Biology15, 47
Two species exist within the artiodactylid family of Giraffidae; the giraffe (Giraffa
camelopardalis) and the okapi (Okapia johnstoni). Giraffids first arose eight million
years ago during the Miocene period, and fossil evidence suggests that the family
was once much more extensive, with over 10 fossil genera described.
Up to nine races or subspecies of giraffe have been described, although genetic research
and the fact that distinct morphologic distinctions between groupings exist despite
the lack of physical boundaries have led some authorities to consider several distinct
species. The subspecies most commonly held by zoos are the reticulated giraffe (Giraffa
camelopardalis reticulata), the Rothschild giraffe (G.c. rothschildi), and the Masai
giraffe (G.c. tippelskirchi). Once widespread across the African continent, giraffes
are now largely confined to national parks and game farms in eastern and southern
Africa, with scattered populations in west Africa.
Because of its height, the giraffe has access to browse unavailable to other species
and thus may coexist with grazers and smaller browsers and even livestock. Adult giraffes
are rarely preyed upon by predators, but calf mortality is high. Giraffes are sociable
animals usually found in dynamic, ever-changing groups, the most stable of which are
those composed by mothers and their young. Subadult males are social, whereas mature
males become more solitary.
With an estimated 80,000 animals left in the wild, the giraffe is classified by the
International Union for the Conservation of Nature (IUCN) as a species “Of Least Concern.”
However, several of the subspecies are now considered “Endangered” (e.g., West African
and Rothschild). At least 2000 giraffes are maintained in captivity, making the captive
population self-sustaining.
Discovered by science only as recently as 1901, the okapi was the last large African
mammal species to be described. The okapi is now endemic to the Democratic Republic
of the Congo in central Africa, where they inhabit dense damp forests on both sides
of the Congo River. Okapis are diurnal and live alone, in pairs, or in small family
groups, but relatively little is known about their social structure, largely because
of their remote habitat and timid nature. Estimated remaining wild population is between
10,000 and 35,000, and the fate of these animals is closely linked to the unstable
political climate of the region. The okapi is listed as “Near Threatened” by the IUCN
but is not listed on the Convention on International Trade in Endangered Species (CITES)
Appendix. With less than 200 animals in captivity, the okapi population is considered
fragile.
Unique Anatomy15, 47
Giraffe
With a height of up to more than 5 meters (m), giraffes are characterized by their
extremely long necks and long legs, with considerably longer forelimbs than hindlimbs.
The head is fairly small, with two horns or ossicones and a central osseous protuberance,
which is particularly developed in the males. The tongue is long and flexible, its
distal 20 cm pigmented. Mature males weigh 850 to 1950 kilograms (kg) and females
700 to 1200 kg. The internal anatomy of giraffes is analogous to that of the domestic
cow and other artiodactylids. The dental formula for giraffes is incisors (I) 0/3,
canines (C) 0/1, premolars (P) 3/3, molars (M) 3/3, for a total of 33. Often, the
gallbladder is absent, although it occurs in some individuals. Two jugular veins run
immediately under the skin on either side of the ventral neck.
The skin varies in thickness from being thin on the ears and medial aspects of the
legs to being thick along the neck and lateral body. The thick skin aids in edema
prevention in the lower leg and forms a dermal armor for protection against predators
or fighting with conspecifics. The dark patches of the skin have been suggested to
have a thermoregulatory role in acting as regions where heat loss to the environment
is enabled by selective vasodilation.
The relative lung mass as well as volume is only approximately 60% of that of other
mammals, and the lung volume-to-body mass ratio decreases during growth.
43
The extremely long trachea has a diameter significantly narrower than in similar-sized
mammals, so the dead space volume, although greater than in most species, is not as
large as could be expected and is compensated for by a slightly larger tidal volume.
43
Previously described as extraordinarily large, the giraffe heart has a relative weight
of approximately. 0.5% of body weight, which is essentially identical to that of other
mammals.
42
The basis for the massive blood pressure generated is smaller ventricular radii and
an unusually thick left ventricular wall with oblique muscle fibers. The giraffe vein
has a venous valve layout similar to that in other large mammals, and no arterial
valves exist.
49
Okapi
The okapi reaches a head-to-body length of 200 to 210 cm and a shoulder height of
150 to 170 cm and has a body weight of 200–300 kg. Females are larger than males.
The eyes and ears are large, and the tongue long enough to reach the ear base. Males
have a pair of short-haired ossicones that are directed backward. The body is short
and compact with a sloping back, as in the giraffe, but the neck is much shorter.
Available information on okapi anatomy and physiology is limited, but the dental formula
and internal anatomy resemble those of the giraffe.
Unique Physiology6, 29, 42, 43, 49
To compensate for the hydrostatic challenge of perfusing the brain, the giraffe heart
generates a blood pressure twice that of other mammals, and its cardiovascular anatomy
and physiology have been subject to considerable speculation and myths. Both stroke
volume and cardiac output are lower than in similar-sized mammals. Blood volume is
unusually low, and compliance of the vascular system is also low. The peculiar vascular
anatomy—with narrow, rigid veins with low compliance in the legs and large, compliant
veins in the neck region—gives rise to an interesting and nonintuitive physiologic
phenomenon.
6
When the head of the anesthetized giraffe is lowered, blood pressure at head-level
briefly spikes, before returning to much lower values. The lowering of the blood pressure
coincides with pooling of blood in the compliant jugular veins, giving rise to a decreased
cardiac preload and consequently lower systemic blood pressure (Frank-Starling mechanism).
As a consequence of this mechanism, the arterial pressure at head level is maintained
at or near 100 millimeters of mercury (mm Hg), and the central blood pressure is directly
proportional to the position of the head relative to the heart. Because of the high
arterial pressures and the hydrostatic pressure, the arterial pressure in the lower
leg may exceed 450 mm Hg. Edema in this region is prevented through a gravity-suit-like
fascia and skin, prominent lymphatics, and well-developed valves in veins and lymphatics,
as well as an abrupt narrowing of the arterial lumen at the level of the elbow or
stifle.
The giraffe kidney experiences much higher pressures compared with the human kidney
and appears to cope with this through a fibrous capsule and an increased interstitial
pressure of about 30 to 40 mm Hg. This means that normal kidney perfusion depends
on a mean arterial pressure of at least 130 mm Hg.
Similar to camels, the giraffe is capable of varying the body temperature within a
couple of degrees Celsius, saving energy otherwise needed for increasing the temperature
at night and cooling during daytime.
Special Housing Requirements
9
Giraffes may learn to lower their heads to walk through doors only slightly higher
than their withers; however, stressed or sedated animals will often not do this, which
necessitates high doors for a giraffe house.
Soft flooring and lack of exercise may lead to overgrowth of feet and the need for
trimming, so the giraffe should be encouraged to walk on abrasive surfaces. Coarse
gravel may be used on top of concrete to provide traction and wear. Neonates require
sure footing and do best when born on pasture or a thick layer of bedding to prevent
splaying.
Giraffes have a high surface-to-volume ratio and are adapted to tropical climates.
In moderate climates, they may be maintained in outdoor enclosures year-round. In
temperate climates, access to stables heated to the range of 18° C to 24° C (65° F–75° F)
must be provided, and in subzero temperatures, outdoor access should be restricted.
Both okapis and giraffes are prone to sterotypies, particularly those involving the
tongue, and it is important to incorporate in enclosure design pulleys and other systems
to provide browse and enrichment items at head level. When designing facilities for
giraffids, the logistics of loading and unloading animals should also be considered.
Ideally, narrow walkways leading to an appropriate docking ramp for transport vehicles
should be incorporated into the design.
Feeding
Both giraffes and okapis are selective browsers seeking out the high-nutrient components
of plants such as fresh leaves and buds. In the wild, giraffes mainly feed on Acacia
species, and the natural diet of the okapi includes a variety of species. In an attempt
to avoid negative energy balance, captive diets have traditionally contained high
levels of protein (15%–20%) and starch (20%–30%). Based on wild diets, current recommendations
include crude protein levels of only 10%–14%, starch levels below 5%, fat 2%–5%, and
high amounts of fiber (minimally 25% acid detergent fiber) all based on a dry-matter
basis.
58
Care should be taken to keep calcium levels high and phosphorus levels low. The new
diet regimens have recently been shown to lead to increased serum levels of magnesium
as well as n3 and n6 fatty acids and decreased levels of phosphorus and saturated
fatty acids36, 41 so that blood nutrient profiles more closely match those of free-ranging
giraffe.
36
The importance of browse, for both the nutritional value and the behavioral well-being
of animals, cannot be overstated and browse should be provided to the greatest extent
possible, but good-quality hay and alfalfa as well as silage may be substituted. Surplus
buds and twigs from rose growers have been used successfully in okapis.
59
The precise mineral and vitamin requirements of giraffids have not been established,
but animals should have access to trace mineral salt blocks, and copper supplementation
should be considered if deficiencies are suspected.
Restraint and Handling
Giraffes may be quite tame and may become habituated to some manipulation, including
blood sample collection and light hoof trimming; however, many individuals do not
respond well to this approach. The safest nonchemical method for collecting routine
samples and closely examining animals is to accustom them to a chute during daily
routines. Forced physical restraint without specialized stalls or chutes is likely
to be unsuccessful and dangerous. Giraffes may deliver a formidable kick with all
four legs in essentially any direction. In tall narrow chutes, with secure footing
for personnel as well as animals, giraffes may be physically restrained for minor
procedures such as injections, blood collections, tuberculosis testing and so on,
but the risks involved for the animal as well as the staff should be kept in mind.
Okapis respond well to training and positive reinforcement and poorly to physical
restraint.
Once they get started, giraffes have the tendency to keep walking along hallways and
so on, which may be exploited for crating or loading into vehicles. A curtain with
a weight at the bottom, which will fall from a horizontal position to a vertical position
behind the animal when released, may be helpful to encourage the animal to take that
last step into an unknown crate.
Chemical Restraint
Giraffe anesthesia remains a challenge because of considerations of size as well as
the peculiar anatomy and physiology of these animals; however, several good protocols
and excellent information resources are now available.
12
Standing Sedation
Standing sedation may work well, but ataxia may develop, so it is important to be
prepared for the animal to go down unexpectedly. A chute or restraint device is ideal,
but a large door that can close off a triangular space may provide a similar confined
area. Several drug combinations have been used with success for procedures such as
clinical examinations, hoof trimming, reproductive manipulation, minor surgery, and
catheter placement (Table 61-1
).
TABLE 61-1
Protocols for Chemical Restraint Used in Giraffidae*
Generic Name
Dosage
Reversal Agent/Dosage
Reference/Comment
GIRAFFE STANDING SEDATION
Xylazine (X)
0.1–0.2 milligram per kilogram, intramuscularly (mg/kg, IM)
Mild sedation (e.g., to allow calf to nurse)
19
Azaperone (Aza)/detomidine (D)
Aza: 0.2–0.5 mg/kg, IMD: 15–30 µg/kg, IM
Yohimbine 0.1–0.2 mg/kg, IV/IM; or atipamezole 0.01–0.05 mg/kg, IV/IM
9, 12
For deeper sedation, add butorphanol 10–25 µg/kg
Detomidine/acepromazine (Ace)/butorphanol (B)/methadone (Met)
D: 30–40 µg/kgAce: 15–25 µg/kgB: 20–30 µg/kgMet: 20–30 µg/kg
Atipamezole 0.03–0.06 mg/kg, IM/IVNaltrexone 40–60 µg/kg, IM/IV
24
For deeper sedation, add xylazine 20–50 µg/kg
GIRAFFE ANESTHESIA
†
Xylazine/etorphine (E)/ketamine (K) (etorphine may be replaced with carfentanil)
X: 0.05–0.1 mg/kgE: 5–8 µg/kgK: 0.5–1 mg/kg
Atipamezole 0.05 mg/kg, IM/IVNaltrexone 0.3 mg/kg, IM/IV
24
Allow 10–20 minutes after xylazine before giving etorphine and ketamine
Medetomidine (Med)/ketamine
Med:40–60 µg/kg, IMK: 1.0–1.5 mg/kg, IM(approximately equal to M: 150 µg + K 3/centimeters
(cm) of shoulder height)
Atipamezole 0.05–0.15 mg/kg IV/IM
8, 39
Tachypnea commonHigh potential for re-sedation from medetomidineRe-dose atipamezole
at 4 hours, and if needed again at 8 hours
Thiafentanil/ketamine/medetomidine
T: 5–6 µg/kgMed: 8–13µg/kgK: 0.6–1 mg/kg
Atipamezole 0.05 mg/kgNaltrexone 0.2 mg/kg
5, 11
Beware of potential re-sedation from medetomidine
GIRAFFE CAPTURE
Etorphine or thiafentanil or 1 : 1 mix.
10–14 mg/sub-adult14–15 mg/adult cowUp to 18 mg/adult bull
Naltrexone 0.3–0.4 mg/kg
63
Immediate reversal required!
Thiafentanil/ketamine/medetomidine
T: 6–10 µg/kgMed: 10–14 µg/kgK: 0.5 mg/kg
Atipamezole 0.05 mg/kgNaltrexone 0.2–0.3 mg/kg
11
Beware of potential re-sedation from medetomidine
OKAPI STANDING SEDATION
Xylazine/butorphanol
X: 0.4–0.8 mg/kg, IMB: 80–200 µg/kg, IM
Yohimbine 0.1–0.2 mg/kg, IV/IM; or atipamezole 0.05–0.1 mg/kg, IV/IM
12
If indicated, reverse butorphanol with naltrexone 1–2 times dose of butorphanol, IM/IV
Detomidine/butorphanol
D: 40–100 µg/kg, IMB: 80–200 µg/kg, IM
Yohimbine 0.1–0.2 mg/kg, IV/IM; or atipamezole 0.05–0.1 mg/kg, IV/IM
12
If indicated, reverse butorphanol with naltrexone 1–2 times dose of butorphanol, IM/IV
Xylazine/ketamine
X:0.4–0.6 mg/kg, IMK: 0.4–0.6 mg/kg, IM
Yohimbine 0.1–0.2 mg/kg, IV/IM; or atipamezole 0.03–0.6 mg/kg, IV/IM
64
Normally, the animal will stay standing, but may lie down
Detomidine/butorphanol/acepromazine/midazolam (Mid)
D: 40–60 µg/kgB: 40–60 µg/kgAce: 30–40 µg/kgMid: 30–40 µg/kg
Atipamezole 0.03–0.06 mg/kg, IM/IV Naltrexone 40–60 µg/kg, IM/IV
24
OKAPI ANESTHESIA
†
Carfentanil/xylazine
X: 0.12 mg/kgC: 5 µg/kg, IM
Naltrexone 0.5 mg/kg, IM
12
Allow 10–20 minutes after xylazine before giving CAdd azaperone 50 mg/adult in stressed
animals
Etorphine/xylazine 1:1
X: 0.1–0.2 mg/kg, IME: 8–15 µg/kg, IM
Atipamezole 0.05 mg/kg, IM/IVNaltrexone 0.2–0.3 mg/kg, IM/IV
Allow 10–20 min after xylazine before giving etorphineDo not use Immobilon because
of risk of regurgitation from acepromazine
Medetomidine/ketamine
Med: 60–120 µg/kg, IMK: 1–3 mg/kg, IM
Atipamezole 0.3–0.6 mg/kg, IV/IM
12, 45, 64
*
Refer to text for details.
†
Provide oxygen via deep nasal cannula or intubate.
Immobilization and Anesthesia
Two main schools in giraffe anesthesia exist: (1) opioid-based protocols7, 11, 66,
67 and (2) ketamine, combined with high-dose medetetomidine.8, 39 The latter approach
has been popular over the past decade because of the avoidance of an opioid component
and relatively smooth inductions; however, it may result in hypertension and tachypnea,
and re-sedation from medetomidine as the reversal agent wears off is a real concern.
The opioids, however, may induce excitation and hyperthermia if underdosed and result
in hypoventilation when used in high dosages. A compromise, which involves incorporating
opioids, ketamine, and α2-agonists in one protocol, appears to be the best solution
so far.11, 24 Refer to Table 61-1 for suggested protocols.
The giraffe has traditionally been considered one of the most challenging animals
to anesthetize, and most problems arise during induction and recovery. The key to
success is careful planning and the availability of trained personnel and necessary
equipment. The ideal induction occurs in a well-designed restraint device, which may
be opened fully once the animal is recumbent. The second-best solution is a chute-system,
where a halter may be placed on the sedated giraffe prior to induction, which will
allow control of the head via a rope and pulley. The third-best option is to place
a loop of thick rope around the base of the neck of the sedated animal and “walk”
the animal to an open area with no obstacles, where it is made to walk in circles,
with one to three handlers holding the rope. The animal is then tripped with another
rope while still awake enough to maintain some control of the head during the fall.
If neither of these options are available, the animal may be allowed to become recumbent
in a padded stall or at least in an area without major obstacles. In either case,
it is crucial to gain control of the animal's head as soon as it becomes recumbent,
as most injuries occur when the heavily sedated giraffe attempts to stand and falls
again.
For anesthetic induction in okapi, a padded restraint device is the safest option,
but a quiet stall with sure footing will suffice. With opioid-based protocols, induction
may sometimes result in excitement or tumbling. A staged approach, in which sedatives
are allowed to set in for 15 to 20 minutes prior to opioid administration, is preferable,
and once the opioid takes effect, two experienced helpers may use mild physical restraint
with mattresses or boards to prevent injury.
12
Regurgitation under anesthesia may be a concern in both giraffes and okapis, but particularly
in the latter. The frequent early reports of regurgitation in okapis sedated with
Immobilon (etorphine and acepromazine) was attributed to etorphine but likely largely
was a reaction to acepromazine, which this author considers contraindicated in okapis.
In animals fed mainly hay and pelleted feed, withholding food and water for 12 hours
prior to a planned procedure is sufficient, but in animals eating large amounts of
fresh browse, a 24-hour period is advisable. To minimize pulmonary compromise and
ventilation–perfusion mismatch, a sternal position is preferable, when feasible, but
giraffes generally do well in lateral recumbency for shorter periods. To reduce the
risk of regurgitation and to stabilize blood pressure (see Unique Physiology section),
the head should be elevated 80 to 150 cm above heart level. The neck should be kept
as straight as possible, and placement of a padded board or ladder under the shoulder
and onto bales of straw or similar material works well for this purpose.
Performing endotracheal intubation is straightforward in giraffes. Direct visualization
of the larynx is possible with the use of a long laryngoscope blade, and insertion
of a relatively thin catheter to subsequently guide the endotracheal tube is a good
option.
12
However, in giraffes larger than 350 to 400 kg, the fastest approach is to manually
insert a stomach tube or similar device into the trachea and then thread the endotracheal
tube over that. Appropriate endotracheal tube sizes are 20 to 25 millimeters (mm)
for okapis and juvenile giraffes and 25 to 30 mm for adult giraffes.
Hypoventilation is often a concern, and oxygen should be provided, whenever possible.
A Hudson demand valve or similar device will provide the animal with oxygen and allow
intermittent ventilation, as needed. Even in animals breathing well, a “sigh” every
2 to 5 minutes appears to be beneficial to avoid alveolar closing and shunting. In
animals not intubated, supplemental oxygen via a deep nasal cannula and flowing at
one liter per 100 kilograms per minute is recommended.
For recovery, a quiet area with good footing should be provided. Adequate space should
be available for the animal to swing its head forward as it gets onto its hindfeet,
and obstacles should be removed to avoid injury if the animal falls over. Reversal
agents may be given intramuscularly or intravenously (IM or IV), depending on the
situation. The goal is to get the animal into sternal recumbency, with strong spontaneous
ventilation as fast as possible, and to then keep it there as long as possible, ideally
for 10 to 15 minutes. Keeping the animal blindfolded during this time helps prevent
its attempts to stand prematurely. Doxapram (0.1 mg/kg, given rapidly IV) may be used
to stimulate animals that are reluctant to get up.
24
Capture12, 63
The immobilization of free-ranging giraffes for capture purposes has little in common
with controlled anesthesia for longer procedures in captive animals. The approach
currently employed by most successful capture crews relies on massive dosing with
potent opioids (etorphine, carfentanil, thiafentanil, or a combination) to reduce
the time from darting to recumbency and subsequent skilled handling of the awake,
but physically restrained, animal.
63
The giraffe is darted from the ground or, more commonly, from a helicopter, and typically
the animal goes down within minutes, although some animals need to be cast with ropes.
Soon after the giraffe becomes recumbent, it is blindfolded, ears plugged, and haltered
and reversal agents are administered. Once the animal stands again after a few minutes,
it is led with ropes into an open trailer used to be transported to a larger contained
trailer that accommodates several animals. Refer to Table 61-1 for doses. Other methods
incorporating ketamine, with or without medetomidine, to reduce the opioid dosage
result in longer induction times but more controlled immobilization.8, 11 Recently,
mass capture using a funnel system has been employed successfully for translocations.
Longer Procedures and Monitoring
Once immobilized, many minor procedures—such as diagnostic sampling, foot care, and
assisted calving—may be performed. Supplementation is rarely necessary for the first
45 minutes, but after that, periodic intravenous ketamine (0.2 mg/kg) or etorphine
or thiafentanil (0.5 microgram per kilogram [µg/kg]) may be used. However, for longer
procedures, a continuous infusion of one or more of these drugs or in combination
with guaifenesin is preferable, and additional monitoring is recommended. Inhalation
anesthesia with isoflurane is another option, but reduced blood pressure and ataxia
following recovery are potential concerns.
At a minimum, monitoring should include heart rate and rhythm, rate and depth of ventilations,
and oxygen saturation by pulse oximetry. Indirect blood pressure may be measured with
an appropriately sized blood pressure cuff placed around the tail base. Measurements
may not be accurate but will provide a trend to help guide supplementary drug administration,
fluid therapy, and head positioning. To ensure kidney perfusion, the mean arterial
pressure should be maintained above 130 mm Hg. As mentioned under “Unique Physiology,”
lowering of the head will result in pooling of blood in the jugular veins and reduced
blood pressure. Therefore, lifting the head will typically result in an increase in
blood pressure. Invasive blood pressure monitoring or arterial samples for blood gas
determination are most easily obtained from the dorsal auricular artery. End-tidal
carbon dioxide, functional oxygen saturation (pulse oximetry), and electrocardiography
are also useful in monitoring prolonged anesthesia in giraffes.
12
Long-Acting Tranquilizers
In both species, mild sedation for transport or introductions may be achieved with
zuclopenthizole acetate (0.5 mg/kg IM, lasting 3 days) or zuclopenthixole decanoate
(2 mg/kg IM, lasting 21 days).
24
In giraffes, haloperidol (15–20 mg/female, 20–30 mg/male IM, lasting 12–24 hours)
is useful for loading, as animals will often start walking in 15–20 minutes.
Surgery
Because of size considerations and the challenges of obtaining minimal ataxia during
recovery, only a rather limited array of surgical interventions have been reported
in giraffes. Tongue tip amputation, partial mandibular resection, mandibular ostrosynthesis,
arthroscopy, arthrotomy, tenotomy, and castration have all been successfully performed.5,
55 Although cesarian sections have been performed, abdominal surgery in giraffes is
generally challenging because of the short body making access difficult. A laparoscopic
approach has been suggested,
53
but its application would likely be limited. Several cases of colonic obstruction
have been documented, and aggressive supportive care and early surgical intervention
have been advocated.
16
A glue-on hoof block was successfully used to treat a distal phalangeal fracture.
33
For the okapi, which is a much better surgical candidate,
57
procedures have included fracture repair, rectal prolapse reduction, rumenotomy and
abomasotomy for foreign body retrieval, and surgery for umbilical hernias.
Diagnostics
Most diagnostic techniques used for other large ungulates may be adapted for use in
giraffids. Blood is readily obtained from the jugular vein or other sites such as
the lateral saphenous vein. As mentioned previously, giraffes may be trained to accept
blood sampling, typically from the jugular vein. In tractable okapis, blood may sometimes
be drawn from an auricular vein using a butterfly needle. Indwelling catheters may
be placed in the same locations, but long-term catheter maintenance is difficult in
conscious adult animals.
Urine may be collected from female animals by direct catheterization by using techniques
and catheters designed for cows. In males, urinary catheters may be placed only with
extreme difficulty because of the long and narrow urethra and sigmoid flexure, so
urine is usually collected opportunistically.
Radiography of the head, neck, and limbs is straightforward, but thoracic radiography
is a challenge in giraffes simply because of their size.
Hematology (Table 61-2
) and serum biochemistry (Table 61-3
) reference values for giraffes and okapis were determined through compilation of
MedARKS records from multiple institutions.
62
TABLE 61-2
Reference Ranges for Hematological Parameters for Giraffidae from Composite MedARKS
records
62
Parameter
Unit
GiraffeMean ± Standard Deviation
OkapiMean ± Standard Deviation
Leukocytes or white blood cell count
109/liter (L)
12.6 ± 4.8 (479)
8 ± 3 (91)
Neutrophils: bands
109/L
0.86 ± 1.2 (181)
0.11 ± 0.1 (14)
Neutrophils: segmented
109/L
9.2 ± 4.2 (446)
5.1 ± 2.5 (81)
Lymphocytes
109/L
2.3 ± 1.4 (451)
2.4 ± 1 (81)
Eosinophils
109/L
0.40 ± 0.40 (266)
0.16 ± 0.11 (32)
Monocytes
109/L
0.41 ± 0.37 (370)
0.29 ± 0.31 (70)
Basophils
109/L
0.29 ± 0.22 (255)
0.15 ± 0.09 (18)
Hematocrit or packed cell volume
Liter per liter (L/L)
0.35 ± 0.06 (550)
0.36 ± 0.08 (92)
Erythrocytes or red blood cell count
1012/L
10.5 ± 2.4 (350)
10.0 ± 2.7 (80)
Hemoglobin
Gram per liter (g/L)
119 ± 18 (376)
124 ± 27 (90)
Mean corpuscular hemoglobin
Picogram per cell (pg/cell)
11.7 ± 2.7 (340)
12.7 ± 1.7 (79)
Mean corpuscular hemoglobin concentration
g/L
348 ± 35 (373)
347 ± 29 (89)
Mean corpuscular volume
Femtoliters (fL)
34.1 ± 8.4 (346)
36.7 ± 4.1 (78)
Platelets
1012/L
0.42 ± 0.17 (93)
0.38 ± 0.11 (20)
Note: Values represent mean ± standard deviation (n).
TABLE 61-3
Reference Ranges for Serum Biochemical Parameters for Giraffidae Based on Composite
MedARKS records
62
Parameter
Unit
GiraffeMean ± Standard Deviation
OkapiMean ± Standard Deviation
Total protein
Gram per liter (g/L)
74 ± 14 (312)
71 ± 10 (77)
Albumin
g/L
31 ± 5 (282)
31 ± 8 (61)
Globulin
g/L
42 ± 14 (280)
40 ± 10 (59)
Fibrinogen
g/L
2.3 ± 1.8 (135)
0.4 ± 0.9 (33)
Glucose
Millimole per liter (mmol/L)
7.7 ± 3.3 (434)
7.2 ± 2.4 (83)
Alanine aminotransferase
Unit per liter (Unit/L)
13 ± 11 (237)
17 ± 20 (73)
Alkaline phosphatase
Unit /L
522 ± 476 (388)
397 ± 547 (77)
Aspartate aminotransferase
Unit /L
96 ± 55 (393)
66 ± 36 (77)
Creatine phosphokinase
Unit /L
1356 ± 1677(198)
615 ± 612 (77)
Gamma glutamyltransferase
Unit /L
61 ± 82 (207)
58 ± 101 (57)
Lactate dehydrogenase
Unit /L
864 ± 650 (235)
522 ± 296 (41)
Blood urea nitrogen
mmol/L
7.1 ± 2.5 (417)
7.5 ± 2.9 (80)
Creatinine
Micromole per liter (µmol/L)
159 ± 44 (373)
194 ± 71 (39)
Iron
µmol/L
16.7 ± 12.5 (28)
25.1 ± 9 (14)
Calcium
mmol/L
2.50 ± 0.45 (404)
2.58 ± 0.40 (80)
Phosphorus
mmol/L
3.0 ± 0.8 (372)
2.6 ± 0.7 (74)
Magnesium
mmol/L
1 ± 0.2 (63)
1 ± 0.3 (7)
Potassium
mmol/L
4.8 ± 0.6 (379)
5.0 ± 0.5 (77)
Sodium
mmol/L
145 ± 4 (381)
142 ± 5 (76)
Chloride
mmol/L
104 ± 6 (358)
103 ± 6 (74)
Triglyceride
mmol/L
0.45 ± 0.3 (245)
0.37 ± 0.3 (35)
Bilirubin: Total
µmol/L
17 ± 15 (377)
7 ± 5 (75)
Note: Values represent mean ± standard deviation (n).
Infectious Disease
In general, infectious diseases are not a major concern in giraffids maintained in
captivity. Overall giraffids are susceptible to most diseases of domestic ruminants,
but while several individual cases of infectious diseases have been reported, no real
patterns or extreme susceptibilities exist.
Bacterial Diseases
Reported bacterial diseases include salmonellosis, paratuberculosis, brucellosis,
anthrax, actinomycosis, listeriosis, Q-fever, and Mycoplasma-associated polyarthritis.9,
14, 27 Both Mycobacterium bovis and M. tuberculosis have caused tuberculosis (TB)
in giraffes. Intracutaneous TB testing appears to be sensitive and may be supplemented
by serologic testing. Enteritis caused by Escherichia coli or Clostridium perfringens
appears to occur with some frequency in okapis.17, 57
Anaplasma marginale infection appears to be a common subclinical infection in free-ranging
giraffe.
46
Similarly, giraffes may be healthy carriers of Ehrlichia (Cowdria) ruminantium transmitted
with Amblyomma sp. and do not develop clinical disease following artificial infection.
51
Otitis, involving various bacteria and fungi, was seen in several okapis in one collection
but not in 15 others, and environmental factors were suspected.
2
Viral Diseases
Viral diseases reported in giraffes and okapis include rinderpest, to which giraffes
are very susceptible,
9
malignant catarrhal fever, foot-and-mouth disease, encephalomyocarditis, and lumpy
skin disease. A rotavirus was commonly involved in diarrhea in okapi calves in the
1980s and 1990s56, 57 but appears less prevalent now. Another rotavirus closely related
to bovine rotavirus was recently isolated from a giraffe calf with diarrhea.
44
Similarly, a coronavirus closely related to bovine coronavirus was isolated from several
giraffes with diarrhea.
30
None of these infections appear to be of particular concern.
Equine herpes virus types 1 and 9 were found to cause severe nonsuppurative meningoencephalitis
in giraffes, and it was suspected that the infection originated from zebras sharing
the enclosures.31, 35
Bovine papillomavirus (BPV-1 and -2) was identified in multifocal to coalescing nodular
and occasionally ulcerated lesions of the head, neck, and trunk of two giraffes.
68
Lesions were similar to equine sarcoids and locally invaded the subcutis but did not
appear to metastasize. A pestivirus related to bovine viral diarrhea (BVD) virus has
been isolated from a giraffe but appears to have little clinical significance.
28
An outbreak of papules, vesicles, and pustules in several okapi caused by an orthopoxvirus
was described in the early 1970s
70
but has not been of major concern since then. A single case of bluetongue has been
described in an okapi, while the giraffe does not appear to be susceptible. Vaccination
appears effective and may be considered for okapi kept in endemic areas.
Parasitic Diseases
Multiple parasites have been described in both giraffes and okapis; however, none
constitute major problems in captive animals. Giraffes appear to be susceptible to
many of the parasites of domestic ruminants,
21
and both species respond well to treatment with anthelmintics used in domestic cattle.
As with any species, these drugs should be used prudently, and resistance has proven
to be a concern, as evidenced by the report of giraffe-derived Haemonchus contortus
resistant to benzimidazoles, imidazothiazoles, and macrocyclic lactones.
22
Orally administered copper oxide wire particles provide an alternative treatment to
traditional anthelmintics and have been used successfully as part of an anthelmintic
strategy in several institutions.
22
Originally identified in a fatal case, a Cytauxzoon sp. was retrieved from several
normal free-ranging giraffes.
37
In contrast, novel species of Babesia and Theileria were identified in the blood of
young semi–free-ranging giraffes and were suspected to be the cause of death in these
animals.
48
Other parasites reported in giraffes include multiple tick species, Rhinoestrus sp.,
Sarcoptes scabei, Thelazia gulosa, Capillaria sp., Camelostrongylus mentulatus, Trichostrongylus
axei, Ostertagia ostertagi, Teladorsagia circumcincta, Teladorsagia trifurcata, Monodontella
giraffae, Marshallagia marshalli, Trichostrongylus vitrinus, Trichostrongylus colubriformis,
Spiculopteragia asymmetrica, Trichuris giraffae, Parabronema skrjabini, Skrjabinema
sp., Haemonchus mitchelli, Echinococcus sp., Cryptosporidium parvum, Giardia sp.,
and Hepatozoon sp.3, 4, 9, 21, 57
Noninfectious Disease
Noninfectious problems are probably more prevalent than infectious disease in captive
giraffids, and several “syndromes” are seen with some frequency. Congestive heart
failure of unknown etiology has been diagnosed in several adult female okapis in a
single collection.
1
Clinical signs were managed with oral furosemide and enalapril. Interestingly, myocardial
hypertrophy or ventricular dilation was a frequent finding in a survey of postmortem
findings.
17
Both species are susceptible to overgrown hooves in captivity mainly because of lack
of movement, dry environments, and shortage of sufficiently abrasive surfaces. Apart
from simple overgrowth, excessively steep stance, crossing over of cleats, and flaring
hoof walls are the most common problems in okapis, whereas in giraffes crossing over
of the cleats is the problem most commonly encountered. The hoof horn, particularly
of giraffes, is extremely hard, and the use of power tools will significantly facilitate
corrective trimming.
Gastrointestinal Disorders
Colic without specific etiology is seen with some frequency in okapis, and intestinal
stasis following anesthetic events has been anecdotally reported.
64
Intestinal volvulus has been seen in both juvenile and adult okapis.
17
Colonic obstruction with phytobezoars or fecal matter was documented in three giraffes
16
and has also been seen in okapis. The spiral colon appears to be particularly prone
to these obstructions, and unless diagnosed and resolved early, these obstructions
hold a poor prognosis.
16
In okapis, excessive maternal grooming of calves may lead to anal trauma and stricture.
59
Giraffids, like other browsing ruminants, have lower chewing efficiency compared with
grazers, and the feeding of traditional “grazer diets” leads to significantly larger
mean fecal particle size in captive giraffes than in free-ranging giraffes.
32
It has been speculated that this deficient particle size reduction could contribute
to potential clinical problems such as gastrointestinal blockage and bezoar formation.
Acute Mortality Syndrome
Acute mortality syndrome was a major cause of death in captive giraffes for decades,
34
but the frequency has decreased in recent years, largely because of improved feeding
practices. Many animals died without any history of illness, others after a mild or
short-term illness or stressful incident. Emaciation with serous atrophy of fat is
the key pathologic finding, often accompanied by pulmonary edema, petechial hemorrhages,
intestinal ulceration, and myocardial degeneration.
13
Essentially, this “syndrome” appears to be simply caused by a negative energy balance,
either from insufficient nutrition
13
or poor dental health,
18
and the “last straw” or event triggering death may be hypothermia or stress.34, 54
Similar pathologic findings are observed in winter in free-ranging giraffes at the
southern margin of their distribution and are interpreted as starvation. A similar
phenomenon appears to exist in the okapi, and emaciation with serous atrophy of fat
was noted in 17 of 134 okapi postmortem reports reviewed.
17
Urolithiasis
Urolithiasis occurs with some frequency in captive giraffes, and some uroliths have
been diagnosed as carbonate or apatite with a shell of struvite.
69
In a recent survey, 6 of 43 zoos reported a history of urolithiasis.
61
High dietary phosphorus content and a high level of concentrate relative to hay (>1)
may be contributing factors to urolith formation.
61
Chronic Interstitial Nephritis
Renal tubular atrophy, with conical and medullary interstitial fibrosis and severe
thickening of the basement membranes of atrophic tubules, has been described in several
okapis.25, 26 Focal glomerular atrophy, probably secondary to ischemic collapse of
the glomerular capillary tuft, was also observed. Although the etiologies and pathogenesis
of these nephropathies are unclear, primary damage of the tubular epithelium appears
to be the most likely cause, and toxicity from ingested plant material, possibly willow
(Salix sp.), has been proposed as an etiologic factor.
26
Glycosuria
Asymptomatic glycosuria is very prevalent in adult captive okapis,20, 23 whereas animals
tested at the Epulu station (Democratic Republic of Congo) were nonglucosuric.
20
The etiology is unknown; animals have normal serum levels of insulin, glucose, and
fructosamine, and no correlation with stress or dietary glucose content has been found.
65
Neoplasia
Neoplasia is not frequently seen in giraffids. Neoplasms reported in giraffes include
embryonal rhabdomyosarcoma, pelvic chondrosarcoma causing dystocia, umbilical cord
teratoma, verrucous squamous cell carcinoma, and glioneuronal hamartoma in the mesencephalic
aqueduct. Findings in okapis include luteoma, ependymoma, and phechromocytoma.
Reproduction
10
Giraffids are considered nonseasonal breeders, with a short cycle of approximately
15 days and a comparatively long gestation of 420 to 468 days in the giraffe and 414
to 491 days in the okapi. Females attain sexual maturity at an age of about 20 months.
Under zoo conditions, both species may live up to an age of well over 30 years. Reproduction
is discussed in Table 61-4
.
TABLE 61-4
Reproductive Characteristics of Giraffids9, 10, 38, 40
Parameter
Giraffe
Okapi
Karyotype (2n)
30
44, 45, or 46
52
Puberty, age (years)
Female at 3–4
Females at 2.5
Male at 4–5
Males at 2–4
Estrus cycle (days)
14–15
15–16
Luteal phase
8
11
Follicular phase
6
5
Duration of copulation
Few seconds
Few seconds
Gestation
420–468 days
414–491 days
Pregnancy determination
Urinary/fecal PdG
Urinary/fecal PdG
Placentation
Cotyledonary placentation
Cotyledonary placentation
Urinary pregnanediol-3-glucuronide (PdG), nanogram per milliliter (ng/mL)
Nongravid:
Follicular
3.6 ± 7 ng PdG/mg Cr
1.9 ± 0.1 ng PdG/mg Cr
Luteal
30.9 ± 1.7 ng PdG/mg Cr
27.2 ± 3.9 ng PdG/mg Cr
Gravid
Persistent luteal levels
Persistent luteal levels
>250 ng PdG/mg Cr in late gestation
With levels >100 ng PdG/mg Cr
Semen volume
4–6 mL
Unknown
The female giraffid has a bicornuate uterus. In the male, the testes are scrotal,
and the penis is fibroelastic and has a long urethral process resembling that of a
goat. Interestingly, three variations of chromosome numbers have been identified in
the okapi (44, 45, 46).
52
The reduction of 46 chromosomes to 45 is the result of a Robertsonian translocation
between chromosomes 8 and 21. Individuals with 45 and 46 have both reproduced successfully
in mixed karyotype pairs. Females are nonseasonal breeders and come into estrus at
15-day intervals. Estrus behavior is fairly subtle and consists of mild mucus production
and vulvar flaring. Breeding normally is uneventful, with copulation lasting only
seconds.
Pregnancy may usually be detected visually about half way through. In trained animals,
ovarian cycles and pregnancy may be monitored with transrectal ultrasonography.
40
In pregnant giraffes, the corpus luteum (CL) reaches a diameter significantly larger
(40 mm) than during the cycle (33 mm), and follicular activity may still be present.
40
Transabdominal ultrasonography may detect later stage pregnancy. Pregnancy may also
be detected by means of urinary and fecal steroid analysis.38, 60
Predicting the time of birth precisely is difficult in giraffes. The udder typically,
but not always, becomes enlarged in the last few weeks prior to parturition. Vulvar
edema and a mucoid discharge may precede parturition by a few days. If possible, the
female should be isolated from the herd shortly before parturition and remain separate
with the calf for at least 24 hours, but if adequate space is available, the female
may simply give birth while with the herd. Giraffids usually give birth to a single
calf; however, twinning does occur. In the okapi, several twin pregnancies have ended
in stillbirths.
59
Labor is usually short (3–6 hours), and the healthy calf should be standing within
an hour or so of birth. The birthing environment is important for neonatal survival.
A proper substrate of compacted soil, rubber pads, or straw bedding is important to
prevent hypothermia and splaying. Nursing should start within the first few hours
after birth. First-time mothers may be nervous and may at first refuse to allow the
calf to suckle. They usually relax after a few hours, but mild sedation has been necessary
in several instances.
19
Neonatal examinations are useful for assessing the general health of the neonate and
determining the success of immunoglobulin transfer from the dam. Normal birth weight
is approximately 60 kg in the giraffe and 15 to 30 kg for okapis.
An okapi that experienced five abortions because of deficient placental progestagen
production was treated with altrenogest in a subsequent pregnancy and carried the
fetus to term.
60
Retained placenta occurs with some frequency in both species, particularly when the
calf is stillborn or dies within the first day. Ideally, as much of the placenta should
be removed as possible, but cases have been managed with only supportive therapy,
including antibiotics.
59
Contraception
In some cases, preventing reproduction in giraffes is desirable. Surgical castration
is an effective, although nonreversible, means of contraception in male giraffes.
Open castration using an emasculator and ligation has been advocated, but partial
or complete scrotal closure is probably a superior technique.
5
For contraception in females, melengestrol acetate (2–3 mg/kg/day) administered in
the feed, or the progesterone-derivative medroxyprogesterone acetate (Depo-Provera,
Pfizer Animal Health), (450–800 mg/female, every 6 weeks) have been the traditional
pharmaceutical means of contraception; however, the gonadotropin-releasing hormone
(GnRH) agonist deslorelin (Suprelorin, Peptech Animal Health/Virbac) administered
as implants has recently proven to be superior and effective for more than a year.
50
It is suggested to check the current recommendations of the Contraceptive Advisory
Group before initiating contraception.
Preventive Medicine
Preventative measures in giraffids include regular inspections of feet and provision
of abrasive surfaces. If necessary, routine foot care should be provided, ideally
through use of training. Regular screening for intestinal parasites and deworming,
if indicated, should be part of the strategy, and regular weighing of animals is highly
recommended.
Routine vaccination is seldom performed, but vaccines against rabies, clostridial
diseases, and bluetongue, as well as rotavirus and coronavirus, are sometimes used.
Preshipment testing is recommended for any giraffe relocation, but specific tests
to be performed depend on local conditions. The following are recommended guidelines
to aid in decision making when planning the safe transfer of a giraffe or okapi: (1)
fecal sample for parasites, particularly nematodes; (2) fecal culture, especially
for Salmonella; (3) tuberculin skin testing and auxiliary TB tests; (4) blood sample
for complete blood cell (CBC) count and serum chemistries; (5) physical examination,
including foot inspection. Intracutaneous TB testing may be performed in the eyelids,
as in primates, to avoid the need for a second restraint of the animal.
Quarantine of individuals should be performed before exposure to animals at the new
location.
Acknowledgments
The author thanks Mira Strøm Braten, Carsten Grøndahl, Sander Hofman, Kristin Leus,
Torsten Møller, Willem Schaftenaar, and Francis Vercamen for their contributions to
this chapter.