Elbow-joint morphology in the North American 'cheetah-like' cat Miracinonyx trumani.

The North American cheetah-like cat Miracinonyx trumani is an extinct species that roamed the Pleistocene prairies 13 000 years ago. Although M. trumani is more closely related to the cougar (Puma concolor) than to the living cheetah (Acinonyx jubatus), it is believed that both A. jubatus and M. trumani possess a highly specialized skeleton for fast-running, including limbs adapted for speed at the expense of restricting the ability of prey grappling. However, forelimb dexterity of M. trumani has not been yet investigated. Here, we quantify the 3D-shape of the humerus distal epiphysis as a proxy for elbow-joint morphology in a sample of living cats to determine whether the extinct M. trumani was specialized to kill open-country prey using predatory behaviour based on fast running across the prairies and steppe terrains of the North American Pleistocene. We show that M. trumani had an elbow morphology intermediate to that of P. concolor and A. jubatus, suggesting that M. trumani had a less specialized pursuit predatory behaviour than A. jubatus. We propose that M. trumani probably deployed a unique predatory behaviour without modern analogues. Our results bring into question the degree of ecomorphological convergence between M. trumani and its Old World vicar A. jubatus.

Comparative neocortical neuromorphology in felids: African lion, African leopard, and cheetah.

The present study examines cortical neuronal morphology in the African lion (Panthera leo leo), African leopard (Panthera pardus pardus), and cheetah (Acinonyx jubatus jubatus). Tissue samples were removed from prefrontal, primary motor, and primary visual cortices and investigated with a Golgi stain and computer-assisted morphometry to provide somatodendritic measures of 652 neurons. Although neurons in the African lion were insufficiently impregnated for accurate quantitative dendritic measurements, descriptions of neuronal morphologies were still possible. Qualitatively, the range of spiny and aspiny neurons across the three species was similar to those observed in other felids, with typical pyramidal neurons being the most prominent neuronal type. Quantitatively, somatodendritic measures of typical pyramidal neurons in the cheetah were generally larger than in the African leopard, despite similar brain sizes. A MARsplines analysis of dendritic measures correctly differentiated 87.4% of complete typical pyramidal neurons between the African leopard and cheetah. In addition, unbiased stereology was used to compare the soma size of typical pyramidal neurons (n = 2,238) across all three cortical regions and gigantopyramidal neurons (n = 1,189) in primary motor and primary visual cortices. Both morphological and stereological analyses indicated that primary motor gigantopyramidal neurons were exceptionally large across all three felids compared to other carnivores, possibly due to specializations related to the felid musculoskeletal systems. The large size of these neurons in the cheetah which, unlike lions and leopards, does not belong to the Panthera genus, suggests that exceptionally enlarged primary motor gigantopyramidal neurons evolved independently in these felid species.

Regional variation in the cheetah (Acinonyx jubatus) revisited: Morphology of wild and captive populations.

The cheetah (Acinonyx jubatus) is listed as a vulnerable species by the International union for the conservation of nature (IUCN), including two critically endangered subspecies, the Saharan cheetah, and the Iranian cheetah, so it is imperative that we understand variation in cheetah morphology to make good decisions regarding the conservation of this species. Here, we aim to determine whether northeastern African cheetahs have smaller body sizes than southern African cheetahs. This study also adds to our knowledge of cheetah morphology from two cheetah populations that do not yet have comprehensive published data: Kenya, and northeastern Africa, including captive individuals. We calculated means and standard deviations on cranial and body measurements of live or in few cases, freshly dead, cheetahs from the aforementioned populations, plus previously published data on Namibian and Botswanan cheetahs and compared them to one another using multivariate analysis of variance. Results show that northeastern African cheetahs have smaller body sizes than southern and eastern African populations. We also found that captive cheetahs retain the morphological characteristics of their ancestral population- captive cheetahs from southern Africa have similar body sizes to wild southern African cheetahs and larger body sizes than captives from northeastern Africa. Other analyses regarding cheetah growth agree with previous studies on Namibian and Botswanan cheetah populations rates. As such, this study can serve as a baseline for the care of captive cheetah populations to maintain healthy weights and body proportions.

Morphology of the Uterotubal Junction of the Cheetah (Acinonyx jubatus).

Less than 7,000 cheetahs survive in the wild. Captive breeding has proved notoriously difficult. The uterotubal junction acts as major barrier and regulator to the passage of sperm. This study describes the morphology of the uterotubal junction of the cheetah. Reproductive tracts were obtained from seven cheetahs that succumbed from natural causes or were euthanized for humane reasons. The uterotubal junction was isolated and examined macroscopically and microscopically. The extramural isthmus made a characteristic 90° bend before entering the mesometrial border of the uterus close to its tip. The intramural isthmus had approximately four primary folds lined by nonciliated cuboidal to low cuboidal epithelium. The Tunica muscularis was robust, merged with its uterine counterparts and consisted of an inner circular layer and outer longitudinal smooth muscle layer. The uterine ostium opened via a muscular and glandular papilla that projected from the apex of the uterine lumen. A sharply demarcated circular zone of simple columnar epithelial cells surrounded the uterine ostium and separated the simple cuboidal to low cuboidal cells of the isthmus and uterine epithelium from each other. Branched tubulo-alveolar glands, some with dilated lumens, were present in the papilla and sometimes extended into the adjacent endometrium. These glands might act as sperm storage areas, and could easily be confused with cystic endometrial hyperplasia. Low transverse endometrial ridges surrounded the papilla and extended caudally for a short distance before disappearing. The uterine glands were lined by a simple cuboidal epithelium. Anat Rec, 302:1855-1864, 2019. © 2019 American Association for Anatomy.

Recent inner ear specialization for high-speed hunting in cheetahs.

The cheetah, Acinonyx jubatus, is the fastest living land mammal. Because of its specialized hunting strategy, this species evolved a series of specialized morphological and functional body features to increase its exceptional predatory performance during high-speed hunting. Using high-resolution X-ray computed micro-tomography (µCT), we provide the first analyses of the size and shape of the vestibular system of the inner ear in cats, an organ essential for maintaining body balance and adapting head posture and gaze direction during movement in most vertebrates. We demonstrate that the vestibular system of modern cheetahs is extremely different in shape and proportions relative to other cats analysed (12 modern and two fossil felid species), including a closely-related fossil cheetah species. These distinctive attributes (i.e., one of the greatest volumes of the vestibular system, dorsal extension of the anterior and posterior semicircular canals) correlate with a greater afferent sensitivity of the inner ear to head motions, facilitating postural and visual stability during high-speed prey pursuit and capture. These features are not present in the fossil cheetah A. pardinensis, that went extinct about 126,000 years ago, demonstrating that the unique and highly specialized inner ear of the sole living species of cheetah likely evolved extremely recently, possibly later than the middle Pleistocene.

Ultrasonographically determined renal values and comparisons to serum biochemistry renal variables in aged semi-captive cheetahs (Acinonyx jubatus).

BACKGROUND: Cheetahs in captivity have a high prevalence of chronic renal diseases. We ultrasonographically evaluated the renal volumes, a variety of renal dimensions, interarcuate artery resistive indices (RI) as well as aortic diameters and the length of the ventral aspect of the 6th lumbar vertebrae in 27 aged semi-captive anesthetized cheetahs. Renal size, dimensions and ratios were compared to urine specific gravity, serum creatinine and urea values. RESULTS: There were minimal differences for all values between left and right kidneys. Mean kidney length was 65.1 mm (range 55.2-76.9) with left kidney length ratios to L6 length being 1.60 (range 1.27-2.06) and to the aortic diameter 7.69 (range 4.54-10.72). Significant correlations between left renal length as well as length:L6 ratio to creatinine values were found ((r - 0.66) and (r - 0.60) respectively). The mean RI values of the different sedation/anesthetic protocols ranged from 0.46-0.55. CONCLUSIONS: Left renal length and L6 ventral vertebral body length as well as left kidney RI values should be routinely measured in all cheetah abdominal ultrasound examinations. These measurements, together with serum creatinine, urea and urine specific gravity values may be relatively sensitive indicators of early renal pathology in the absence of gross ultrasonographic changes.

Intrinsic factors, adrenal gland morphology, and disease burden in captive cheetahs (Acinonyx jubatus) in South Africa.

Adrenal gland weight (AW) and corticomedullary ratio (ACMR) are used as indicators of stress in animals. Captive cheetahs (Acinonyx jubatus) have higher ACMRs than free-ranging ones and stress has been linked to gastritis, amyloidosis, glomerulosclerosis, and myocardial fibrosis. We reviewed age, sex, body weight (BW), kidney weight (KW), and left AW and ACMR with necropsy findings in 51 South African captive cheetahs. Eleven common histopathologic lesions were counted for each animal as measure of its disease burden. Adrenal corticomedullary hyperplasia was significantly correlated with left AW and ACMR. Males had significantly higher AWs than females; other parameters showed no difference between the sexes. Disease burden, gastritis, and myocardial fibrosis were moderately correlated with adrenal morphology supporting prior evidence that gastritis and myocardial fibrosis are linked to stress. Glomerulosclerosis was not correlated with adrenal morphology and neither kidney nor liver amyloidosis contributed significantly to variation in AW or ACMR on multivariate analyses. Interstitial nephritis showed much stronger correlations with kidney and liver amyloidosis than gastritis. All three adrenal parameters were correlated with age; age was the only significant variable affecting ACMR on the multivariate analyses; and disease burden as well as systemic amyloidosis and kidney disease (except for fibrosis) showed moderate correlations with age. Age may, therefore, be important in the pathogenesis of disease in captive cheetahs, particularly of amyloidosis and kidney disease. None of the intrinsic measurements or adrenal parameters were sufficiently closely linked to disease to be used as ante-mortem proxies for disease burden or specific diseases. Zoo Biol. 36:40-49, 2017. © 2016 Wiley Periodicals, Inc.

Spotting Cheetahs: Identifying Individuals by Their Footprints.

The cheetah (Acinonyx jubatus) is Africa's most endangered large felid and listed as Vulnerable with a declining population trend by the IUCN(1). It ranges widely over sub-Saharan Africa and in parts of the Middle East. Cheetah conservationists face two major challenges, conflict with landowners over the killing of domestic livestock, and concern over range contraction. Understanding of the latter remains particularly poor(2). Namibia is believed to support the largest number of cheetahs of any range country, around 30%, but estimates range from 2,905(3) to 13,520(4). The disparity is likely a result of the different techniques used in monitoring. Current techniques, including invasive tagging with VHF or satellite/GPS collars, can be costly and unreliable. The footprint identification technique(5) is a new tool accessible to both field scientists and also citizens with smartphones, who could potentially augment data collection. The footprint identification technique analyzes digital images of footprints captured according to a standardized protocol. Images are optimized and measured in data visualization software. Measurements of distances, angles, and areas of the footprint images are analyzed using a robust cross-validated pairwise discriminant analysis based on a customized model. The final output is in the form of a Ward's cluster dendrogram. A user-friendly graphic user interface (GUI) allows the user immediate access and clear interpretation of classification results. The footprint identification technique algorithms are species specific because each species has a unique anatomy. The technique runs in a data visualization software, using its own scripting language (jsl) that can be customized for the footprint anatomy of any species. An initial classification algorithm is built from a training database of footprints from that species, collected from individuals of known identity. An algorithm derived from a cheetah of known identity is then able to classify free-ranging cheetahs of unknown identity. The footprint identification technique predicts individual cheetah identity with an accuracy of >90%.

Ultrasonographic adrenal gland findings in healthy semi-captive cheetahs (Acinonyx jubatus).

Cheetahs in captivity are believed to suffer from stress predisposing them to poor health. To date fecal glucocorticoids have been used as a non-invasive indicator of chronic stress. This study examines, the feasibility of transabdominal adrenal gland ultrasonography in cheetahs and determined normal adrenal measurements that can potentially be used as a more reliable indicator of chronic stress and/or adrenal function. Thirty-three adult cheetahs, aged between 2 and 13 years, accommodated in large off-display camps were examined over 9 days under general anesthesia. The adrenals were readily identified, with the right adrenal being more difficult to find and measure than the left, and were smaller than those expected in similar sized dogs. The left adrenal was shorter and slightly more oval shaped than the right with a length and cranial pole width at a 95% prediction interval of 16.3-22.4 and 4.1-8.7 mm. The same measurements for the right adrenal were 16.8-26.2 and 3.4-10.8 mm, respectively. Corticomedullary ratios were larger for the left adrenal. When corrected for body size, females had significantly longer and greater left adrenal corticomedullary ratios than males. Adrenal measurements did not correlate with left renal length, body size measurements, or enclosure size. Measurements that increased with age included the cortical and total adrenal widths. Adrenal ultrasonography offers potential benefits in assessment of individual cheetah adrenal pathology or the evaluation of stress induced adrenomegally especially in combination with other evaluations such as non-invasive fecal glucocorticoid analyses. Zoo Biol. 35:260-268, 2016. © 2016 Wiley Periodicals, Inc.

Increasing age influences uterine integrity, but not ovarian function or oocyte quality, in the cheetah (Acinonyx jubatus).

Although the cheetah (Acinonyx jubatus) routinely lives for more than 12 yr in ex situ collections, females older than 8 yr reproduce infrequently. We tested the hypothesis that reproduction is compromised in older female cheetahs due to a combination of disrupted gonadal, oocyte, and uterine function/integrity. Specifically, we assessed 1) ovarian response to gonadotropins; 2) oocyte meiotic, fertilization, and developmental competence; and 3) uterine morphology in three age classes of cheetahs (young, 2-5 yr, n = 17; prime, 6-8 yr, n = 8; older, 9-15 yr, n = 9). Ovarian activity was stimulated with a combination of equine chorionic gonadotropin and human chorionic gonadotropin (hCG), and fecal samples were collected for 45 days before gonadotropin treatment and for 30 days after oocyte recovery by laparoscopy. Twenty-six to thirty hours post-hCG, uterine morphology was examined by ultrasound, ovarian follicular size determined by laparoscopy, and aspirated oocytes assessed for nuclear status or inseminated in vitro. Although no influence of age on fecal hormone concentrations or gross uterine morphology was found (P > 0.05), older females produced fewer (P < 0.05) total antral follicles and oocytes compared to younger counterparts. Regardless of donor age, oocytes had equivalent (P > 0.05) nuclear status and ability to reach metaphase II and fertilize in vitro. A histological assessment of voucher specimens revealed an age-related influence on uterine tissue integrity, with more than 87% and more than 56% of older females experiencing endometrial hyperplasia and severe pathologies, respectively. Our collective findings reveal that lower reproductive success in older cheetahs appears to be minimally influenced by ovarian and gamete aging and subsequent dysfunction. Rather, ovaries from older females are responsive to gonadotropins, produce normative estradiol/progestogen concentrations, and develop follicles containing oocytes with the capacity to mature and be fertilized. A more likely cause of reduced fertility may be the high prevalence of uterine endometrial hyperplasia and related pathologies. The discovery that a significant proportion of oocytes from older females have developmental capacity in vitro suggests that in vitro fertilization and embryo transfer may be useful for "rescuing" the genome of older, nonreproductive cheetahs.

Functional anatomy of the cheetah (Acinonyx jubatus) forelimb.

Despite the cheetah being the fastest living land mammal, we know remarkably little about how it attains such high top speeds (29 m s(-1)). Here we aim to describe and quantify the musculoskeletal anatomy of the cheetah forelimb and compare it to the racing greyhound, an animal of similar mass, but which can only attain a top speed of 17 m s(-1). Measurements were made of muscle mass, fascicle length and moment arms, enabling calculations of muscle volume, physiological cross-sectional area (PCSA), and estimates of joint torques and rotational velocities. Bone lengths, masses and mid-shaft cross-sectional areas were also measured. Several species differences were observed and have been discussed, such as the long fibred serratus ventralis muscle in the cheetah, which we theorise may translate the scapula along the rib cage (as has been observed in domestic cats), thereby increasing the cheetah's effective limb length. The cheetah's proximal limb contained many large PCSA muscles with long moment arms, suggesting that this limb is resisting large ground reaction force joint torques and therefore is not functioning as a simple strut. Its structure may also reflect a need for control and stabilisation during the high-speed manoeuvring in hunting. The large digital flexors and extensors observed in the cheetah forelimb may be used to dig the digits into the ground, aiding with traction when galloping and manoeuvring.

Functional anatomy of the cheetah (Acinonyx jubatus) hindlimb.

The cheetah is capable of a top speed of 29 ms(-1) compared to the maximum speed of 17 ms(-1) achieved by the racing greyhound. In this study of the hindlimb and in the accompanying paper on the forelimb we have quantified the musculoskeletal anatomy of the cheetah and greyhound and compared them to identify any differences that may account for this variation in their locomotor abilities. Specifically, bone length, mass and mid-shaft diameter were measured, along with muscle mass, fascicle lengths, pennation angles and moment arms to enable estimates of maximal isometric force, joint torques and joint rotational velocities to be calculated. Surprisingly the cheetahs had a smaller volume of hip extensor musculature than the greyhounds, and we therefore propose that the cheetah powers acceleration using its extensive back musculature. The cheetahs also had an extremely powerful psoas muscle which could help to resist the pitching moments around the hip associated with fast accelerations. The hindlimb bones were proportionally longer and heavier, enabling the cheetah to take longer strides and potentially resist higher peak limb forces. The cheetah therefore possesses several unique adaptations for high-speed locomotion and fast accelerations, when compared to the racing greyhound.

Myosin heavy chain composition of tiger (Panthera tigris) and cheetah (Acinonyx jubatus) hindlimb muscles.

Felids have a wide range of locomotor activity patterns and maximal running speeds, including the very fast cheetah (Acinonyx jubatas), the roaming tiger (Panthera tigris), and the relatively sedentary domestic cat (Felis catus). As previous studies have suggested a relationship between the amount and type of activity and the myosin heavy chain (MHC) isoform composition of a muscle, we assessed the MHC isoform composition of selected hindlimb muscles from these three felid species with differing activity regimens. Using gel electrophoresis, western blotting, histochemistry, and immunohistochemistry with MHC isoform-specific antibodies, we compared the MHC composition in the tibialis anterior, medial gastrocnemius (MG), plantaris (Plt), and soleus muscles of the tiger, cheetah, and domestic cat. The soleus muscle was absent in the cheetah. At least one slow (type I) and three fast (types IIa, IIx, and IIb) MHC isoforms were present in the muscles of each felid. The tiger had a high combined percentage of the characteristically slower isoforms (MHCs I and IIa) in the MG (62%) and the Plt (86%), whereas these percentages were relatively low in the MG (44%) and Plt (55%) of the cheetah. In general, the MHC isoform characteristics of the hindlimb muscles matched the daily activity patterns of these felids: the tiger has daily demands for covering long distances, whereas the cheetah has requirements for speed and power.

A primitive Late Pliocene cheetah, and evolution of the cheetah lineage.

The cheetah lineage is a group of large, slender, and long-limbed cats with a distinctive skull and dental morphology, of which only the extant cheetah (Acinonyx jubatus) is present today. The lineage is characterized by having abbreviated, tall, and domed crania, and a trenchant dentition with a much reduced, posteriorly placed protocone on the upper carnassial. In this article, we report on a new discovery of a Late Pliocene specimen from China with an estimated age of approximately 2.2-2.5 million years, making it one of the oldest specimens known to date. A cladistic analysis confirmed that it is the most primitive cheetah known, and it shares a number of unambiguous derived cranial traits with the Acinonyx lineage, but has more primitive dentition than previously known cheetahs, demonstrating that the many unusual skull and dental characters hitherto considered characteristic of cheetahs evolved in a gradual fashion. Isolated teeth of primitive cheetahs may not be recognizable as such, but can be confused with, for instance, those of leopards or other similar-sized pantherine cats or pumas. The age and morphology of the new specimen supports an Old World origin of the cheetah lineage, not a New World one, as has been suggested. We name the new species Acinonyx kurteni in honor of the late Björn Kurtén.

Motions of the running horse and cheetah revisited: fundamental mechanics of the transverse and rotary gallop.

Mammals use two distinct gallops referred to as the transverse (where landing and take-off are contralateral) and rotary (where landing and take-off are ipsilateral). These two gallops are used by a variety of mammals, but the transverse gallop is epitomized by the horse and the rotary gallop by the cheetah. In this paper, we argue that the fundamental difference between these gaits is determined by which set of limbs, fore or hind, initiates the transition of the centre of mass from a downward-forward to upward-forward trajectory that occurs between the main ballistic (non-contact) portions of the stride when the animal makes contact with the ground. The impulse-mediated directional transition is a key feature of locomotion on limbs and is one of the major sources of momentum and kinetic energy loss, and a main reason why active work must be added to maintain speed in locomotion. Our analysis shows that the equine gallop transition is initiated by a hindlimb contact and occurs in a manner in some ways analogous to the skipping of a stone on a water surface. By contrast, the cheetah gallop transition is initiated by a forelimb contact, and the mechanics appear to have much in common with the human bipedal run. Many mammals use both types of gallop, and the transition strategies that we describe form points on a continuum linked even to functionally symmetrical running gaits such as the tölt and amble.

Ejaculate traits in the Namibian cheetah (Acinonyx jubatus): influence of age, season and captivity.

The objective was to examine the influence of animal age, season and captivity status on seminal quality in wild-born cheetahs (Acinonyx jubatus) in Namibia, Africa. Animals were divided into three age categories: juvenile (14-24 months; n = 16 males, 23 ejaculates); adult (25-120 months; n = 76 males, 172 ejaculates); and aged (>120 months; n = 5 males, 5 ejaculates). Seasons were categorised into hot-wet (January-April), cold-dry (May-August) and hot-dry (September-December). A comparison between freshly wild-caught (n = 29 males, 41 ejaculates) and captive-held cheetahs (n = 68 males, 159 ejaculates) was also conducted. Raw ejaculates contained 69.0 +/- 1.1% motile spermatozoa (mean +/- s.e.m.) with 73.6 +/- 1.5% of these cells containing an intact acrosome. Overall, 18.4 +/- 0.9% of spermatozoa were morphologically normal, with midpiece anomalies being the most prevalent (approximately 39%) defect. Juvenile cheetahs produced ejaculates with poorer sperm motility, forward progressive status, lower seminal volume and fewer total motile spermatozoa than adult and aged animals. Spermatogenesis continued unabated throughout the year and was minimally influenced by season. Proportions of sperm malformations were also not affected by season. Ejaculates from captive cheetahs had increased volume and intact acrosomes, but lower sperm density than wild-caught counterparts. In summary, Namibian cheetahs produce an extraordinarily high proportion of pleiomorphic spermatozoa regardless of age, season or living (captive versus free-ranging) status. Young males less than 2 years of age produce poorer ejaculate quality than adult and aged males. Because (1) all study animals were wild born and (2) there was little difference between freshly caught males and those maintained in captivity for protracted periods, our results affirm that teratospermia in the cheetah is mostly genetically derived. It also appears that an ex situ environment for the Namibian cheetah can ensure sperm quality comparable with that for free-living males.

Ultrasonography of the liver, spleen, and urinary tract of the cheetah (Acinonyx jubatus).

Diseases of the abdomen of the cheetah (Acinonyx jubatus) include those affecting the liver, spleen, and urinary tract. The most common diseases of captive-bred cheetah are gastritis, gastric ulceration, glomerulosclerosis, and hepatic veno-occlusive disease, and are the most frequent causes of mortality in these animals. The purpose of this study was to describe the ultrasonographic anatomy of the normal liver, spleen, kidney, and urinary bladder of the anesthetized captive-bred cheetah. Twenty-one cheetahs were examined. Eight of the 21 animals had subclinical evidence of either gastritis or chronic renal disease. The ultrasonographic appearances of the liver, gall bladder, common bile duct, and spleen were evaluated and various measurements made. Statistical analyses of the measurements were performed on all the healthy and subclinically ill animals taking sex, age, mass, and anesthetic protocol into account. There were no significant differences in any parameters between the healthy and subclinically ill animals (P > 0.25) and data were combined for statistical analyses. The mean mass was 41.1kg ( +/- 8.8) and the mean age was 5.0 years (+/- 2.2). The mean thickness of the liver medial to the gall bladder was 67.0 mm (+/- 14.8) and the liver was within the left costal arch in 75% of animals, extended caudal to the right costal arch in 50% of animals for an average of 30 mm, and extended caudal to the sternum in 63% of animals for an average of 32.5 mm. The maximum mean hepatic vein diameter at the entrance to the caudal vena cava was 8.6 +/- 2.8 mm; the mean diameters of the portal vein at the hilus and that of the caudal vena cava as it entered the liver were 7.5 +/- 1.6 and 9.9 +/- 4.1 mm, respectively. The mean diameter of the caudal vena cava was significantly affected by the type of anesthetic used (P < 0.10). The mass of the animals was significant in explaining the variance in maximum portal vein diameters (P < 0.10). The mean maximum velocity of the hepatic vein flow at the entrance to the caudal vena cava was 25.3 +/- 2.8 cm/s (n=4), the hilar portal vein was 11.7 +/- 3.3 cm/s (n=7), and the caudal vena cava was 33.8 +/- 19.8 cm/s (n=5). The mean maximum gall bladder length and width, and the mean common bile duct diameters were 44.6 mm (+/- 10.4), 23.3 mm (+/- 5.0), and 8.1 mm (+/- 2.4), respectively. Age was significant in explaining the variance in gall bladder lengths (P<0.10). Urinary tract ultrasonography was performed only in animals that had normal urea and creatinine levels (n=13). Renal cortico-medullary distinction was present in all kidneys and a cortico-medullary rim sign was seen in 21 of 26 kidneys. Mean kidney length, height, and width was 63.9 +/- 5.7, 38.1 +/- 5.2, and 42.1 +/- 5 mm, respectively. The average resistivity index was 0.58 (n=5). Mean urinary bladder length, height, and width were 57.0, 19.2, and 34.9 mm, respectively.

Radiographic kidney measurements in captive cheetahs (Acinonyx jubatus).

The prevalence of chronic renal disease is substantial among captive cheetahs (Acinonyx jubatus). The purpose of this study was to determine kidney measurements from radiographs of captive cheetahs (n = 15) with normal renal function. The ratio of kidney length to length of the body of the second lumbar vertebrae has been established for domestic cats with normal renal function. The mean ratio of renal length to length of the second lumbar vertebra was 1.81 +/- 0.14 in cheetahs. This baseline data may allow an objective evaluation of radiographic kidney size in cheetahs. However, evaluation of a small number of cheetahs with confirmed renal failure resulted in a similar ratio.

The morphological characteristics of the antebrachiocarpal joint of the cheetah (Acinonyx jubatus).

A morphological study of the structures of the antebrachiocarpal (AC) joint of the cheetah was carded out by dissection of eight forelimbs obtained from four adult cheetahs culled from the Kruger National Park, Republic of South Africa. The aim was to evaluate the deviations of this joint from the normal feline pattern and to consider their possible relationship to the cheetah's adaptation to speed. Although published data on the AC joint of the other felids show general resemblance to that of the cheetah, there are nevertheless slight, but significant variations and modifications which tend to suggest adaptation to speed. The shafts of the radius and ulna of the cheetah are relatively straight and slender, with poorly developed distal ends. The ulnar notch is reduced to a very shallow concavity while the corresponding ulnar facet is a barely noticeable convexity, separated from the distal ulnar articular facet by an ill-defined groove. The movement of the distal radio-ulnar joint is highly restricted by the presence of a fibro-cartilaginous structure and a strong interrosseous membrane, limiting pronation and supination normally achieved by the rotation of the radius around the ulna. The extensor grooves at the distal extremity of the radius are deep and narrow and are guarded by prominent ridges. A thick extensor retinaculum anchors the strong extensor tendons in these grooves. The distal articular surface of the radius is concave in all directions except at the point where it moves into its stylold process. At this point it is convex in the dorsopalmar direction, with a surface that is rather deep and narrow. The proximal row of carpal bones presents a strongly convex surface, which is more pronounced in the dorsopalmar direction with the greatest convexity on the lateral aspect. Medially, there is a ridge-like concavity across the base of the tubercle, which rocks on the flexor surface of the radius, limiting excessive flexion as well as restricting lateral deviation of the AC joint.