WR, I hope y'all are doing okay!
While we wait, just thought you dog lovers might want to share with me what I learned from hours spent yesterday researching zinc in dog's diets. We have an appointment this afternoon for Mink and I'm trying to have something definite to show the vet on his diet so we won't waste hundreds or even thousands of dollars chasing other diagnoses when his pattern of hair loss precisely fits that of "zinc deficient dermatosis."
Zinc is important in the dog's diet, they can't make it or store it, so commercial kibble manufacturers list the minimum quantity of zinc their ration is supposed to contain. If a feed has the AAFCO stamp of compliance on it, you'd feel sure it was sufficient, right?
Well, I learned there are 2 complications with that:
1. what kind of zinc they add as a supplement to the meat, eggs or organ meats that are natural zinc sources.
And 2. What plant matter such as grains the feed contains that tend to hinder zinc absorption in the dog's system. Some grains have a lot of phytates and phytate cancels out the zinc to where it won't be available in the gut, mixed with the plant matter. I found a list of the major phytate-rich grains, and going just from memory here, don't hold me to it precisely, the top 5 are: 1. corn, 2. wheat bran, 3. wheat, 4. oats, 5. legumes (such as peas, soybeans, lentils, chickpeas).
That might explain some of why commercial dry feeds aren't always best for certain dogs, especially fast-growing large breed pups like our boy.
Fortunately, the 2 feeds he gets each meet minimum AAFCO nutrition levels for growth of large breed dogs, and I was relieved to know neither of them list corn, wheat or legumes as ingredients anywhere down the list.
So that led me to looking at what kind of zinc the dog food producers may be using. I came across research on the relative bioavailability of zinc in dog foods and again, here's the list from memory, ranked from superior to inferior: 1. zinc gluconate or zinc piccolinate, 2. chelated zinc, 3. zinc methionine, 4. zinc sulfate, 5. zinc oxide, which is largely unavailable in the gut. So I saw that if my kibble just got sprayed with a zinc sulfate solution after the other ingredients are ground up and formed into pellets, it wouldn't be nearly as rich a source as if zinc was from the actual meat in the mix. One of my foods lists zinc sulfate, the other (the salmon) doesn't even list zinc, but it's AAFCO certified so I assume it meets the minimum requirements.
All this research was me trying to figure out just how much zinc my dog is supposed to be getting! I found that data pretty hard to locate, as minimum recommended analyses are directed at dog food manufacturers, not the individual dog, and are given as a mathematical ratio of zinc to dry matter. Finally found some veterinary research I'm going to bring with us today showing that an intact male, 1 year old, 80 pound dog needs upwards of 90 mg per kilogram of HIS weight, not the food bag's weight. I ran calculations on what we feed and found that we're there, but just barely. So any absorption issues could tip the scales to zinc deficiency for a hyper boy like our Mink.
Most of his training treats are jerky of some kind or dried liver. We use a heck of a pile of treats doing this positive training and just in managing this wild child around the house, yard and vehicles. This morning I looked at the bag of peanut butter biscuits we most often use, to save our more expensive ones. Sure enough, the #1 ingredient in them was wheat flour, then oats, then wheat bran: all are phytate rich! Could cheap cookies be the culprit?! Stay tuned....
Hope this little booklet helps anybody else save some heartache and cash, wondering what's wrong with their dog!
