To bleed or not to bleed – Rat bait poisonings

Lots of options for getting even with rats, if that's what you're after.

There are other options to removing rodents if you have pets. I must admit, my cat does a fine job at killing the ones around our house and I’m not talking about the out of doors variety!

Rat bait, or rodenticide, poisonings are a relatively common occurrence in emergency practice.  The majority of cases present after the owner has noticed some baits moved about where their dogs may have access, or occasionally, they notice very green pooh which may indicate what pooch has been eating.  In the past weeks we have seen two clinical cases of rodenticide poisoning in our veterinary hospital, as well as the early non-clinical ones, which made me think, maybe it is time to write a blog about the dangers of rat baits.

Funnily enough, many people think if their dog eats the rat bait, they will get sick very quickly.  I’m not sure what signs they are expecting…vomiting? Diarrhoea? Seizures?  Rodenticides don’t cause any of these signs in the first day or two, and in fact not cause any abnormal signs initially apart, perhaps, from green pooh!  The vomiting, diarrhoea and seizures may develop several days later, but that depends on which organ system is first affected by the poison.

Rat baits cause a slow and probably very horrible death for rats.  They are designed so that the rat will eat the bait and go away to die in their nest, and hopefully the human in charge doesn’t have to see rotting mice bodies lying around their kitchen.  At least that is one way to put it I guess.  When dogs eat the bait (cats are a little smarter but are at risk if they eat the rat before it is killed by the bait) it will similarly take several days before the signs develop.  This can lead to a false sense of security for the pet owner who is expecting their dog to start seizuring or vomiting or show some other sign of poisoning, only to find them flat and pale several days later.

How do they work?  Well, there are a few different generations of rodenticides with the newer ones taking longer to kill and requiring a longer course of treatment.  Warfarin is the earliest type and is still used today.  It is much shorter acting than the newer poisons and only requires a week of therapy to reverse the signs.  The longer acting, newer generation rodenticides require up to 4 weeks of therapy.

Rodenticides act by causing a depletion of vitamin K1 in the liver.  In the healthy animal, vitamin K1 is utilized in the formation of clotting factors and then regenerated in the liver by another mechanism.  It is not a vitamin that is commonly obtained through food, like vitamin C for example.  The rodenticide blocks this recycling step so that there will no longer be any active vitamin K1 for inclusion in the production of clotting factors.  It takes time for all the clotting factors that have been produced to be utilized in the body but once they have passed their “use by date”, the body’s internal homeostatic mechanisms don’t function as well so normal tissue repair cannot occur and animals can bleed to death.

Often the cause of such severe internal bleeding is not obvious, however, without treatment it will not cease and death will occur.  Without fail.  Signs of rodenticide poisoning are not always clear.  In some cases blood loss is not obvious, particularly if the animal has bled into the brain cavity or the spinal cord.  Such bleeds may cause the animal to have seizures or become paralysed, respectively.  In many cases, the bleeding occurs into the abdomen or chest cavities though other sites are occasionally seen.  One of our patients bled into the bladder and was seen to pass urine that looked exactly like blood!

The treatment for rodenticide toxicity is so easy and simple to perform if implemented early, and so there is really no reason why it shouldn’t be sought early when owners are aware of their pet’s access. Treatment involves making the dog vomit if caught within hours of ingestion, possibly followed by administration of activated charcoal to mop up any toxins that may be wandering around the gastrointestinal tract.  Charcoal will not provide any benefit once the clinical signs have developed.

If the ingestion has been caught early, lots of the poison has been vomited up and there is a very strong assumption that the dose eaten may be less than that required to cause clinical poisoning, the dog may not require any treatment.  However, this is ideally a decision for your vet to make.  If the decision to NOT treat is made, it is extremely important that your dog has a blood test 48-72hrs later to determine for certain whether or not treatment is required (one very specific blood test may tell us if there is a problem developing with blood clotting).

Fortunately there is an antidote, vitamin K1 tablets (injection or liquid forms are also available).  That’s right, just a simple, twice daily vitamin tablet!  Yep, this simple vitamin will ensure that your dog, who may have eaten a whole packet of rat bait, will not bleed to death as a result.  Ok, maybe it is not as simple as that, I mean you can’t just go to the pharmacy and buy a multi-vitamin for your dog, and the wrong type of vitamin K won’t do an awful lot of good.  The medication is not cheap, however, much more cost effective and successful than treating with fresh frozen plasma and possibly blood transfusions if the dog reaches the point of severe internal haemorrhage.

It is not worth taking the risk with your pet if you think they may have, or know they have, eaten a rat bait.  Even if you make them vomit at home yourself, it is so important to have a vet check them than to just sit and wait until you see signs of poisoning.  Why gamble with your dog’s life?

Fortunately the two dogs we saw, despite coming into the hospital looking close to death, responded extremely well to therapy and within 24 hours were bright and happy with no further bleeding.  The last point I wish to make is to never assume that because the bait is placed in a position where you think your dog can’t reach it, that your dog won’t reach it.  They are ingenious at accessing the unaccessible, and more so if your rats have shifted the bait from one place to another!


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