Tuesday, October 9, 2007

Toxicology Tuesday, October 9

[Next week, I promise we will go back to the True/False format, and stop with the hard stuff. My sister says "It doesn't matter what the toxic principle is, if your pet eats poison, take it to the vet. You are being too picky with this series." But, the Science Chimp says "Knowledge is Good," or words to that effects, so bear with me one more time.]

The last poison in our rodenticide series is bromethalin, found in brand names like Rampage and Real Kill.

Remember the questions:

1) What is the toxic principle? (How does it kill?)
2) What are the signs/symptoms of poisoning?
3) Is there any treatment?
4) How bad is it -
(On a relative scale of Fair - treatable if caught in time, Poor - might not survive even with treatment, or Grave - likely to be fatal even with treatment)

Give it a try, answer any or all questions, in part or in total. No one is laughed at for wrong guesses, and all attempts at answering will receive praise and public accolades.


Bromethalin is a neurotoxin, and the signs are related to dysfunction of the CNS (Central Nervous System), primarily brain swelling. These signs are highly variable, depending on the dose ingested. Low doses in dogs lead to depression, anorexia, vomiting, and tremors, which may not show up for several days. Paresis (muscle weakness) or paralysis may also occur. High doses can cause a hyperexcitable state, tremors, increased reflexes, running fits, and localized or generalized seizures. In cats, the signs include depression, ataxia (incoordination), abdominal swelling, paralysis, and convulsions. Death can result from either high or low dose toxicity in both species.

These signs are non-specific; they are seen in many kinds of neurologic disease. If you don't have a history of exposure to the toxin, it might go undiagnosed, as it wouldn't show up in any of the routine laboratory work. It can take up to 4 days for initial signs to show in a dog, and may progress for one or two weeks before death from respiratory failure.

There is no antidote to bromethalin. It is rapidly absorbed into the system, and reaches peak blood levels a mere 4 hours after ingestion. If ingestion is observed, immediate decontamination (as discussed in previous posts) is the first course of action, and may be of some benefit. Otherwise, treatment is mainly supportive, including cautious use of IV fluids, diuretics, and steroids and mannitol to reduce brain swelling. The prognosis is grave in pets which are exhibiting symptoms.

Bormethalin was the second most common rodenticide I found when I shopped several local stores. About 75% of the products readily available were Vitamin K antagonists and about 25% contained bromethalin. I only found one store that carried one brand of cholecalciferol (Vitamin D) based mouse poison.

To sum up our three main types of mouse and rat poison:

1) Brodificoum, bromadiolone, and warfarin: Deplete the body's store of Vitamin K, causing bleeding problems. Antidote is Vitamin K. Prognosis: Fair. A good chance for recovery if treatment is started in time. Most common poison on the market.

2) Cholecalciferol: Vitamin D. Causes mineralization of soft tissues, especially the kidneys. No antidote, but early and aggressive treatment can speed the excretion of excess calcium, limiting the injury to major organs. Prognosis: Poor. Even with treatment, kidney or heart damage may leave animal with long-term health problems. Least common product available.

3) Bromethalin: A neurotoxin causing nonspecific signs. No antidote. Prognosis: Grave. Death is likely even with treatment. Second most common product.

So, how do you get rid of mice? Sticky traps are non-toxic, but I think we all agree that it is a cruel way for a critter to die. Old fashioned snap-traps are easy, quick, painless and non-toxic.
If you can't stand to take the mouse off the trap, toss it - they're cheap. Unless you have a tiny pet, there is limited injury to "non-target organisms." Or, get a cat. I have one I will rent you.


Julie Zickefoose said...

Sisters always know better, right?
;-) Maybe this isn't much of an endorsement, coming from a chimp, but I really really want to know this stuff. So you can count one (chimp) who's diggin' T. Tuesdays.
I have not a clue about this poison. I know a bit about warfarin, nothing about bromethalin. Tell us, O Oracle of Poison.
I've caught four cute white-footed mice in the last two days with my decidedly non-toxic Victor traps. It's a lot quieter at night around here now...and there's no secondary kill to worry about.

Kathy said...

I agree that knowlege is good, but to take the pet to the vet right away.

This week I'm answering without doing any research, so may be completely off base with my answer. One package says "single feed" results, so that sounds pretty toxic to me.

My best guesses are:
toxic principal: nerve toxin
signs/symptoms: cardiac/respiratory arrest
treatment: none
how bad: grave

Now, I'm off to do research! :-)

Anonymous said...

1) It is a neurotoxin, affecting the central nervous system.
2) Symptoms largely of the nervous system...hyperexcitability, paralysis or weakness of hind legs, tremors, seizures, staggering gait. Can cause heart irregularities.
3) Induce vomiting. Gastric lavage with activated charcoal. Symptom management since there is no specific antidote.
4) Can be fatal, usually at higher amounts of ingestion, but some dogs will show symptoms even at relatively low amounts.

Keep up the Toxic Tuesday. It's amazing how these facts stay in one's head. Just last week my neighbor laughed about her little dog eating more than half a box of raisins. Recalling a Toxic Tuesday, I told her to contact her veterinarian immediately. He kept her in the clinic for treatment. She's fine now, thanks to your blog. I gave my neighbor your Web address and she has accessed the archives for Tuesdays. She's passing the information along to all the dog owners she knows.

Lisa said...

Ugh. Looked this one up - bad news, esp. since it can masquerade as a lot of other CNS problems if you don't already know the dog (or cat) ate the bait. The other thing I found interesting was that the ASPCA recommends you *don't* do activated charcoal once the critter's become symptomatic - that it's really only good as an initial attempt to reduce the amount of poison in the animal's system.

KatDoc said...


Glad that the grapes and raisins post could help your neighbor's dog. That is what Tox Tues is all about.

By clicking on the "Toxicology" link of the "Labels" section, you can pull up all the posts I have done on this subject, including the non-toxic foolies that I put in from time to time, just to keep you all on your toes.

Waiting for more guesses before I put up the answer to this one.


Anonymous said...

Just thought you would like to know. My neighbor whose dog ate the raisins said she started by checking the Tuesday Tox blogs, and became so interesting in your blog...the writing and pictures that she read all the archives. You've won over another reader.

She has called me several times with such things as: did you know sugar-free gum is toxic? etc., etc., etc. And did you read the posts about dog training? I assured her that I read your blog and never miss a one.

KGMom said...

First, full disclosure--I did research, which is what I'd do were it not for the Toxic Tuesday seminar series.
) What is the toxic principal? (How does it kill?)
It causes a build up of cerebral spinal fluid, which causes a buildup of intracranial pressire. First comes paralysis, convulsions then death (for rats).
2) What are the signs/symptoms of poisoning?
Lack of movement in pet, vomiting, seizures.
3) Is there any treatment?
Induce vomiting, use charcoal to bind poison, use steroids to reduce swelling.
4) How bad is it--depends on how much the dog or cat got. So probably best option would be treatable if caught in time.

nina said...

Hmm. Sounds pretty awful:
Affects CNS,
symptoms--lack of ability to bark, lethargy, coma
No antidote
Corticosteroids help, but must remain on them forever?

Which, for me, adds up to something I would never choose to use!

nina said...

And--another reason to leave the snakes alone! (except for Julie's copperheads)

KatDoc said...

Well done! Give yourselves a standing ovation - this was a hard series of quizzes.

The answer to today's Tox. Tues. summarizes what we have learned in the past few weeks about mouse and rat poisons. If you have to use one, the Vitamin K antagonists are the best, in my opinion.

Yep, Nina - snakes are good mousers, but don't work so well in the cooler weather.

Anon: Thanks for your kind comments and for getting your neighbor hooked on the blog, too. I have several more toxicology posts in the hopper (and some non-toxic tricks, just you keep you all honest.) Not sure what I will do when I run out - Maybe "Foreign Body Friday?"


Anonymous said...

According to an article i read recently an extremely large dose of bromethalin is necessary to be toxic to dogs.


KatDoc said...

According to Purdue's Animal Disease Diagnostic Lab's newsletter article from Spring of 1997, a 10 lb dog would need to eat 5-6 packages, and a 10 lb cat would need to eat 1 or 2 packages to ingeste a fatal dose. Dr. Peay's number of 15 packs for a 30 lb dog is right, so obviously, a bigger dog has a better chance of surviving.

BUT, small dogs would need a lot less - a 5 lb dog would only need to eat two or three packs - and smaller amounts, while perhaps not fatal, would still mean the animal suffers severe neurologic signs. Also, there is no antidote or specific treatment for this poison. Do you want to take a chance?