ANESTHETIC MANAGEMENT OF A 4-MONTH-OLD RED FOX (VULPES VULPES) FOR ORTHOPEDIC SURGERY Author(s): Tilemahos Anagnostou, D.V.M., Ph.D., Eugenia Flouraki, D.V.M., Charalampos Kostakis, D.V.M., Anastasia Komnenou, D.V.M., Ph.D., Nikitas Prassinos, D.V.M., Ph.D., and Dimitrios Raptopoulos, Ph.D., Dipl. E.C.V.A.A. Source: Journal of Zoo and Wildlife Medicine, 46(1):155-157. Published By: American Association of Zoo Veterinarians DOI: http://dx.doi.org/10.1638/2014-75R1.1 URL: http://www.bioone.org/doi/full/10.1638/2014-75R1.1
BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/ terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder.
BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research.
Journal of Zoo and Wildlife Medicine 46(1): 155–157, 2015 Copyright 2015 by American Association of Zoo Veterinarians
ANESTHETIC MANAGEMENT OF A 4-MONTH-OLD RED FOX (VULPES VULPES) FOR ORTHOPEDIC SURGERY Tilemahos Anagnostou, D.V.M., Ph.D., Eugenia Flouraki, D.V.M., Charalampos Kostakis, D.V.M., Anastasia Komnenou, D.V.M., Ph.D., Nikitas Prassinos, D.V.M., Ph.D., and Dimitrios Raptopoulos, Ph.D., Dipl. E.C.V.A.A.
Abstract: A 4-mo-old red fox (Vulpes vulpes) was found recumbent after a vehicular accident. Radiology revealed several limb fractures and the fox underwent surgery after 24 hr of initial stabilization. Premedication consisted of dexmedetomidine and morphine. Anesthesia was induced with ketamine and midazolam and maintained with isoflurane. Lidocaine, bupivacaine, and morphine were administered epidurally and further analgesia was provided with meloxicam. The heart rate and respiratory rate of the fox remained stable during surgery and, except for a mild hypothermia, the recovery from anesthesia was uneventful. The postoperative pain scores were low and the animal was transported to a rehabilitation facility and eventually released to the wild. The low pain scores postoperatively should be attributed to the successful application of epidural anesthesia and analgesia. Key words: Dexmedetomidine, epidural anesthesia, general anesthesia, red fox, Vulpes vulpes.
BRIEF COMMUNICATION The red fox (Vulpes vulpes) is a wild carnivore of the Canidae family native to Greece and is not currently under threat. A search in scientific databases came up with a few reports regarding anesthetic protocols for the immobilization and capture of wild red foxes,3,6,8–10 but no report could be found regarding anesthesia for major surgery. A wild 4-mo-old red fox weighing 1.95 kg was found recumbent by a wildlife rescue organization (Action for Wildlife, http://drasi-agriazoi.gr/), presumably after a vehicular accident, and was referred to our clinic. On presentation, the animal was alert with 115 heartbeats/min, 52 respirations/min, a strong pulse, pink mucous membranes, a rectal temperature of 398C, and no clinical signs of any contagious disease. The animal could easily be handled with the use of a basket muzzle and no sedation was needed. The complete blood count was within normal limits, but orthopedic examination and diagnostic imaging revealed three physeal fractures, one in the distal physis of the right femur, one in the left femoral head, and one in the left greater trochanter, as well as a spiral diaphyseal fracture of the right humerus. The animal was hospitalized for 24
From the Companion Animal Clinic, Department of Clinical Sciences, Faculty of Veterinary Medicine, School of Health Sciences, Aristotle University of Thessaloniki, St. Voutira 11, GR-54627, Thessaloniki, Greece (Anagnostou, Flouraki, Kostakis, Komnenou, Prasinos and Raptopoulos). Correspondence should be directed to Dr. Anagnostou ([email protected]).
hr receiving Lactated Ringer’s solution (L-R Lactated Ringer’s Injection, Vioser S.A., GR42100, Trikala, Greece; 2 ml/kg per hour i.v.) along with cefazolin (Vifazolint 1 gr/vial, Vianex S.A., GR-14671 Athens, Greece; 20 mg/kg i.v., b.i.d.) and meloxicam (Metacamt 5 mg/ml, Boehringer Ingelheim Vetmedica GmbH, Ingelheim/ Rhein, 55216, Germany; 0.1 mg/kg i.v., s.i.d.), and was fed commercial canned dog food. On the day of surgery, the animal received its last meal 4 hr prior to sedation and was presented to the anesthesia and intensive care unit without an intravenous catheter in place, because of inadvertent dislodgment the previous night. Preanesthetic evaluation of respiratory and cardiovascular parameters gave results within normal limits and the fox was premedicated with dexmedetomidine (Dexdomitort, Orion Pharma, Espoo FL-02101, Finland; 5 lg/kg i.m.) and morphine (morphine sulfate 10 mg/ml, Famar S.A., GR17456, Athens, Greece; 0.1 mg/kg i.m.). All intramuscular injections were carried out at the thigh after muzzling the fox. Thirty minutes later, the level of sedation was deemed insufficient and dexmedetomidine was administered anew at a higher dose (10 lg/kg i.m.). Adequate sedation was achieved 20 min later and anesthesia was induced using ketamine (Imalgenet 100 mg/ml, Merial, Lyon 69007, France; 7.5 mg/kg i.m.) and midazolam (Dormicumt 5 mg/ml, Hoffmann-La Roche Inc., Nutley, New Jersey 07110, USA; 0.2 mg/kg i.m.). Within 10 min of the ketamine– midazolam injection, a new intravenous catheter was placed at the cephalic vein and the trachea of
155
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the animal was intubated using a cuffed 3-mm rubber endotracheal tube. Anesthesia was maintained using isoflurane (IsoFlot 100% w/w, Abbott Laboratories Ltd., Berkshire SL6 4XE, United Kingdom) in oxygen, delivered through a Jackson-Ree’s modification of an Ayre’s T-piece. Oxygen flow was set at 1.5 l/min. After induction of anesthesia, meloxicam (0.2 mg/kg i.v.) was administered and an epidural injection of lidocaine (Xylocainet injection 2%, Recipharm Monts, Monts 37260, France; 2.5 mg/kg), bupivacaine (bupivacaine hydrochloride/Baxter 0.5% w/v, Bieffe Medital S.P.A., Grosotto 23034, Italy; 0.625 mg/kg) and morphine (0.1 mg/kg) was carried out at the lumbosacral junction using a 22-ga, 2.5-cm spinal needle (Spinocant, B. Braun, Meslungen 34212, Germany). The ‘‘hanging drop’’ technique used was performed exactly as it would have been carried out in a dog without any difficulty. A standard monitoring protocol was applied from induction to discontinuation of anesthesia, including electrocardiography (lead II) and pulse oximetry (PC Scout; Spacelabs healthcare, Snoqualmie, Washington 98065, USA), capnography, measurement of O2 and isoflurane concentrations in inspired and end-tidal gas, and measurement of tidal volume and airway pressure (sampling at the endotracheal connector) (Capnomac Ultima; Datex-Engstrom, FIN-00031, Finland). Arterial blood pressure could not be measured noninvasively, due to the fact that three legs were being operated on and the intravenous catheter was placed on the fourth leg, or invasively, due to the small size of the animal. Lactated Ringer’s solution was administered intravenously from induction to recovery from anesthesia at a rate of 10 ml/kg per hour. Intraoperatively, heating pads were used to maintain normothermia. Surgery lasted 2.5 hr. An intramedullary pin and four circlage wires were used for humeral fracture fixation. Kirschner wires were used for physeal fractures osteosynthesis, combined with a tension band wire only in the case of the greater trochanter fracture. The vaporizer dial setting ranged from 0.6 to 1.5% with corresponding end-tidal isoflurane concentrations of 0.5 to 1.2%. The heart rate varied between 60 and 85 beats/min, the respiratory rate between 5 and 10 breaths/min, and the end-tidal CO2 between 30 and 63 mm Hg. At the end of surgery, the fox had mild hypothermia (rectal temperature 36.48C) and its blood glucose was measured using a handheld glucose meter (Accu-Check Aviva Blood Glucose Meter System,
Roche Diagnostics, Mannheim 68305, Germany) and was 142 mg/dl. Recovery from anesthesia was otherwise uneventful and the fox remained hospitalized for another week, receiving cefazolin (20 mg/kg i.v., b.i.d.), meloxicam (0.1 mg/kg i.v., s.i.d.) and Lactated Ringer’s solution (2 ml/kg per hour i.v., only for the first 2 days). During the first three postoperative days of hospitalization a visual analog pain score was attributed to the animal four times daily based on physiologic parameters, such as heart rate and respiratory rate, as well as on the animal’s posture and behavior. The highest pain score during this period was 30%. A week later the fox was transported to a rehabilitation facility until its release to the wild. The anesthetic effects of many a2 agonists have been previously studied in the red fox.3,4,6,8,10 In this particular case, dexmedetomidine was preferred over medetomidine, as a newer a2 agonist. The failure of the first administration to induce adequate sedation could be attributed to the high level of stress causing release of catecholamines and potentially interfering with the reduction of release of excitatory neurotransmitters.7 Anesthesia was induced using ketamine–midazolam intramuscularly in order to achieve complete immobilization of the fox, as there was only one site available for the placement of an intravenous catheter. The use of ketamine–midazolam in the red fox was first described in 19906 (ketamine 30 mg/kg i.m., midazolam 0.6 mg/kg i.m.), producing adequate depth of anesthesia for immobilization and capture. The dose used in the present case was less than a third of the one used in the aforementioned study because, in this case, preanesthetic medication was used. Ketamine has been combined with medetomidine in other studies in foxes,1,2,4,5,8 even for minor surgical procedures, given at 2.5–4 mg/kg and 40–76 lg/ kg, respectively. The dose of ketamine used in this case was higher (7.5 mg/kg), but the dose of the a2 agonist was quite lower (15 lg/kg) given that dexmedetomidine is twice as potent as medetomidine, and also because a higher dose of ketamine would contribute longer to analgesia because of ketamine’s antihyperalgesic properties. The systemic dose of morphine used in the present study could be considered low if used as a sole analgesic agent, but it was chosen given the fact that ketamine and meloxicam were also administered systematically, as well as local anesthetics and morphine administered epidurally, thus contributing to a balanced multimodal analgesic approach.
ANAGNOSTOU ET AL.—ANESTHESIA FOR MAJOR SURGERY ON A RED FOX
The key feature of the anesthetic management implemented in the present case was the decision to use epidural anesthesia and analgesia. The fox was a perfect candidate for epidural anesthesia as it had fractures to be operated on in both hind legs, and also for epidural analgesia, as the epidural administration of morphine has been proven to provide analgesia for the hind and the front legs in the dog.11 Furthermore, the use of epidural anesthesia and analgesia allowed for omission of repeated intramuscular morphine injections, reducing the stress induced on the fox by hospitalization. Although there are no reference data on the isoflurane minimum alveolar concentration (MAC) in red foxes, the isoflurane setting in this case can be considered low, especially compared to other carnivores undergoing similar surgeries. However, sampling at the endotracheal connector with high fresh gas flows may have affected the accuracy of the measurement as the sample could have been contaminated with fresh gas, thus increasing the observed reading. Nevertheless, many factors surely contributed to the low isoflurane setting, including systemic opioid and ketamine administration, as well as application of epidural anesthesia/analgesia. In conclusion, dexmedetomidine was used in a red fox in the present case without any unexpected adverse effects. When used in red foxes, it can be administered similarly to medetomidine, keeping in mind that it is twice as potent. Epidural anesthesia and analgesia should be attempted in surgical cases of red foxes as it can provide excellent surgical conditions and patient comfort.
LITERATURE CITED 1. Acosta-Jamett G, Astorga-Arancibia F, Cunningham AA. Comparison of chemical immobilization methods in wild foxes (Pseudalopex griseus and Pseudalopex culpaeus) in Chile. J Wildl Dis. 2010;46:1204– 1213.
157
2. Aguirre AA, Principe B, Tannerfeldt M, Angerbjorn A, Morner T. Field anesthesia of wild arctic fox (Alopex lagopus) cubs in the Swedish Lapland using medetomidine–ketamine–atipamezole. J Zoo Wildl Med. 2000;31:244–246. 3. Baldwin JR, Winstead JB, Hayden-Wing LD, Kreeger TJ, Dzialak MR. Field sedation of coyotes, red foxes, and raccoons with medetomidine and atipamezole. J Wildl Manag. 2008;72:1267–1271. 4. Bertelsen MF, Villadsen L. A comparison of the efficacy and cardiorespiratory effects of four medetomidine-based anaesthetic protocols in the red fox (Vulpes vulpes). Vet Anaesth Analg. 2009;36:328–333. 5. Fuglei E, Mercer JB, Arnemo JM. Surgical implantation of radio transmitters in arctic foxes (Alopex lagopus) on Svalbard, Norway. J Zoo Wildl Med. 2002;33:342–349. 6. Kreeger TJ, Seal US, Tester JR. Chemical immobilization of red foxes (Vulpes vulpes). J Wildl Dis. 1990; 26:95–98. 7. Lemke K. Anticholinergics and sedatives. In: Tranquilli WJ, Thurmon JC, Grimm KA (eds.). Lumb and Jones’ veterinary anesthesia and analgesia. 4th ed. Oxford, UK: Blackwell Publishing Ltd.; 2007. p. 203– 239. 8. Shilo Y, Lapid R, King R, Bdolah-Abram T, Epstein A. Immobilization of red fox (Vulpes vulpes) with medetomidine–ketamine or medetomidine–midazolam and antagonism with atipamezole. J Zoo Wildl Med. 2010;41:28–34. 9. Travaini A, Delibes M. Immobilization of freeranging red foxes (Vulpes vulpes) with tiletamine hydrochloride and zolazepam hydrochloride. J Wildl Dis. 1994;30:589–591. 10. Travaini A, Ferreras P, Delibes M, Aldama JJ. Xylazine hydrochloride–ketamine hydrochloride immobilization of free-living red foxes (Vulpes vulpes) in Spain. J Wildl Dis. 1992;28:507–509. 11. Valverde A, Dyson DH, McDonell WN. Epidural morphine reduces halothane MAC in the dog. Can J Anaesth. 1989;36:629–632. Received for publication 26 April 2014
BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/ terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder.
BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research.
Journal of Zoo and Wildlife Medicine 46(1): 155–157, 2015 Copyright 2015 by American Association of Zoo Veterinarians
ANESTHETIC MANAGEMENT OF A 4-MONTH-OLD RED FOX (VULPES VULPES) FOR ORTHOPEDIC SURGERY Tilemahos Anagnostou, D.V.M., Ph.D., Eugenia Flouraki, D.V.M., Charalampos Kostakis, D.V.M., Anastasia Komnenou, D.V.M., Ph.D., Nikitas Prassinos, D.V.M., Ph.D., and Dimitrios Raptopoulos, Ph.D., Dipl. E.C.V.A.A.
Abstract: A 4-mo-old red fox (Vulpes vulpes) was found recumbent after a vehicular accident. Radiology revealed several limb fractures and the fox underwent surgery after 24 hr of initial stabilization. Premedication consisted of dexmedetomidine and morphine. Anesthesia was induced with ketamine and midazolam and maintained with isoflurane. Lidocaine, bupivacaine, and morphine were administered epidurally and further analgesia was provided with meloxicam. The heart rate and respiratory rate of the fox remained stable during surgery and, except for a mild hypothermia, the recovery from anesthesia was uneventful. The postoperative pain scores were low and the animal was transported to a rehabilitation facility and eventually released to the wild. The low pain scores postoperatively should be attributed to the successful application of epidural anesthesia and analgesia. Key words: Dexmedetomidine, epidural anesthesia, general anesthesia, red fox, Vulpes vulpes.
BRIEF COMMUNICATION The red fox (Vulpes vulpes) is a wild carnivore of the Canidae family native to Greece and is not currently under threat. A search in scientific databases came up with a few reports regarding anesthetic protocols for the immobilization and capture of wild red foxes,3,6,8–10 but no report could be found regarding anesthesia for major surgery. A wild 4-mo-old red fox weighing 1.95 kg was found recumbent by a wildlife rescue organization (Action for Wildlife, http://drasi-agriazoi.gr/), presumably after a vehicular accident, and was referred to our clinic. On presentation, the animal was alert with 115 heartbeats/min, 52 respirations/min, a strong pulse, pink mucous membranes, a rectal temperature of 398C, and no clinical signs of any contagious disease. The animal could easily be handled with the use of a basket muzzle and no sedation was needed. The complete blood count was within normal limits, but orthopedic examination and diagnostic imaging revealed three physeal fractures, one in the distal physis of the right femur, one in the left femoral head, and one in the left greater trochanter, as well as a spiral diaphyseal fracture of the right humerus. The animal was hospitalized for 24
From the Companion Animal Clinic, Department of Clinical Sciences, Faculty of Veterinary Medicine, School of Health Sciences, Aristotle University of Thessaloniki, St. Voutira 11, GR-54627, Thessaloniki, Greece (Anagnostou, Flouraki, Kostakis, Komnenou, Prasinos and Raptopoulos). Correspondence should be directed to Dr. Anagnostou ([email protected]).
hr receiving Lactated Ringer’s solution (L-R Lactated Ringer’s Injection, Vioser S.A., GR42100, Trikala, Greece; 2 ml/kg per hour i.v.) along with cefazolin (Vifazolint 1 gr/vial, Vianex S.A., GR-14671 Athens, Greece; 20 mg/kg i.v., b.i.d.) and meloxicam (Metacamt 5 mg/ml, Boehringer Ingelheim Vetmedica GmbH, Ingelheim/ Rhein, 55216, Germany; 0.1 mg/kg i.v., s.i.d.), and was fed commercial canned dog food. On the day of surgery, the animal received its last meal 4 hr prior to sedation and was presented to the anesthesia and intensive care unit without an intravenous catheter in place, because of inadvertent dislodgment the previous night. Preanesthetic evaluation of respiratory and cardiovascular parameters gave results within normal limits and the fox was premedicated with dexmedetomidine (Dexdomitort, Orion Pharma, Espoo FL-02101, Finland; 5 lg/kg i.m.) and morphine (morphine sulfate 10 mg/ml, Famar S.A., GR17456, Athens, Greece; 0.1 mg/kg i.m.). All intramuscular injections were carried out at the thigh after muzzling the fox. Thirty minutes later, the level of sedation was deemed insufficient and dexmedetomidine was administered anew at a higher dose (10 lg/kg i.m.). Adequate sedation was achieved 20 min later and anesthesia was induced using ketamine (Imalgenet 100 mg/ml, Merial, Lyon 69007, France; 7.5 mg/kg i.m.) and midazolam (Dormicumt 5 mg/ml, Hoffmann-La Roche Inc., Nutley, New Jersey 07110, USA; 0.2 mg/kg i.m.). Within 10 min of the ketamine– midazolam injection, a new intravenous catheter was placed at the cephalic vein and the trachea of
155
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JOURNAL OF ZOO AND WILDLIFE MEDICINE
the animal was intubated using a cuffed 3-mm rubber endotracheal tube. Anesthesia was maintained using isoflurane (IsoFlot 100% w/w, Abbott Laboratories Ltd., Berkshire SL6 4XE, United Kingdom) in oxygen, delivered through a Jackson-Ree’s modification of an Ayre’s T-piece. Oxygen flow was set at 1.5 l/min. After induction of anesthesia, meloxicam (0.2 mg/kg i.v.) was administered and an epidural injection of lidocaine (Xylocainet injection 2%, Recipharm Monts, Monts 37260, France; 2.5 mg/kg), bupivacaine (bupivacaine hydrochloride/Baxter 0.5% w/v, Bieffe Medital S.P.A., Grosotto 23034, Italy; 0.625 mg/kg) and morphine (0.1 mg/kg) was carried out at the lumbosacral junction using a 22-ga, 2.5-cm spinal needle (Spinocant, B. Braun, Meslungen 34212, Germany). The ‘‘hanging drop’’ technique used was performed exactly as it would have been carried out in a dog without any difficulty. A standard monitoring protocol was applied from induction to discontinuation of anesthesia, including electrocardiography (lead II) and pulse oximetry (PC Scout; Spacelabs healthcare, Snoqualmie, Washington 98065, USA), capnography, measurement of O2 and isoflurane concentrations in inspired and end-tidal gas, and measurement of tidal volume and airway pressure (sampling at the endotracheal connector) (Capnomac Ultima; Datex-Engstrom, FIN-00031, Finland). Arterial blood pressure could not be measured noninvasively, due to the fact that three legs were being operated on and the intravenous catheter was placed on the fourth leg, or invasively, due to the small size of the animal. Lactated Ringer’s solution was administered intravenously from induction to recovery from anesthesia at a rate of 10 ml/kg per hour. Intraoperatively, heating pads were used to maintain normothermia. Surgery lasted 2.5 hr. An intramedullary pin and four circlage wires were used for humeral fracture fixation. Kirschner wires were used for physeal fractures osteosynthesis, combined with a tension band wire only in the case of the greater trochanter fracture. The vaporizer dial setting ranged from 0.6 to 1.5% with corresponding end-tidal isoflurane concentrations of 0.5 to 1.2%. The heart rate varied between 60 and 85 beats/min, the respiratory rate between 5 and 10 breaths/min, and the end-tidal CO2 between 30 and 63 mm Hg. At the end of surgery, the fox had mild hypothermia (rectal temperature 36.48C) and its blood glucose was measured using a handheld glucose meter (Accu-Check Aviva Blood Glucose Meter System,
Roche Diagnostics, Mannheim 68305, Germany) and was 142 mg/dl. Recovery from anesthesia was otherwise uneventful and the fox remained hospitalized for another week, receiving cefazolin (20 mg/kg i.v., b.i.d.), meloxicam (0.1 mg/kg i.v., s.i.d.) and Lactated Ringer’s solution (2 ml/kg per hour i.v., only for the first 2 days). During the first three postoperative days of hospitalization a visual analog pain score was attributed to the animal four times daily based on physiologic parameters, such as heart rate and respiratory rate, as well as on the animal’s posture and behavior. The highest pain score during this period was 30%. A week later the fox was transported to a rehabilitation facility until its release to the wild. The anesthetic effects of many a2 agonists have been previously studied in the red fox.3,4,6,8,10 In this particular case, dexmedetomidine was preferred over medetomidine, as a newer a2 agonist. The failure of the first administration to induce adequate sedation could be attributed to the high level of stress causing release of catecholamines and potentially interfering with the reduction of release of excitatory neurotransmitters.7 Anesthesia was induced using ketamine–midazolam intramuscularly in order to achieve complete immobilization of the fox, as there was only one site available for the placement of an intravenous catheter. The use of ketamine–midazolam in the red fox was first described in 19906 (ketamine 30 mg/kg i.m., midazolam 0.6 mg/kg i.m.), producing adequate depth of anesthesia for immobilization and capture. The dose used in the present case was less than a third of the one used in the aforementioned study because, in this case, preanesthetic medication was used. Ketamine has been combined with medetomidine in other studies in foxes,1,2,4,5,8 even for minor surgical procedures, given at 2.5–4 mg/kg and 40–76 lg/ kg, respectively. The dose of ketamine used in this case was higher (7.5 mg/kg), but the dose of the a2 agonist was quite lower (15 lg/kg) given that dexmedetomidine is twice as potent as medetomidine, and also because a higher dose of ketamine would contribute longer to analgesia because of ketamine’s antihyperalgesic properties. The systemic dose of morphine used in the present study could be considered low if used as a sole analgesic agent, but it was chosen given the fact that ketamine and meloxicam were also administered systematically, as well as local anesthetics and morphine administered epidurally, thus contributing to a balanced multimodal analgesic approach.
ANAGNOSTOU ET AL.—ANESTHESIA FOR MAJOR SURGERY ON A RED FOX
The key feature of the anesthetic management implemented in the present case was the decision to use epidural anesthesia and analgesia. The fox was a perfect candidate for epidural anesthesia as it had fractures to be operated on in both hind legs, and also for epidural analgesia, as the epidural administration of morphine has been proven to provide analgesia for the hind and the front legs in the dog.11 Furthermore, the use of epidural anesthesia and analgesia allowed for omission of repeated intramuscular morphine injections, reducing the stress induced on the fox by hospitalization. Although there are no reference data on the isoflurane minimum alveolar concentration (MAC) in red foxes, the isoflurane setting in this case can be considered low, especially compared to other carnivores undergoing similar surgeries. However, sampling at the endotracheal connector with high fresh gas flows may have affected the accuracy of the measurement as the sample could have been contaminated with fresh gas, thus increasing the observed reading. Nevertheless, many factors surely contributed to the low isoflurane setting, including systemic opioid and ketamine administration, as well as application of epidural anesthesia/analgesia. In conclusion, dexmedetomidine was used in a red fox in the present case without any unexpected adverse effects. When used in red foxes, it can be administered similarly to medetomidine, keeping in mind that it is twice as potent. Epidural anesthesia and analgesia should be attempted in surgical cases of red foxes as it can provide excellent surgical conditions and patient comfort.
LITERATURE CITED 1. Acosta-Jamett G, Astorga-Arancibia F, Cunningham AA. Comparison of chemical immobilization methods in wild foxes (Pseudalopex griseus and Pseudalopex culpaeus) in Chile. J Wildl Dis. 2010;46:1204– 1213.
157
2. Aguirre AA, Principe B, Tannerfeldt M, Angerbjorn A, Morner T. Field anesthesia of wild arctic fox (Alopex lagopus) cubs in the Swedish Lapland using medetomidine–ketamine–atipamezole. J Zoo Wildl Med. 2000;31:244–246. 3. Baldwin JR, Winstead JB, Hayden-Wing LD, Kreeger TJ, Dzialak MR. Field sedation of coyotes, red foxes, and raccoons with medetomidine and atipamezole. J Wildl Manag. 2008;72:1267–1271. 4. Bertelsen MF, Villadsen L. A comparison of the efficacy and cardiorespiratory effects of four medetomidine-based anaesthetic protocols in the red fox (Vulpes vulpes). Vet Anaesth Analg. 2009;36:328–333. 5. Fuglei E, Mercer JB, Arnemo JM. Surgical implantation of radio transmitters in arctic foxes (Alopex lagopus) on Svalbard, Norway. J Zoo Wildl Med. 2002;33:342–349. 6. Kreeger TJ, Seal US, Tester JR. Chemical immobilization of red foxes (Vulpes vulpes). J Wildl Dis. 1990; 26:95–98. 7. Lemke K. Anticholinergics and sedatives. In: Tranquilli WJ, Thurmon JC, Grimm KA (eds.). Lumb and Jones’ veterinary anesthesia and analgesia. 4th ed. Oxford, UK: Blackwell Publishing Ltd.; 2007. p. 203– 239. 8. Shilo Y, Lapid R, King R, Bdolah-Abram T, Epstein A. Immobilization of red fox (Vulpes vulpes) with medetomidine–ketamine or medetomidine–midazolam and antagonism with atipamezole. J Zoo Wildl Med. 2010;41:28–34. 9. Travaini A, Delibes M. Immobilization of freeranging red foxes (Vulpes vulpes) with tiletamine hydrochloride and zolazepam hydrochloride. J Wildl Dis. 1994;30:589–591. 10. Travaini A, Ferreras P, Delibes M, Aldama JJ. Xylazine hydrochloride–ketamine hydrochloride immobilization of free-living red foxes (Vulpes vulpes) in Spain. J Wildl Dis. 1992;28:507–509. 11. Valverde A, Dyson DH, McDonell WN. Epidural morphine reduces halothane MAC in the dog. Can J Anaesth. 1989;36:629–632. Received for publication 26 April 2014
