Toxic Doses by Dog Body Weight: The Chart Reference

How to read these charts

Each curve plots an amount against body weight in pounds. Find your dog's weight along the bottom, read up to the band, and the y-axis gives the amount at which the published guidance says effects begin. The bands are drawn from the figures in the named source and nowhere else, which is why some substances appear here and many do not.

Two things the curves cannot show. They cannot capture individual variation, which is real and sometimes large. And they cannot capture the concentration of what was actually eaten, which for several substances varies enough to swamp the arithmetic: see why grape counts are unreliable for the clearest example.

A published number is not one kind of thing

This is the part almost every comparable page gets wrong, and it matters more than any individual figure below.

The numbers in veterinary toxicology come in at least three flavours and they are not interchangeable. A **signs threshold** is the amount at which effects are reported to begin, which is what most of the curves here plot. An **LD50** is a lethality statistic, the dose at which half of an exposed group died, and it sits far above the amount that makes a dog ill. And some guidance is not a mass at all: Merck's grape figure is a count of fruit per unit of body weight.

Metaldehyde is the case in point on this page. The figure available for it is an LD50 of 210 to 600 mg/kg, and tremors and other neurologic effects are reported at substantially lower exposures. Reading that curve as "safe below the line" would be a serious error, which is why it is described here rather than plotted alongside the signs thresholds as though it were the same measurement.

Xylitol

The steepest small-dog problem on this page. Merck reports hypoglycaemia above roughly 100 mg/kg and hepatic insufficiency above roughly 500 mg/kg, and because Xylitol content varies several-fold between products, converting the threshold into a piece count is unreliable. The realistic sources are Chewing Gum and xylitol-sweetened Peanut butter, and the second is the larger dose because it is served by the spoonful. The product checker covers which products actually contain it and which sugar-free sweeteners do not.

Chocolate and caffeine

Methylxanthines are the one threshold set with three usable bands rather than one line, which makes them unusually informative: Merck reports mild signs from about 20 mg/kg, cardiotoxic effects from about 40 mg/kg, and seizures from about 60 mg/kg.

The complication is that the mg of theobromine in a given amount of Chocolate depends entirely on the type: Cocoa Powder and baking chocolate carry several times the load of milk chocolate per gram, while M&M's sit at the low end. Caffeine adds to the same total, so Coffee, Espresso and Energy Drinks stack with any chocolate eaten alongside it. The chocolate page does that conversion.

Grapes and raisins

The only entry here expressed as a count rather than a mass. Merck states that more than one Grapes or Raisins per 4.5 kg of body weight may pose a risk, and Dried Fruit in baking is the usual uncounted route. It is also the entry where the threshold is least useful as a safety line, because tartaric acid content varies between bunches, which is why grapes are flagged as an any-amount item despite having a published figure.

Onion and garlic

Onion is commonly cited at or above 0.5% of body weight in a single meal, which is 5 g per kg. Garlic is reported several times more potent by mass, at around 1 g per kg, and its curve lives on the dedicated page rather than being duplicated here. Onion Powder and Garlic Powder are the practical hazard, because drying concentrates the load per gram.

Both are delayed: the anaemia that matters appears one to five days later, so same-evening reassurance means nothing. The allium dose page carries both curves, the powder-versus-fresh problem and the timeline.

Metaldehyde, and the number that is not a threshold

Snail & slug bait is the reason metaldehyde is on this page, and it is the entry that most needs its caveat read. The published figure is an oral LD50 in dogs of 210 to 600 mg/kg. An LD50 is a lethality statistic derived from group studies; it is not the amount that makes a dog ill.

Tremors, hyperthermia and seizures are reported at substantially lower exposures, and metaldehyde toxicosis moves fast, often within an hour. So the honest presentation is the one this page gives: state the number, state what kind of number it is, and do not draw a curve a reader could mistake for a safe-below line.

The practical detail worth knowing is that slug bait is often laid around exactly the plants dogs dig in, and the pellets are dyed colours that look like kibble.

Alcohol

Merck reports clinical signs of ethanol toxicosis in dogs from roughly 0.6 g/kg. The exposures that reach it are rarely a poured drink: Raw bread dough produces ethanol in the stomach as it proves, and Vanilla Extract is around 35% alcohol by volume, stronger than most spirits.

Alcohol carries a second, separate problem in Hops, used in home brewing, which causes malignant hyperthermia in dogs by an unrelated mechanism and has no dose threshold on this page because none is established.

What each substance actually damages

Knowing the target organ is what turns a number into a decision, because it tells you what the vet will be looking for and how fast the window closes. A renal toxin and a neurologic one produce completely different urgencies from the same size of exposure.

Threshold reference table

Every threshold on this site with a traceable published source, in one place. Read the third column carefully: it says what kind of number each figure is.

What is deliberately missing from this page

The gaps are as informative as the entries, and leaving them visible is the point.

Macadamia nuts produce a well-documented syndrome of weakness and tremors, and the mechanism remains unidentified. Avocado is widely listed as toxic on the strength of persin, which is far more dangerous to birds and livestock than to dogs. Cooked bones and Corn on the Cob have no dose at all, because the hazard is mechanical rather than chemical, which is what the obstruction page covers.

For each of these, the honest sentence is that published toxic doses are not well established, and that sentence is more useful than a number invented to fill the column. Any page that gives you a confident mg/kg for macadamia is telling you something the literature does not support.

How much is too much, in practice

Body weight is the biggest single variable and the reason this page exists, but it is not the only one. Age, breed, existing kidney or liver disease, and other medications all move the margin, which our guide to size and breed effects covers in more depth. How our severity scores work explains how these thresholds feed the per-item ratings.

A dog at the small end of the scale is in a genuinely different situation from a large one eating the same object, and that is worth internalising rather than looking up each time: a 4 lb dog and an 80 lb dog differ twentyfold, so a single dropped tablet or one piece of gum is a different event entirely.

What to do next

• Do not use these charts to decide that an exposure was fine. Use them to understand how urgent it is.
• Weigh your dog if you do not know the number. An estimate that is out by a third moves you a whole band.
• Keep the packaging, and note the time and the largest plausible amount rather than the likeliest.
• Call a veterinarian or poison control for anything near or above a line, and for any amount of an any-amount item.
• Use the checker for a weight-specific read, and the first ten minutes if this has just happened.