The case for iodine supplementation for birds in NZ

The case for iodine supplementation for birds in NZ

The case supplementing iodine in some birds in NZ is quite an easy one to make.  It requires a bit of history and knowledge around human and avian health here in this country.


New Zealand soils are low in iodine and historically there has been a large proportion of people, mainly children, suffering from diets chronically low in iodine.  In 1930, one study found almost 30% of NZ children suffered from goitre (swelling of the thyroid gland) due to this deficiency.  Even with a mild level iodine deficiency in humans there can be issues with hearing, intelligence and mental capabilities. 

 Low iodine soils in New Zealand


Low soil iodine levels result in iodine being low to non-existent in most locally grown fruits, vegetables and grains.  Even with modern day farming practices iodine content in most food stuffs have not increased.  The New Zealand Government in 2008 took measures to ensure higher iodine intake by mandating the supplementation of iodine into breads and salts.  With modern culture often going without bread to reduce carbohydrate intake and the reduction of iodized salt in many diets there has been a resurgence in the number of adults and children experiencing deficiencies today.


Many Australian birds require high levels of iodine in their diet.  Budgerigars and cockatiels have the highest demand for iodine in their diets compared to most other birds. However, hypothyroidism, the condition that is caused by the lack of iodine, has also been documented in chickens, finches, pigeons, macaws amongst others. 


The thyroid gland produces thyroid hormones (thyroxine) that are important for metabolism and thermogenesis (heat production) in birds but also play roles in growth and development of all vertebrates (birds, dogs, cats, cows, humans etc.).


When iodine is limited the thyroid gland swells due to an abnormal proliferation (increase) of epithelial cells in the follicles of the thyroid.  This is an attempt by the body to produce more of the metabolic hormones needed.  Without the necessary amount of iodine, the body struggles to keep up and so the cells keep dividing, trying in vain to form the needed hormones.


Thyroid hyperplasia (goitre) can result in a number of clinical signs including:


  1. Convulsions/death due to the glands putting pressure on the heart and major vessels
  2. Vomiting, weight-loss and crop issues as a result of esophageal obstruction
  3. Respiratory noises and difficulties recovering from exertion
  4. Change to voice including absence of vocalisation
  5. Obesity and Fatty Liver Syndrome
  6. Depression and lethargy (Fluffed up look)
  7. Immuno-suppression
  8. Non-puritic (non-itchy) feather loss and poor feather re-growth with altered colour, size and/or structure (even a “greasy” feather condition has been noted)
  9. Abnormal skin
  10. Delayed moult
  11. Increased embryo mortality and decreased hatchability



In one pivotal study (Blackmore 1965) studied a captive flock of around 400 budgerigars.  On post mortem they found 85% of the budgerigars had some degree of thyroid hyperplasia and almost 24% of the birds died as a direct result of thyroid hyperplasia (Goitre).  The cause of the issues was a result of the low iodine levels of an all-seed diet commonly fed to these types of birds. 


In addition to much of our natural produce being low in iodine, many of them also contain chemicals called goitrogenic agents.  Goitrogens bind iodine, making it unavailable for biological functions.  This family of chemicals can be found in spinach, sweet potato, broccoli, kale, radish, cabbage, brussel sprouts and other cruciferous vegetables.  These are also found in some fruits (berries), nuts and grains.  Peanuts, soybeans, flax, rapeseeds and millet are a few examples of foodstuffs that also contain these goitrogens. 

 iodine blocking vegetables


With these facts in mind it is hard to believe that iodine supplementation isn’t needed in some way to prevent the effects of hypothyroidism especially for those birds fed scratch feeds, whole grains or even whole foods grown in New Zealand for a majority of their diet.  This issue would be doubly so for an iodine demanding budgie or cockatiel in captivity fed a primarily millet seed diet.  From a professional perspective parrots show "no nutritional wisdom" and so we must help guide their intake in one form or another.


A veterinarian can help diagnose issues with hypothyroidism in birds by looking at the diet, history and clinical signs of the patient.  You may not even be able to feel a swollen thyroid gland on a physical exam, even at 200 X the normal thyroid size, as it is encased in the thoracic area of the bird.  Radiographs can often be used to show displacement of the oesophagus.  Thyroid hormone testing has proved to be inconsistent with some birds showing enlarged thyroids but hormone production in a normal range.  This is due to the thyroids efforts to compensate for the lowered hormone levels by swelling and trying to increase the outputs.


Goitres and hypothyroidism (mild to severe) can be dealt with in a range of ways.  Often iodine supplements are needed at higher than normal requirements.  This can be done intensively over a few weeks or longer depending on the patient needs. For prevention, formulated pellet diets tend to have enough iodine to meet the demands of the bird they are fed to.  Lugol’s iodine can also be given, but should be directed by your veterinarian.  Including thyroid supporting natural foods in a whole food diet may help reduce the effects goitrogens but will not do much to enhance the amount of iodine consumed.  Other natural iodine supplements are also useful but can require some planning in order to accommodate them properly into the everyday diet of your birds.


Attention to micro nutrient needs of our feathered friends is a great way to ensure they are having a long and healthy life.  Speak to a knowledgeable veterinarian about your bird’s diet and needs and plan out your customisable options for iodine supplementation here in New Zealand.


Read a book for once Clive




Blackmore, D.K.  The pathology and incidence of thyroid dysplasia in budgerigars (Melopsitticus undulatus).  Vet Rec 75: 1068-1072, 1965

Koutsos, E.A, Matson, K.D, Klasing, K.C.  Nutrition of birds in the order Psittaciforms: a review.  Journal of Avian Medicine and Surgery 15, 257-275, 2001 

Loukopoulos P, Bautista AC ,Puschner B , et al.  An Outbreak of thyroid hyperplasia (goitre) with high mortality in budgerigars (Melopsittacus undulatus).  Journal of Veterinary Diagnostic Investigation: 27(1): 18-24.  2015

Mann J, Aitken E.  The re-emergence of iodine deficiency in New Zealand?  New Zealand Medical Journal 351, 1161 – 1170, 2003 Visited on-line 2023

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