Unusual Pathologic Brain Changes Associated with Zinc Toxicosis in a Blue-Fronted Amazon Parrot (Amazona aestiva).

An adult blue-fronted Amazon parrot (Amazona aestiva) was presented for a 6-wk history of ataxia and weight loss. Complete blood count, plasma chemistry panel, bile acids, and radiographic imaging were considered normal or unremarkable. The patient was hospitalized and supported with subcutaneous fluids, vitamin B complex, meloxicam, enrofloxacin, gavage feeding, and fenbendazole. While hospitalized, the ataxia significantly improved, and the bird began eating on its own and gaining weight. The bird was discharged from the hospital and prescribed enrofloxacin, meloxicam, and fenbendazole to be administered by the owner with recommendations for routine follow-up care. Medications were discontinued before emergent representation; at the time of reevaluation, the patient's condition had deteriorated severely. Given the poor prognosis, the owners elected for euthanasia. No gross abnormalities were noted on postmortem examination. Liver tissue zinc levels measured 125 ppm; normal limit is less than or equal to 25 ppm. Histopathologic changes to the brain were consistent with severe zinc toxicosis demonstrated by vasculopathy of the cerebral arteries and arterioles with multifocal areas of hemorrhage and astrocyte swelling. These findings have been reported in humans and other mammals but not birds. Although the source of this bird's heavy metal exposure is unknown, the high tissue zinc concentrations imply chronic exposure. This case presentation and unusual pathologic findings will be beneficial to the further understanding of avian zinc toxicosis.

Assessment of Blood Lead, Zinc, and Mercury Concentrations and Cholinesterase Activity in Captive-reared Alligator Snapping Turtles ( Macrochelys temminckii) in Louisiana, USA.

The alligator snapping turtle ( Macrochelys temminckii) is a freshwater apex predator that has experienced severe population declines throughout its range due to historical overharvesting and habitat degradation. Because of its long lifespan, high trophic level, and limited home range, it is a suitable sentinel species for monitoring environmental contaminants. In Louisiana, US a pilot program aims to augment free-ranging populations by releasing captive-reared individuals. Baseline values of potential environmental contaminants were determined as part of an overall health assessment to evaluate captive-reared alligator snapping turtles for release. Blood samples from 3-yr-old ( n=23) and 4-yr-old ( n=11) captive-reared alligator snapping turtles were tested for lead (Pb), mercury (Hg), and zinc (Zn) levels by atomic absorption spectrophotometry and cholinesterase (ChE) activity (as a biomarker for organophosphate and carbamate exposure) by the modified Ellman method. Reference intervals were determined for Zn (34 to 295 µg/dL), Hg (0 to 4.8 µg/dL), and ChE (0.17 to 1.65 µmole acetylthiocholine/mL per minute). Elevations of Pb, Zn, or Hg, or decreases in ChE activity levels of this cohort during recapture sampling may indicate point-source intoxications or bioaccumulation, both ultimately attributable to environmental contamination. The released animals may serve as sentinels for biomonitoring of their new habitat for the evaluated toxicants.

Relationship between plasma iron concentration and gastric pH in captive adult bottlenose dolphins (Tursiops truncatus).

OBJECTIVE: To determine the correlation between plasma iron concentrations and gastric pH in a population of captive Atlantic bottlenose dolphins (Tursiops truncatus). ANIMALS: 6 adult female dolphins that ranged from 16 to 30 years of age. PROCEDURES: Blood and gastric samples were collected from each dolphin to allow measurement of plasma iron concentrations and gastric pH, respectively. Samples were collected each month for 12 months. RESULTS: Within each dolphin, plasma iron concentrations and gastric pH did not differ significantly over time. There was a strong negative correlation (r = -0.85) between plasma iron concentration and gastric pH, which suggested that dolphins with a lower gastric pH had a higher plasma iron concentration. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of results reported here suggested that gastric pH may play an important role in iron absorption in dolphins.

Acetylcholinesterase concentrations in heparinized blood of Hispaniolan Amazon parrots (Amazona ventralis).

Organophosphate and carbamate pesticides inhibit acetylcholinesterase (AChE) at nerve synapses. Blood samples from 22 Hispaniolan Amazon parrots (Amazona ventralis) were assayed for cholinesterase levels by two different techniques. Using the modified Michel method, the whole-blood cholinesterase activity levels ranged from 0.082 to 0.616 deltapH/hr with a mean value of 0.35 deltapH/hr. A reference range (0.08-0.62 deltapH/hr) for cholinesterase was established in birds. The modified Ellman spectrophotometric method was used to measure AChE activity by adding acetylthiocholine or pseudocholinesterase (plasma cholinesterase) activity by adding butyrylthiocholine. The reference range of the AChE activity using the modified Ellman spectrophotometric method was 0-1.12 micromol/ml/min with a mean of 0.48 micromol/ml/min, and for pseudocholinesterase the range was 0.09-0.98 micromol/ml/min with a mean of 0.53 micromol/ml/min.