Most dog owners are aware of the fact that rat poison is toxic to dogs, but what if a dog ate a dead rat that was poisoned, can the dog indirectly get poisoned too? This is a very good question and a reasonable concern too. On top of that, another concern is whether eating a dead rat can expose the dog to any potential illnesses or other problems. Turns out, rats can indeed pose some risks to dogs and sometimes some serious ones too. If your dog ate a dead rat, you may therefore want to play it safe and consult with your vet.
Problems with Secondary Poisoning
If the dog ate a rat that was likely to be poisoned, there are risks that your dog can become poisoned too. The medical term for this is "secondary poisoning," also known as "relay toxicosis."
Secondary poisoning is therefore the phenomenon of an animal becoming poisoned from ingesting another animal that has poison in its system.
If the level of toxicity in the eaten animal is high enough, then the predator can be harmed from such ingestion. According to National Pesticide Information Center, rat poisons with the highest risks for causing secondary poisoning to dogs include chlorophacinone, diphacinone, bromadiolone, and brodifacoum.
The good news is though that when a dog ingests a mouse or a rat, the amount of poison ingested is often not enough to cause problems considering that the amount that it takes to kill a mouse is significantly less than what it takes to affect a dog, explains veterinarian Dr. Hewitt.
Live Versus Dead Rat
How serious the issue of eating a dead rat may be depends on several factors. For instance, there may be a difference depending on whether the rat was killed by the dog or the rat died from the ingestion of poison. Also, there can be differences on the outcome based on the type of poison ingested.
The majority of rat poisons contain anticoagulants such as warfarin. How do they work? They work by interfering with the correct functioning of certain chemicals made by the liver. These chemicals are responsible for allowing platelets to plug up any holes in blood vessels and create clotting factors that are meant to prevent serious bleeding. These chemicals are what anticoagulant rat poisons prevent the body from making, explains veterinarian Dr. Hewitt.
When the rat therefore ingests an anticoagulant product, its body basically bleeds to death. In most cases, this doesn't happen immediately though, but only days later once the rat's body's reserve of active clotting factors is being depleted.
If the mouse was therefore already dead from the poison when the dog ate it, there are chances that the rat or mouse did not have any remaining traces of poison in its body the day it died, explains veterinarian Dr. Fiona. The poison was likely out of the rodent's system by then and the rat or mouse therefore died slowly from internal bleeding.
If the rat or mouse was alive though but the dog killed it, there may be chances that the rat or mouse may have still had some poison stored in its stomach and intestines. Again though, the amount in the stomach is minimal and it would take eating several mice or rats for the dog to ingest a significant amount of poison that would be concerning.
"Anticoagulants: Relay toxicosis (poisoning by eating a poisoned animal) is unlikely unless a large percentage of the diet consists of rodents or other prey species, which might be ingesting rodenticides." ~Veterinary Information Network, Inc.
Other Types of Poisons
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Things may be more problematic in dogs who ingest mice that have been poisoned with the newer generation neurotoxic rodenticides that were meant to replace warfarin as more and more mice became resistant to it.
These types of rat poison require a one-time-ingestion (single-dose anticoagulants) for them to be lethal to mice and the worst part is that for dogs who ingest this type of poison there is no antidote. Only supportive care is available.
Many of these single-dose anticoagulants are found to be more toxic because they bind more to the chemicals responsible for making blood clot. They also tend to be stored in the liver and are therefore not easily excreted from the body. For example, the plasma half life of bromethalin is considered to be six days, making relay toxicosis likely, explains Dr. Karyn Bischoff.
These products are known for causing seizures and other neurological signs such as hyperexcitability, muscle tremors and other neurological problems.
Fortunately, most single-dose rodenticides are not sold in stores to the public but rather are only supplied to licensed applicators . However, the inquisitive nature of dogs and their powerful senses makes them prone to finding and being attracted to dead mice.
"It is a concern if the rodenticide contained bromethalin which can cause seizures within hours after exposure. The anticoagulant rodenticides don't cause uncontrolled bleeding for up to 4 days after exposure and it's unlikely that there would be enough of that type of rodenticide present in a mouse to be harmful to your dog in any event."~Dr. Salkin, veterinarian
Other Possible Problems
There are a few other concerns in dogs eating mice or rats other than secondary poisoning. One concern is the risk for an obstruction. The bones of a rat can get lodged and cause a blockage or their sharp edges can puncture the dog's intestines, points out veterinarian Dr. Scott. Signs that warrant a trip to the vet for x-rays include loss of appetite, lethargy and vomiting of water and food. The risks for obstructions are higher for small dogs.
As with eating anything new and unusual, the ingestion of a rat may cause digestive upset in dogs. This stomach upset is usually only temporary, but these symptoms though can also be sign of an obstruction as discussed above, therefore it's always best to tread carefully and consult with the vet when in doubt.
Other possible problems associated with licking or ingesting dead mice is the potential for contracting leptospirosis. Most dogs are fortunately vaccinated against lepto. The vaccine is the 'L" part of the DHLPP distemper combo most dogs receive from their vets. And for those who live in the in the desert Southwest (New Mexico, Arizona, and southern California), a concern of dogs who lick or eat mice is the plague which can be carried by rats and their fleas.
Did you know? Rodents like mice and rats do not usually carry rabies. Rabies is more of a concern with raccoons and bats.
Course of Action
If you suspect your dog ate a rat that could have been poisoned, consult with your vet. Your vet may decide to induce vomiting if still on time (generally within 2 hours of ingestion) or may run some blood clotting tests (called PT/PTT).
Generally, dogs start showing signs of secondary poisoning from anticoagulant rat poisons after 2 to 3 days of ingestion. Signs of trouble to watch for include pale gums, bruising of the belly, pinpoint blood blisters on the gums and whites of the eyes, lethargy, coughing up blood or blood in the stool or urine.
For anticoagulant rat poisoning there is fortunately an an antidote: Vitamin K 1, but it's not the same vitamin K that you find over the counter. To obtain vitamin K1 for your dog you will need a prescription from your vet. Vitamin K1 can be given to dogs who have eaten a poisoned mouse just to be safe and it's fortunately a fairly inexpensive drug.
- Rodenticides: Topic Fact Sheet, National Pesticide Information Center
- ASPCA: Cholecalciferol Poisoning
- Cornell University: Rodenticides & Regulations