Is the crate door a hidden “supplement”? Chronic zinc exposure from galvanized bars and copper depletion from long-term chewing
We obsess over bowls and diet formulations but ignore the giant metal grid many dogs lick and chew daily: the crate door. A lot of wire crates and door latches are galvanized (zinc-coated) steel or powder-coated over zinc phosphate. We know acute zinc toxicosis happens from pennies and ointments, and that excess zinc can suppress copper absorption over time. Yet I never see crate hardware discussed as a potential chronic trace mineral input.
Questions for the group:
- Has anyone measured serum zinc and copper in heavy crate-chewers before/after switching to stainless or aluminum? Any changes in coat color, anemia markers, GI signs?
- Do we have data on zinc leaching rates from galvanized steel into canine saliva or food slurry (salt + moisture) versus when dogs actually ingest flakes from chewed bars?
- Could galvanic corrosion be accelerating this? Example: a stainless bowl or clip-on feeder touching a zinc-coated door with salty wet food bridging the metals.
- Are powder-coated crates truly inert if the coating chips? What’s in the chips when swallowed, and do pretreatments add bioavailable metals?
- For “stainless” crates: which alloys are used (201/430 vs 304/316), and do they matter for leaching in real-world dog use?
Why I’m skeptical of the status quo:
- Diets already meet zinc minimums; chronic micro-doses from hardware could tip some dogs toward marginal copper deficiency without tripping obvious toxicity.
- I see “mystery” anemia, pale coat/eye rim depigmentation, soft stool, or picky eating blamed on diet brand-hopping-rarely on environmental metals.
What I’m looking for:
- Lab data, case reports, or manufacturer disclosures on materials and coatings.
- Experiences where removing/isolating crate contact (swap to true 304/316 stainless, solid-sided crates, barrier sleeves on bars) changed labwork or symptoms.
- Practical testing ideas that don’t damage the crate or poison the dog-short of full material assay.
If this checks out even partially, “fix the hardware” might be safer than tinkering with copper supplements. Who has evidence, either way?