All animals need some iron in their diets to survive, but too much iron can be deadly to dogs. If a dog eats a significant amount of ionizable iron, there may be toxic effects on the cardiovascular, metabolic, liver, nervous, and gastrointestinal systems. If you suspect your dog has ingested iron-containing compounds, contact your veterinarian immediately.
Dogs cannot excrete excess iron from their bodies. Left untreated, iron toxicity may be fatal.
How Dogs Get Iron Poisoning
Dogs are known to get into things they shouldn't, leading them to eat dangerous things. Iron poisoning most often occurs after a dog eats large quantities of vitamins and mineral supplements. Because some tablets are sugar-coated, they are attractive to dogs.
Though less common, dogs may ingest fertilizers containing iron. Even dome hand warmers have toxic iron in them. Fortunately, metallic iron, iron-containing alloys, and iron oxide (rust) are not ionizable (bioavailable), and therefore not toxic.
In dogs, the toxic dose can be calculated by milligrams of ionizable iron ingested per kilogram of body weight.
- Less than 20 mg/kg: non-toxic to dogs
- 20-60 mg/kg: may lead to clinical signs of toxicity
- Over 60 mg/kg: can cause serious or even fatal toxicity
Signs of Iron Poisoning in Dogs
If a dog ingests too much ionizable iron, it can have a toxic effect on the cardiovascular, metabolic, liver, nervous, and gastrointestinal systems. This means poisoned dogs may show a variety of signs.
Gastrointestinal signs tend to appear within six hours of iron ingestion, the first stage of iron toxicity. Signs commonly include vomiting and diarrhea. Dogs often also have lethargy in this stage. Abdominal pain and gastrointestinal bleeding may also occur.
The second stage of iron poisoning tends to occur six to 24 hours after ingestion. At this stage, it may seem like the dog has recovered as signs of toxicity stop.
Around 12-96 hours after iron ingestion, the third stage of iron toxicity begins. Dogs again begin to have GI signs including vomiting, diarrhea, lethargy, GI bleeding, and abdominal pain. In addition, dogs may develop tremors, show signs of shock, and develop metabolic acidosis (when too much acid accumulates in the body).
Dogs that survive the third stage may develop a GI stricture, causing an obstruction. This is typically a secondary effect of the GI damage that occurred in the earlier stages.
If you suspect your dog has iron poisoning, contact your vet immediately, whether or not you see signs. Your vet may recommend you induce vomiting if your dog recently ate iron-containing compounds. Never induce vomiting without speaking first with your vet. In some cases, vomiting up toxins can cause more harm than good.
Treatment of Iron Poisoning in Dogs
The faster your pet is seen by a vet after iron ingestion, the better the chances of recovery. If your dog has eaten the iron recently, your vet may induce vomiting or perform gastric lavage (pump the stomach). Gastric lavage should not be performed if the dog is vomiting blood or if too much time has passed since ingestion.
If more time has passed since your dog ingested iron, your vet will need to run some diagnostic tests. This typically includes blood work and urinalysis. Radiographs (X-rays) may be needed to look for pills that have attached to the lining of the GI tract. Treatment recommendations will depend on the test results.
Surgery may be necessary if pills have adhered to the GI tract.
Chelation agents can be used to bind to free iron, preventing further damage to the body.
Additional supportive care includes IV fluids, gastroprotective medications, and anti-vomiting medications. Most dogs will need hospitalization during these treatments.
Activated charcoal is often used in cases of toxin ingestion because it binds to many toxins and prevents them from being absorbed into the body. However, activated should not be used in cases of iron poisoning as it does not bind with iron to deactivate the toxin.
Recovery from Iron Poisoning in Dogs
Dogs have the best chance of recovery from iron poisoning if they receive treatment before they develop clinical signs of toxicity. If signs do not appear within eight hours of iron ingestion, then the dog is very likely to recover. Close observation is necessary during this time period.
The prognosis is guarded if the dog begins to show signs of iron toxicity. These dogs must be closely monitored for several days while they receive treatment. Once discharged, these dogs must be watched closely at home for signs of GI obstruction. Follow up vet visits will also be necessary for about six weeks following the ingestion of iron. Your vet may also recommend specific restrictions on food intake and activity.
Be sure to follow your vet's instructions in order to give your dog the best chance of recovery.
Remember that the best way to protect your dog from iron exposure is to keep dangerous items out of your dog's reach.
Hovda, Lynn R et al. Blackwell's Five-Minute Veterinary Consult Clinical Companion: Small Animal. 2nd ed., John Wiley & Sons, 2016, pp. 707-715.