Zinc and its Danger to Parrots
The primary use of zinc is to coat iron or steel in a process called galvanization to prevent rust. Zinc protects steel and iron from rusting it also dissolves in aqueous acids or bases. Recently zinc powder coating has become a very popular way to finish steel cages. The incredible success of breeding parrots in captivity and keeping them as pets, has led to many cage manufacturers producing galvanized powder coated cages in the moderate price range.
Although a bird requires a certain amount of zinc to remain healthy, too much zinc is very dangerous and can cause degeneration in the liver, kidney and pancreas and even death. Certainly parrots must be viewed as very likely to be affected by all environmental zinc. Parrots are commonly housed in wire cages. Most are housed outside or in avicultural situations are in galvanized steel wire cages or aviaries. But parrots will be parrots and many regard their cages or aviaries as something else to chew on. Parrots are unfortunately cases of zinc poisoning waiting to happen due to their persistent habit of chewing at the galvanized aviary wire mesh or galvanized powder coated cages.
So it is up to the parrot owners and breeders to learn more about this deadly metal and how to safeguard their birds. They need to know how to recognize the symptoms of zinc poisoning and what can be done if our bird becomes ill.
There are two types of zinc poisoning:
Acute toxicity is caused when a bird ingests a metallic object containing zinc or flakes of paint which contain zinc pigments. In this case a relatively large amount of zinc is ingested at one time and the levels of zinc in the body quickly become elevated.
Chronic toxicity usually occurs when small amounts of zinc are consistently consumed.
Zinc is soluble in soft water and in acids. When galvanized dishes are used for water or for acidic foods (fruits and juices), the zinc can contaminate the food and be consumed. The amount of zinc ingested is less, but it is continually being resupplied and causing damage to the bird's internal organs. Zinc rust from galvanized wire can be another cause of chronic poisoning.
Zinc is a cumulative poison, which is not easily eliminated from the body. Once ingested, it is deposited in the liver, kidneys, muscle and pancreas. There is limited excretion through the urine, intestinal tract and bile. Prevention is the best method of dealing with zinc toxicity. Remove the sources of zinc and your bird will be safe and you will sleep better. Zinc comes from a wide variety of sources, but it must be ingested to cause harm. Since birds spend a majority of their time in their cages, this is the first area to protect. Paint - Birds can ingest flakes of paint. Today, most cage manufacturers use safe paints and powder coating, but do ask questions when buying a cage. If you have a cage with chipping paint, you should get the paint flakes tested for toxicity. If it is toxic, then either strip and repaint the cage or replace it. Be sure to use paints which are both lead and zinc free. Many anti-rust paints contain zinc, so check with someone knowledgeable. If you don't want to bother, then replace the cage.
Galvanized metal which has been electroplated is safe, but galvanized wire (hot dipped) is not. According to Avian Medicine: Principles and Application by Ritchie, Harrison and Harrison, birds can ingest zinc from cages and clips made of galvanized wire. Toxicity can be reduced considerably by scrubbing the wire with a brush and vinegar or a mild acidic solution. This removes any loose pieces and the white rust (zinc oxide) which forms on the wire. Over time more white rust which is also poisonous will form, so enclosures must be re-treated periodically.
The cheaper forms of galvanized wire are very poorly made and should never be used. If you examine it closely you will see pools of lead and zinc metal in the corners of each square of the mesh - an invitation to a curious bird. Although a bit more expensive, if you must use galvanized wire, purchase galvanized after welded wire, which has less pooling and should flake less, or electroplated wire mesh if available.
There have been instances of zinc toxicity caused by padlocks. This has been reported in larger birds who are able to flake pieces of the coating off or to place parts of the lock in their beaks and dissolve some of the zinc.
Toys & chains
Cheaper metal toys, links, chains or fasteners may contain zinc, and so pose a risk to captive parrots. These should be avoided, or again washed regular in diluted vinegar.
Common signs of zinc intoxication include excessive urine in the droppings (polyuria), polydipsia, weight loss, weakness, gastrointestinal problems, anaemia, cyanosis, hyperglycaemia and seizures. Feather plucking has also been a reported symptom (Resolution of zinc toxicosis has resulted in dramatic improvement in feather picking in many instances). Acute toxicity cases demonstrated lethargy, weight loss, birds may vomit, but may stop eating, greenish diarrhoea, loss of balance (ataxia), and death. Chronic toxicity symptoms included intermittent lethargy, and depression, gastro-intestinal upset may occur. Kidney damage may result in a bird developing increased urination and water drinking. Feather picking is commonly observed in Parrots with zinc poisoning.
If you suspect your bird may have zinc poisoning, take him immediately to a veterinarian. (S)he can perform a blood serum test which measures the level of zinc in the blood. Blood zinc levels of greater than 2 ppm (parts per million) are considered evidence of zinc toxicosis. For example, 1.63 ppm is considered an average normal level for cockatiels. The White Blood Count may also be elevated. If your vet suspects zinc, they may also take x-rays pictures, looking for a piece of metal which may have been swallowed.
One method of treatment is the use of a chelating agent which binds with the zinc in the body and is then expelled. Injections of Calcium EDTA and D-penicillamine have been used. There is also an oral chelating agent, DMSA (dimercaptosuccinic acid). If a piece of metal has been swallowed, then the primary treatment is removal either via catheter or forceps or by cathartics such as sodium sulphate, activated charcoal or mineral oil. Surgical removal can be used as well. Additional treatments are also available. Choice of treatment(s) should be made by a veterinarian based upon the individual situation. (References: Avian Medicine: Principles and Application by Ritchie, Harrison and Harrison)
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