Beavers (Castor fiber)

Beavers (Castor fiber)

Drug	Dose	Comments
Anaesthetics:
Ketamine + diazepam	Sedation: Ketamine (10–12.5 mg/kg) + diazepam (0.2 mg/kg) i.m.b,c	Sedation generally occurs within 15–20 minutes after which anaesthesia can be induced using isoflurane delivered in 100% oxygen via a facemask or after intubation
Ketamine + medetomidine	Ketamine (6.0–9.5 mg/kg) + medetomidine (0.07 mg/kg) i.m.c	No problems were associated with this regime
Ketamine + butorphanol + medetomidine	Ketamine (5 mg/kg) + butorphanol (0.1 mg/kg) + medetomidine (0.05 mg/kg) i.m.a	Mean induction time was 8.4 ± 5.0 minutes Muscle relaxation poor and variable (see below)
Ketamine + butorphanol + medetomidine + midazolam	Ketamine (5 mg/kg) + butorphanol (0.1 mg/kg) + medetomidine (0.05 mg/kg) + midazolam (0.25 mg/kg) i.m.a	Mean induction time was 7.8 ± 2.6 minutes Note that better muscle relaxation was achieved with this regime compared with ketamine + butorphanol + medetomidine
Atipamezole	5x dose (mg/kg) medetomidine used a	Reversal of medetomidine: 5 times the medetomidine dose (i.e. equal volume of the 5 mg/ml atipamezole solution) In common with most species, a delay in reversal of medetomidine of at least 20 minutes after the administration of combinations with ketamine is recommended
Analgesics:
Buprenorphine	0.01—0.03 mg/kg i.m., s.c. q8—12hrd
Butorphanol	0.5 mg/kg i.m., s.c. q4hrd
Ketoprofen	1—3 mg/kg i.m., s.c. q24hrd	The usual considerations for the careful use of NSAIDs in dehydrated, hypovolaemic or hypertensive animals, as well as those with underlying gastrointestinal disease, should be observed
Meloxicam	0.1—0.33 mg/kg s.c., p.o. q12—24hrd
Morphine	1—3 mg/kg i.m., s.c. q4—6hrd
Tramadol	0.5—5 mg/kg p.o. q12—24hrd
Antibiotics: Antibiotic use (both appropriate and inappropriate) imposes a powerful selection pressure on bacteria and is the primary driver of antibiotic resistance. Eliminating unnecessary use in people and animals is, therefore, essential to safeguard this invaluable resource. Prudent use is especially indicated where treated wild animals are being returned to the wild. The reader is referred to the Guidelines for responsible antibiotic use https://www.bsavalibrary.com/content/formulary/backmatter/exotic-petsguidelinesforresponsibleantibioticuse for more information
Enrofloxacin	10 mg/kg s.c., p.o. q12—24hb 7.5—10 mg/kg of a long-acting product (Baytril Max®; Bayer) every 2—4 daysb	Fluroquinolones should ideally be reserved for infections where culture and sensitivity testing predict a clinical response and use of first- and second- line antimicrobials would not be considered effective Fluroquinolones are used in beavers owing to the high prevalence of Gram-negative bacterial infections, such as Pseudomonas spp. and Aeromonas spp. Not to be used in growing animals
Parasiticides: Parasiticide use in wildlife may reduce the development of natural resistance to parasites, as well as exerting selection pressure on organisms which can lead to drug resistance and may risk environmental contamination. Careful selection and use of these drugs, only where there is a clinical need, and then using narrow spectrum products, is essential where treated wild animals are being returned to the wild. Reader is referred to the joint BVA, BSAVA and BVZS policy statement
Ivermectin	0.2 mg/kg i.m.b	Appears effective against intestinal nematodes Anecdotal evidence to suggest that the use of clorsulon-containing compounds (e.g. Ivomec super injection for cattle®; Merial, which also contains ivermectin and dosed at 1 ml per 50 kg bodyweight) do have some effect against intestinal flukes in beaversb

References and further reading

a Ranheim B, Rosell F, Haga HA and Arnemo JM (2004) Field anaesthetic and surgical techniques for implantation of intraperitoneal radio transmitters in Eurasian beavers (Castor fiber) Wildlife. Biology 10, 11–15

bCampbell-Palmer R and Rosell F (2013) Captive management guidelines for Eurasian beavers. Available at: https://www.researchgate.net/profile/Roisin-Campbell-Palmer/publication/237164255_Captive_management_guidelines_Eurasian_beaver_2013/links/0deec51b9fa3bcd7be000000/Captive-management-guidelines-Eurasian-beaver-2013.pdf

c Goodman G, Girling S, Pizzi R, Meredith A, Rosell F and Campbell-Palmer R (2012) Establishment of a health surveillance program for reintroduction of the Eurasian beaver (Castor fiber) into Scotland. Journal of Wildlife Diseases 48(4), 971–978

d Heard D (2025) Mice, rats, guinea pigs, hamsters, chinchillas and other rodents. Zoo Animal and Wildlife Immobilization and Anaesthesia, 3rd edition, ed. G West G, D Heard and N Caulkett. John Wiley and Sons

Campbell-Palmer R and Rosell F (2015) Captive care and welfare considerations for beavers. Zoo Biology 34, 101—109

Campbell-Palmer R, Rosell F, Naylor A et al. (2021) Eurasian beaver ( Castor fiber ) health surveillance in Britain: Assessing a disjunctive reintroduced population. Vet Record 118, 8

Saunders R (2016) Other insectivores and rodents. BSAVA Manual of Wildlife Casualties, 2nd edition, ed. E Mullineaux and E Keeble, pp. 152—175. BSAVA Publications, Gloucester

Beaver trust https://beavertrust.org

BSAVA library https://www.bsavalibrary.com/

BVA, BSAVA, BVZS joint policy statement: Responsible use of parasiticides https://www.bva.co.uk/take-action/our-policies/responsible-use-of-parasiticides-for-cats-and-dogs/