Anticoagulant rodenticide poisonings in dogs and cats

RE: Anticoagulant rodenticide poisonings in dogs and cats

Aine Seavers — Tue, 06 Oct 2015 01:39:57 GMT

typo- same days should be some days later

RE: Anticoagulant rodenticide poisonings in dogs and cats

Aine Seavers — Tue, 06 Oct 2015 01:33:36 GMT

I will ask if we can get permission to post the article as don't want to cause whole c/r issues publishing to a forum. It certainly makes one question what one does- about a whole heap of things -and updates on new approaches in human medicine.

My take is never with-hold the Vit K, vomiting a bait up the same days makes me question whether one has vomiting up the toxin or the vehicle it is in? and whether they go off and die 2 weeks later and not connected.

So many times we get them 2-3 days later as owner watched for 'fitting' post eating the bait and when fine the next morning they think they are home and safe.

We have not seem first gen packets here in Oz for years, 2nd/3rd gen and in couple years ago mouse plague they ran out of both baits and antidotes- zinc phosphide analogue was used under special licence.

We always get them to bring the packet in- if in doubt we treat for the worst anti-coagl option ingested-using BSAVA formulary as a guideline.

We never make them vomit and if a remote location dog, it goes home on Vit K- if closer to clinic and we may be able to blood test- then we may do so- but again venepuncture is to be minimised in this presentation. We have veterinary generics of Vit K here which keep the cost down to probably cheaper the blood testing- it all depends on where you are and your clientele.

Re the article- its written based on extensive toxicology experience and study by the 2 vets- we may not agree as clinicians with all they have to say- it certainly caused controversy here- but it does make you really think.

RE: Anticoagulant rodenticide poisonings in dogs and cats

Evelyn Barbour-Hill — Mon, 05 Oct 2015 22:12:47 GMT

Crikey, can people really buy strychnine just like that?

Inducing emesis would be a little irrelevant there.......

RE: Anticoagulant rodenticide poisonings in dogs and cats

Silvia Maldonado — Mon, 05 Oct 2015 21:51:20 GMT

Interesting discussion! Here is my opinion and my point of view, though I'm considering changing my protocol after reading your comments:

Although most of the rat poison our clients will buy in any store are vitamin K antagonists (like brodifacoum, bromadiolone, chlorophacinone, coumatetralyl, difenacoum, diphacinone, flocoumafen, warfarin), others are acting in a different way (ANTU, bromethalin, cholecalciferol, strychnine, vacor, or zync for instance)

Within the vit K antagonists, risks are both drug and dose dependent. Surprisingly, all of the cases reported to VPIS of flocoumafen intoxication were asymptomatic, and none of warfarine's were fatal.
According to the "handbook of poisoning in dogs and cats" (Alexander Campbell and Michael Chapman), as little as 5g bait of brodifacoum (in a commercial preparation) could potentially kill a chihuahua, whereas the same breed would need to ingest 1kg bait of chlorphacinone (even so, 9 deaths have been reported to VPIS). On the other hand, dogs can tolerate low doses of bromadiolone for several days, but others died with 10mg/kg dose. Difenacoum has been the most reported to VPIS.

To crown cases off, symptoms will appear ONLY once prothrombin factors/platelets/vit K has been depleted, which might occur in 1-3 days, in some cases it took as long as 2 weeks, or it might not occur. The good news is that the coag test will show prolonged PT/PTT before it happens. Treatment may be need to be prolongued for days.

Having said that, given the conmplexity, variety and cost of the treatment (how much konakion for a German shepherd?), plus the likelihood of the patient/notes being transferred to another practice who trust us, I would suggest that we create some protocol for these cases. My proposal would be sort of:

1- Request owner to bring the rodenticide box/bag with them, when possible, at the time the appointment is booked. It will help us give a more accurate prognosis.

2- Look for symptoms like: MM pale, CRT>2s, lethargy, dyspnoea, exercise intolerance, internal and external hamorrhage, hypovolaemic shock, bruising, anemia.

3- Induce vomiting. In theory, it should be done within 2h of ingestion. I personally have seen dogs vomiting the gastric content 6h later (or the owner lied to me ). Don't forget the activated charcoal afterwards (I would repeat dose q4h for 12-24h)

4- Ideally, run a coag test if seen any symptom (citrate tubes in the fridge. Not sure, but I think we need to prepare the coag machine sometime before taking the blood sample, otherwise it will be clotted already by the time we run the test). If the results are wnl, advise daily coag test for, at least 3 consecutive days.

5- Give vit K if coag test is altered, even if there are no clinical signs of intoxication (in fact, TP will be prolonged before clinical signs are seen), or if there are clinical signs, the emesis was unproductive, or there is a good reason to use it as a preventive treatment.

6- Don't restrict treatment to vit K. Some cases might need IVFT, other vits supplements, iron, even transfusion.

RE: Anticoagulant rodenticide poisonings in dogs and cats

Anthony Dennison — Mon, 05 Oct 2015 18:05:27 GMT

What's the general consensus on activated charcoal? Yay or nay?

If it was a recent ingestion and the dog isn't showing clinical signs, I don't check coags until 3 days later, read it in that article I mentioned

RE: Anticoagulant rodenticide poisonings in dogs and cats

Martin Atkinson — Mon, 05 Oct 2015 17:38:57 GMT

[quote user="Anthony Dennison"]

recommends emesis if recently ingested. Apparently some forms of bait can stay in the stomach longer so you can make them vomit 4-8 hours afterwards succesfully.

[/quote]I induce vomiting so long as it is the same day! Surprising how much comes up several hours later. Never had a dog that needed treatment yet if it brought the bait up. Never had any issues with oesophagitis/inhalation yet. For all the pontificating on this if it works it works.

RE: Anticoagulant rodenticide poisonings in dogs and cats

Michael Woodhouse — Mon, 05 Oct 2015 15:42:20 GMT

Aine - sent me a paper suggesting the polar opposite. I have messaged her to find out the status and whether we can run it as a journal club on here. Would be nice to thrash out once and for all. I'd enjoy that.

Arlo Guthrie - keeps telling me we can have a sub forum for this, and I will keep asking.

Arlo Guthrie

RE: Anticoagulant rodenticide poisonings in dogs and cats

Wren — Mon, 05 Oct 2015 15:41:24 GMT

Just a cautionary tale to add...

I used to work in rural mixed practice. Saw many cases, treated them broadly as most of you have above. One day the local hunt terrierman brought in his JRTx the day following a mammoth ratting session on a farm known to lay bait: the dog was pale, quiet, had been seen vomiting with the odd bit of fresh blood, the usual sort of thing. I whipped some bloods off him (terrier, not terrierman!), treated him as normal and sent him on his way.... only to have to ring him very urgently the following morning and ask him to come back as the haematology (and subsequent Coombs test) indicated IMHA, not poisoning at all! A bucket load of preds and a transfusion from my Lab later and he lived out the rest of his days, but I very nearly missed it.

RE: Anticoagulant rodenticide poisonings in dogs and cats

Anthony Dennison — Mon, 05 Oct 2015 15:32:16 GMT

I recently read an article on this subject as part of my CertAVP. It recommends emesis if recently ingested. Apparently some forms of bait can stay in the stomach longer so you can make them vomit 4-8 hours afterwards succesfully.

Article below:

CeClementi C, Sobczak B.R (2012) Common Rodenticied Toxicoses in Small Animals Vet Clin Small Anim 42: 349-360

RE: Anticoagulant rodenticide poisonings in dogs and cats

Braden Collins — Sat, 03 Oct 2015 13:05:14 GMT

For us:

1. vomiting only induced if suspicious of/confirmed ingesion within the last 2 hours

2. if uncertain of ingestion or if have induced emesis, run PT/PTT 48 hours later. If clotting prolonged start straight onto oral Vit K for 4 weeks, then retest PT/PTT 48 hours after last tablet given. Injectable only given s/c if clinical bleeding a problem.

3. at presentation if clinical bleeding, otherwise as above

4. none where owners ahve been financial enought to treat appropriately. One fatality where blood/plasma transfusion was declined on financial grounds.

RE: Anticoagulant rodenticide poisonings in dogs and cats

Michael Woodhouse — Sat, 03 Oct 2015 00:06:46 GMT

Aine Seavers do you have a reference?

RE: Anticoagulant rodenticide poisonings in dogs and cats

Aine Seavers — Fri, 02 Oct 2015 23:54:55 GMT

The article runs about 15 pages long- evidence galore- still controversial as doesnt go with what we instincively want to do. They explain absorption times- getting evidence' back up is not necessaruily getting the toxin back up, the baits become a waxy hot form so aspiration and oesph damage etc. Human meds gone away from emesis etc but in fairness 30yes ago I was taught if not within 30mins then you dont achieive much. The article provides evidence down to mathematical formulation way beyond my brain of risk and effect- it made many of us uncomfortable because of our clinical experience protocols differing. Equally here in Oz, we would rarely see a case within 20mins- so we treat with vit k- esp as some animals may be many hours round trip-others will blood test if closer, Vit k acts like a water soluble vik so rarely accumulates so over use not such a concern. I wrote the post to stimulate discussion, not say anyone is wrong in what they do-but certainly you should read well well outside the list's experience of rat bait if you want to design an evidence based protocol on rat bait esp as all of us who read the article were deeply challenged by 2 vets who are also significant specialists in toxicology arena.

RE: Anticoagulant rodenticide poisonings in dogs and cats

Michael Woodhouse — Fri, 02 Oct 2015 22:28:11 GMT

[quote user="Aine Seavers"]

in anticoagulant rodenticide baits. Dont make them vomit it back up...

Very few indications now to induce emesis- esp if > 20mins.

[/quote]

[quote user="Catriona MacIntyre"]What is the evidence for this? In 90% of the rat bait poisoning cases I induce vomiting in, we retrieve blocks/pellets of bait. Surely this reduces the absorption of the poison?[/quote]

Agreed - although I'm selective and only induce vomiting if there is certainty of ingestion and it's relatively recent (2 hours), I can see the rationale if the product ingested is caustic, but these products are not.

There is a big difference between "there is no evidence to support" and this does no good. If there was evidence that inducing vomiting was harmful, then I really want to know about it.

I talk to other vets working in towns and cities and they see fewer of these cases. I'm sure the farm wax blocks are the issue - nibbling a few wheat pieces dyed blue or pink from B&Q seems pretty innocuous.

RE: Anticoagulant rodenticide poisonings in dogs and cats

Catriona MacIntyre — Fri, 02 Oct 2015 20:30:05 GMT

[quote user="Aine Seavers"]

in anticoagulant rodenticide baits. Dont make them vomit it back up...

Very few indications now to induce emesis- esp if > 20mins.

[/quote]

What is the evidence for this? In 90% of the rat bait poisoning cases I induce vomiting in, we retrieve blocks/pellets of bait. Surely this reduces the absorption of the poison?

The only cases I have ever lost were those that were not caught quick enough and digested all of the bait block

RE: Anticoagulant rodenticide poisonings in dogs and cats

Aine Seavers — Fri, 02 Oct 2015 12:39:14 GMT

In an article superbly written by 2 specialist toxicologists who are also vets- they have some fascinating in depth info-
- in short they do a full research and find no evidence for
emesis/catharsis/stomach flushing in the vast majority of cases (chocolate,
lily, slug fish, toad fish some of the rare exceptions) and the procedures
no longer done in human medicine -despite our perception that it is done
commonly.

what happens to rat bait when it is ingested? From the same persspective above--It should not be overlooked by veterinary practitioners that oils includewaxes that melt at internal body temperature. Such waxes are routinely used

in anticoagulant rodenticide baits. Dont make them vomit it back up...

Very few indications now to induce emesis- esp if > 20mins.

In 30yrs I rarely made poison cases vomit ost 1-a cat who fell into a petrol drum.

RE: Anticoagulant rodenticide poisonings in dogs and cats

Richard Carter — Fri, 02 Oct 2015 09:15:26 GMT

have you seen the latest Vet poisons newsletter - they say acute exposure is of low risk, to look at chronic exposure.

In farming area, relatively common emergency following ingestion, never seen a fatality. We use apomorphine in known ingestion cases, followed by instructions to give high fat diet (cream/ milk or similar) to speed up transit through git. Hardly ever give Vit K unless showing signs, check 5 days later when coag deficiencies likely to start appearing

My Vit K has 'do not give i.v.' written all over it??

RE: Anticoagulant rodenticide poisonings in dogs and cats

Joyce Whitehead — Thu, 01 Oct 2015 21:18:01 GMT

1. We would induce vomiting if consumption was within the previous 90-120 minutes. If it is known to be very recent consumption, we would induce vomiting and nothing more. (Usually it is easy to see the poison in the vomit).

2. If there is doubt as to whether there has been consumption over a few days we would treat with vit K, or we would check clotting times 24-48 hours after last known access. Then treat if needed.

3. We would check clotting 48 hours after known access if needed (see above) and 48 hours after end of treatment, if vit K treatment is needed.

4. I can only remember one fatal case in the last 5 years or so. It was a lab who belonged to a farm owner who had no idea she had eaten poison, was seen on a Friday night for a mild cough, no sign of blood, and not anaemic. Brought back the next morning collapsed and coughing up blood. Died whilst we were collecting blood for transfusion. We have had 3-4 others in the last 5 years that have needed whole blood or plasma transfusions.

We are in a rural area so probably see more rodenticide poisoning than the average. I'm guessing that this year I've induced vomiting in at least 5 dogs who have eaten poison.

RE: Anticoagulant rodenticide poisonings in dogs and cats

Michael Woodhouse — Thu, 01 Oct 2015 21:16:47 GMT

I was typing slowly while Catriona slipped a reply in. Seems we broadly agree (other than the route of administration of the injectable).

RE: Anticoagulant rodenticide poisonings in dogs and cats

Michael Woodhouse — Thu, 01 Oct 2015 21:14:25 GMT

1. We will only make them sick if we are confident that something has been consumed and it's been in the last couple of hours. We see relatively few of these.

2. If known then we would start with injections (IV) whilst hospitalised and continue with tablets once home. Also see 3.

3. If known intoxication then would give tablets for 4 weeks and then check clotting time (ACT in house on the I-Stat). If only suspected and no signs then would check clotting time now, and possibly after 48 hours depending on changing signs and history. If it was a farm dog presenting pale and this was suspected would run clotting time. I have a reasonable threshold for testing so many are prolonged. Most animals, even with known ingestion, are normal at 4 weeks. I've had many dogs presented as white and collapsed that have normal clotting times at 4 weeks (whatever the books say). Typing this I can't recall a case where they needed more than 4 weeks treatment, even when a long half life product was ingested.

4. We've had 1 fatality ever. Farmer came at 9.30 to a busy morning surgery and took a seat. The dog waited over an hour in the Landrover. Diagnosis made as soon as seen, but died whilst collecting blood for transfusion.

I don't know what sorts of numbers you all see, but I'd say we average 1 per month, with maybe 2 per year requiring transfusion. Personally my last transfusion for this was Christmas day 2014. That was a fun evening with me and the farmer. A number of times I've made the diagnosis over the phone and got the farmer to bring another dog too. It's our most common single reason for transfusion.

I've also come to the conclusion that the domestic rat baits are fairly innocuous - it's pretty universally the wax blocks on farms that make the dogs sick.

All anecdote, nothing but practical experience of this.

RE: Anticoagulant rodenticide poisonings in dogs and cats

Catriona MacIntyre — Thu, 01 Oct 2015 21:02:22 GMT

1) For known, or suspected rodenticide poisonings, how often would vomiting be induced (irrespective of time of ingestion)?

Not really sure how to answer this. If it was ingested less than 60-90 minutes, I would always induce vomiting. Otherwise, probably not

2) For known or suspected rodenticide poisonings, how often would either injectable or oral vitamin K be prescribed?

ALWAYS

3) For known or suspected rodenticide poisonings, how often would blood testing (clotting times) be performed? If so, how many samples would be checked (ie. one at presentation, one after three days etc)? For those that have blood samples performed, what percentage of results are abnormal (prolonged PT or APTT)?

I always check clotting times 2 days after the end of a course of vit K. The length of course depends on the poison ingested and duration of action. The most common in my experience is bromodialone and I give a 3 week course starting with subcutaneous injection (split into 4-5 sites to increase absorption. Not happy with thought of venepuncture in dog with possible anticoag poisoning) and continue with oral. I may well have been lucky, but in 14 years I have never had an abnormal result post Vit K treatment.

4) For known or suspected rodenticide poisonings, how often is the outcome fatal?

I have only known 1 fatal case in our practice in 10 years. Haven't got exact figures for total number of cases but can find out if you need it The fatality was not presented until it was passing bright blue faeces and was unwell at presentation.