Tuesday, September 25, 2007

Toxicology Tuesday, September 25

Last week's "essay question" style Toxicology Tuesday wasn't as popular as previous "True/False" or multiple guess quizzes, but let's give it another try. I'll even give you some hints this week.

Here is a different type of rodenticide (mouse/rat poison): cholecalciferol. We know if it poisons mice and rats it is toxic to dogs and cats, since they are mammals, too. The question is how does it affect them?

What is the toxic principal/how does it poison? (Hint: Last week, we had a toxin that
altered Vitamin K metabolism, this week is another poison that involves a vitamin.)

What signs might you see?

Is there a treatment?

How poisonous is cholecalciferol/what is the prognosis? Remember our scale of: Fair
- treatable if caught in time; Poor - might not survive even with treatment; or Grave - likely to be fatal even with treatment. (Another hint, last week's anticoagulants had a Fair prognosis, this week is different.)

Be bold, be brave - jump in with your guesses. Partial credit is awarded for any attempt to answer, and please show all your work. Neatness counts!
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ANSWERS:
Cholecalciferol is Vitamin D3. Not only is it found in rodenticides like Rampage, Quintox and Rat-B-Gone, it is also found in multivitamins and some calcium supplements like Viactiv. While it is possible for a pet to be overdosed on Vitamin D3 by eating vitamin or mineral supplements, the risk is much greater from ingesting rodenticides containing cholecalciferol.

Vitamin D3 is a fat soluble vitamin. It is necessary to maintain the delicate balance of calcium and phosphorous in the body. Calcium is not only needed for strong bones, it is a major part of the electrical system of the heart muscle. Excessive intake of Vitamin D3 leads to abnormal calcium and phosphorous levels, irregular heart beats, and the mineralization of soft tissues. In other words, calcium is deposited in the soft tissues of the body, essentially “turning them into bone.” The GI tract, skeletal muscle, heart and blood vessels may be affected, but the kidneys are usually the primary problem.

Clinical
signs are vomiting and diarrhea (sometimes bloody.) The bait pellets are blue, so blue vomitus is a key finding. Other signs, including increased water intake and urination, lethargy, and muscle weakness, may be seen in the first 48 hours after poisoning. High doses results in acute renal (kidney) failure. Death can occur in severely affected animals. Those which survive may have long-term consequences, including chronic renal failure and cardiac arrhythmias.

If an animal is observed eating this type of poison, immediate attention is mandatory. It must be treated immediately after ingestion by decontamination (induce vomiting, gastric lavage, administer cathartics and activated charcoal) and must be monitored for physical symptoms and any changes in blood calcium, phosphorous, and kidney levels. If there are no physical or biochemical changes in four days, the prognosis is good for recovery.

In animals with clinical signs or elevated calcium levels, treatment consists of IV saline solution, furosemide (a diuretic) and prednisone to increase excretion of calcium in the urine. Diets low is calcium and phosphorous and oral phoshate binders are also part of the treatment process, which may last 6 weeks or longer. Prognosis in these cases is poor, due to the potential for chronic, lifetime kidney and heart damage.

The toxic dose starts at 0.5mg/kg body weight. This is the equivalent of 6 grams (about ½ tablespoon) of the typical 0.075% concentration bait in a 20 pound dog. (Another source gave a much higher level, 12-20mg/kg, as the toxic dose.) Secondary poisoning, from eating a mouse or rat which died from cholecalciferol poisoning, has not been reported.

This is not a common poison, at least in my area. I had to go to 10 different stores to find one example of a Vitamin D3-based rodenticide. I have only seen one case of cholecalciferol toxicity in 21 years of practice.

12 comments:

Lynne said...

Here's what I remember without looking it up:
-cholecalciferol is vitamin D.
-it is fat soluble so it stores readily and metabolizes slowly.
-it causes high plasma calcium levels which interferes with heart function, skeletal muscle function and kidney function.

I'm guessing that treatment would include reducing the plasma calcium level (chelation?)

Prognosis: poor

Sara said...

I think that Lynne is right on. My guess for symptoms are loss of appetite, vomiting, and kidney failure. Seems that vitamin D, cholecalciferol would be slow acting as a poison, is it ?

Kathy said...

Even with trying to look it up, under its name or CAS 67-97-0, I really couldn't find much information. :-(

It is also called D3, and too much of it elevates calcium, which would affect the kidneys and heart.

I have no idea for how to treat it.

I will take a guess and say poor prognosis...that gives me a 50% chance of being right. :-)

Anonymous said...

Poor prognosis. Very toxic to dogs even in relatively small amounts. Elevates calcium level in the blood which often causes irregular heartbeat and bleeding. Dogs will have vomiting and diarrhea (sometimes bloody) and will drink massive amounts of water.

Treatment is to "pump" the stomach and give activated charcoal. IV fluids and diuretics to dilute and excrete the calcium. May need seizure control.

Toxicity is especially dangerous because the half-life of cholecalciferol is very long, so the dog may need treatment for several weeks.

It's an awful, painful, and often fatal type of poisoning.

Anonymous said...

Oh, I forgot to show my work. Unfortunately it's personal experience. Readers should know cholecalciferol is also used as an additive in some farm animal feed. That's where our dog got into it...in Grandpa's barn.

Lisa said...

Too hard, KatDoc! Let's go back to "Fluffy drank my kiwi-mango smoothie! Will she die?"

KGMom said...

Toxic.
Don't know the answers to the rest.
I like Lisa's suggestion--there are so many times people are tempted (and in fact give in) to feed pets bits of people food.
Chocolate is out; and so are hazelnuts? Am I remembering correctly.
Anything else?

KatDoc said...

Very good, guys, you got almost everything right! See how smart you are!!

Lynne: I seem to remember the one case we had, we used EDTA to chelate (bind up) the calcium so that it would excreted more readily, but in my reading, I didn't find that mentioned. Either it has fallen out of favor, or it was something we made up.

Sara: You would think it would be slow, but no, it is pretty quick, as you can read in the "answer" section. Most commercial mouse/rat poisons are designed to work fast.

Anon: So sorry to hear you have had first hand experience with this poison. Hope the dog did OK. You're right on about the long half-life, requiring prolonged therapy (weeks to months.) I didn't find any reports of seizures or bleeding associated with cholecalciferol. I didn't know it was an additive in some animal feeds, tho. Thanks for that info.

Lazy Lisa: We will get back to the True/False questions soon. I think kiwi-mango is OK, but who is Fluffy? Do you have a new cat?

KGMom: You are half right - chocolate is bad, but it is macadamia nuts you need to watch out for. Other human foods that we have already covered are grapes and raisins, and the whole Alium family, including garlic, onions, leeks, and scallions. There are other food toxicities in the future, but you don't expect me to give that away now, do you?

You all worked hard this week, so next week you get a break. No Tox Tues on Oct. 2 - I will be away on vacation, storing up blog-worthy stuff to beguile you.

~Kathi

Sara said...

Thanks, Katdoc for this interesting information, it prompted me to read your earlier posts on toxicology and I was surprised to find that grapes, raisins, and macadamia nuts can be toxic. Which led me to a question about another food: peanut butter. Would you expect to see negative consequences, in addition to excess weight gain, in a dog that ate peanut butter every day ? Thanks for your help.

KatDoc said...

Sara:

I don't know of any toxic effects of peanut butter, and I have never heard of a dog having allergies to it.
The fat content of peanut butter might put a dog with high triglycerides and cholesterol at risk for pancreatitis.
Weight gain or dietary imbalance would result if a dog ate a lot of peanut butter every day, but I don't a dab a day would hurt.
We use peanut butter to give pills to many of our patients when they are boarding, and I have never seen any problems from it.

Thanks for asking,

~Kathi

Lisa said...

I can attest to the sometimes "explosive" effects of peanut butter on a dog who's not used to it...

KatDoc said...

"I don't *think* a dab a day..."

And oh,yeah - I forgot about Murph. Take that back, Sara. I HAVE seen problems with peanut butter in one dog. Murphy, the 100 lb Rott, has a very sensitive tummy (He looks tough on the outside, but is a big ole softy on the inside.) and had diarrhea from a peanut butter-stuffed Kong. Not toxic, but boy-howdy, the results sure were!

~K