Last Saturday, a very special friend of mine died. Pooh was a beautiful little peachfaced lovebird, purchased last April and cared for with love. She turned a year old in February and had chosen for her mate, Peanut, a very special violet factor male, hand raised from day one by a friend in California. Pooh was anxious to set up nest keeping, and a nest box had been purchased to give to her as soon as I found time to give it a precautionary cleaning.
When I uncovered my birds Saturday morning, it was obvious that Pooh was not feeling well. She was very fluffed, her head buried in her back feathers, and she seemed exhausted. I moved her to an enclosed container with a ventilated top, placed halfway on top of a heating pad. She spent the day sleeping in a warm corner. Twice I got her to take about 5 cc of handfeeding formula, but she was clearly not interested in eating. Though she had never before showed any signs of illness, by evening she was gone.
After Pooh’s death, I recalled that about three weeks earlier, while cleaning her cage, I discovered she had been chewing on the Dri-Dek matting on the cage floor. Working on one corner, she had removed the outer edge of two squares in either direction, and the cross bar in the corner square (1). I was concerned that she might have swallowed some of the chewed Dri-Dek, and that it could become impacted in her crop. When a couple of days passed without symptoms, I had breathed a sigh of relief, — perhaps too soon.
Monday morning’s necropsy found Pooh had non-functional kidneys, all normal tissue replaced by scar tissue, and urates backed up into her soft tissues. The diagnosis was Visceral Gout (2). I was told that, most likely, Pooh had been sick for a long time, and that the cause was probably either a genetically inherited tendency toward kidney problems or too much protein. Since I feed my birds almost exclusively on sprouts from a seed mixture sold by a company highly recommended to me, I asked where excess protein might have come from. I was told me that legumes are high in protein. If the seed mixture was heavy in legumes, and Pooh was eating only certain of the sprouts and leaving others, it could have resulted in a diet too high in protein for her needs (3). Before the necropsy was done, I had mentioned Pooh’s chewing of Dri-Dek, but no visible sign of the bright yellow matting was found inside her.
I was shaken by the possibility that Pooh’s death was diet related. I had tried to give my birds the food that I thought was the very best for them. Now I felt as if I had poisoned my little Pooh. If diet had caused her to die of kidney failure, I wondered how many of my other birds would also die in the next few weeks and months. I calculated how long each bird had been with me, and which would, therefore, be at greatest risk. If diet were the cause of Pooh’s death, I figured I could lose as many as two-thirds of my birds, with only the babies and those most recently acquired likely to not yet have been harmed.
One way in which I deal with a crisis is to compile as much information on the subject as I can. I needed to know exactly what I was facing, and to be prepared. Logging onto the Internet, I opened the Birds N Ways site and requested articles on kidney disease. What I found was a Winged Wisdom article by Carol Highfill entitled “Dangers of Soft PVC Toys and Vinyl Products!” (Exclamation point hers) (4) warning owners about the dangers of giving their birds baby toys made from soft polyvinyl chloride.
The article stated in part: “There is now a growing awareness that toys made from SOFT PVC (polyvinyl chloride) or vinyl contain toxic chemicals as well as lead and cadmium.”
“Chemicals from soft PVC (vinyl), if chewed upon, can leach into the mouth and when ingested can cause a variety of tumors, organ damage and abnormalities in children and animals.”
“In addition, a laboratory analysis of a number of common vinyl products demonstrated that they release toxic metal dust to their surfaces. This dust, contaminated with lead and cadmium can enter the body via licking, chewing, inhalation, and hand-to-mouth transfer. Lead is a well known toxin. Cadmium is a known carcinogen and kidney toxin.”
I was startled by this information. What was Dri-Dek composed of, I wondered? Perusing the information on their site, I soon had my answer — Polyvinyl Chloride (5)! Could chewing on Dri-Dek have released enough toxins into Pooh’s body to have destroyed her kidneys? Might some of the Dri-Dek have been swallowed, passing through her gastrointestinal tract, releasing toxins as it came in contact with her digestive fluids? If so, could the damage to her kidneys have been enough to quickly cause damage that might have taken months to occur with improper diet?
Consulting my copy of Avian Medicine: Principles and Application, I found this statement in chapter 21, Nephrology (6): ” Gout should not be regarded as a disease entity, but as a clinical sign of any severe renal dysfunction that causes a chronic, moderate hyperuricemia.” Further on it states, “Renal dysfunction may result from any progressive destructive condition affecting both kidneys (chronic renal failure), but can also occur in any condition wherein the function of the kidneys is rapidly and severely, but often reversibly compromised (acute renal failure)” (7).
I want to make it clear that the purpose of this account is not to criticize or accuse the folks who make and market Dri-Dek. This product has proven valuable in many applications. It is easily cleaned, and therefore more sanitary than many materials which might be used in its stead. According to their website, Dri-Dek is widely used as non-water-pooling, non-slip flooring on boats, in veterinary clinics and human hospitals, on manufacturing floors, and in food handling facilities and animal kennels. I have used it in most of my cages, and never had a problem until Pooh began to chew on it. However, I do not see that the company has suggested, anywhere in their product information that Dri-Dek is suitable for use with birds. It was my assumption that it was safe to use around my birds, and my decision to put it into their cages.
The histology report which we received a few days later from the Department of Veterinary Pathology at the University of Georgia stated:
“The spleen has lymphocytolysis and plasmacytosis. The kidneys have scattered necrotic tubules filled with inflammatory cells and urates. The remainder of the renal tubules are lined by hyperplastic epithelium. The liver has scattered hepatocytes with enlarged nuclei. The lung has plant material in larger airways indicating terminal aspiration. There is mineralization of the proventricular glands. The intestine, ventriculus, heart and pancreas have no significant changes.”
COMMENT: “The changes in the kidney are suggestive of nephrotoxicosis. The mineralization in the proventriculus is a common finding in birds with renal failure. The mineralization did not seem extensive enough to consider vitamin D toxicosis. The lymphocytolysis in the spleen could be a stress response.”
DIAGNOSIS: “1) Necropathy with urate deposition; 2) Proventricular mineralization”
According to Avian Medicine: Principles and Applications, causes of nephrotoxicity include nephrotoxic substances like heavy metals, mycotoxins such as aflatoxin/ochratoxin/oosporein/cirtrinin (all from molds and fungi), excessive sodium chloride, nephrotoxic drugs (8). When the report was explained to me, I was told that because of the diet Pooh was on, we could rule out excessive salt or vitamin D toxicosis, and that we could rule out nephrotoxic drugs, since Pooh was not on any medication, but that we really could not rule out the mycotoxins, since those could not be tested for in the tissue samples. However, since those would most likely have been spread in the food Pooh received, it seems unlikely that none of my other birds would develop the same problem, since all of my lovebirds received sprouts measured out from the same container at the same time for each feeding.
Was Dri-Dek the source of the poison that caused Pooh’s death? The lab tests that were done on her tissue did not deal with that specifically enough for us to ever know, for sure, but having been able to rule out most causes of nephrotoxicosis, it seems quite likely that the cause of death was chemicals and/or heavy metals which Pooh ingested when she chewed on the Dri-Dek in the bottom of her cage.
In pursuing the topic of soft PVC on the internet, I have found many articles which state that its use is ill advised in baby toys and other products which infants may have occasion to suck (9-17). In all fairness, I need to say that I have also found articles refuting that possibility (18,19). Those who quote from independent laboratory tests about the dangers of soft PVC tend to be environmental groups, those who speak in favor of PVC tend to be chemical companies and manufacturers who make wide use of this material. So you will have to read the articles and decide for yourself. In my Internet searches, I have yet to locate a scientific article detailing the methods and statistical results of the studies to which the other articles refer.
What I can tell you — what you already know — is that there is potential trouble whenever our birds become adventuresome in what they chew. I can tell you that there is reason to exercise caution when using any soft Polyvinyl chloride product on which our birds might have occasion to chew. And I can tell you that any intelligent bird can find ways to misuse almost any product we might use around them. There is still much controversy surrounding the use of soft PVC. You must make your own decision, but I would urge you as strongly as I can to err on the side of caution.
Did Pooh die from genetic problems, improper diet, toxins ingested from polyvinyl chloride or from some other cause which we have failed to consider? We will never be able to tell you that with absolute certainty. But what I can tell you is that a beautiful little female named Pooh will never again fly to me and land on my shoulder, that a lonely confused little male named Peanut sits in his cage in the quarantine room, hoping that his mate may yet return, and that I would do anything I could to keep this from ever happening again to one of my birds.
1. When I later cut a similar sized piece from another corner of the piece of Dri-Dek Pooh had chewed on, I found that she had chewed in excess of 4 grams. A great deal of this was still evident on the floor of her cage. Although I do not know her exact weight at the time of her death, I know that it was around 50 grams.
2. http://www.mbauman.com/gout.htm “Avian Gout”
3. Ingredients in sprout mixture are as follows: Triticale, Rice, Millet, Alfalfa, Fenugreek, Buckwheat, Fennel, Flax Seed, Dill Seed, Sesame Seed, Amaranth, Quinoa, Mung Bean, Radish Seed, and Red Clover Seed.
5. http://www.blackwatchmarine.com/dridek.html (See section entitled “specifications”)
6. Avian Medicine: Principles and Application, Abridged Edition, Wingers Publishing, Inc., 1997, Lake Worth, Florida, p 283 top
7. 5 Ibid., “Acute and Chronic Renal Failure”, p 283 bottom
8. Ibid. p. 289 “many nephrotoxins cause renal tubular necrosis, including aminoglycosides, heavy metals and mycotoxins such as aflotoxin (A. flavus and A. parasiticus), ochratoxin (A. ochraceus and Penicillium viridicatum), oosporein (Chaetomium trilaterale) and citrinin (P. citrinum). Salt (NaCl) poisoning has been documented in various species”
10. http://www.envirotrust.com/toys.html “Toxic Toys: Petition To The Consumer Product Safety Commission Concerning PVC In Children’s Toys”
11. http://www.checnet.org/science/hk_pvc.html “Check The Facts: PVCs In Children’s Toys”
12 http://gopher.essential.org/listproc/dioxin-l/msg00441.html DEHP again
13. http://easyweb.easynet.co.uk/~mwarhurst/phthalates.html Phthalates
14. http://ens.lycos.com/e-wire/february/feb019903.html National Environmental Trust: “Uncertainties About Phthalates Are Not Worth Risking the Health of Children Parents, Toymakers, Retailers, Consumer And Environmental Advocates, Governments and CPSC All Agree”
15. http://www.800lawinfo.com/articles/article128.cfm Commission recommends to watch soft PVC child-care articles and toys intended to be put into the mouth and act if necessary
16. http://www.greenpeace.org/~comms/pvctoys/whatsnew.html “Play Safe Buy PVC Free”