humans, it would be foolish to ignore it here and the papers I read did include recommendations for exercise in companion parrots.


The literature on human health names inflammation in the body as a primary cause for the development of atherosclerosis. In fact, inflammation is currently being discussed in what is being called “a unifying theory of disease.” (Harvard Health, 2006) In other words, inflammation is now considered as a significant factor in the development of many chronic human illnesses.

Nevertheless, inflammation as a process “remains a mystery.” (Anft, 2016) However, scientists are beginning to agree that lifestyle choices like diet and exercise may increase (or reduce)  inflammation.parrot eating cracker

Common foods that cause inflammation, which are often fed to parrots, are fried foods and those containing refined carbohydrates (white flours and sugars).

Co-Infection with Psittacosis

The disease Psittacosis, also known as Parrot Fever, is more accurately referred to as Chlamydia psittaci. This disease is still relatively common among companion parrots, especially those who have come from large collections. While researchers disagree about whether there is a conclusive correlation between infection with Chlamydia and atherosclerosis, some studies appear to agree on this.

Signs and Symptoms

Sadly, the most common sign of atherosclerosis is sudden death. In the late stages, there may be symptoms such as weakness, lethargy, neurological  signs (including seizure-like activity), trouble breathing and exercise intolerance. However, these may be less observable due to parrots spending long hours in cages. It is easier to identify exercise intolerance, for example, in parrots who fly.

At this point in time, diagnosis is extremely difficult. Most people will never imagine that their parrots are ill until they lose them unexpectedly, well before their time. With better imaging techniques, as well as a better understanding of identifying factors in serum chemistries, this may change in the future.

What Can We Do?

Atherosclerosis in companion parrots is still not well-understood. Direct and specific correlations from the human health field may only be suggestive. Thus, we do not have well-defined risk factors that would allow us to target flawless measures for prevention.

FoodSkewerMoreComplexSuggested lifestyle changes reported in the literature include “increasing physical activity by providing more opportunities for locomotion and foraging behaviors and decreasing the stress level  in their captive environment. Limiting dietary excess and obesity also seem to be a reasonable strategy, but species-specific dietary needs should be considered.”(Beaufrere, 2013)

“Birds should be provided ample opportunities for exercise and activities such as foraging, and even flight, if considered safe for the bird. Excessive energy content in the food should be avoided, such as excess carbohydrates and fats. Birds should receive regular preventative veterinary care with periodic bloodwork monitoring.” (Powers, 2015)

Diets that contain relatively high levels of Omega-3 fatty acids reduce the prevalence of the disease. (Petzinger and Bauer, 2013) Nordic NaturalsNewer research indicates that fish oil may be more effective in this than alpha-linolenic acid, the type of omega-3 found in plants, such as in flax seed oil. Supplementation with fish oil may be an excellent addition to the diets of many companion parrots, but this should not be undertaken without the advice of your veterinarian.

Pectin in the diet has also decreased the occurrence of atherosclerosis. (Petzinger and Bauer, 2013) Pectin is the soluble fiber found in fruit. Too much pectin can result in a decrease in the absorption of nutrients from the intestine, however. Thus, fruit should be fed in moderation for most species.

Reducing the overall amount of food, i.e. not over-feeding, can also decrease the prevalence of atherosclerosis. This  information too, however, could be harmful if implemented to the extreme. Hunger and malnutrition do nothing to improve overall health. It is best to consult with your veterinarian about the quantity of foods to offer.

Suggested Action Steps:

After as thorough a review as I could muster with the research I was able to access, I think the following steps are prudent:

  • Identify an avian vet who specializes in birds and schedule annual visits.
  • If your veterinarian tells you your bird is fat, take this seriously and formulate a plan for gradual weight reduction.
  • Discuss with your veterinarian supplementation with fish oil. (The correct dose is important and should be obtained from your vet.) Nordic Naturals is an excellent choice.
  • If you have a female parrot, do everything you can to minimize triggers for the increased production of reproductive hormones. (You should do this for males too.)
    • Discourage a pair bond
    • Avoid cuddling and other highly affectionate interactions
    • Prevent cavity seeking (getting into closets, boxes, etc.)
    • Feed a low-fat, low-carbohydrate diet013
  • Do not feed foods high in saturated fat (fatty meats, butter, margarine, cheese, coconut oil, palm oil, fried food, or snack foods).
  • Do not feed pasta, white rice, or any foods that contain white flour or sugar and other sweeteners.
  • If your bird eats a seed mix as a dietary staple, convert him to a pelleted diet with supplementation of fresh foods.
  • Avoid overfeeding. Remember the size of the creature you are feeding.
  • Encourage foraging and try to incorporate some physical activity into this.
  • Encourage exercise.
    • Determine whether you and your bird might be a candidate for flight in the home.
    • If not, work to discover ways to encourage as much movement as possible.Green And Red Healthy Food
  • Do feed foods high in pectin, in moderation (apples, pears, plums, peaches, apricots, cherries, strawberries, guava, carrots and peas). Apples are especially high.
  • Do feed foods high in omega-3 fatty acids or that are otherwise known to reduce cholesterol (oats, barley and other grains, walnuts, flax seeds, chia seeds, hemp seeds, edamame, almonds, beans, tofu, salmon)
  • Do feed foods that fight inflammation (green leafy vegetables, blueberries, salmon, broccoli, cauliflower, kale, peppers, grapes, celery, ginger, tumeric)

parrot-2960562__340Atherosclerosis is a scary prospect, given what we now know about the susceptibility of our companion parrots. However, I suspect that we have in our hands the tools for prevention, just as people do. Granted, risk factors outside of our control exist, such as age and gender. However, we do have enough information to take action and keep our parrots as healthy as absolutely possible.

Thank you for reading my blog. I am Pamela Clark, an IAABC Certified Parrot Behavior Consultant. My passion is helping people with parrots by offering behavior consultations and publishing information you can trust. To access free resources, schedule a consultation, or subscribe to my newsletter (which is a different publication from this blog), please visit me at Until next time!


Anft, M. 2016. “Understanding Inflammation.” Johns Hopkins Health Review. Volume 3, Issue 1.

Beaufrere, H.  Dr. Med Vet, PhD, Dip. ECZM, Dip. ABVP. 2013. “Avian Atherosclerosis: Parrots and Beyond. Topics in Medicine and Surgery.

Bavelaar F. J. & Beynen, A.C. (2004) “Atherosclerosis in Parrots: A Review. Veterinary Quarterly, 26:2, 50-60.

Nemeth, N.M. , Gonzaliz-Astudillo, V., Oesterle, P.T. Howerth. E. W.  “A 5-Year Retrospective Review of Avian Diseases Diagnosed at the Department of Pathology, University of Georgia”. Journal of Comparative Pathology. Volume 155, Issues 2–3, August–October 2016, Pages 105-120.

Harvard Health Publishing. April 2006. Harvard Medical School. “Inflammation: A Unifying Theory of Disease.

Petzinger, C. PhD, Bauer, J, DVM, PhD, Dip. ACVN. 2013. Journal of Exotic Pet Medicine. Volume 22, Issue 4, October 2013, Pages 358-365. “Dietary Considerations for Atherosclerosis in Common Companion Avian Species.

Petzinger,C BS, Heatley, J DVM, MS, DABVP, DACZM, Cornejo,J BS, Brightsmith, D. PhD; Bauer, J DVM, PhD, DACVN. Journal of the American Veterinary Medical Association. March 1, 2010, Vol. 236, No. 5, Pages 523-528.

Powers, L. DVM, DABVP. 2015. “The Silent Killer: Atherosclerosis in Pet Birds.” CVC in Washington, D.C. Proceedings.  Published on DVM 360.

Published by

Pamela Clark, CPBC

I am an IAABC Certified parrot behavior consultant who successfully helps parrot owners to resolve behavior problems and train their parrots. I also help determine the best diet, social and physical environments to help that individual parrot flourish.

14 thoughts on “Atherosclerosis: The Hidden Killer”

  1. Great article Pam! This is such an important health topic. There also is a product available for parrots thanks to Scott Echols, DVM, Dipl. called VetOmega. The nice thing is that it gives a suggested dose amount by bird weight. It’s also a plant-based product which in my experience is usually suggested unless a parrot has shown high cholesterol via blood work then fish oil may be recommended for a time.

    1. Thanks very much, Shauna. I’m aware of VetOmega. However, I remain on the fence. For one thing, It’s more than twice as expensive as Nordic Naturals. And, the research that I can find is clear that fish oil is more effective. Plus, I trust the Nordic Naturals brand. I’ve talked to their company extensively about their sourcing and quality, information they make easily available to anyone interested. On the other hand, the suggested dose by weight for the VetOmega is certainly an advantage. And, I suspect in some cases, it may be more palatable. However, I can’t find any information online about sourcing and manufacturing, or even ingredients. Plus, it’s not as readily available. And, unfortunately, high cholesterol on blood work is not always correlative to the development of atherosclerosis, if you read the literature. I think both are great products and I will keep watching and learning about which one might be preferable. Pam

  2. Hello Pamela, One diet item that is of great concern is eggs. Here are two examples known to me…one from a client and one from my vet, Dr. Paul Welch. The client called to purchase an eclectus. She said she had a male that died at the age of three years. I asked about the dead bird and the necropsy. She had the bird necropsied at a university facility. She indicated that the bird had plaque filled arteries and died of a stroke. I asked about the diet. A major item was eggs, fed routinely a couple times a week. The second example: Talking with Dr. Paul Welch about diet, he mentioned the necropsy performed on a one year old African grey parrot. He said the arteries were so full of plaque that they were as “stiff as sticks.” He asked the client about the diet. Eggs were fed routinely, a couple times a week. These two examples indicate to me that it might be a good idea NOT to feed eggs to parrots. At our facility with many eclectus parrots and a few of several other parrot species, we never feed eggs to any birds. I have read that some veterinarians recommend feeding eggs and some breeders also recommend eggs. IMO this is a serious mistake. From my reading it appears that in the wild most parrots are not egg eaters, with the exception of eating the shell of infertile eggs for the calcium content.

    1. Laurella,

      Thanks so much for your comment. I think you bring up an interesting subject. The debate about whether eating dietary cholesterol or eggs contributes to cardiovascular disease has been going on for decades.

      Initially, studies reported a direct correlation and people were warned against eating eggs in order to ensure heart health. Then, two other factors were discovered. First, it was found that most of the cholesterol in the body does not come from ingested sources. Instead, it is manufactured by the liver. Second, lecithin is a substance that reduces the amount of cholesterol in the body and, correspondingly, the risk of heart disease. Egg yolks contain both significant quantities of cholesterol and lecithin, so the conclusion was that the lecithin in the eggs “counterbalanced” the cholesterol. However, the debate rages on and studies offer credible arguments for both sides.

      I do not believe that we can target one particular food as the villain in the development of atherosclerosis in parrots. This is a lifestyle disease. I would have wondered what else those birds were eating and what types of exercise they enjoyed. As the research indicates, the primary cause of atherosclerosis is not any particular food; it is inflammation. There are may causes for inflammation in the body.

      I too have never heard of parrots eating eggs in the wild. However, neither do they eat the seed mixes typically sold for parrots, or pellets, or broccoli…for that matter. And, wild parrot often fly for miles a day, while companion parrots lead fairly sedentary lives, even if flighted indoors. I concluded some time ago that it is not particularly helpful to compare wild diets to captive diets.

      That said, however, I think that caregivers do not understand critical pieces in their dietary provisions that are significant to this discussion and this is where your point is well-taken.

      The first is the relative amount of each food that is fed. I spoke to an owner yesterday who offers her large macaw a French fry or potato chip when she is enjoying these foods. To her, one little potato chip did not seem like a big deal. However, when I compared for her the relationship between a 2-pound bird eating one chip and a 100-pound person eating 50 chips, this took on greater significance. I think that many owners who offer eggs do so in vastly inappropriate quantities….because the bird *likes* them.

      The second is the overall amount of carbohydrates and fats consumed by parrots in captivity on a daily basis. This truly is the more important factor. One study performed by the World Parrot Trust many years ago confirmed that the diet of some large macaws in the wild contained 29% fiber. That is a staggering statistic, which sheds light on the fact that most parrots in captivity are eating far fewer fresh foods containing fiber than they perhaps should.

      The third factor of course is exercise. If any creature lives a relatively sedentary life, the entire diet comes into question from many sides.

      Truly, I think we have much to learn still about heart disease in parrots and I hope that more people will ask to perform necropies on their birds and then contribute this knowledge to “the pool.” Far too little is being done in this regard. We need some good studies to confirm the contributing factors that threaten our parrots.



  3. Thank you very much for this amazing article.
    Avian medicine unfortunately has not evolved well in some countries yet.
    I currently live in the UK but my cockatiel is 9yo and lives with my parents.
    The vets there don’t know about supplementation with Omega 3. What should I do in this case? I imagine just starting my bird on it by myself would not be the best idea and not sure who to turn to in this situation. She is very picky and doesn’t eat most vegetables and fruits but is on a pellet based diet.

    Thank you

    1. Dear Carla,

      I’m delighted to hear that she is on a pellet-based diet. I’m assuming this means that you don’t feed a seed mix also as a staple in the diet. (When owners feed a mix of seed and pellets, the birds usually focus on eating the seeds.) Supplementation with omega-3 fatty acids would be a good idea for any bird, in my opinion. To do so, you might first offer foods that are highest in these., such as walnuts, chia seeds, flax seeds, and hemp seeds. If he turns his noise up at those, just tell your parents to keep offering them. At some point, he will accept them. If you decide to supplement, you can always purchase a good quality flax seed oil that has been refrigerated from a health food store and offer a couple of drops on his food a few times a week. Good luck! Your little cockatiel is lucky to be in your hands.


  4. I’m hoping you can help me with an answer. My African Grey has started having seizures & she has lost her vision. What should I do? And will this affect her lifespan? Thank you

    1. Hello Traci,

      I’m so sorry to hear this. I’m assuming you have seen a veterinarian. I would be happy to have a consultation with you, for there is no simple answer to this question. I would need a great deal more information in order to make recommendations. If you are interested in pursuing this idea, you can find all details of my fees and the consulting process on the homepage of my website at


      1. It is very much deserved. I just had a 35 year old female Scarlet die from atherosclerosis, she did not fit most of the criteria listed, except that she was inactive. However, I have seen many posts from people, who also had birds die from atherosclerosis, since her death that are very similar to what you describe.

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