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Case Reports
Combined Epidural Lidocaine and Medetomidine-KetamineIsoflurane Anaesthesia for Management of Femoral Fracture in a
Cheetah (Acinonyx jubatus)
Mwangi, W.E.,1* Mogoa, E.M.,1 Kimeli, P.,1 Muasya, D.W.,1 Kipyegon, A.N.,1 Kirui, G.,1 Mande,
J.D.,1 Kariuki, E.2 and Mijele, D.2
1
2
Department of Clinical Studies, Faculty of Veterinary Medicine, University of Nairobi, P.O Box 29053-00625, Kangemi, Kenya.
Kenya Wildlife Services, P.O. Box 40241-00100, Nairobi, Kenya.
* Corresponding Author: Dr. W.E. Mwangi, Department of Clinical Studies, Faculty of Veterinary Medicine, University of Nairobi, P.O Box 29053 – 00625,
Kangemi-Kenya. drwillymwangi@gmail.com
AB ST RAC T
A 17 kg adult female cheetah was presented with a history of lameness of the left hind limb sustained in
the wild approximately a week earlier. The animal was anaesthetized for clinical examination by darting
using medetomidine-ketamine cocktail. Palpation of the left mid-shaft femur revealed a firm swelling and
crepitation. Radiography confirmed a complete transverse and overriding fracture of the left femur which
required open reduction and internal fixation. Hematology revealed lymphocytosis while biochemistry
showed hypoproteinemia, hypoglobulinemia and low alanine aminotransferase activity. Epidural lidocaine
hydrochloride was administered in the lumbosacral region to supplement medetomidine-ketamineisoflurane anaesthesia for the surgical procedure. Isoflurane concentration was maintained at 0.5-1.0% using
a rebreathing anaesthesia machine throughout the surgery. Temperature and cardiopulmonary parameters
remained stable intra-operatively. Hind limb paralysis extended for about seven hours post-operatively,
suggestive of prolonged post-operative local anaesthesia. The successful management of this surgical
procedure demonstrated the suitability of using the described anaesthesia protocol in surgical procedures
of the hind limbs in wild felidae.
Keywords: Cheetah; Epidural Anaesthesia; Isoflurane; Sparing Effect; Analgesia.
BACKGROUND
Epidural anaesthesia is a method of administering drugs in
close proximity to their site of action either at the receptors
in the dorsal horn of the spinal cord or at the nerves as they
leave the spinal cord (1). This technique has been used in surgical patients as an adjunct to general anesthesia and with the
aim of reducing the dose requirement for general anesthetic
agents, especially inhalant anesthetics that cause a dosedependent cardiopulmonary depression (1, 2). Reduction in
the dose of anesthetic agents is of value particularly in general
anesthesia of high risk patients (3). Furthermore, epidural
anesthesia has been shown to provide excellent pre-operative,
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Mwangi, W.E.
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intra-operative and post-operative analgesia (4, 5) which is
of benefit to patients undergoing surgical procedures caudal
to the umbilicus.
A number of experimental studies in domestic cats have
reported on efficacy of epidural lidocaine (6, 7, 8, 9), xylazine (6), medetomidine (7), bupivacaine (9), ketamine (8),
lidocaine-xylazine combination (10), lidocaine-bupivacaine
combination (9) and lidocaine-ketamine combination (8).
Studies have reported successful use of ketamine in combination with medetomidine (11, 12) or midazolam (12) in anaesthetizing cheetah either for clinical examination or surgical
procedures. Tiletamine–zolazepam combination has also
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been used successfully, either alone (13) or in combination
with ketamine and xylazine (14), medetomidine (12, 15) or
midazolam (12). One study has described the use of epidural
morphine in combination with tiletamine–zolazepam in a
cheetah undergoing total hip replacement (16). However,
there is currently no report on the use of epidural lidocaine
in cheetahs.
This study details a successful use of epidural lidocaine
in an adult cheetah under a light plane of medetomidineketamine-isoflurane anesthesia during management of a
femoral fracture. To the best knowledge of the authors this is
the first publication describing epidural lidocaine anesthesia
in a cheetah.
CASE PRESENTATION
An adult female Cheetah weighing 17 Kg was presented to
the Small Animal Clinic, University of Nairobi with a history
of leg carrying lameness of the left hind limb sustained in the
wild approximately a week earlier. Clinical examination under
Medetomidine (50μg/Kg)-Ketamine (5mg/Kg) anaesthesia
revealed slight dehydration and a firm swelling around the
left femoral shaft region. Crepitation was present on manipulation and radiography confirmed a complete transverse
and overriding fracture of the left femoral diaphysis with
callus (Figure 1). A decision was taken to reduce and fix
the fracture using a compression bone plate and screws.
Presurgical hematological parameters revealed lymphocytosis
(Table 1) while the biochemistry revealed hypoproteinemia,
hypoglobulinemia and low alanine aminotransferase activity
(Table 2).
Twenty four hours later, anesthesia was induced using
50μg/Kg of Medetomidine Hcl (Domitor; S5 Veterinary
Medicine; Pfizer laboratories, Sandton-South Africa) and
5mg/Kg of Ketamine Hcl (Ketalar 50 mg/ml, Pfizer Inc,
New York-USA) combination by darting using a blowgun
to allow preparation for aseptic surgery and endotracheal
intubation. To facilitate intubation, 2 ml of 2% lidocaine was
splashed in the larynx to minimize laryngeal spasm and intubation was achieved using a size 8.0 mm endotracheal tube.
About 30 minutes after induction of general anesthesia,
the lumbosacral region was shaved, washed and disinfected
with 70% ethyl alcohol in preparation for aseptic epidural
injection. The patient was restrained on a table in left lateral recumbency, with its pelvic limbs extended cranially to
Table1: Hematological parameters of the cheetah before the surgery
Hematology parameters
WBC (X103/μL)
Lymphocytes (%)
Monocytes (%)
Granulocytes (%)
RBC (X106/μL)
MCV (fl)
Hct (%)
MCH (ρg)
MCHC (g/dL)
RDW
Hb (g/dL)
THR (X103/μL)
MPV (fl)
Pct (%)
PDW
Values
15.24
38.1
2.1
59.8
8.14
53.8
43.7
19.2
35.9
13.9
15.7
411
9.4
0.39
6.9
Normal range (Domestic cat)
5.0-18.0
5.0-30.0
2.0-6.0
40-80
4.0-9.0
35.5-55.0
24.0-45.0
16.0-24.0
28.0-40.0
8.0-12.0
9.5-15.0
120-500
4.0-7.0
_
8.0-12.0
Table 2: Biochemistry parameters of the cheetah before the surgery
Figure 1: Radiography of left femur showing an overriding fracture
and callus
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Biochemistry parameters
BUN mg/dL
Creatinine mg/dL
Total protein mg/dL
Albumin mg/dL
Globulin mg/dL
Phosphorus mg/dL
AST (IU)
ALT (IU)
Values
23.9
1.9
3.5
3.2
0.2
4.2
12.2
18
Normal range (Domestic cat)
19-34
0.9-2.2
6-7.9
2.5-3.9
2.6-5.1
3.0-6.1
7-38
25-97
Anesthesia in a Cheetah
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maximally separate the lumbar vertebrae. The lumbosacral
(between L7 and S1) space was then located as described by
Skarda (17). The injection site was infiltrated subcutaneously
with 1.0 ml of 2% lidocaine hydrochloride (Lidocaine, Mac
Pharmaceuticals Limited, Nairobi-Kenya) to minimize the
pain of epidural puncture.
A sterile 21-gauge hypodermic needle was inserted
percutaneously in the midline at the prepared site into the
epidural space. An empty sterile 5ml syringe was attached
to the needle and suction applied to confirm correct needle
placement by absence of blood or cerebrospinal fluid (CSF)
aspirate. This was followed by injection of about 1 ml of air to
ascertain absence of resistance to injection, which was further
proof of correct needle placement. Four ml of 2% lidocaine
hydrochloride (Lidocaine, Mac Pharmaceuticals Limited,
Nairobi, Kenya) was injected into the epidural space slowly
over a period of 60 seconds. Thereafter, the pedal reflex was
assessed every 2 minutes by clamping the inter-digital tissue
with an Allis tissue forceps to determine the onset of analgesia. Complete analgesia of the limb was achieved within 6
minutes of epidural lidocaine administration as ascertained
by complete loss of the pedal reflex.
Anesthesia was maintained with isoflurane (Forane,
Aesica, Queenborough Ltd., Kent, United Kingdom) vaporized in oxygen using a rebreathing circuit anesthetic
machine. The maintenance concentration of isoflurane
ranged between 0.5 and 1.0%, throughout the procedure.
An intravenous catheter (G21) was inserted in the cephalic
vein and warm lactated Ringer’s solution (10 ml/kg/hr) was
administered intravenously throughout the surgery. Mild
hypothermia was observed but cardiopulmonary parameters
remained stable intra-operatively. Rectal temperature ranged
between 34.3°C and 37.9°C, heart rate between 69 and 98
beats/minute, respiratory rate between 12 and 19 breaths/
minute and blood oxygen saturation between 84% and 98%.
Excellent muscle relaxation of the hind limbs was also observed intra-operatively.
The surgery took 2 hours 40 minutes and immediately
after surgery isoflurane was switched off leaving the animal
inhaling 100% oxygen for 10 minutes. Thereafter, atipamezole
(Antisedan, 5 mg/mL; Pfizer laboratories, Sandton, South
Africa) at 1mg/kg was injected intramuscularly and immediately the animal was extubated. The patient was awake 7
minutes after atipamezole injection and completely recovered
from anaesthesia 12 minutes later however she could not
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Mwangi, W.E.
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stand due to hind limb paralysis. The observed hind limb
paralysis extended for 7 hours post-operatively suggesting
prolonged motor and possible sensory blockade.
DISCUSSION
To the best of the researchers’ knowledge, this is the first case
documenting the use of epidural lidocaine in supplementing
general anesthesia in order to facilitate hind limb surgery in
an adult cheetah.
Patients that suffer untreated pain for a prolonged period
pose a major anesthetic risk intra-operatively as high doses of
anesthetic drugs are required to produce a surgical plane of
anesthesia (18). The use of local anesthetic blocks in such patients allows the dose of anesthetic drugs to be tapered while
providing excellent peri-operative analgesia and minimizing
anesthesia related morbidity and mortality (18).
The patient in the current case was deemed an anesthetic
risk due to lymphocytosis, impaired liver function, hypoproteinemia, slight dehydration and the long standing pain. To
minimize the doses of medetomidine and ketamine and at
the same time produce a safe surgical plane of anesthesia,
epidural lidocaine was administered at 5 mg/kg BW (80
mg) in the lumbosacral space. The technique provided anesthesia of superior quality characterized by excellent muscle
relaxation, rapid onset and prolonged duration of analgesia.
This was attributed to the fact that local anesthetic agents
indiscriminately block motor, sensory, and sympathetic fibers
when administered epidurally (19).
The dose of isoflurane used for maintenance of anesthesia
was reduced to 0.5-1.0% throughout the surgery, and this
was adequate, as the animal did not respond to deep surgical stimuli elicited by an orthopedic procedure. A similar
isoflurane-sparing effect of epidural lidocaine has been reported in pigs (2). Minimizing the concentration of inhalant
anesthetics is of great value as these agents can cause a dose
dependant cardiopulmonary depression (1).
The cardiopulmonary function remained stable intraoperatively. This observation was in agreement with studies
carried out in dogs which have shown that epidural lidocaine
has no significant changes on heart rate, mean arterial pressure and respiratory rate (20, 21). The maintenance of stable
blood oxygen saturation was an additional proof of well
maintained cardiac and respiratory functions. However, it is
worth noting that when high volume of epidural lidocaine is
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administered, the drug may extend cranially into the thoracic
region and block the nerves innervating intercostal muscles
as well as the sympathetic nerve fibers (1). Consequently, this
results into depression of respiration and vasodilation of the
dural blood vessels causing hypotension and bradycardia as
well as hypothermia due to increased surface area for heat
loss (17).
The observed mild hypothermia may be attributed to
decrease in metabolic rate, muscle relaxation and CNS depression caused by the action of anesthetic drugs and adjunct.
In addition, pre-surgical preparation of the surgical site with
cold scrubbing fluids as well as the prolonged and invasive
nature of the surgical procedure could have contributed to
hypothermia. This is despite the draping of the surgical site.
Epidural lidocaine provides analgesia of about 1-4 hours
in domestic cats. Notably, hind limb paralysis in this case extended for 7 hours post-operatively. This might be attributed
to the observed hepatic insufficiency and hypoproteinemia.
Lidocaine is metabolized in the liver by the P450 isoenzyme
CYP 3A4 system (22) which may be impaired during hepatic
damage resulting into prolonged duration of action as was
observed in this case. Further, hypoproteinemia might have
contributed to prolonged duration of action since 64% of
lidocaine in circulation is bound by plasma proteins (23). In
addition, Thomasy et al. (24) demonstrated that isoflurane
anesthesia in domestic cats is associated with decreased
clearance and elimination half-life of lidocaine mainly due
to decrease hepatic blood flow. However, in view of this case
prolonged postoperative analgesia was beneficial as it helped
to mitigate immediate postoperative pain and therefore enhance healing.
CONCLUSION
The use of epidural lidocaine with a light plane of general
anesthesia for management of femoral fracture in an adult
cheetah proved successful. This protocol provided good
quality anesthesia characterized by excellent muscle relaxation, rapid onset and long duration of analgesia. Epidural
lidocaine had a sparing effect on Isoflurane as evidenced by
the concentration used for maintenance of anesthesia and
the stability of the cardiopulmonary function. Recovery was
smooth and uneventful. This anesthesia protocol is therefore
recommended for surgical procedures of the hind limb in
wild felidae.
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