# Toxicity of Panacur (Fenbendazole)



## Feefo

I have always been a bit wary of Panacur and switched to Moxidectin Plus.

Just found this when browsing:

Mortality Associated with Fenbendazole Administration in Pigeons (Columba livia). 
[My paper] Alfonso S Gozalo , Rebecca S Schwiebert , Gregory W Lawson 
A group of 12 domestic pigeons (Columba livia domestica) was treated for capillariasis by use of fenbendazole at 30 mg/kg orally once daily for 5 d. After treatment, 8 of the 12 pigeons exhibited signs of anorexia, lethargy, and dehydration; these birds died within 2 d after the onset of clinical signs. A total of 6 birds were necropsied, and all had unremarkable gross findings. Microscopic examination of tissues revealed acute hemorrhagic enteritis, diffuse lymphoplasmacytic enteritis, small intestinal crypt necrosis, periportal lymphoplasmacytic hepatitis, bile duct hyperplasia, and renal tubular necrosis. Erythrocytes in blood samples collected from surviving birds demonstrated polychromasia compatible with a regenerative anemia. The clinical and histopathologic findings in these pigeons were consistent with recent reports of fenbendazole toxicity in domestic pigeons and other columbiform birds.


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## Reti

I used Panacur on many birds until my peeper got sick. He had the symptoms described, anorexia and lethargy. I knew it was from the Panacur cause he was a healthy strong pij otherwise.
Then later I had another one with the same symptoms after giving Panacur. Both survived. All I did for them while they were ill was hydrating with pedialyte and feeding a dilute formula. They were fine in 2-3 days.
I never used it since, but seems like Panacur can kill the ones that are more sensitive to it.

Reti


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## Pidgey

I only ever give it for one day and one day only. I think I can see them react even to that little bit. I usually only use it if there's Capillaria eggs in the fecal float.

Pidgey


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## Skyeking

Hi Cynthia,

Thanks for sharing that.

Seems like I have heard nothing but negative results from Panacur. I don't think it should be used at all with such side effects. It's not worth it.


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## feralpigeon

Cynthia, I've been posting the following link from PigeonNetwork for quite some
time now for members to read:

http://www.pigeonnetwork.com/vetdirectory/vetnorway/drnillsreither/anthelminiticdrugs.cfm

The statistics for Fenbendazole are pretty clear from the chart accompanying the narrative in the link above. It is unfortunately however, still listed in more recent formularies for treating pigeons. 

fp


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## mr squeaks

THANK GOODNESS I didn't know all this stuff when my Vet prescribed Panacur for Squeaks' ROUND WORMS!! 

Of course, he was also older and did not take every day...


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## Maggie-NC

I had never heard Panacur was possibly toxic. The vet prescribed this for our birds years ago but then switched to Pyrentel for worms. I have not had a chance to do a thread on our adventures with ****** who has a severe case of worms but hope to soon. After two treatments with Pyrentel eggs were still visible in stool so the vet put her on Panacur for three straight days and then repeated it again three weeks later. So far, no ill effects but I'll argue the issue next time.


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## Guest

You can't rely on the article. They deliberately overdosed the birds in order to kill them and study the effects of Panacur on the body. They gave 30 mg per kilogram. For a 250 gram pigeon, the dose they gave was 7.5 mg.
That's a killer overdose and that's what they wanted to do. The normal dosing for a pigeon using liquid Panacur is .1 ml (point 1) so there you are.

Every wormer is dangerous especially to the liver which stores the drug. If you read the instructions for Ascapilla + (which is Panacur configured for pigeons), it's recommended to also use Vitamin B12. Why is it that vets, in treating with Panacur, do not tell us to use the vitamin? It's remiss on their part. 

I haven't used all of the various wormers that are available but I think that all of them have the potential to cause a lot of damage and at the minimum, make a bird feel poorly for a while. I use Ascapilla or Ivermectin. I think Ascapilla is better because it also hits the two tapeworms that pigeons can get. After using it, I put the bird on Brewers Yeast for a few days. It will increase the red blood cell count because Panacur can cause some bleeding. It's a necessary evil but it doesn't mean you have to like using these wormers. So, I get stuck using a yeast pill that if the bird already has a yeast problem, will exacerbate it. In the extreme, this is a no win situation.

This goes back to my original thought. Every medicine has side effects and can be dangerous in and of themselves. I think that's one reason why Treesa may have turned to natural remedies. (Treesa, sorry if I spoke for you...just a guess)


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## Pigeonpal2002

I've always heard that panacur is potentially toxic for pigeons and that it has to be dosed very precisely. There is very, VERY little margin for error with this drug. Drugs like ivermectin, moxidectin are considered much safer wormers and these have a margin for error with dosing as well are considered much "gentler" on the pigeons.

My vet prescribes ivermectin normally and this is what I've always used since. Once I did overdose Eggbert by a quite a bit topically. I also administered the wrong kind of ivermectin orally a long time ago to both pigeons that wasn't meant to be given orally and both times the pigeons showed no harmful effects, thank heavens.

Now I only dose them once a year with ivomec injectible given orally. I also bought moxidectin and have used this once too. Moxidectin is very similar to ivermectin in how it works and it's level of safety.


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## Skyeking

pigeonperson said:


> This goes back to my original thought. Every medicine has side effects and can be dangerous in and of themselves. I think that's one reason why Treesa may have turned to natural remedies. (Treesa, sorry if I spoke for you...just a guess)


That's okay,

I use them for myself, so why shouldn't I use them for my birds. Also, I know someone who has used them for 30 years with great success.

You don't need a diagnosis to use them, although I won't recommend that. Unlike medications, there are no side effects using herbal/natural remedies (used within guidelines). You can use as many different ones at the same time, without major side effects, and they don't compromise the immune system.


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## Guest

Brad,
Why automatically dose them at all? If a vet does a fecal once a year, it would tell him if there are worm eggs. If yes, then dose but if not, why subject them to unnecessary medication? I'm becoming very conservative these past few years.


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## Feefo

> They gave 30 mg per kilogram. For a 250 gram pigeon, the dose they gave was 7.5 mg.
> That's a killer overdose and that's what they wanted to do. The normal dosing for a pigeon using liquid Panacur is .1 ml (point 1) so there you are.


That rather depends on what formulary is used. 

As the active ingredient in 1ml of the 2.5 % solution of Panacur is 25mg your recommended dosage would be 2.5mg per kilo. 

The pale blue and darker blue Panacur capsule contains 8mg of Fenbendazole...that is 16mg per kg if used on a 500mg pigeon but 32mg per kilo if used on a 250 mg feral. A fatal dose.

Nooti , a most experienced pigeon rescuer, recommends a single dose of 10 to 16 mg per kilo in her Drug Chart. 

The Royal Pigeon Racing Association recommends 5mg per bird daily for 3 days. They consider the average weight of a racing pigeon is 500gm. so that would equate to 10mg per kilo.

So, these are large variations for a drug that allows for a small margin of error.

But it is the small animal vets that tend to prescribe overdoses and as far as I remember the Panacur related deaths and close calls on this forum were related to veterinary prescriptions. I suspect this is because as there is no dosage for birds on the bottle they follow the dosage recommended on the bottle for cats and dogs which is 4ml Panacur (*100 mg!!!*) per kilo of bodyweight, rather than track down the correct dosage for pigeons. 

fp's link (sorry fp I either missed that in the past or was influenced by it but forgot where I saw the information) supports the findings of this study and unless there are parallel studies that show that Panacur is safe then I will not be using it and I hope others will also avoid it in favour of safer wormers. 

Hence the warning.


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## Pidgey

Pigeon-Talk example of a vet's mistake leading to extensive deaths in a loft (the second link is a "Part II" installment):

http://www.pigeons.biz/forums/showthread.php?t=10546

http://www.pigeons.biz/forums/showthread.php?t=10564

In AVIAN MEDICINE: PRINCIPLES AND APPLICATION, in the formulary, it does not show a specific dosage for pigeons. It has one for Anseriformes and then a couple for "Most". The largest of those is 20-50 mg/kg, Oral for 5 days, which has the capacity to be a greater intake of active ingredient than the one referenced by Cynthia in the first post of this thread ("30 mg/kg orally once daily for 5 d"). Therefore, it's easily possible for a vet to derive a fatal dose from a widely accepted formulary if the assumption is made that pigeons fall into the "Most" category.

For myself, I always test the birds before ever giving any wormers. It's actually pretty rare that I find an infested bird that's pumping out worm eggs. I've only seen Capillaria eggs twice and the first time was in Winston. I could never find them again in Winston's fecals after the first one that I ran on him leading me to believe that it was possible that he'd recently eaten something with a worm egg that wasn't "ripe" yet so it went all the way through. I did finally treat him for one day for insurance purposes before I put him out in the loft.

Otherwise, I've never found any worms in my loft (with the sole exception of Debbie who was infested without pumping out worm eggs and she was given to me by a vet) and never have flock treated for worms. Anytime that I get a new bird that I'm going to put out in the loft, it gets tested for worm eggs and then again some weeks later. If none show up then I don't treat it. I've probably only had to treat individual birds for worms about 10 times in the last 5 years. For the ones that I treated with an individual 8 mg Ascapilla capsule on a "one-time" basis that have had consistent worm eggs in the fecal floats, that ended it. That is, I could no longer find worm eggs in successive fecal floats performed after a 48 hour interval.

I've got plenty of the stuff and have sent single doses out to folks. I don't have a problem using it in the single-dose shots based on what I've seen.

Pidgey


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## Pigeonpal2002

pigeonperson said:


> Brad,
> *Why automatically dose them at all?* If a vet does a fecal once a year, it would tell him if there are worm eggs. If yes, then dose but if not, why subject them to unnecessary medication? I'm becoming very conservative these past few years.


Hi pigeonperson, 

You bring up a good point here and have given me some food for thought. I have routinely treated my older pigeons since I first got them and because they were in run down condition in the beginning. The person who bred and sold them didn't look after them properly at all. They had lice, mites, worms, cocci and whatever else that might have gone undiagnosed over the years that various tests were done. 

After Foghorn died from thread worms way back in 2001 and because he contracted them from Henny, I've been extremely paranoid of this particular parasite. I've read many times over the years; during the time I was trying to get my pigeons healthy, that worms are extremely difficult to eradicate from the birds' environment. The eggs can remain dormant on surfaces for years, just waiting for the right conditions to "reactivate them" and get ingested again by a pigeon in some way or another.

I used to prophylactically treat for canker and coccidia too but I have stopped that. I've kept up with the Ivomec & moxidectin for internal and external parasites however.

I don't have annual fecals done or for no reason, but this might be a good idea and might end up being cheaper in the long run. I usually place routine orders from Siegels or Foys for certain meds that so seldom get used and before expiration. The two youngsters I have have only been treated once for worms and canker though, they will be 3 in May.


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## feralpigeon

Clinical Avian Medicine has nine entries for Fenbendazole listed for pigeons, two 
of which are referenced as the 'Manufacturers recommendations', the other two
categories of reference are either 'published without reference' or 'anecdotal'.

The highest dosage from the manufacturer listed in the formulary would be 20mg per kilogram 'for gastrointestinal roundworms', however, there is a higher
dose rate (anecdotal) of 50mgs per kgs with no description in the comment section and another higher entry of 20-50mgs per kgs (published w/out reference) that states 'capillariasis' in the comments.

fp


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## Feefo

The variations are very disturbing. It never occured to me to question the dosage of a prescribed medicine until my vet prescribed a Baytril dosage for a pigeon that was far lower the one that Helen and Terry recommended.

When I visited the Baytril site to double check I found that the dosage he was using was the one recommended for cats.

Cynthia


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## Pidgey

feralpigeon said:


> Clinical Avian Medicine has nine entries for Fenbendazole listed for pigeons, two
> of which are referenced as the 'Manufacturers recommendations', the other two
> categories of reference are either 'published without reference' or 'anecdotal'.
> 
> The highest dosage from the manufacturer listed in the formulary would be 20mg per kilogram 'for gastrointestinal roundworms', however, there is a higher
> dose rate (anecdotal) of 50mgs per kgs with no description in the comment section and another higher entry of 20-50mgs per kgs (published w/out reference) that states 'capillariasis' in the comments.
> 
> fp


Also disturbing in that one (the formulary that fp wrote about) is the "QD" for several of those which is translated as "Every Day". Every day for... how long? What's a vet to think, especially if he or she doesn't have familiarity with the problem? Something bad certainly happened to Aldante's birds due to the vet's mistake. 

Several of the other Fenbendazole references for pigeons in that one also say "Once", and so if you take them as a whole, you might (or might not) think it'd be best to err to the side of caution but that'd probably be a personality thing rather than what it should be--a red flag.

Pidgey


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## Guest

Brad,
I would go with fecal floats once a year and if the microscopy is negative, there's no need for medicine. As far as canker, it's the most sensitive subject for me because I've seen so much of it. However, if the birds are indoors and the water cups are kept meticulously clean the chances of their getting a full blown infection are dramatically reduced. 

You may even find that the birds have some coccidia in them and again, it's normal to find some but why go crazy with medications? You can't completely eradicate coccidia in a system anyway and if it's not at an infection level, why bother?

Before I even talk about this, I'm going to say that it's up to you as far as treating prophylactically with a canker drug. It has to be your decision so don't rely on what I'm saying about this to make a choice.

All pigeons have at a minimum, a modicum of trichomanads and medicine can't totally eradicate them. It's normal for them to have the organism. It's only when something else goes wrong that causes them to become run down, and the canker can then rise to infection levels. I think we have to assume that even a bird sitting home in a clean environment can have some of the organisms. So if one of your birds develops canker, I think there is more to worry about than just canker.

What happens if we treat with only one pill that deals with canker? It will kill the weaker organisms but the remaining ones will not only be the stronger trichomonads but they will be more resistant to the meds so what good is giving one pill? There is a lot of evidence lately that birds kept in a loft are becoming immune to the canker killers so much so that research is being done to find another. Berimax is one such drug. 

I don't know the answer for birds living in a home. My personal opinion is that one treatment in a homed bird may do more harm than good but again, don't rely on my personal opinion because this is all hypothetical. This only goes to show that it's extremely difficult to keep a healthy bird, healthy. We aren't just talking about a pigeon. It's any bird including parrots and passerines that is very hard to keep going. Birds can be far tougher than cats and dogs to keep well.

What about the feral pigeon? If we take one in, it's because something is wrong with it. If something is wrong with it, the resistance is down and that means the canker can rise to infection levels. We don't see canker symptoms but we know that it's in the system. Is it right to give only one Spartrix or Ronidazole? We talk ourselves into believing that we are cleaning out the system so that the bird can concentrate on healing whatever is going on. Nature hates a vacuum so what might very well happen is that the bird could develop a very bad case of canker after we release it and we would never know this happened. For that reason, I'll no longer give prophylactic meds but treat only for what I see wrong. Again, this is hypothetical and frankly, I really don't know what is right anymore in the real world.


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## Pigeonpal2002

Thank you for your input and expertise, Pigeonperson

I agree with most if not all of what you've said and mentioned. I thought I was doing well with just using the Ivomec or moxidectin now. I may still continue with these wormers/anti-parasitics however and because of the external parasites that may be bothering my pigeons, especially during summer. Even though they are indoor pigeons, they might still be exposed to ecto bugs via windows in their room. Worms STILL scare the heck out of me and for the reasons I mentioned in my previous post. 

Oddly enough, canker is something that I don't think I've ever seen in my pigeons, ever, or that was obvious anyway. None of the tell-tail clinical signs have ever been observable in their mouths or throats. I've treated them for trich in the past because I know that nearly all pigeons carry the protozoa and did it as a preventative measure. Now, I'm seeing your point that it's probably un-neccessary as they are indoor pets and unless they have something else going on to trigger an overgrowth, it'd likely be a secondary problem to something else. The same thinking applies to coccidia mostly as with canker as this is another thing that many pigeons carry and becomes secondary to something else more dangerous & when the immune system is not working up to par.

I think I'm going to take your advice and start having yearly fecal tests done on my 3 birds and go from there but still continue with the anti-parasitic drug(s) and because I think this is different from other medications that are targetting actual "diseases".


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## Skyeking

Brad,

Are you giving your birds a garlic capsule twice a week?

That would certainly help keep their immune system in check, as well as keep parasites away.


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