My Dog Killed a Rat: Should You Be Worried?
Killing a rat does not automatically make a dog ill, and no study gives the odds, so call your vet today if yours ate any of it, was bitten, or rat poison could be nearby, and check its leptospirosis vaccine date. Poison is the risk you cannot see: bleeding from anticoagulant bait usually shows 3 to 7 days after a toxic dose, so a dog that looks fine tonight has not been cleared. Infection is the other concern, since 11 to 18 per cent of urban rats tested positive for Leptospira in three North American PCR surveys.
What happened, the risk, and what to do today
| What happened | The risk | What to do today |
|---|---|---|
| Dog is vomiting, bleeding, very weak, shaking, having seizures or struggling to breathe | Poisoning or serious infection | Emergency vet now; bring any bait packaging |
| Ate any of the rat, and bait may be in use nearby | Secondary (relay) poisoning | Call your vet or a poison line now, before signs appear |
| Ate any of the rat, no known bait | Roundworm larvae; plague in parts of the West | Tell your vet and ask whether a faecal test is worthwhile |
| Bite or puncture on the face, mouth or paws | Wound infection; rat-bite fever bacteria | Vet visit the same day |
| Killed it, did not eat it, no wounds, vaccine current | Lower, not zero: leptospirosis | Bag the rat safely; watch for two weeks |
| Killed it, did not eat it, leptospirosis vaccine missing or overdue | Leptospirosis | Phone your vet for advice and book the vaccine |
Compiled by The Pest Control Brief from the Merck Veterinary Manual, the ACVIM consensus statement on leptospirosis and CDC. This is triage, not a diagnosis; your vet decides on any testing or treatment.
What to tell the vet, and who to call
- When it happened, and whether the dog swallowed anything or only shook the rat.
- Any bait in use at your home, a neighbour’s, your building or a nearby business. Get the product name or label, because Merck warns that baits should not be identified by colour, shape or size alone.
- The date of the last leptospirosis, rabies and parasite doses.
- Where it happened, especially if you are in Arizona, California, Colorado or New Mexico.
- Any wounds you found on the face, lips, gums or paws.
The ASPCA Animal Poison Control Center is on (888) 426-4435 and Pet Poison Helpline, which runs 24 hours, is on (855) 764-7661. The ASPCA says a consultation fee may apply. Do not try home treatments: the vet or poison line decides what happens next.
Was the rat poisoned? Four bait types, four different answers
Most articles on this query treat “rat poison” as one thing, or leave it out altogether. Merck treats each class separately, and the picture differs sharply.
| Bait class | Poisoning from eating a poisoned rodent (Merck) | Signs after a toxic dose | Usual onset |
|---|---|---|---|
| Anticoagulants (warfarin, diphacinone, chlorophacinone, brodifacoum, bromadiolone, difenacoum, difethialone) | Listed as a cause of poisoning in non-target animals | Poor appetite, lethargy, weakness, nosebleed, breathing difficulty | 3 to 7 days |
| Bromethalin | Not documented in research; theoretically possible, particularly in cats; anecdotal reports in very rare cases | Tremors, seizures, hind leg weakness or paralysis | Usually 1 to 7 days; 4 to 36 hours at high doses |
| Cholecalciferol (vitamin D3) | Acute cases not documented in research; chronic eating of poisoned prey caused mild, reversible signs | Weakness, poor appetite, vomiting, heavy thirst and urination | 12 to 48 hours |
| Zinc and other phosphides | Theoretically possible | Rapid vomiting, sometimes with blood | Minutes, rarely up to 24 hours |
Compiled by The Pest Control Brief from the Merck Veterinary Manual chapters on each class and EPA’s list of active ingredients. Onset figures come from direct exposure; a dog that ate a poisoned rat may receive a smaller dose. We found no study giving the odds that one poisoned rat makes a dog ill.
EPA says second-generation anticoagulants (brodifacoum, bromadiolone, difenacoum, difethialone) stay in animal tissue longer and pose greater risks to animals that feed on poisoned prey. They are not registered for consumer products, so a rat from a site with a professional bait contract deserves more caution than one from a house with snap traps. A bait station does not settle it either, because a rat can feed, leave and die in your yard.
Wildlife testing shows how far these compounds travel: California’s state laboratory found anticoagulant residues in 128 of 158 wild animals tested in 2022, though exposure is not the same as poisoning. Our rodenticide exposure data breaks that down by group.
None of the top results we read mention this: Merck says fumes from the vomit of a phosphide-poisoned animal are toxic to humans. If phosphide bait is a possibility and your dog vomits, keep people back from it, ventilate, and tell the clinic before you arrive.
How likely is leptospirosis from one rat?
The 2023 ACVIM consensus statement calls rodents, especially Rattus norvegicus, the most important reservoir hosts worldwide. Merck says the bacteria often spread through direct contact with urine or other body fluids of an infected host, which shaking a rat can involve. The share of rats infected varies far more than most articles suggest.
Antibodies show past exposure, while PCR finds current infection, so Baltimore’s 65.3 per cent is not directly comparable with the rest. Location matters as well: in Vancouver, block-level prevalence ran from 0 to 66.7 per cent within one neighbourhood, so a city average says little about your rat. Assume it could be a carrier.
- Timing. ACVIM gives an incubation period of about 2 to 14 days. CDC gives 2 to 30 days for people, so tell a vet about the rat if your dog falls ill later.
- Early signs. Poor appetite, lethargy, vomiting, and increased thirst and urination. Merck says acute kidney injury is the most common presentation in recent years.
- Vaccination. ACVIM recommends vaccinating all dogs annually from 12 weeks of age, regardless of breed. Merck says current vaccines give good protection for at least one year.
- Your own risk. ACVIM says shedding in urine usually starts 7 to 10 days after infection and that transmission from sick dogs to people appears to be low with basic precautions. Wash up after handling the dog’s urine or anything soiled by the rat.
The other diseases: which ones apply to you
| Concern | What the source says | Where it applies |
|---|---|---|
| Rabies | A 2002 CDC report says no rodent-to-human transmission has been documented and small rodents are not a wildlife reservoir. Bats, skunks, raccoons and foxes are the usual US carriers | Low concern; still give your vet the vaccine date |
| Rat-bite fever | CDC says dogs can be infected through contact with infected rodents. S. moniliformis turned up in 23 of 133 New York City rats (17 per cent) | Any bite wound |
| Roundworm | CDC says Toxocara can pass when a dog eats a host carrying larvae in its tissue | Dogs that eat the rat |
| Plague | Merck says dogs are less likely than cats to fall ill but can be infected by eating infected rodents or through flea bites; severe disease is rare | Mostly Arizona, California, Colorado and New Mexico, plus other western states |
| Tularaemia | CDC reports cases in every state except Hawaii, with rodents, rabbits and hares especially susceptible. Its page does not address dogs | Mention any local die-off to your vet |
| Fleas | CDC says fleas pick up flea-borne typhus from rats, cats and opossums | Ask whether your dog’s flea product is current |
Compiled by The Pest Control Brief from CDC, Merck and Firth and others, mBio, 2014.
What to do with the dead rat
- Keep the dog away, and do not use bare hands. CDC says to wear rubber or plastic gloves.
- Spray the rat and the surrounding area with disinfectant and let it soak for 5 minutes, or longer if the label says so.
- Put it in a plastic bag, knot it, place that in a second bag and knot that too.
- If poison is a live question, ask your vet before binning it. Merck lists liver and kidney among the samples used in an anticoagulant screen, though not every clinic will want it.
- Otherwise put it in a covered bin that is regularly emptied. Wash gloved hands, remove the gloves, then wash your hands with soap and warm water.
If it was a mouse or a possum
Mouse. EPA lists bromethalin, cholecalciferol and zinc phosphide as compounds used to control mice, and Merck rates secondary poisoning from those as undocumented in research or theoretical. Anticoagulants are used on mice too, so the triage table still holds, though a mouse is a smaller meal than a rat. Deer mice spread the most common US hantavirus, per CDC, so follow the same cleanup steps. Our rat vs mouse guide helps if you are not sure which it was.
Possum. UC IPM says opossums carry leptospirosis, tularaemia and other diseases, host cat and dog fleas, and that pets are often injured in confrontations because of their sharp teeth. Check the mouth and face for wounds and call your vet.
Stopping the next one
A dog that catches a rat has told you rats are close. Our guide to what attracts rats covers the food, water and shelter side, and rodent removal costs sets out what a professional job involves. If you hire one, ask for trapping and exclusion over bait where pets roam: see pet-safe pest control products. Ask neighbours and your landlord what they use, since their bait can end up in your yard inside a rat.
Frequently asked questions
What to do if my dog killed a rat?
Check the mouth, face and paws for wounds, keep the dog away from the body and find out whether anyone nearby uses bait. Call your vet today if it ate any of the rat, was bitten or poison is possible. Bag the rat using gloves and check the leptospirosis vaccine date.
Should I be worried if my dog killed a rat?
Be alert rather than alarmed. A dog can look well at first: anticoagulant bleeding usually appears 3 to 7 days after a toxic dose, and leptospirosis takes about 2 to 14 days to show. A healthy-looking dog on the first evening does not rule out either, so watch for two weeks.
Is it dangerous if my dog killed a rat?
It can be, mainly through secondary poisoning, leptospirosis and bite wounds. Merck lists anticoagulants as a cause of poisoning from eating prey, while relay poisoning from other bait classes is rare or theoretical. The ACVIM consensus statement recommends annual vaccination against leptospirosis. Rabies from rats is a low concern.
Can a dog get sick from killing a mouse?
Yes, though a mouse is a smaller exposure than a rat. The same routes apply: bait inside the mouse, Leptospira, parasites and fleas. Compounds often used for mice, such as bromethalin, have little documented secondary risk according to Merck. Call your vet if your dog ate it or if any signs appear.
My dog killed a rat but did not eat it: will he be OK?
Probably, particularly if he has no wounds and a current leptospirosis vaccine. Not swallowing the rat largely removes the poison route, but mouth contact with blood and urine still carries a leptospirosis risk. Watch for poor appetite, lethargy, vomiting or heavy thirst for two weeks, and phone your vet if any appear.
Sources
- Merck Veterinary Manual, Professional Version: Overview of Rodenticide Poisoning; Anticoagulant Rodenticide Poisoning; Bromethalin Poisoning; Cholecalciferol (Vitamin D3) Poisoning; Phosphide Poisoning in Animals.
- Merck Veterinary Manual: Leptospirosis in Dogs; Plague in Animals.
- Sykes, J.E. and others, 2023 Updated ACVIM consensus statement on leptospirosis in dogs, Journal of Veterinary Internal Medicine 37(6), 2023.
- US Environmental Protection Agency, Restrictions on Rodenticide Products.
- Centers for Disease Control and Prevention: About Leptospirosis; About Rat-bite Fever; About Plague; About Tularemia; About Rabies; About Flea-borne Typhus; About Hantavirus; How to Clean Up After Rodents; DPDx: Toxocariasis.
- Centers for Disease Control and Prevention, Rabies in a Beaver: Florida, 2001, MMWR 51(22), 2002.
- Easterbrook, J.D. and others, A survey of zoonotic pathogens carried by Norway rats in Baltimore, Maryland, USA, Epidemiology and Infection, 2007.
- Firth, C. and others, Detection of zoonotic pathogens and characterization of novel viruses carried by commensal Rattus norvegicus in New York City, mBio, 2014.
- Himsworth, C.G. and others, Ecology of Leptospira interrogans in Norway rats in an inner-city neighborhood of Vancouver, Canada, PLoS Neglected Tropical Diseases, 2013.
- Stone, N.E. and others, Host population dynamics influence Leptospira spp. transmission patterns among Rattus norvegicus in Boston, Massachusetts, US, PLoS Neglected Tropical Diseases, 2025.
- California Department of Fish and Wildlife, Wildlife Health Laboratory, 2022 annual report on pesticide exposures and mortalities in non-target wildlife, 2023.
- University of California Statewide IPM Program, Pest Notes: Opossum, Publication 74123.
- ASPCA Animal Poison Control Center; Pet Poison Helpline.
