Medical Misinformation on the Internet and how it can Harm your Tortoise

While the internet is an incredible invention allowing vastly improved communications as well as conveying massive amounts of information rapidly, one of my primary concerns with it as a clinician is the amount of medical misinformation that is published on the web.  While 99% of it is relatively harmless, it is the medical (as well as husbandry) misinformation that concerns me the most as a medical professional who has dedicated his life to helping chelonians.  Countless chelonia (as well as other "self medicated" taxa) have been affected by misinformation on the web and I've decided to do what I can to try to help clean up the worst of it.

After several bad experiences, I decided long ago not to send out or publish dosaging information.  Dosages were either altered or the drugs were used in inappropriate situations.  However, this doesn't stop some authors with no medical training from publishing non peer reviewed nor referenced medical information as gospel across the internet which is subsequently followed.  In the case of low traffic web sites, this probably does not affect many if any animals.  In this case, this is a high traffic, respected web site which is closely followed and thus capable of inflicting great harm with bad information. 

Lastly, while there are a number of further problems with other medical information posted on the site cited below, my hope is that they can be dealt with professionally and privately offline.  The only thing that counts to me is the health and well being of the animals which is the sole purpose of this page.  Human politics merely waste time and take away from the primary goal: the animals.

Chris Tabaka, DVM

Staff Veterinarian

Memphis Zoo

World Chelonian Trust- veterinary advisor and trustee

Turtle Survival Alliance- veterinary advisor and TMG point person

AZA Chelonian Taxon Advisory Group- veterinary advisor

 

 

The following article, written and referred to often by Mr. Highfield, is one example of poorly written medical information without references nor medical assistance yet published on the World Wide Web as fact.  Mr. Highfield has a large following which treats his information as gospel which makes the type of medical information below particularly disturbing to me as someone who cares deeply about chelonians.  The direct web address for the following information is: http://www.tortoisetrust.org/articles/worming.html  

The article has been posted in its entirety below with the only changes being the red superscript additions which correspond with my footnoted comments below the article.

To clarify in advance the problems with this article lest this be seen as a simple problem with a typo or two:

1. Panacur paste compounds vary in concentrations between the UK and US and other countries.

2. There is not a universal dosage for every species and individual turtle or tortoise.  Veterinary medicine is not that easy.  It is an art as much as a science.  For example, I would not treat a healthy captive bred red-footed tortoise with the same approach I would utilize in an Asian wild caught market animal. 

3. Panacur (fenbendazole) is a DRUG which can kill or cause a variety of problems including gastrointestinal impaction, loss of the mucosal lining, bone marrow toxicity, and even death.  The treatment regimen below is extremely, extremely aggressive; too much so in this clinician's opinion.

4. All treatments should be based on the parasites found during fecal testing.    Panacur is NOT effective against a wide range of parasites.  A wide range of drugs are needed in different circumstances. 

5. The article is extremely unclear and confusing throughout.  I've been contacted by a number of chelonian owners who have had problems understanding it.

6. Major generalities are made in terms of dosaging information.   Medicating animals requires precision in order to be effective.

7. In certain situations, the usage of panacur is inappropriate. 

8. Lastly, panacur is rapidly losing it's effectiveness as an anthelminthic (anti parasite drug) due to developing drug resistance in chelonia.

http://www.tortoisetrust.org/articles/worming.html

 

        

  

 

        

Worming difficult to handle tortoises and turtles

Andy C. Highfield

Although "worming" tortoises by means of a stomach-tube is often entirely satisfactory, in some species this means of administration can prove extremely difficult. Hinge-back tortoises (Kinixys spp.) and large Leopard (G. pardalis) or African Spurred tortoises (G. sulcata) can be particularly strong and resistant.

As an alternative, a paste preparation of Fenbendazole (e.g. Panacur Paste for horses or Equine paste) may be applied to favourite items of food. The dose rate in such applications is 100mg fenbendazole per Kg total bodyweight of tortoise each day for 5 days.1 Repeat after 2 weeks but this time for 3 days only. 

Panacur Paste for horses contains 3.5mg 2 fenbendazole in 20g of paste 3 (i.e. a little under 19% concentration). For practical purposes, 4 a concentration of 20% can be assumed. This makes calculating the paste volume for dosing very straightforward;

For a 2kg tortoise: 2 x 100mg x 5 = 1000mg = 1g of paste 5

For a 1.5kg tortoise 1.5 x 100mg x 5 = 750mg of paste 6

1g is approximately equal to 1/4 teaspoon.  7

Panacur is a particularly safe drug and there is a considerable margin of safety with regard to overdosing. 8

As a method of routine "worming" difficult tortoises this system is extremely easy, results in zero stress to the animals and has proven effectiveness 9 . It can also be used with great success on other species - including aquatic and semi-aquatic species provided these feed out of water.

© A. C. Highfield 1989-1999.

 

1- The author has chosen to "prescribe" (I use this term loosely since the author does not have a medical degree) and publicize a rather aggressive course of therapy.  This dosaging regimen is overly aggressive at best and if used in immunosuppressed, heavily parasitized, severely dehydrated, and/or young chelonia can cause serious harm and even death.

2-   The author writes that 3.5 mg fenbendazole in 20 grams of paste is "a little under 19% concentration".   In actuality, 3.5 mg divided by 20 grams of paste is a concentration of .0175%.  This is a far cry from what is written in this document.  The medical mathematics are off by a factor of 1000 as it is written.  While this is likely a typo, there is no room for error with drugs and being off by a factor of 1000 is not a simple error. 

3- The concentration of fenbendazole in the Panacur paste from the United States and the United Kingdom is different.  It probably varies in other countries as well.  Inappopriate, misleading dosaging and treatment instructions can cause serious harm (see references at the bottom of this document for published reports).

4- "For practical purposes"? This type of subjective generality is persistent throughout this publication.  And the fact that these generalizations are being made repeatedly (see below) with complete disregard for the medication that is being utilized here is very disturbing to me as a clinician.  By repeatedly making these types of generalities (such as 1 gram= 1/4 teaspoon), potential problems are rapidly compounded one upon another.  If this were in the medical field (MD, DVM, or a pharmacist), this type of generality would be considered malpractice.

5- "For a 2kg tortoise: 2 x 100mg x 5 = 1000mg = 1g of paste"   This does not make any sense.   Is this 1 gram of paste to be given all at once?  Is this 1 gram of paste to be given over 5 days or 8 days or more?  Posting confusing dosaging information as fact on a web site which is highly travelled and respected is extremely dangerous. 

6- "For a 1.5kg tortoise 1.5 x 100mg x 5 = 750 mg of paste"  Again, there is major confusion as to what exactly is being said here. 

7- 1 gram is equal to about 1/4 teaspoon?  This is a massive generality and it is completely inappropriate for drug dosaging.  This isn't innocuous Play-doh that is being fed out...this is a medication which has proven toxicity. 

8- "Panacur is a particularly safe drug and there is a considerable margin of safety with regard to overdosing" - this is simply completely false.  Article after article has been written on the perils of overdosing with fenbendazole.  Even standard treatment regimens are currently being questioned.  See the references below for more information on this.   

9- "results in zero stress to the animals and has proven effectiveness".   

If you treat an animal at this dosage level for this long that is:

    a. Young

    b. Already immunosuppressed

    c. Dehydrated

    d. Heavily parasitized

you are taking major, major chances with your animal. 

As for proven effectiveness, I've run into a large number of animals over the last several years where panacur quite simply is no longer effective (particularly some recent Turtle Survival Alliance Manouria emys emys from the 2001/2002 Hong Kong confiscation).  Fecals need to be run and appropriate, effective medications prescribed. 

© C. S. Tabaka, DVM 2002.

REFERENCES

1. J Am Vet Med Assoc 2002 Aug 1;221(3):417-9, 369

Bone marrow hypoplasia and intestinal crypt cell necrosis associated with fenbendazole administration in five painted storks.

Weber MA, Terrell SP, Neiffer DL, Miller MA, Mangold BJ.

Disney's Animal Kingdom, Lake Buena Vista, FL 32830, USA.

Five painted storks were treated with fenbendazole for 5 days for internal parasitism. Four birds died following treatment. Profound heteropenia was a consistent finding in all samples evaluated; additionally, the 1 surviving bird had progressive anemia. Consistent necropsy findings in the 4 birds that died were small intestinal crypt cell necrosis and severe bone marrow depletion and necrosis. Fenbendazole has been associated with bone marrow hypoplasia and enteric damage in mammals and other species of birds. The dosages of fenbendazole used in birds are often substantially higher than those recommended for mammals, which may contribute to bone marrow hypoplasia and intestinal crypt cell necrosis associated with fenbendazole administration in birds.

2. Alvarado, T., M. Garner, K.Gamble, G. Levens, J. Raymond, and R. Nordhausen. 2001. Fenbendazole overdose in four Fea's vipers (Azemiops feae). Proc. Annu. Conf. Am. Assoc. Zoo Vet. Pp. 28-29.

3. Barron, S., B.J. Baseheart, T.M. Segar, T. Deveraus, and J.A. Willford. 2000. The behavioral and teratogenic potential of fenbendazole: a medication for pinworm infestation. Neurotoxicol. Teratol. 22:871-877.

4. Dalvi, RR. 1989. Comparative studies on the effect of fenbendazole on the liver and liver microsomal enzymes in goats, quail, and rats. Vet. Res. Commun. 13:135-139.

5. Deiana, L., A.M. Congiy, C. Carru, G.M. Pes, and G. Arru. 1990. Embryotoxicity of fenbendazole in Paracentraotus lividus, Bull. Soc. Ital. Biol. Sper. 66:1137-1144.

6. Hayes, R.H., F.W. Oehme, and H. Leipold. 1983. Toxicity investigation of fenbendazole, an anthelmintic of swine. Am. J. Vet. Res. 44:1108-1111.

7. Howard, L.L., R. Papendick, I.H. Stalis, J.L. Allen, M. Sutherland-Smith, J.R. Zuba, D. Ward, and B.A. Rideout. 1999. Benzimidazole toxicity in birds.  Proc. Annu. Conf. Am. Assoc. Zoo Vet. Pp.36.

8. Papendick, R.I. Stalis, C.Harvey, B. Rideout, J. Zuba, J. Allen, and M. Sutherland-Smith. 1998. Suspected fenbendazole toxicity in birds. Proc. Annu. Conf. Am. Assoc. Zoo Vet. and Am. Assoc. Wildl. Vet. Pp 144-146.

9. Stalis, I.H., B.A. Rideout, J.L.Allen, and M. Sutherland-Smith. 1995. Possible albendazole toxicity in birds. Proc. Annu. Conf. Am. Assoc. Zoo Vet, Wo;d;/ Dos/ Asspc/. and Am. Assoc. Wildl. Vet. Pp. 216-217.

10. Stokol, T., J.F. Randolph, S. Nachbar, C. Rodi, and S.C. Barr. 1997. Development of bone marrow toxicosis after albendazole administration in a dog and a cat. J. Am. Vet. Med. Assoc. 210: 1753-1756.