Chemicals / Complex Chemical Agents/ Chemical:

Fenbendazole (with special reference to Hedgehogs, Elephants, Bears, Lagomorphs, Ferrets and Great Apes)




Information in this page has been entered to support the current volumes of Wildpro and further information will be added as new volumes are completed. This page is not intended to substitute for the manufacturer's data sheet and the information is not yet complete for all species, or for all contra-indications etc.

CAUTION: Before any pharmaceutical product is used, the manufacturer's data sheet, containing information on uses, dosage and administration, contra-indications, warnings etc., should always be consulted. It is important to remember that licensing of pharmaceutical products for use in a particular species/condition, as well as mandatory meat and milk withdrawal times for food-producing animals, varies between countries and changes with time. Withdrawal times also may vary between different pharmaceutical formulations and depending on route of administration. In the EU, the prescription cascade must be followed (see LCofC1.2H and W564.Apr05.w1); note that specific restrictions apply for food-producing animals. In the USA, FARAD may be consulted regarding residues and meat and milk withdrawal times.

General Chemical Information

Benzimidazole anthelmintic agent. (B201.2.w2)

Return to Top of Page

Names and Formulae
Type Benzimidazole anthelmintic. (B201.2.w2, B263)
Alternative Names
  • Panacur; [5-(phenylthio)-1H-benzimidazol-2-yl]carbamic acid methyl ester. (W324)
  • 1,2-dimethyl-5-nitroimidazole
  • Trade names include Panacur (Intervet, UK), Curazole (Tulivin, UK)
Chemical Formula C15H13N3O2S (W324)
Chemical Structure --
Molecular Weight 299.3466. (W324)
Related Chemicals --

Return to Top of Page

Physical Properties / Chemistry

White, crystalline powder. (B263)

Melting point --
Boiling point --
Density --
Water solubility
  • Slightly soluble in water. (B263)
Other solubility --
Acid/Base --

Return to Top of Page

Pharmacology & General Information
  • Binds to tubulin, a protein required for functions including nutrient uptake, thus disrupting parasite energy metabolism. (B201.2.w2)
Storage / Stability
  • Store at room temperature. (B263)
Legal Category (In UK) --

Return to Top of Page


Associated Techniques




(Further Reading)
Click image for full contents list of ELECTRONIC LIBRARY

Authors Debra Bourne (V.w5); Gracia Vila-Garcia (V.w67)
Referees Suzanne I. Boardman (V.w6); Becki Lawson (V.w26); Susan Mikota (V.w72)

Return to Top of Page

Therapeutic Information

  • Active against adult roundworms and larvae, also kills roundworm eggs (ovicidal). (B201.2.w2)
  • Active against tapeworms. (B201.2.w2)
Appropriate Use
  • Dog: used in pregnant and lactating bitches to reduce  roundworms in their puppies. (B201.2.w2)
  • Dog, cat: against lungworm infections. (B201.2.w2); against some tapeworms. (B201.2.w2)
  • Ruminants: against roundworms, tapeworms. (B201.2.w2)
  • Generally considered safe for use in pregnant animals. (B263)
  • Has been used in the treatment of cats, sheep, goats, llamas and pet birds. (B263)


  • UK: "Gastro-intestinal roundworms in horses, ruminants, pigs, dogs, cats, and pigeons; Type II ostertagiosis; transplacental roundworm transmission in dogs; lungworms in ruminants, pigs, dogs, and cats; Trichostrongylus tenuis in grouse; tapeworms in ruminants; Taenia in dogs and cats; Giardia in dogs." (B201.2.w2)
  • USA:
  • Dogs: labelled for removal of ascarids (Toxocara canis, Toxocara leonina), hookworms (Ancyclostoma caninum, Uncinaria stenocephala), whipworms (Trichuris vulpis), tapeworms (Taenia pisiformis). Also used clinically for treatment of Capillaria aerophila, Filaroides hirthi and Paragonimus kellicotti.
  • Cattle: labelled for removal of adult Haemonchus contortus, Ostertagia ostertagi, Trichostrongylus axei, Bunostomum phlebotomum, Nematodirus helvetianus, Cooperia spp., Trichostrongylus colubriformis, Oesophagostomum radiatum, Dictyocaulus vivaparus. Also effective against the immature stages of most of these parasites, and has good activity (although not labelled for) Monezia spp. and arrested 4th stage Ostertagia ostertagi. (B263)
  • Horses: labelled for removal of large strongyles (Strongylus edentatus, Strongylus equinus, Strongylus vulgaris, small strongyles (Cyathostomum spp., Cylicocylus spp., Cylicostephanus spp., Triodontaphorus spp.), pinworms (Oxyuris equi. (B263)
  • Pigs: labelled for removal of large roundworms Ascaris suum, lungworms Matastrongylus apri, nodular worms Oesophagostomum dentatum, Oesophagostomum quadrispinulatum, small stomach worms Hyostrongylus rubidus, whipworms Trichuris suis and kidney worms Stephanuris dentatus (mature and immature). (B263)
  • Not effective against flukes (trematodes). (B201.2.w2)
  • In dogs, cats, singled dose treatment, even at a high dose rate, is not effective; a minimum of three days of treatment is required. (B263)
  • Not effective against Dipilidium caninum. (B263)
Notes --

Return to Top of Page

Pharmacokinetics and Drug Interactions
Absorption /Bioavailability
  • Oral administration results in only marginal absorption from the gut:
    • Peak blood levels in calves 0.11 µg/ml, in horses 0.07 µg/ml. (B263)
Distribution --
Plasma Protein binding / Storage
  • In ruminants and horses the rumen or large intestine respectively acts as a drug reservoir, thereby maintaining therapeutic concentrations for longer periods (compared with a single does in dogs, cats or pigs). (B201.2.w2)
Elimination Route
  • Absorbed fenbendazole is metabolised to active oxfendazole sulfoxide and to the sulfone. (B263)
  • Cattle, sheep, pigs: excreted mainly (44-50%) in the faeces (unchanged), with only very small amounts (less than 1%) eliminated in urine. (B263),
Elimination half-life / Clearance Rate --
Drug Interactions
  • Use concurrently with brosalan flukicides (dibromsalan, tribromsalan) has resulted in abortions in cattle and been fatal in sheep. (B263)

Return to Top of Page

Formulations available
  • Various preparations are available for oral administration. (B201.2.w2, B263)
Doses / Administration Routes / Frequencies

Use of Drugs (Medication):

  • Before administration of any pharmaceutical product the manufacturer's datasheet must be consulted regarding operator safety, relevant withdrawal times etc.
  • Many drugs are not registered for use in particular species and additional care should be taken in their use, with proper regard for possible toxic effects. 
  • Consideration should be given to relevant legislation regarding the use of drugs.
  • In the UK, guidelines regarding the use of drugs are set out in the Royal College of Veterinary Surgeons' Guide to Professional Conduct 2000: (See: LCofC1 - RCVS Guide to Professional Conduct 2000 - Choice of Medicinal Products).
General comments:
  • Dogs, cats: single dose not effective; three days of treatment are required. (B263)


  • Generally 50 mg/kg orally for three consecutive days, e.g. for susceptible ascarids, hookworms, whipworms and tapeworms (active against Taenia spp. tapeworms but not against Dipylidium caninum). (B263)
  • For Giardia infection, 50 mg/kg orally daily for three days, or 25 mg/kg orally every 12 hours for 3-7 days. (B263)
  • For Capillaria aerophila, 25-50 mg/kg every 12 hours for 10-14 days, or 50 mg/kg orally once daily for 10-14 days. (B263)
  • For roundworms, tapeworms and Giardia. Orally, 50 mg/kg daily for three days (treatment in adults); 50 mg/kg daily for three days in pups under six months old, for prophylaxis; 100 mg/kg as a single dose for treatment in adults. (B373.2.w2)
    • For transplacental transmission, 25 mg/kg daily from day 40 of pregnancy through to two days postpartum. (B373.2.w2)
  • For lungworms, 50 mg/kg daily for seven days. (B373.2.w2)

Bears (Ursidae - Bears (Family)):

Erinaceus europaeus - West European Hedgehog:
  • 100 mg/kg oral once daily for five to seven days. (J15.21.w1)
  • > 500 bodyweight, 10 mg/100g bodyweight; <500 g bodyweight, 5mg/100g bodyweight or 20-30 mg/kg bodyweight, oral. for five days (lungworm); for two days (gastro-intestinal worms). For lungworms Crenosoma, Capillaria; nematodes of the stomach and intestines, Acanthocephala, Capillaria spp.. (B22.27.w3)
  • 100 mg/kg once daily for five days. Useful as an in-feed treatment of gastro-intestinal nematodes and against lungworms; may have some effect against tapeworms. (B284.6.w6)
  • 220 mg/kg oral, three doses at two-week intervals. (D107)

Atelerix albiventris - Four-toed hedgehog:

  • 20-30 mg/kg orally for ten days. For nematodes. (B267)
  • 10-30 mg/kg oral; repeat after 2-3 weeks. (J204.59.w1)

"Hedgehog" (species not distinguished between Atelerix albiventris - Four-toed hedgehog or Erinaceus europaeus - West European Hedgehog):

  • 5 mg/kg orally every 24 hours for five days. For nematodes. (B267)
  • 10-30 mg/kg orally for five days. For nematodes such as Crenosoma and Capillaria spp. (B267)
  • 10-15 mg/kg orally; repeat after two or three weeks. For nematodes. (B150.w1)
  • 10-25 mg/kg orally once, repeated after two weeks. For nematode infections. (J34.24.w1)


Elephas maximus - Asian Elephant:

For gastro-intestinal nematode infection:

  • 12 g dissolved in 200 ml of water as a single dose. (J12.65.w1)
  • 5 mg/kg orally as a single dose. (J12.65.w2)

The following information is taken with permission directly from the Elephant Care International website (W580.Aug2005.w12):

For strongylosis:
a) 5 mg/kg po (Raman,, 2000).

b) 2.5 mg/kg orally as a single dose (Chandrasekharan,2002);(Chandrasekharan,1995).

c) 2.0 –2.5 mg/kg orally as a single dose mixed with jaggery or rice (Chandrasekharan, 1992).
d) 5 mg/kg po in feed as a single dose (Strao, 1992).

e) Chronic murshidiasis in an Asian elephant was resolved with 50 g fenbendazole repeated at 30 days (Tripathy 1991).

f) 5 mg/kg po as a single dose (Roy and Mazumdar, 1988).

g) 12 g of Panacur dissolved in 2000 ml water in 2 divided doses at a 3 -day interval (Lahkar and Das,1988).
Elephant References:
a) Raman,M., Jayathagaraj,M.G., Rajavelu,G., and John,M.C. 2000. Strongylosis in captive elephants - a report. Indian Journal of Animal Health 39:(2):85-86 Summary: Strongylosis was observed in a group of elephants (n=4) maintained in a private circus in Chennai, Tamil Nadu, India [date not given]. Examination of faecal samples showed larvae which were identified as Murshidia sp., Quilonia sp., and Decrusia sp. larvae. All elephants were treated with fenbendazole at a dose of 5 mg/kg body weight. A decline of egg count was observed after 1-2 days of treatment. Identification at the earlier stages of infection, good nutrition and hygiene, and less exertion might be the cause of absence of significant clinical signs like anaemia, dehydration and others. It is concluded that use of fenbendazole at the rate of 5 mg/kg body weight in the mega herbivores with repetition after 3 weeks, and regular deworming every 3-6 months, yield satisfactory results.

b) Chandrasekharan,K. 2002. Specific diseases of Asian elephants. Journal of Indian Veterinary Association Kerala 7:(3):31-34

b) Chandrasekharan,K., Radhakrishnan,K., Cheeran,J.V., Nair,K.N.M., and Prabhakaran,T., 1995. Review of the Incidence, Etiology and Control of Common Diseases of Asian Elephants with Special Reference to Kerala. In: Daniel,J.C. (Editor), A Week with Elephants; Proceedings of the International Seminar on Asian Elephants. Bombay Natural History Society; Oxford University Press, Bombay, India pp. 439-449
c) Chandrasekharan,K., 1992. Prevalence of infectious diseases in elephants in Kerala and their treatment. In: Silas,E.G., Nair,M.K., and Nirmalan,G. (Editors), The Asian Elephant: Ecology, Biology, Diseases, Conservation and Management (Proceedings of the National Symposium on the Asian Elephant held at the Kerala Agricultural University, Trichur, India, January 1989). Kerala Agricultural University, Trichur, India pp. 148-155

d) Rao, D.S.T., Yathiraj, S., Choudhuri, P.C., and Reddy, P.K. 1992. Treatment of helminthiosis in elephants. Indian Journal of Animal Science 62(12):1155-1156. Ref ID: 2648 Abstract (Summary): Strongyle and paramphistome eggs were found in the faeces of 3 elephants belonging to S V Dairy Farm, Tirupati. The body weights of these elephants were calculated using the formula: weight (kg) = 12.8 (n+ng) - 4281, where g is chest girth (cm) and ng is neck girth (cm). A drug containing 25% fenbendazole was given orally at a dosage of 5 mg/kg. One elephant had diarrhoea and was also given astringent. No eggs were detected after 7 days in 2 cases and after 14 days in all 3 cases.

e) Tripathy,S.B., Acharjyo,L.N.M., and Padhi,N.K. 1991. Use of fenbendazole against murshidiasis in zoo elephant. International Seminar on Veterinary Medicine in Wild and Captive Animals, Nov. 8-10, Bangalore, India. Pages: 29  Abstract: Treatment of a chronic case of murshidiasis in a captive elephant with fenbendazole has been reported. Large numbers (epg 4200) of Murshidia eggs were detected in the faeces. Differential count of the blood revealed lymphocytosis (63%) and neutropenia (27%). Reduction in feed intake, oedematous swelling on dependent parts of the body, debility and reduction in body weight were recorded. Oral administration of 50 g of Panacur (25% fenbendazole) repeated after 30 days, 50 g of Minamil (mineral mixture) once daily for 30 days and 100 g of Livol (liver tonic) daily for 15 days along with 30 ml of Neurobiocin IM every third day for 5 injections brought clinical recovery and gain in body weight 2 months and 4 months after initiation of treatment respectively. The number of Murshidia eggs reduced by 70% and 100% in per gram of faeces when examined 5 and 10 days post treatment with anthelmintic, respectively.

f) Roy,S. and Mazumdar,B.K. 1988. Anthelmintic activity of fenbendazole (Panacur) against Murshidia murshida in zoo elephants. Indian Veterinary Journal 65:(6):531-532 Summary:  Three Indian elephants, Elephas maximus, infected with M. murshida were treated with a single dose of fenbendazole at 5 mg/kg mixed into feed (cooked rice). Faecal samples were negative in one elephant 3 days after treatment, and in all animals 7 days after treatment. No side effects were recorded.

g) Lahkar,B.C. and Das,M.R. 1988. A note on the successful treatment of trichostrongyle infection of elephants (Elephas maximus) with Panacur (fenbendazole). Indian Veterinary Journal 65:(6):538 Summary:  Six Indian elephants, E. maximus infected with gastrointestinal nematodes (700-1400 epg faeces) were given 12 g Panacur (fenbendazole) in the form of a bolus with flour, in 2 doses 3 days part. Faecal samples from all animals were negative 3 days after the second dose. No side effects were recorded.

Lagomorphs - Oryctolagus cuniculus domesticus - Domestic rabbit:

Ferrets - Mustela putorius fero - Ferret:

  • 20 mg/kg orally, daily for five days. (B201, B602.41.w41, B631.21.w21) For the treatment of nematodes. (B631.21.w21)
  • 50 mg/kg once daily orally for three days. (B626.App.w22)

Great Apes

  • 10 - 100 mg/kg orally every 24 hours for 3 - 14 days. For the treatment of gastrointestinal nematode infections. (B336.39.w39)
  • Adult Pan troglodytes - Chimpanzee: 50 mg/kg per day orally for three days; repeat after three weeks. (W768.Jun2012.w1)
  • Primates: 50 mg/kg once or daily for three day. In the treatment of nematode infections. (D425.3.15.w3o)


  • 50 - 100 mg/kg orally, repeated after 14 days as required. For the treatment of infections with intestinal strongyle or ascarids. (B336.20.w20)
    • 100 mg/kg orally repeated after 14 days. (B12.56.w14)
  • 50 - 100 mg/kg orally daily for five days, repeated after 14 days. For the treatment of gapeworms and capillarids. (B336.20.w20)
  • 100 mg/kg orally daily for five days, repeated after 14 days for the treatment of Gapeworm Infection. (B12.56.w14)
  • 100 mg/kg orally for five days, repeated after 10-14 days. For the treatment of capillariasis and other nematode infections.(B115.8.w4)


  • Against Trichostrongylus tenuis. Given in feed at 1kg/tonne feed, to give 7-10mg/kg bodyweight in divided doses over 14 days. Contra-indication treatment after March. (B201)
Partridges, pheasants:
  • Against Syngamus, Heterakis, Ascaridia, 12mg/kg as a single dose, orally by addition to feed. (B201)
  • Against Capillaria, 24mg/kg in divided doses over 3 days, orally by addition to feed. (B201)
  • May give repeated doses every 6-8 weeks for prevention of helminth infections. (B201)
  • 20mg/kg, orally. (B201)
Exotic birds
  • Against nematodes 50-100 mg/kg, orally, single dose, repeat after 10 days (B201).
  • Against microfilaria and trematodes 33mg/kg orally, repeat daily for three days (B201).
  • Against capillaria 20mg/kg, repeat daily for five days (B201).
  • 50-100mg/kg bodyweight orally every 5-7 days for roundworms. (B201)
  • Against roundworms. 50-100mg/kg orally, every 14 days. (B201)
Monitoring parameters --

Return to Top of Page

Withdrawal period / Withholding time
Notes Before the use of any pharmaceutical product in food-producing animals the label instructions for the product should be consulted regarding withdrawal requirements.

Return to Top of Page

Toxic Information

Toxic effects of Pharmaceutical Products
Contraindications / Precautions
  • Contra-indicated for administration within 14 days of treatment for liver fluke. (B201.2.w2)
  • Administration of ruminal bolus is contra-indicated in cattle which are not ruminating or are less than 100 kg and three month old. 
  • Ruminal bolus is contra-indicated for administration concurrent with other ruminal boluses. (B201.2.w2)
  • Contra-indicated for treatment of grouse later than March. (B201.2.w2)
  • Not for administration within 14 days of the second dose of vaccine in cattle being vaccinated against lungworm. (B201.2.w2)
  • Not recommended for treatment of pigeons during the main moult. (B201.2.w2)
  • Not recommended for treatment of pigeons when rearing young. (B201.2.w2)
  • Toxicity has been reported or suspected in several bird species. (P20.1998.w1)
Adverse Effects / Side Effects / Warnings
  • Rarely causes any adverse effects. (B263)
  • Hypersensitivity reactions may occur secondary to release of antigens by dying parasites; this is more likely to occur at high dose rates. (B263)
  • Dogs, cats: infrequently vomiting occurs. (B263)
Operator Warnings Before the use of any pharmaceutical product the label instructions for the product should be consulted regarding operator safety/warnings.
Overdose / Acute Toxicity
  • Generally well tolerated at doses as high as 100 times recommended. (B263)

Return to Top of Page

Detailed Toxicological Information
Acute Toxicity
  • Laboratory animals oral LD50 greater than 10 g/kg. (B263)
  • Toxicity has been reported or suspected in several bird species. (P20.1998.w1)
Chronic Toxicity --
Reproductive effects --
Teratogenic effects --
Mutagenic effects --
Carcinogenic effects


Organ toxicity --
Bird Toxicity --
Aquatic organism activity --
Other organism toxicity --

Return to Top of Page

Nutrient Information

Nutritional Data
Sources --
Biological Use --
Recommended Daily Allowance / Recommended level in food --
Stability in food (Storage time) --
Interactions --

Return to Top of Page

External / Environmental Information

External / Environmental Uses
Use --
Formulation --
Application method --
Application Concentration --
Persistence of Effect / Frequency of Application --

Return to Top of Page

Effects on the Environment
Effects in the aquatic environment


Effects on land --

Return to Top of Page

Persistence in the Environment
Breakdown in soil and groundwater


Breakdown in water --
Breakdown in vegetation --

Return to Top of Page