Is Milorganite Safe for Dogs?

What You Need to Know

Milorganite is a biosolids-based organic fertilizer produced by the Milwaukee Metropolitan Sewerage District. It has been manufactured since 1926 and has a long track record of safe use around pets, which is why it is the fertilizer veterinarians and pet safety organizations recommend most often for dog owners because it contains zero herbicides, insecticides, or added chemical salts.

The safety profile of Milorganite stems from what it does not contain. Unlike many lawn fertilizers, Milorganite has no added herbicides (no 2,4-D, dicamba, or MCPP), no insecticides (no bifenthrin, carbaryl, or organophosphates), and no fungicides. These chemical additives are the components in combination lawn products that pose the greatest risk to dogs. By using a pure nutrient source without these additions, you eliminate the most dangerous exposure pathways.

Milorganite's NPK analysis is 6-4-0 with approximately 2.5% iron. The iron content is the primary concern from a toxicity standpoint. Iron toxicity in dogs typically requires ingestion of more than 20 mg of elemental iron per kilogram of body weight to cause symptoms, and more than 60 mg/kg for serious toxicity. Given Milorganite's iron concentration, a 50-pound dog would need to consume several pounds of the product to reach concerning iron levels. While not impossible (dogs have been known to eat surprising quantities of things), this is unlikely from normal lawn exposure.

The more common scenario is a dog eating a small amount of Milorganite granules from the lawn surface or the bag. In these cases, mild symptoms may include temporary vomiting, loose stool, or decreased appetite lasting 12-24 hours. These symptoms typically resolve on their own without veterinary intervention. If your dog consumes a large quantity, contact your veterinarian for guidance based on the amount ingested and your dog's weight.

One quirk of Milorganite is that some dogs are attracted to its smell. As an organic product derived from biological materials, Milorganite has a distinct odor that some dogs find interesting. This can lead to dogs rolling in freshly applied Milorganite or attempting to eat it from the lawn surface. To mitigate this, always water Milorganite in immediately after application. Thorough watering washes the granules into the soil, reduces the surface odor, and makes the product less accessible to curious dogs.

Milorganite also has the advantage of being a slow-release fertilizer. The nutrients are bound in organic matter and released gradually through microbial decomposition in the soil. This means there is no concentrated salt burst on the soil surface like quick-release synthetic fertilizers produce, further reducing any irritation risk to pets that walk on treated areas.

For maximum safety, follow these practices when using Milorganite with dogs in the household. Apply at the recommended rate of 32 pounds per 2,500 square feet. Water the lawn thoroughly after application, aiming for at least a quarter inch of water to move granules off grass blades and into the soil. Keep dogs off the lawn until the grass has completely dried, which usually takes 12-24 hours depending on weather conditions. Store bags in a sealed container or closed area that your dog cannot access.

While Milorganite is significantly safer than most alternatives, it is not marketed or certified as "pet safe" by any regulatory body because no fertilizer carries such a certification. The manufacturer acknowledges on their website that Milorganite is frequently used by pet owners and does not contain ingredients known to be harmful to animals when used as directed. This practical track record, combined with the absence of toxic chemical additives, makes it a top choice for pet-owning households looking for effective lawn nutrition.