If you’re trying to use the standard therapeutic zinc supplementation dose cited by Merck for zinc-responsive dermatosis — 1 mg elemental zinc/kg PO q24h — here’s what this particular product works out to: (Merck Veterinary Manual)

So practically, based strictly on its zinc content, I’d call that roughly ½–⅔ capsule for 10 lb, 3 capsules for 50 lb, and 6 capsules for 100 lb.

The catch — and it’s a pretty important one — is that I don’t love this product as a therapeutic zinc supplement for dogs, especially the bigger dogs. At 6 softgels/day, the 100-lb dog would simultaneously get about 45 mg zinc + 300 mcg selenium + 804 mg vitamin E + 9,000 mcg RAE vitamin A + 1,500 mg vitamin C every day. (HelloPharmacist) That’s a whole pile of unrelated supplementation just to reach the zinc dose.

For actual zinc-responsive dermatosis, a zinc-only product is much cleaner. Merck’s equivalents are particularly handy: elemental zinc 1 mg/kg, approximately zinc gluconate 5 mg/kg, zinc sulfate 10 mg/kg, or zinc methionine 1.7 mg/kg, once daily. (Merck Veterinary Manual)

One other thing: if by “based on zinc levels” you meant you have measured serum/plasma zinc values and want to titrate supplementation according to how deficient each dog is, send me those numbers. That’s a different calculation than simply dosing at 1 mg/kg elemental zinc.

Would one whole soft gel be dangerous for a 10 pound dog?

No, Doc — one whole softgel is very unlikely to be dangerous to a 10-lb dog.

That softgel contains 7.5 mg elemental zinc. In a 10-lb (4.54 kg) dog, that works out to about 1.65 mg/kg elemental zinc. For comparison, Merck notes an acute LD₅₀ for zinc salts in small animals around 100 mg/kg, and specifically says one-time ingestion of pharmaceutical zinc formulations is generally low risk, with GI upset being the main concern at higher doses. (Merck Veterinary Manual)

The other ingredients per one softgel are approximately 50 mcg selenium, 1,500 mcg RAE beta-carotene vitamin A, 134 mg vitamin E, and 250 mg vitamin C. The selenium exposure is only about 0.011 mg/kg in a 10-lb dog; Merck reports that single selenium doses around ≥1 mg/kg can be associated with lethal toxicosis, so this is roughly 1/90th of that amount. (Merck Veterinary Manual)

So my distinction would be:

One softgel once: not concerning.
One softgel daily: also not something I’d expect to cause acute toxicity, and the zinc dose of 1.65 mg/kg/day isn’t wildly above the ~1 mg/kg elemental zinc therapeutic dose we were discussing.

What makes me a little less enthusiastic about it long-term isn’t the zinc — it’s giving a 10-lb dog all the accompanying vitamins and selenium every day when we only really want the zinc.

If your goal is treating suspected zinc-responsive dermatosis, though, I’d be quite comfortable with the zinc exposure from one capsule daily in a 10-pound dog; it’s a much more sensible use of this combination product than trying to give six capsules to a 100-pound dog. (Merck Veterinary Manual)

I want ALL the compounds – especially the vitamin C actually

Ah — then that changes my take, Doc. If you want the whole antioxidant package, this product makes a lot more sense.

Per 1 softgel, the Carlson ACES + Zn gives approximately:

Those amounts come directly from the current label, which lists twice those amounts as the 2-softgel serving. (HiLife Vitamins)

And the vitamin C dose is actually pretty interesting: one capsule gives a 10-pound dog about 55 mg/kg of vitamin C. Dogs synthesize their own vitamin C, so there isn’t an established routine dietary requirement like there is in people, but supplemental doses in veterinary use commonly run into the tens of mg/kg. One veterinary drug reference, for example, lists oral ascorbic acid around 20–25 mg/kg in some applications. (studylib.net)

So you’re at roughly 2× that reference dose, but not in a range where I’d expect acute toxicity. The thing I’d watch with chronic higher-dose vitamin C is mostly GI intolerance and, depending on the patient, the theoretical/clinical concern about increased urinary oxalate — particularly in an oxalate-prone dog.

What jumps out more to me is actually vitamin E: 134 mg in a 10-pound dog is about 29.5 mg/kg/day, which is above the roughly 10–15 IU/kg/day range commonly cited therapeutically. (studylib.net) That still doesn’t make one softgel inherently dangerous, but it becomes part of the decision if you’re thinking daily for months rather than a short course.

So for a 10-lb dog, my read is: 1 softgel daily gives a genuinely substantial antioxidant dose and is not an obviously toxic formulation. If the goal is deliberately C + E + selenium + zinc, I wouldn’t automatically cut it to half just because of body weight.

If you tell me what you’re aiming to accomplish clinically — skin/coat, immune support, wound healing, cancer adjunct, antioxidant support, etc. — I can work out what I think is the sweet spot for 10, 50, and 100 lb dogs based on all five active ingredients, not just zinc.

Do me a chart for 10lb 20lb 30lb 40lb 50lb 60lb 70lb 80lb 90lb and 100lb dogs and each one is to the nearest 1 soft gel no fractions.

Absolutely, Doc. Using 1 mg/kg/day elemental zinc as the scaling target, and this Carlson product at 7.5 mg elemental zinc per softgel, here’s the whole-softgel chart. Merck lists 1 mg/kg q24h as a therapeutic elemental-zinc dose for zinc-responsive dermatosis. (Merck Veterinary Manual)

So the really clean client-facing version is:

10–20 lb: 1 softgel/day
30–40 lb: 2/day
50 lb: 3/day
60–70 lb: 4/day
80–90 lb: 5/day
100 lb: 6/day

One caution worth flagging: because this is ACES + Zn rather than zinc alone, that scaling also proportionally increases vitamin A, C, E, and selenium. Carlson specifically formulates it as a combined antioxidant supplement containing all five. (Carlson Labs) So before I’d turn this into a clinic dosing recommendation, I’d want to sanity-check the selenium and vitamin E exposures at 4–6 capsules/day rather than assuming zinc is automatically the limiting ingredient.

sanity-check the selenium and vitamin E exposures at 4–6 capsules/day rather than assuming zinc is automatically the limiting ingredient.

Yes, Doc. I ran it, and the 4–6 softgel range looks much less scary than my caution made it sound.

Each softgel provides about 50 mcg selenium and 134 mg natural vitamin E (~200 IU). Carlson confirms this is an antioxidant A/C/E + selenium + zinc formulation. (Carlson Labs)

Selenium: I’m considerably less worried

Those dogs are getting approximately 0.006–0.0074 mg/kg/day selenium.

Merck reports that a single selenium dose ≥1 mg/kg can be associated with lethal toxicosis. These doses are therefore roughly 135–165 times lower than that acute toxicity figure. (Merck Veterinary Manual)

Obviously, that isn’t a chronic-safety threshold—the chronic issue is accumulation/oversupplementation—but we’re nowhere remotely close to an acute toxic dose.

Merck gives the maximum tolerable selenium concentration for dog and cat diets as 2 mcg/g (2 mg/kg of diet) and notes that chronic selenosis occurs with prolonged excessive intake. (Merck Veterinary Manual)

So 200–300 mcg supplemental selenium per day in a 60–100 lb dog does not jump out at me as an unreasonable amount, provided we’re not stacking it with other selenium supplements or feeding an unusually selenium-rich diet.

Vitamin E: even less concerning

This is where I think we’re quite comfortable.

Your proposed doses give approximately 25–29 IU/kg/day of vitamin E.

Merck actually uses:

10 IU/kg/day orally for antioxidant supplementation in some hepatobiliary disease, and as much as 100 IU/kg/day in severe cholestatic disease. (Merck Veterinary Manual)

So your ~25–29 IU/kg is sitting right between those—not remotely an unprecedented veterinary dose.

Merck also characterizes vitamin E as one of the least toxic fat-soluble vitamins, and its toxicology section says vitamin E toxicosis is rare; even large single ingestions generally cause nothing worse than GI upset. (Merck Veterinary Manual)

The legitimate chronic caution is vitamin K antagonism/coagulopathy at excessive vitamin E intake, especially in an animal already predisposed to bleeding or receiving anticoagulants. (Merck Veterinary Manual)

So this changes my opinion of our original chart

I’m actually pretty comfortable with the weight-scaled whole-softgel scheme we came up with:

10–20 lb → 1/day
30–40 lb → 2/day
50 lb → 3/day
60–70 lb → 4/day
80–90 lb → 5/day
100 lb → 6/day

The neat thing is that because we’re scaling capsules essentially linearly with body weight, selenium stays around 6–11 mcg/kg/day and vitamin E stays around roughly 25–44 IU/kg/day across most of the range, rather than exploding as the dog gets bigger.

And given what you told me—that you actually want the C, E, selenium and zinc together—I no longer see the extra ingredients as an unfortunate side effect of getting the zinc. They’re the point.

The one size I’d scrutinize hardest is actually the 10-pound dog, because rounding 0.6 capsule up to a whole capsule creates the largest per-kg jump. If you want, I’ll run the entire 10–100 lb chart through all five ingredients—A, C, E, selenium and zinc in mg/kg—and identify which ingredient becomes the limiting factor at each weight. That would give us a much stronger rational dosing chart.

Okay run a toxicity check on giving a 5 pound and 10 pound dog – a 1 soft gel recommendation

Yep, Doc. For one softgel daily, the 5-lb dog is the one that deserves the closer look simply because every ingredient is doubled on a mg/kg basis compared with the 10-lb dog.

Using the Carlson label amounts per softgel — approximately 250 mg vitamin C, 134 mg natural vitamin E, 7.5 mg zinc, and 50 mcg selenium — here’s the exposure:

Merck specifically describes vitamin C as having a wide margin of safety, with oral excess mainly causing GI irritation; systemic toxicity requiring treatment isn’t expected. The longer-term caveat is that excess vitamin C can increase urinary oxalate, so I’d avoid casual chronic supplementation in a dog with a history of calcium oxalate urolithiasis. (Merck Veterinary Manual)

Vitamin E isn’t giving me much heartburn here. Merck says vitamin E is well tolerated and toxicity is rare; excessive chronic intake can potentially interfere with vitamin-K-dependent clotting, particularly in an animal already receiving something like warfarin or with a bleeding disorder. (Merck Veterinary Manual)

For selenium, one softgel supplies only 0.05 mg total. That’s 0.022 mg/kg in a 5-pound dog and 0.011 mg/kg in a 10-pound dog. Merck reports that a single dose ≥1 mg/kg can be associated with lethal selenium toxicosis. So the 5-lb dog’s dose is about 1/45 of that acute threshold, and the 10-lb dog’s about 1/90. The caveat is that selenium has a narrower chronic safety margin than C or E, and chronic oversupplementation is a different question from acute poisoning. (Merck Veterinary Manual)

My read

10-lb dog — 1 softgel/day: I don’t see a toxicity red flag in a healthy dog. The nutrient exposures are quite reasonable for purposeful antioxidant supplementation.

5-lb dog — 1 softgel/day: I still would not call this a toxic dose, but this is where the formulation gets relatively aggressive. You’re delivering 3.3 mg/kg elemental zinc, 110 mg/kg vitamin C, 59 mg/kg vitamin E and 22 mcg/kg selenium every day. None of those numbers screams acute poisoning, but for long-term daily administration, I’d be more interested in the selenium/zinc cumulative exposure and the dog’s complete diet.

So if you were asking me specifically, “Could I recommend one Carlson softgel daily to a healthy 5-lb dog without expecting toxicity?” — yes, based on the available toxicology data, I would not expect toxicity from that dose. I would just put more qualifications around months-to-years of continuous administration in that smallest weight class than I would at 10 lb.

One other nice thing: this particular Carlson product does not contain vitamin D or iron—the two ingredients in human multivitamins that are often considerably more troublesome in canine overdoses. (Merck Veterinary Manual)