Lead and Zinc Poisoning in Parrots
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Lead and Zinc Poisoning in Parrots

Published on Friday, 24th January 2014
Parrots are naturally inquisitive and enjoy chewing a variety of objects. Although they are mostly highly selective as to what they will eat, cases of accidental poisoning are not uncommon. Lead and zinc poisoning are the most common heavy metal poisonings we see in our Parrot patients.

Lead is found in a variety of household items, mainly in older houses, as the use of lead is being replaced with other metals. Lead poisoning in our practice is most commonly seen in birds that swallow lead curtain weights. This seems to be a particular problem with Cockatiels and smaller Parakeets that seem particularly drawn to playing with them.
 
People are often concerned about the toxic effects of chewing paint, however thankfully modern paints no longer contain lead and so it usually has to be very old paint to cause a problem.
 
We should remember, however that a surface may be coated with several layers – we have had toxicity problems when Parrots have chewed sash windows where the under layers of paint have contained lead. Other sources of lead include leaded windows, lead window putty and plumbing/electrical clips.
 
It is the action of the stomach acid on the lead that results in toxic levels being absorbed. Birds that have survived being shot with lead containing particles (obviously unlikely for Parrots, but common in pigeons, game birds and birds of prey) rarely have problems with lead poisoning.
 
Birds with lead poisoning mostly appear very unwell, depressed and lethargic. They are usually not eating and have watery droppings (due to polyuria, an excess of urine).
 
The urates (white part of the dropping) can appear green/yellow and, especially in Amazons, can appear red or pinkish. Affected Parrots may regurgitate profusely. If left untreated, the condition may worsen such that the bird becomes paralysed and has seizures which can be fatal.
 
The diagnosis of lead poisoning can be complicated by the lack of specific signs to the treating vet and, more often than not, the owner is unaware that the bird has eaten something containing this metal.
 
The clinical signs above however should always raise suspicions of heavy metal poisoning. X-rays reveal if the bird has swallowed pieces of metal, which show up as bright white objects in the ventriculus (gizzard, stomach).
 
Sometimes the metal may have already passed out of the gut and so won’t be seen on an x-ray, even though the bird has absorbed enough lead to make it sick. Blood samples are taken and tested for lead levels to confirm the diagnosis.
 
As affected Parrots are very unwell, emergency hospitalisation treatment is required. Diazepam is used to control seizures and fluids are given by injection to replace losses by vomiting and excessive urination. Good nursing, with extra warmth, oxygen and crop feeding helps speed recovery.
 
Injections of sodium calciumedetate are given twice daily for up to 5 days initially to bind up the metal in the body (a treatment known as chelation). Usually we let the Parrot pass the lead particles naturally and cathartics, such as peanut butter, can help speed the exit of the metal from the gut.
 
The chelation treatment protects the bird whilst this happens and we can repeat x-rays to check their progress. Occasionally the particles are best removed, which is usually done by retrieving the pieces through the mouth or a small incision made in the crop using a fine endoscope camera.
 
Lead can be stored for a long time in the body, especially in the bones, and so we usually continue medication to bind the lead for a number of weeks after the initial poisoning. This is achieved by giving penicillamine as drops by mouth at home.
 
Early treatment is essential for lead poisoning, as the longer it is present in high concentrations, the more damage it does to various organs in the body.
 
A strange phenomenon in female birds is that, at the time of egg-laying, the bird will move calcium stores out of bone. This can release previously stored lead, with possible signs of repeat poisoning quite a while after the initial lead ingestion.
 
Zinc is the other common metal poison we encounter at our practice. In cases where the bird has taken in large amounts in a short time, the signs will be similar to lead poisoning and the treatment is similar.
 
More commonly however is chronic zinc poisoning, where small amounts are taken in over a period of time. This is often not in the form of zinc metal, so x-rays may not show up any metal particles in the stomach.
 
Signs of chronic zinc poisoning may be vague, with depression, lethargy, weight loss and problems eating. Chronic zinc poisoning has been show to be a cause of feather picking in some birds and appears to cause feather loss, skin changes and itching in others.
 
Chelation treatment can resolve picking in these cases. There are obviously many causes of feather destructive behaviour and zinc poisoning is perhaps over diagnosed as a cause of feather picking. Feather loss on the head, where the bird cannot pick the feathers, can be suspicious for zinc poisoning, although again this is only one of many possible causes.
 
The most common source of zinc is newly galvanised wire. This can be made safer by brushing the wire and applying a mild acetic acid (vinegar) to remove powder and particulates.
 
Zinc or zinc alloys are found in a number of household items, including coins, keys, wire, staples and jewellery. The metal in older or less reputably sourced cages can contain zinc. Powder coatings prevent access to the metal, but care should be exercised if the coating is chewed off to expose the metal underneath.
 
Blood samples can be used to determine zinc poisoning, however the diagnosis is a little trickier than with lead. Firstly when taking the blood sample, a special syringe that does not have a rubber plunger must be used, as contact with rubber will affect the result.
 
Also normal zinc levels vary widely across different species of Parrot and even within some species. Some birds will have high zinc levels with no apparent ill effects. This can make it problematic to definitively say that the level of zinc within the bird is high enough to cause a problem.
 
In our experience, Australasian Parrots, particularly Eclectus Parrots and Cockatoos are most frequently affected by chronic zinc poisoning. These cases have high blood zinc levels that lower after treatment together with an improvement in clinical signs.
 
Interestingly these species have naturally high blood zinc levels, so perhaps they are more susceptible to toxicity due to the difference in zinc levels in the diet or their feeding habits in wild compared to captivity or the efficiency of their uptake of zinc from the diet.
 
Treatment for chronic zinc poisoning is usually by giving penicillamine once daily at home for several weeks, whilst trying to identify and remove possible sources of zinc exposure.
 
Accidental poisonings with lead or zinc can be avoided by choosing appropriate cage and toy materials, together with attempting to Parrot-proof the house when they are out.

 
Obviously this is easier said than done and so owners need to remain vigilant for signs of metal poisoning and seek veterinary attention promptly in any suspicious circumstances.
 


X-ray of a Cockatoo that has several metal items in the ventriculus / stomach  (white arrow). The bird was depressed and regurgitating.

High zinc levels on a blood test confirmed acute zinc poisoning. The bird was started on chelation treatment and the metal items removed by endoscopy after several days.

 
 
A selection of the items removed from the Cockatoo’s stomach by endoscopy, including a metal clothing stud and button.

Note the pieces of wood that do not show up on the x-ray.
 

X-ray of a Cockatiel with multiple small circular metal items in the ventriculus / stomach (white arrow) which were found to be lead curtain weights.

Unfortunately two of the owners’ three birds had died before coming to us, but this bird recovered with treatment.

The bird passed the lead weights on its own after 5 days.

Matthew Fiddes BVSc DZooMed(Avian) MRCVS is head vet at CJ Hall Veterinary Surgeons in East Sheen, London. The practice specialises in avian and exotic animal medicine, treating patients from all over London and the Home Counties.

Parrots are brought to the practice directly or can be referred from other vets. Matthew is one of only 6 vets holding the RCVS Avian Zoological Medicine Diploma – the highest level of UK examined qualification in bird medicine.




CJ Hall Veterinary Surgeons, 15 Temple Sheen Road, East Sheen, London SW14 7PY. Tel: 020 8876 9696. www.cjhall-vets.co.uk

For a list of vets in your area please click here

 

 
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