Tuesday, September 18, 2007

Toxicology Tuesday, September 18

This is Toxicology Tuesday with a Twist. I’m not going to insult you by asking you if rat and mouse poisons are toxic or not. You know they are. What I am going to do is present you with three different types of rodenticides over the next three weeks and ask you the following questions:

What is the toxic principal? (That is, how does it poison – kidney failure, liver damage, etc.)

What signs might you expect to see?

What, if any, treatment is available?

How toxic is it/what is the prognosis? (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)

This week, we are looking at D-Con and other brands of mouse poison that contain brodifacoum, bromadiolone and diphacinone.

Are you ready for the challenge? Try it; see how much you know, or can guess.

Answer: By far, the most commonly available rodenticides are the anticoagulants. The toxic principal of these agents is to cause depletion of the body's store of Vitamin K. Since this fat soluble vitamin is necessary for the manufacture of several clotting factors, running out of Vitamin K means losing the blood's clotting ability, and the development of bleeding problems. Warfarin was the original product, and is still available, though not common. It fell out of favor because it requires rodents to feed multiple times in order to ingest enough poison to kill them. Those early animals which didn't receive a fatal dose bred, leading to the creation of warfarin-resistant populations. The second generation products, like brodificoum, kill with one feeding, thus eliminating the resistance problem.

It typically takes 3 to 5 days for an animal to run out of Vitamin K, so the signs don't show up right away. Bleeding can be obvious - blood in the urine, stools, or vomitus, bloody nose, bleeding from the gums, excessive bleeding from a minor wound or from clipping a toenail too short - or it can be more subtle. Pinpoint spots of blood under the skin called petechiae may be seen. (Birding note: The Yellow Warbler got his Latin name, Dendroica petechia, from
the fine red streaks on his breast.) Bleeding into the joints can cause lameness, internal bleeding may cause shock with no external signs of injury.

In cases of known ingestion, treatment consists of decontamination (induce vomiting, gastric lavage, use of cathartic agents, and administration of activated charcoal) and monitoring blood clotting values. If the blood tests show toxic changes, the pet is started on Vitamin K therapy. If the pet is already symptomatic, Vitamin K treatment is initiated immediately and continues for up to 30 days, while monitoring blood values regularly. Severe cases may need blood or plasma transfusions.

On my "how bad is it" scale, the anticoagulants have a Fair prognosis. With early and aggressive treatment, most pets are likely to survive this poisoning.

Because of the wide variability in the types of anticoagulant agents and the differences in individual pets, it is impossible to give a rule of thumb for how much poison is significant. Take ALL pets who ingest any kind of mouse or rat poison to the vet immediately, and bring the package with you, even if it is shredded or damaged. Important information may still be obtained from the label.

This final question always comes up: What if a cat (or dog) eats a mouse (or rat) who has eaten poison? In the majority of cases, there is not enough of the active ingredient in the rodent to affect the pet, however, barn cats who eat a lot of poisoned mice could accumulate enough poison to develop bleeding problems.


Kathy said...

1. Toxic principal: anticoagulants that block vitamin K clotting factors, causing death from internal bleeding
2. Signs:
anorexia, lethargy, weakness, bleeding from nose or rectum, blood in vomit or stool
3. Treatment:
emesis, activated charcoal and vitamin K
4. Prognosis:
fair, can be treated if caught in time

holly said...

I'm not ignoring this one, I was waiting for more knowledgeable people to post because I don't have a clue (and I wasn't going to cheat and look it up online!)

KatDoc said...

Wow, I guess this format isn't too popular! What happened to all my genius toxicologists? It's only because you got all the other posts right that I made this one harder.

"BING, BING, BING!!!" Blue ribbons and gold stars to Kathy, who had the courage to answer and got everything right! And a big Smiley face sticker for Holly, because she didn't cheat.

Don't be intimidated, folks - give it a try next week. You don't have to answer every question. Partial credit is given if you attempt any part of the quiz, especially when you show all your work. Neatness counts!


holly said...

Well, I was going to ask the "What if a pet eats a mouse or rat" question and then I figured you would probably include that in your answer. And I was right!

KGMom said...

What? I missed Toxic Tuesday--how did that happen.
Oh, that's right--I was grading papers, and planning a church retreat.
I can hardly wait until next week when I have more time to read blogs early, not late.

P.S. I would not have KNOWN the answer.

Kathy said...

I'm not sure that I deserve the gold stars, since I did "on-line research" to make sure what I thought was right (that they were anticoagulants). If it isn't okay to do that, I won't anymore.

KatDoc said...

There are no rules for Tox Tues. The goal is to learn something that will make life safer for your pets. So, on-line research won't get your hand slapped with a ruler. I just want to encourage participation and make learning fun.

Confession is good for the soul, Kath! :-)

~Kathi, who would like to point out that this is the 25th anniversary of the "smilie face" emoticon

Kathy said...

Kathi, thank you for the clarification on the rules. After Holly's comment, I was concerned I had done a no-no, and had trouble sleeping Tuesday night. I agree that confession is good...slept fine last night. I love learning about things, so really appreciate the information you present. 25th anniversary? Well, I've been a fan of the smilie face ever since it was introduced, but hadn't been keeping track of how long it had been around. :-)

AnimalEnthusiast said...

This is a great post. You bring up a lot of great points!

holly said...

Oh, no, no no, Kathy!!! I wasn't making any accusations or assumptions about other posters. I was simply being a goody goody brown-noser (who was too lazy too look it up because I knew Kat would post the answer!!!!!)

Actually, I was impressed that your answer sounded so scientific. I thought that anything I posted after would be a let down-and yours sounded so *right*- that I thought anything I posted would sound pretty lame. I was so impressed by yours!!!

I didn't mean to make you feel bad!

Kathy said...

It's okay Holly...at least now we know it is okay to check things out if we don't know. I don't know anything about the other rodent killers we will be tested on next week, but they will probably be even more deadly, just as a guess. My terrier dog has been going nuts the past few days because of mice coming in the house to get out of the cooler fall weather, and the snap traps aren't catching them. Today I relectantly set out the d-con before they chew up stuff. This old house has so many holes for mice to get in, it is a losing battle. :-)