My dogs Sheba and Tiki, both 13 years old, get lots of compliments on their eyes. It’s not just that they’re deep, brown, and amazingly soulful. Perhaps I sound biased, but I believe 91 years of life experience – i.e. 13 times 7 – will impart a profound look to anyone’s eyes (just wait and see).

The windows of my best friends’ souls are also impressively clear, without the heavy cloud cover one would expect in the eyes of such superannuated dogs. So, what’s our secret? Milk thistle.

One of nature’s most potent antioxidants, milk thistle is a plant – its proper Latin name is Silybum Marianum – that supports healthy liver function (it’s good for the kidneys too). Maintaining optimal liver health is especially important in senior dogs, who’ve had long lifetimes of exposure to a variety of damaging chemical substances. Medications such as antibiotics, conventional parasite prevention, whether administered orally or topically, undergoing anesthesia for anything from emergency surgery to routine dentistry, all take a toll on the liver, the organ that acts as a filter for the entire body, ridding it of toxins.

Now add to that liver load the extra stress of inhaling the exquisitely polluted air of New York City, our home town. Dogs are especially vulnerable to automobile emissions; as they walk along on the street, their snouts are directly at exhaust-pipe level.

The liver is an amazing organ, but it could use some backup, especially after years of hard work. Living strong depends on having a strong liver. Hepatoprotection – the ten-dollar word for liver support – is especially important for anyone who has undergone chemotherapy, which can take a huge toll on the liver. Oncologists frequently recommend milk thistle to human cancer patients for this reason, and it’s equally important for dogs undergoing chemotherapy.

Incidentally, homeopaths believe that you can also support this vital organ by…eating liver. With that in mind, I sometimes treat my dogs to liver-flavored canned food or freeze-dried liver treats. Hey, it can’t hurt – and the dogs certainly don’t complain.

My holistic vet sells me milk thistle produced by Buck Mountain Botanicals; the product is organic and very pure, hence its high potency. According to Buck Mountain’s Dr. Terence Fox, liver and eye health are closely linked, so taking milk thistle daily can actually help prevent and, in some cases, even reverse cloudy eyes in senior dogs.

Since learning this, my senior dogs have not missed a single dose; I sneak one capsule of milk thistle into each of their twice-daily meals. (They are large dogs, so if you have a small dog, half a capsule will do.) Just push the capsule into canned food, which disguises it nicely, or deliver it in a piece of cheese.

You can also open the capsule and sprinkle out its contents over food, but be warned that very finicky dogs might not eat their food this way, as milk thistle tastes bitter, and you wouldn’t want it going to waste. My less-discriminating dogs have been fine with the taste of sprinkled milk thistle, so long as it’s “sweetened” with a dash of organic cinnamon and a splash of Omega-3 fish oil. Yum!

If any of my dogs happen to undergo anesthesia for any surgical procedure, I double their milk thistle dose for a week afterward, to be sure their liver and kidneys won’t be unduly compromised. If you’re using lots of this excellent stuff, it’s more cost-effective to purchase milk thistle seeds that you grind yourself in a nut grinder dedicated for that purpose. The amount of one capsule is a scant half-teaspoon.

Encouraged by the positive results in my dogs, I’ve been diligent about taking milk thistle every day myself. I’ve been known to dip into my dogs’ stash when I run low on my mainstay, Blue Bonnet brand.

Here’s a helpful hint: Any time you happen to have one too many at the cocktail hour, take a couple of milk thistle capsules before crashing. This will eliminate the need for any wild “hair of the dog” remedy you could think to concoct the morning after, I promise, and you’ll be in great shape for the early-morning dog walk!