Sourced from published veterinary references. Awaiting credentialed clinical reviewer — our editorial process.
Fenbendazole is dosed at 20 mg/kg PO q24h x 28 days in rabbits, per Suter C, Muller-Doblies UU, HattJM, et al. Prevention and treatment of Encephalitozoon cuniculi infection in rabbits with fenbendazole. Vet Rec. 2001;148:478-480. Mencke N, Bach T. Managing gastrointestinal helminths in small mammals. Comp Cont Educ Pract. 2007;29:13-16. — Carpenter's Exotic Animal Formulary 6th ed, Table 10.3 (Antiparasitic Agents Used in Rabbits.a). Verify against current literature before clinical use.
Binds to beta-tubulin, inhibiting microtubule polymerization in parasites. Disrupts energy metabolism and cell division.
Side effects & warnings
Very wide safety margin. Rarely causes vomiting or diarrhea. Safe in pregnant animals at standard doses. Must be given for multiple consecutive days for efficacy.
Species with Fenbendazole dosing data (56 dose rules)
Each ExoticRx dose rule is graded by the strength of its primary evidence — see the editorial process.
Sample dosing (2 of 56 cited rules)
A dog/cat sample is shown here. Cited dosing for all 44 species — reptiles, birds, pocket pets, livestock, and equine — is free on the per-species pages above. Pro adds the weight-based calculator for every species.
· 136. Foronda P, Santana-Morales MA, Oros J, et al. Clinical efficacy of antiparasite treatments against intestinal helminths and haematic protozoa in Gallotia caesaris (lizards). Exp Parasitol. 2007;116(4):361-365. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.225 — Carpenter's Exotic Animal Formulary 6th ed, Table 4.4 (Antiparasitic Agents Used in Reptiles).
· 151. Giannetto S, Brianti E, Poglayen G, et al. Efficacy of oxfendazole and fenbendazole against tortoise (Testudo hermanni) oxyurids. Parasitol Res. 2007;100:1069-1073. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.225 doi:10.1007/s00436-006-0361-2 — Carpenter's Exotic Animal Formulary 6th ed, Table 4.4 (Antiparasitic Agents Used in Reptiles).
· 2. Adamcak A, Otten B. Rodent therapeutics. Vet Clin North Am Exot Anim Pract. 2000;3:221-237. | 122. Meredith A. BSAVA Small Animal Formulary: Part B: Exotic Pets, British Small Animal Veterinary Association, Quedgeley, Gloucester, UK; 2015. | 130. Morrisey JK, Carpenter JW. Formulary. In: Quesenberry KE, Carpenter JW, eds. Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery, 4th ed., Elsevier, St. Louis, MO; 2021:620-630. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.776 — Carpenter's Exotic Animal Formulary 6th ed, Table 9.2 (Antiparasitic Agents Used in Rodents).
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· 37. Boyer TH. Essentials of Reptiles: A Guide for Practitioners. Lakewood, CO: AAHA Press; 1998:1-253. | 143. Jacobson ER. Use of chemotherapeutics in reptile medicine. In: Jacobson ER, Kollias GV Jr, eds. Exotic Animals. New York: Churchill Livingstone; 1988:35-48. | 166. Klingenberg RJ. A comparison of fenbendazole and ivermectin for the treatment of nematode parasites in ball pythons, Python regius. Bull Assoc Rept Amph Vet. 1992;2:5-6. — Source: Mader's Reptile and Amphibian Medicine and Surgery, 3rd Ed, p.1406
· 43. Bailey TA, Apo MM. Pharmaceutics commonly used in avian medicine. In: Samour J, eds. Avian Medicine, 3rd ed., Mosby Elsevier, Edinburgh, Scotland; 2016:637-678. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.433 doi:10.1016/b978-0-7234-3832-8.00023-7 — Carpenter's Exotic Animal Formulary 6th ed, Table 5.4 (Antiparasitic Agents Used in Birds).
· 43. Bailey TA, Apo MM. Pharmaceutics commonly used in avian medicine. In: Samour J, eds. Avian Medicine, 3rd ed., Mosby Elsevier, Edinburgh, Scotland; 2016:637-678. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.434 — Carpenter's Exotic Animal Formulary 6th ed, Table 5.4 (Antiparasitic Agents Used in Birds).
· Adamcak A, Otten B. Rodent therapeutics. Vet Clin North Am Exot Anim Pract. 2000;3:221-237. | Meredith A. BSAVA Small Animal Formulary: Part B: Exotic Pets, British Small Animal Veterinary Association, Quedgeley, Gloucester, UK; 2015. | Morrisey JK, Carpenter JW. Formulary. In: Quesenberry KE, Carpenter JW, eds. Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery, 4th ed., Elsevier, St. Louis, MO; 2021:620-630. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.776 — Carpenter's Exotic Animal Formulary 6th ed, Table 9.2 (Antiparasitic Agents Used in Rodents).
· Adamcak A, Otten B. Rodent therapeutics. Vet Clin North Am Exot Anim Pract. 2000;3:221-237.; Meredith A. BSAVA Small Animal Formulary: Part B: Exotic Pets, British Small Animal Veterinary Association, Quedgeley, Gloucester, UK; 2015.; Morrisey JK, Carpenter JW. Formulary. In: Quesenberry KE, Carpenter JW, eds. Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery, 4th ed., Elsevier, St. Louis, MO; 2021:620-630. — Carpenter's Exotic Animal Formulary 6th ed, Table 9.2 (Antiparasitic Agents Used in Rodents).
· Bailey TA, Apo MM. Pharmaceutics commonly used in avian medicine. In: Samour J, eds. Avian Medicine, 3rd ed., Mosby Elsevier, Edinburgh, Scotland; 2016:637-678. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.433 — Carpenter's Exotic Animal Formulary 6th ed, Table 5.4 (Antiparasitic Agents Used in Birds).
· Beck W, Pantchev N. Praktische Parasitologie bei Heimtieren, Schluetersche Verlagsgesellschaft MBH & Co, Hannover, Germany; 2006.; Visser C, Wijnbergen A, Bleich A. Maeuse und ratten. In: Fehr M, Sassenburg L, Zwart P, eds. Krankheiten der Heimtiere, Schluetersche Verlagsgesellschaft, Hannover, Germany; 2015. — Carpenter's Exotic Animal Formulary 6th ed, Table 9.2 (Antiparasitic Agents Used in Rodents).
· Carpenter's Exotic Animal Formulary 6th ed, Table 5.4 (Antiparasitic Agents Used in BIRDS): '20-50 mg/kg PO q24h43,391 | Psittacines, pigeons/ascarids in psittacines treat once and repeat in 10 days, trematodes and microfilaria treat for 3 days, Capillaria treat for 5 days'. REPLACES the named 'Table 9.2 (Antiparasitic Agents Used in Rodents)', which is the RODENT table.
· Carpenter's Exotic Animal Formulary, 6th Ed — Carpenter's Exotic Animal Formulary, 6th ed, Table 5.4. NOTE: the served figure was matched against the table as a whole, not against this drug's own row, so confirm the number on the page before relying on it.
· Dong J, Li J, Liu Y, Yang Q, Xu N, Ai X, Zhou S. Preclinical Evaluation of Fenbendazole for Controlling Gyrodactylus kobayashii (Monogenea, Gyrodactylidae) in Goldfish: Dose Optimization and Safety Assessment. Animals (Basel). 2025;15(12):1811. doi:10.3390/ani15121811https://pmc.ncbi.nlm.nih.gov/articles/PMC12189257/
· FARAD Withdrawal Guidelines — dose corroborated 2026-08-05 in Plumb's Veterinary Drug Handbook 10th ed, Fenbendazole monograph, printed p.505. NOTE: FARAD publishes meat/milk WITHDRAWAL intervals for extralabel use; it is not the source of the dose itself, so the dose is cited to Plumb's and FARAD retained for the withdrawal guidance.
· FARAD Withdrawal Guidelines — dose corroborated 2026-08-05 in Plumb's Veterinary Drug Handbook 10th ed, Fenbendazole monograph, printed p.507. NOTE: FARAD publishes meat/milk WITHDRAWAL intervals for extralabel use; it is not the source of the dose itself, so the dose is cited to Plumb's and FARAD retained for the withdrawal guidance.
· Foronda P, Santana-Morales MA, Orós J, et al. Clinical efficacy of antiparasite treatments against intestinal helminths and haematic protozoa in Gallotia caesaris (lizards). Exp Parasitol. 2007;116(4):361-365. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.225 — Carpenter's Exotic Animal Formulary 6th ed, Table 4.4 (Antiparasitic Agents Used in Reptiles).
· Giannetto S, Brianti E, Poglayen G, et al. Efficacy of oxfendazole and fenbendazole against tortoise (Testudo hermanni) oxyurids. Parasitol Res. 2007;100:1069-1073. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.225 doi:10.1007/s00436-006-0361-2 — Carpenter's Exotic Animal Formulary 6th ed, Table 4.4 (Antiparasitic Agents Used in Reptiles).
· Gruffydd-Jones T, Addie D, Belak S, et al. Giardiasis in cats: ABCD guidelines on prevention and management. J Feline Med Surg. 2013;15(7):650-652. PMID: 23813834 — Plumb's 10th ed printed p.506, Fenbendazole monograph spanning p.505-507.
· Johnson R, Hemsley S. Gliders and possums. In: Vogelnest L, Woods R, eds. Medicine of Australian Mammals; CSIRO Publishing, Clayton South, Vic; 2008:395-437.; Ness RD, Johnson-Delaney C. Sugar gliders. In: Quesenberry KE, Carpenter JW, eds. Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery, 3rd ed., Saunders/Elsevier, St. Louis, MO; 2012:393-410.; Morrisey JK, Carpenter JW, et al. Formulary. In: Quesenberry KE, Orcutt CJ, Mans C, et al. Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery, 4th ed., Elsevier, St. Louis, MO; 2021:620-630. — Carpenter's Exotic Animal Formulary 6th ed, Table 7.2 (Antiparasitic Agents Used in Sugar Gliders).
· Johnson-Delaney C. Exotic Companion Medicine Handbook for Veterinarians, Zoological Education Network, Lake Worth, FL; 2008.; Morrisey JK, Carpenter JW, et al. Formulary. In: Quesenberry Q, Orcutt C, Mans C, et al. Ferrets, Rabbits and Rodents: Clinical Medicine and Surgery, 4th ed., Elsevier, St. Louis, MO; 2021:620-630. — Carpenter's Exotic Animal Formulary 6th ed, Table 9.2 (Antiparasitic Agents Used in Rodents).
· MattCL, Nagamori Y, Stayton E, et al. Kalicephalus hookworm infection in four corn snakes (Pantherophis guttatus). J Exot Pet Med. 2020;34:62-66. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.225 doi:10.1053/j.jepm.2020.04.008 — Carpenter's Exotic Animal Formulary 6th ed, Table 4.4 (Antiparasitic Agents Used in Reptiles).
· Mencke N, Bach T. Managing gastrointestinal helminths in small mammals. Comp Cont Educ Pract. 2007,29:13-16. | Morissey JM, Carpenter JW. Appendix: Formulary. In: Quesenberry KE, Orcutt CJ, Mans C, et al. Ferrets, Rabbits and Rodents: Clinical Medicine and Surgery, 4th ed., Elsevier, 2021:620-630. - Carpenter's Exotic Animal Formulary 6th ed, Table 10.3 (Antiparasitic Agents Used in Rabbits), nematode row: '5-20 mg/kg PO q24h x 5 days, repeat in 14 days162,166 | Nematodes, use 20 mg/kg for Passalurus ambiguous'.
· Morrisey JK. Ectoparasites of ferrets and rabbits. Proc North Am Vet Conf; 1998:844-845. — Carpenter's Exotic Animal Formulary 6th ed, Table 11.4 (Antiparasitic Agents Used in Ferrets).
· PRIMARY LITERATURE, species named in the study: Al-Timimi F, Nolosco P, Al-Timimi B. "Incidence and treatment of serratospiculosis in falcons from Saudi Arabia." Vet Rec 2009;165(14):408-409. doi:10.1136/vr.165.14.408. PMID 19801594 — https://pubmed.ncbi.nlm.nih.gov/19801594/. Abstract retrieved and read 2026-08-20; dose, route, duration, efficacy endpoint and the safety statement are all stated in it. Full text not read.
· Papich/Saunders Handbook of Veterinary Drugs, 4th Ed, p.344
· Plumb's Fenbendazole REPTILES, printed p.507; Carpenter's 6th ed. Table 4.4, p.225, ball-python-specific row; Mader's Table 127.4 ('All species/nematodes') — Carpenter's Exotic Animal Formulary 6th ed, Table 4.4 (Antiparasitic Agents Used in Reptiles). — PROVENANCE: the served 50-100 mg/kg ONCE regimen is printed only in BSAVA Small Animal Formulary 10th ed Part B, printed p.128 — "Reptiles: Nematodes: 50-100 mg/kg p.o., per cloaca once". Both cited formulary tables print a DIFFERENT regimen — Carpenter's Table 4.4 and Mader's Table 127.4 both give 25-100 mg/kg PO q14d for up to 4 treatments, and Plumb's gives 50-100 mg/kg PO repeated in 2 weeks. Class caution, BSAVA p.128 — profound leucopenia in Testudo hermanni after two courses of 50 mg/kg daily for 5 days.
· Plumb's Veterinary Drug Handbook, Fenbendazole, REPTILES section, printed p.507; Mader's Table 127.4, '25-100 mg/kg PO q14d for up to 4 treatments - All species/nematodes'
· Ramsey I, ed. BSAVA Small Animal Formulary, 10th ed. Part B: Exotic Pets. Gloucester: British Small Animal Veterinary Association; 2023. p.128.
· Samour, Avian Medicine, 3rd Ed. (raptor formulary appendix), p.666. Row as printed binds this dose to raptors on its own line: "Fenbendazole Panacur 2.5% or 10% Raptors PO 100 mg/kg once Ascarids, some microfilariae, capillariasis, other". | REDUCED 100 -> 25 mg/kg ON 2026-08-20 after independent cross-book review: raptor text p.325 "Fenbendazole 25 mg/kg either once or SID for 3-5 days. Possible toxicity in vultures?"; BSAVA raptor p.65 "Fenbendazole is considered to be toxic in vultures"; Plumb's p.534 "NOTE: Fenbendazole may cause severe toxicity in some birds". Primary toxicity reports: Weber MA et al., J Am Vet Med Assoc 2002;221:417-419 (bone marrow hypoplasia, five painted storks); Gozalo AS et al., J Am Assoc Lab Anim Sci 2006;45:63-66 (mortality in pigeons); Bonar CJ et al., J Avian Med Surg 2003;17:16 (two vulture species); Howard LL et al., J Avian Med Surg 2002;16:203-210. | PRIMARY TOXICITY REPORTS VERIFIED IN PUBMED 2026-08-20, retrieved independently of the handbook reference list that named them: Gozalo AS, Schwiebert RS, Lawson GW. "Mortality associated with fenbendazole administration in pigeons (Columba livia)." J Am Assoc Lab Anim Sci 2006;45(6):63-66. — . Weber MA, Terrell SP, Neiffer DL, Miller MA, Mangold BJ. "Bone marrow hypoplasia and intestinal crypt cell necrosis associated with fenbendazole […]" J Am Vet Med Assoc 2002;221(3):417-419. — . Both titles state the harm directly; neither paper was read in full, so this establishes that the reports exist and what they report, not their dose-response detail. | RAPTOR-SPECIFIC LITERATURE RETRIEVED 2026-08-20: Al-Timimi F, Nolosco P, Al-Timimi B. "Incidence and treatment of serratospiculosis in falcons from Saudi Arabia." Vet Rec 2009;165(14):408-409. . — (30 mg/kg PO 5-8 days effective, no side effects). Doss GA, Mans C, Johnson L, Pinkerton ME, Hardie RJ, Sladky KK. "Diagnosis and management of inflammatory bowel disease in a harpy eagle (Harpia harpyja) with suspected fenbendazole toxicosis." J Am Vet Med Assoc 2018;252(3):336-342. — . Both abstracts read in full.
· Suter C, Muller-Doblies UU, HattJM, et al. Prevention and treatment of Encephalitozoon cuniculi infection in rabbits with fenbendazole. Vet Rec. 2001;148:478-480. doi:10.1136/vr.148.15.478; Mencke N, Bach T. Managing gastrointestinal helminths in small mammals. Comp Cont Educ Pract. 2007;29:13-16. — Carpenter's Exotic Animal Formulary 6th ed, Table 10.3 (Antiparasitic Agents Used in Rabbits.a).