Zinc toxicity (new wire disease) in aviary birds

Synthetic Access to Aromatic α-Haloketones

α-Haloketones play an essential role in the synthesis of complex N-, S-, O-heterocycles; of which some exhibit a remarkable biological activity. Research further illustrated that α-bromo-, α-chloro-, and α-iodoketones are key precursors for blockbuster pharmacological compounds. Over the past twenty years, substantial advances have been made in the synthesis of these industrially relevant building blocks. Efforts have focused on rendering the synthetic protocols greener, more effective and versatile. In this survey, we summarised and thoroughly evaluated the progress of the field, established in the past two decades, in terms of generality, efficacy and sustainability.

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.

Perforating foreign body in the ventriculus of an umbrella cockatoo (Cacatua alba)

A 4-year-old male umbrella cockatoo (Cacatua alba) with a history of ingestion of foreign material from chewing on a household appliance presented for lethargy, inappetance, and regurgitation of 2 days duration. Foreign bodies identified on radiograph included a wire 2 cm in length in the proventriculus, a wire 3 cm in length in the ventriculus, and several pieces of rubber and plastic throughout the gastrointestinal tract. Diagnosis of a perforating ventricular foreign body was made through plain and contrast radiography. The proventricular wire was removed endoscopically but endoscopic retrieval was not successful in locating the ventricular wire. A ventriculotomy was done to remove the wire, which had perforated the ventriculus cranially and imbedded into the parenchyma of the liver. The wire was extracted from the center of a large nonresectable granuloma that incorporated the left liver lobe. The bird recovered from surgery but died from complications 3 months later. Postmortem examination revealed localized coelomitis and hepatic necrosis associated with the perforation.

Assessment of erythrocyte morphologic abnormalities in mallards with experimentally induced zinc toxicosis

OBJECTIVE

To describe and quantify morphologic abnormalities in RBCs of mallards (Anas platyrhynchos) with experimentally induced zinc toxicosis.

ANIMALS

120 female mallards.

PROCEDURE

Farm-raised mallards (6 to 8 months old) were used in the study. On day 0, 60 ducks received shot pellets orally by gavage (mean dose of zinc, 0.97 g); another 60 ducks underwent the same procedure without administration of pellets. On day 15, Romanowsky-stained blood smears were prepared from 53 control and 45 zinc-treated ducks (smears were examined retrospectively). In each smear, 200 RBCs were examined and numbers of erythrocytes with abnormal size, shape, or color were expressed as a percentage. Results were compared with PCV values and zinc dose.

RESULTS

Mean PCV value was lower in all zinc-treated ducks, compared with control ducks, and was lower in zinc-treated ducks that died or were euthanatized before day 30 because of severe clinical disease, compared with those that survived. Zinc-treated ducks that survived had a high percentage of polychromatophilic RBCs, and those that that died before day 30 had high percentages of hypochromic RBCs, fusiform RBCs, and RBC nuclear abnormalities. There was no correlation between PCV value or RBC morphologic abnormalities and dose of zinc.

CONCLUSIONS AND CLINICAL RELEVANCE

In ducks with severe zinc-induced hemolysis, findings indicated that functional iron deficiency may impair the effectiveness of the erythroid regenerative response and contribute to death. Erythrocyte nuclear abnormalities were consistent with mild dyserythropoiesis. These findings may be applicable to effects of other metal toxicoses and regenerative anemias in birds.

Normal and toxic zinc concentrations in serum/plasma and liver of psittacines with respect to genus differences

Determination of zinc concentration in serum/plasma and tissue of caged and aviary birds is commonly requested by practitioners because of an increased awareness of zinc toxicity. However, interpretation of zinc levels is often based on normal zinc concentrations established for poultry. Also, it is likely that intergenus differences exist in normal zinc concentrations of pet birds. In an attempt to determine normal and toxic concentration ranges, zinc concentrations in liver (n = 276) and serum/plasma (n = 260) collected from psittacines between 1990 and 1998 were analyzed. Zinc concentrations were determined by inductively coupled argon plasma emission spectroscopy analysis. The results were categorized by genus and, when available, by history. Birds that were diagnosed with zinc toxicosis (on the basis of history, clinical examination, pathology, and laboratory findings) were exempt and not included in establishing normal ranges. The results indicate that important differences occur with respect to genera. For example, cockatoos and Eclectus parrots have higher normal zinc concentrations in serum or plasma than other psittacines. In addition, analysis of all the submitted cases suggests that potentially toxic zinc concentrations in livers of psittacines can be well below the range considered toxic in chickens (> 200 ppm).

The ecotoxicology of lead shot and lead fishing weights

: Lead shot ingestion is the primary source of elevated lead exposure and poisoning in waterfowl and most other bird species. For some species (e.g. Common Loons, Gavia immer), lead sinker ingestion is a more frequent cause of lead poisoning. In freshwater environments where recreational angling activity and loon populations co-occur, lead poisoning from ingestion of small (<50 gram) lead sinkers or jigs accounts for 10-50% of recorded adult loon mortality, depending on the locations studied. Lead shot ingestion occurs in waterfowl, and in a wide variety of non-waterfowl species, including upland game birds, shorebirds, raptors, and scavengers. Where it has been explicitly studied in Canada and the US, lead poisoning mortality of bald (Haliacetus leucocephalus) and golden eagles (Aquila chrysactos) from eating prey animals with lead shot embedded in their tissues accounts for an estimated 10-15% of the recorded post-fledging mortality in these raptorial species. In addition to environments that experience hunting with lead shot, clay target shooting ranges, especially those in which the shotfall zones include ponds, marshes, lakes, rivers, beaches, or other aquatic-type environments, create a significant risk of shot ingestion and poisoning for waterbirds. Metallic lead pellets deposited onto soils and aquatic sediments are not chemically or environmentally inert, although tens or hundreds of years may be required for total breakdown and dissolution of pellets. Functional, affordable non-toxic alternatives to lead shot and sinkers are being currently produced, and additional such products are being developed. Several countries have successfully banned the use of small lead sinkers, and of lead shot for waterfowl and other hunting, also for clay target shooting, using a phasing-out process that gives manufactures, sellers, and users adequate time to adjust to the regulations.

Avian toxicology

Owing to the unique physiology of birds, most toxicities are life-threatening and require prompt, well-informed action. It is often hard to ascertain which specific toxin or the amount of toxin to which the bird has been exposed. Therefore, the most important action is to treat the bird, not the poison. This article discusses the steps in diagnosing and treating toxicoses, from both natural and man-made toxins, that have been reported in avian species.

Toxicology of selected pesticides, drugs, and chemicals. Zinc

Zinc poisoning in small animals has been described in dogs, cats, birds, and ferrets, but the dog appears to be the species most often affected. Ingestion of zinc-containing metallic objects, including pennies, and zinc oxide ointments has been associated with the majority of the toxicoses. Clinical signs include anorexia, vomiting, diarrhea, hemolytic anemia, kidney dysfunction, and possible liver and pancreatic abnormalities. Treatments that have proven efficacious include fluid diuresis, blood transfusions as needed, general supportive care, and removal of the source of zinc. Further evaluation of the benefit of chelation therapy is urgently needed.