Electrolytes, PH, and Ionized Calcium as Health Indicators in Free-Living Nestling Macaws
American Association of Zoo Veterinarians Conference 2009
J. Jill Heatley1, DVM, MS, DABVP (Avian) DACZM; Karen Russel2, DVM, PhD, DACVP; Bo Norby3, DVM, PhD; Donald Brightsmith2, MS, PhD2
1Department of Small Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA; 2Department of Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA; 3Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA


Electrolytes, ionized calcium and pH as health indicators are routinely used in small animal medicine to assess health and prognosis in the critical patient. However, baseline values from healthy free living nestling parrots are extremely limited. The Tambopata macaw project has access to baseline biologic data from nestling macaws, predominantly Ara macao. In the last two field seasons, 56 blood samples from 31 healthy scarlet macaw and other parrot nestlings were analyzed. Sodium, potassium, ionized calcium and pH, and HCT were determined bird-side using an i-STAT portable analyzer which reliably determines these analytes in avian species including parrots.1,3 Sodium and chloride increase with age as has been reported in captive juvenile blue and gold macaws.4 Age-related changes in wild macaws may be attributable to the crop contents of nestling macaws, which have relatively high potassium and low sodium when compared to captive hand feeding diets.5 The blood pH of nestling scarlet macaws (7.569 + 0.061) is also higher than adults (7.421 + 0.618). Ionized calcium was not affected by age or weight in 35 samples from 25 juvenile scarlet macaws. The normal distribution of this analyte allows creation of a 95% confidence interval of 0.96–1.33 mmol/L, comparable to reported values in other parrot species.2 Both HCT and PCV increase with age in nestling macaw. The calculated hematocrit of the i-STAT is consistently lower than the gold standard of a spun hematocrit (PCV), however, at this time variability is too great to create a standardized correction factor.


The authors wish to acknowledge the staff and multiple field biologists and guides working at TRC. In addition, Dr. Sharman Hoppes and Lizzie Ortiz-Cam, MedVet were instrumental in the collection of these data.

Literature Cited

1.  Acierno M, Smith J, Tully T, Migallon-Guzman D, Mitchell M. Evaluation of indirect blood pressure measurement techniques (doppler) and point of care blood gas analyzer (I-STAT) values. In: Proceeding of the Association of Avian Veterinarians Annual Meetings. 2007:15–16.

2.  Brightsmith DJ, Matsafuji D, McDonald D, Bailey CA. Nutritional content of free-living scarlet macaw chick diets in southeastern Peru. J Avian Med Surg. 2010;24(1):9–23.

3.  Clubb S, Schubot R, Joyner K, Zinkl JG, Wolf S, Escobar J, Kabbur MB. Hematologic and serum biochemical reference intervals for juvenile macaws (Ara sp.). J Assoc Avian Vet. 1991;5:154–162.

4.  Howard LL, Kass PH, Lamberski N, Wack RF. Serum concentrations of ionized calcium, vitamin D3, and parathyroid hormone in captive thick-billed parrots (Rhynchopsitta pachyrhyncha). J Zoo Wildl Med. 2004;35:147–153.

5.  Steinmetz HW, Vogt R, Kastner S, Rioud B, Hatt J-M. Evaluation of the I-STAT portable clinical analyzer in chickens (Gallus gallus). J Vet Diagn Invest. 2007;19:382–388.


Speaker Information
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J. Jill Heatley, DVM, MS, DABVP (Avian) DACZM
Department of Small Animal Clinical Sciences
College of Veterinary Medicine and Biomedical Sciences
Texas A&M University
College Station, TX, USA

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