AORTOILIAC THROMBUS SECONDARY TO A MINERALIZED ARTERIOSCLEROTIC LESION

A 12-year-old, neutered female, Siberian Husky dog presented with a hind limb weakness of one month duration. To facilitate making a diagnosis multiple imaging modalities were performed. These modalities included radiography, ultrasonography, magnetic resonance imaging (MRI), magnetic resonance angiography (MRA) and selective angiography of the abdominal aorta. In this dog, the MRI/MRA studies provided the first documentation of the external iliac thrombi and the collateral circulation via the lumbar arteries. At necropsy, an aortoiliac thrombus caused by a mineralized arteriosclerotic plaque was noted.     

Internal aorto-iliac thrombosis in a Thoroughbred: Unsuccessful surgical thrombectomy,a proposed aetiopathogenesis and spontaneous partial regression

A 4-year-old Thoroughbred gelding with severe left hindlimb lameness and colic-like signs lasting 30–60 min post-exercise was diagnosed with unilateral internal aorto-iliac thrombosis. The thrombus was identified using transrectal ultrasonography in the terminal aorta and was initially thought to extend into the left external iliac artery. However, attempted thrombectomy via a left femoral arteriotomy performed under general anaesthesia using thrombectomy and angioplasty catheters was unsuccessful, as the thrombus was located in the left internal iliac artery. Transrectal ultrasound evaluation was repeated monthly for 12 months post-operatively during which time the gelding remained asymptomatic at rest. As removal of thrombi in the external but not internal iliac artery may be possible, correct diagnosis of the location of the thrombus is critical in preventing unnecessary attempts at surgical correction. The aetiology remains unknown, but altered haemodynamics within the abdominal aorta with mechanical stresses during intense exercise are proposed as a cause of thrombus formation. The sequential monitoring of this case also conflicts the assumption that thrombi in this location propagate over time as partial regression was observed 6 months after referral and 9 months after onset of clinical signs.     

Arterial distribution to the pelvic cavity and pelvic limb in the pampas deer (Ozotoceros bezoarticus,Linnaeus 1758)

This research is a study about the arterial vascularization of pelvic cavity and pelvic limb in pampas deer. For this study, 25 dead animals were used. The vascularization of the organs was investigated using a latex injection technique. Two animals were injected in the common carotid artery with contrast to cardiac angiography, and then, radiographs were taken. The aorta showed the two external iliac arteries, and after a short course, the aorta ended in two internal iliac arteries. The median sacral artery was originated from the dorsal surface cranially to the emergence of the internal iliac arteries. The last one gave off parietal (iliolumbar, cranial and caudal gluteal arteries) and visceral (umbilical and internal pudendal arteries) branches. The external iliac artery gave as first branch the deep circumflex iliac artery which was divided into a cranial and a caudal branch. After a short distance from the external iliac artery, the femoral and deep femoral arteries were originated. The deep femoral artery gave origin to the pudendoepigastric trunk and to the medial femoral circumflex artery. Based on the arterial distribution of the pelvic cavity and pelvic limb in the pampas deer, it is concluded that the internal iliac artery has a pattern of intermediate development. In reference to the distribution of the external iliac artery and its branches, the pattern of development is the cranial tibial type.     

The Hindlimb Arterial Vessels in Lowland paca (Cuniculus paca,Linnaeus 1766)

This study aims to describe the origin and distribution of the hindlimb arterial vessels. Five adult lowland pacas (Cuniculus paca) were used. Stained and diluted latex was injected, caudally to the aorta. After fixation in 10% paraformaldehyde for 72 h, we dissected to visualize and identify the vessels. It was found out that the vascularization of the hindlimb in lowland paca derives from the terminal branch of the abdominal aorta. The common iliac artery divides into external iliac and internal iliac. The external iliac artery emits the deep iliac circumflex artery, the pudendal epigastric trunk, the deep femoral artery; the femoral artery originates the saphenous artery, it bifurcates into cranial and caudal saphenous arteries. Immediately after the knee joint, the femoral artery is called popliteal artery, which divides into tibial cranial and tibial caudal arteries at the level of the crural inter‐osseous space. The origin and distribution of arteries in the hindlimb of lowland paca resembles that in other wild rodents, as well as in the domestic mammals.     

Spectral waveform analysis of major arteries in conscious dogs by Doppler ultrasonography

Normal values of arterial blood flow velocity and waveforms in major arteries of 10 healthy conscious Beagle dogs were determined using Doppler ultrasonography. Peak systolic, early diastolic, and end-diastolic velocities of the basilar artery, common carotid artery, abdominal aorta, external iliac artery, femoral artery, and peak ejection velocity of the valvular aorta were evaluated. Pulsatility index (PI) of the basilar artery and blood pressure were recorded. All arteries had a high-resistance flow pattern with triphasic flow velocity except the basilar artery, which had a low-resistance pattern. Mean peak systolic velocities of the basilar artery, common carotid artery, abdominal aorta, external iliac artery, and femoral artery were 72 +/- 19, 115 +/- 17, 121 +/- 24, 105 +/- 25, and 110 +/- 17 cm/s, respectively. The PI of the basilar artery and peak ejection velocity of the valvular aorta were 1.37 +/- 0.13 and 96 +/- 16 cm/s, respectively. Mean systolic and diastolic blood pressures were 137 +/- 13 and 78 +/- 15 mmHg, respectively. Present findings may be used as references in future studies on vascular diseases and hemodynamics in dogs.     

Comparative macroanatomic investigations on the formation of the external iliac vein in akkaraman sheep and Angora goat

To evaluate the formation of the external iliac vein in Akkaraman sheep and Angora goats, 8 adult healthy Akkaraman sheep and 8 Angora goats of both sexes, 3 to 4 years of age, were examined. The external iliac vein was formed by the deep femoral and femoral veins in 6 Akkaraman sheep and 7 Angora goats and by the medial circumflex femoral and femoral veins in 2 Akkaraman sheep and I Angora goat. Results from this study are thought to throw light on the future studies on the venous system, and to contribute considerably to the present anatomical knowledge concerning the external iliac vein of sheep and goats.     

Bilateral iliac arterial thrombosis in an alpaca (Vicugna pacos) cria

A 3-month-old male alpaca was presented for acute onset of non-weight-bearing left hind limb lameness. Antemortem diagnostics revealed a mass to the right of the urinary bladder and no blood flow in the left femoral artery. Necropsy revealed bilateral iliac arterial thrombi and an abscess near the urinary bladder.     

Multidetector computed tomographic angiography evaluation of micropig major systemic vessels for xenotransplantation

Due primarily to the increasing shortage of allogeneic donor organs, xenotransplantation has become the focus of a growing field of research. Currently, micropigs are the most suitable donor animal for humans. However, no standard method has been developed to evaluate the systemic vascular anatomy of micropigs and standard reference values to aid in the selection of normal healthy animals as potential organ donors are lacking. Using 64-channel multidetector row computed tomographic angiography (MDCTA), we evaluated morphological features of the major systemic vessels in micropigs and compared our results to published human data. The main vasculature of the animals was similar to that of humans, except for the iliac arterial system. However, diameters of the major systemic vessels were significantly different between micropigs and humans. Specifically, the diameter of the aortic arch, abdominal aorta, external iliac artery, and femoral artery, were measured as 1.50 ± 0.07 cm, 0.85 ± 0.06 cm, 0.52 ± 0.05 cm, and 0.48 ± 0.05 cm, respectively, in the micropigs. This MDCTA data for micropig major systemic vessels can be used as standard reference values for xenotransplantation studies. The use of 64-channel MDCTA enables accurate evaluation of the major systemic vasculature in micropigs.     

Anatomical and Morphometric Variations in the Arterial System of the Domestic Cat

We document the anatomical architecture and frequency of occurrence of variations in the branching pattern of the brachiocephalic artery and the origin of the internal iliac arteries in the domestic cat, a widely used model organism in both anatomical training and research. Based on the study of 56 preserved specimens, we observed three distinct arrangements in the branching pattern of the brachiocephalic artery. The most common pattern (52% of the examined specimens) was that in which the brachiocephalic artery was divided into two branches, the left common carotid artery and a common branch for the right subclavian artery and the right common carotid artery. The frequency of occurrence of each variation type was independent of the gender and body size. The internal iliac arteries originated caudal to the point at which the external iliac arteries branched off from the abdominal aorta. However, the portion of the abdominal aorta between the external and internal iliac arteries varied greatly in length and was not significantly correlated with its width, nor with body size or gender. This study is the first to report and quantify the occurrence of such variations in North American cats. Given the anatomical similarity between the cat and other felids, the results of this study can be applied to other species, including endangered species.     

Spectral Doppler ultrasound in the major arteries of normal conscious immature micropigs

Spectral waveform analysis of blood flow velocity in the major arteries of six healthy, conscious immature micropigs was determined using Doppler ultrasonography. Doppler spectral tracings were recorded from the external iliac artery, femoral artery, and renal arcuate artery. Tracings were also taken from three parts of the common carotid artery and two parts of the abdominal aorta. Spectral Doppler parameters included peak systolic velocity, early diastolic velocity, peak systolic velocity-to-end diastolic velocity ratio, resistive index, and pulsatility index. In addition, the diameter of major arteries and indirect blood pressure were measured. These results from spectral Doppler analysis in major arteries may be useful as reference ranges in the future studies of vascular hemodynamics in immature micropigs.     

IMAGING DIAGNOSIS—ACUTE MESENTERIC ISCHEMIA ASSOCIATED WITH HYPERTROPHIC CARDIOMYOPATHY IN A CAT

A middle‐aged cat was presented with vomiting, diarrhea, and pelvic limb paresis. Radiography showed cardiomegaly, interstitial pulmonary infiltration, distended intestinal loops, and portal venous gas. Hypertrophic cardiomyopathy (HCM) was confirmed. On CT, thrombi were identified at the abdominal aorta, superior mesenteric artery, bilateral renal arteries, and cauda vena cava at the level of the iliac vein bifurcation. Dilated and gas‐filled loops of bowel with a “paper thin wall” were observed on CT images and were considered indicative of necrotic bowel. This case report describes the CT findings of acute mesenteric ischemia associated with HCM in a cat.     

Arteriosclerosis in a rabbit

Extensive mineralization of the aorta, brachiocephalic trunk, and the left subclavian, both iliac, common carotid, and renal arteries were found at necropsy in a 3-year-old French Lop rabbit. The rabbit had been examined previously for seizures, at which time abdominal radiography revealed calcification of the abdominal aorta and external iliac arteries. Treatment was not initiated, and the rabbit died 4 months later of bacterial pneumonia. The rabbit also had hypercalcemia. In contrast to many species, the blood calcium concentrations of rabbits reflect dietary intake.     

ARTERIOGRAPHIC ANATOMY OF THE ABDOMINAL AORTA IN THE GOAT, DOG, PIG, AND RABBIT

Arteriographic anatomy of the major branches of the abdominal aorta of rabbits, dogs, pigs, and goats was investigated. The origin and location of the celiac, cranial mesenteric, right renal, left renal, caudal mesenteric, and external iliac arteries were demonstrated, and their placement was described in relation to the iliac bifurcation and lumbar vertebral bodies.     

Specific contrast ultrasound using sterically stabilized microbubbles for early diagnosis of thromboembolic disease in a rabbit model

Specific contrast ultrasound is widely applied in diagnostic procedures on humans but remains underused in veterinary medicine. The objective of this study was to evaluate the use of microbubble-based contrast for rapid ultrasonographic diagnosis of thrombosis in small animals, using male New Zealand white rabbits (average weight about 3.5 kg) as a model. It was hypothesized that the use of microbubble-based contrast agents will result in a faster and more precise diagnosis in our model of thrombosis. A pro-coagulant environment had been previously established by combining endothelial denudation and external vessel wall damage. Visualization of thrombi was achieved by application of contrast microbubbles [sterically stabilized, phospholipid-based microbubbles filled with sulfur hexafluoride (SF₆) gas] and ultrasonography. As a result, rapid and clear diagnosis of thrombi in aorta abdominalis was achieved within 10 to 30 s (mean: 17.3 s) by applying microbubbles as an ultrasound contrast medium. In the control group, diagnosis was not possible or took 90 to 180 s. Therefore, sterically stabilized microbubbles were found to be a suitable contrast agent for the rapid diagnosis of thrombi in an experimental model in rabbits. This contrast agent could be of practical importance in small animal practice for rapid diagnosis of thrombosis.     

Aberrant migration and surgical removal of a heartworm (Dirofilaria immitis) from the femoral artery of a cat

A cat was evaluated for an acute‐onset of right pelvic limb paresis. Thoracic radiographs revealed normal cardiac size and tortuous pulmonary arteries. Abdominal ultrasound identified a heartworm (HW) extending from the caudal abdominal aorta into the right external iliac artery and right femoral artery. The cat was HW‐antigen positive. Echocardiography revealed a HW within the right branch of the main pulmonary artery and evidence of pulmonary hypertension. An agitated‐saline contrast echocardiogram revealed a small right to left intracardiac shunt at the level of the atria. Surgical removal of the HW was performed with no substantial postoperative complications. There was return of blood flow and improved motor function to the limb. The cat remains mildly paretic on the affected limb with no other clinical signs.     

A model for the preferential delivery of isoflurane to the spinal cord of the goat

To identify the blood supply of the caprine central nervous system, six anaesthetised goats were perfused with coloured suspension into the brachiocephalic artery, the aorta, the iliac artery and the femoral artery. The subsequent distribution indicated that the brain and the main segments of the spinal cord were supplied by the brachiocephalic artery and aorta, respectively. Ten similarly anaesthetised goats then received emulsified isoflurane randomly via either the proximal part of the descending aorta (arterial group) or an ear vein (venous group). In the arterial group, the isoflurane partial pressure (P_iso) in femoral arterial blood was almost double the P_iso in jugular venous blood. The model showed that preferential delivery of isoflurane to the goat spinal cord in situ was possible and could be used for further research into the mechanisms of anaesthetic action, particularly factors affecting immobility.     

FIRST-PASS RADIONUCLIDE ANGIOGRAPHY IN THE DIAGNOSIS OF AORTOILIAC THROMBOEMBOLISM IN A HORSE

First-pass radionuclide angiography of the terminal aorta was performed in 3 normal horses and a 6-year old Standardbred intact male with aortoiliac thromboembolism. Thromboembolism caused chronic bilateral hind limb lameness, more severe in the right hind limb, was detected by rectal examination, and confirmed using transrectal ultrasonography. Using ^99mTc-HDP, first-pass radionuclide angiography was combined with hind limb and pelvis bone(delayed) scintigraphy and revealed marked reduction in blood flow through both external iliac arteries and absence of blood flow in the internal iliac arteries. Quantitative analysis showed a decreased activity in the right iliac vessels in the clinic patient consistent with reduced blood flow when compared to control horses. First-pass radio-nuclide angiography provided a method to obtain diagnostic images of the terminal aorta and branches and a method to diagnose aortoiliac thromboembolism in the horse.     

Aortic and iliac thrombosis associated with angiosarcoma of skeletal muscle in a dog

A seven-year-old, neutered male greyhound was presented with a history of episodic shifting hindlimb lameness and pain. Ischaemic necrosis of areas of the hindlimb digits and skin and a firm swelling within the medial right thigh musculature were found on physical examination. Investigation demonstrated thrombosis of the terminal aorta and right external iliac artery with ischaemic necrosis of muscular and dermal tissue distal to the sites of thrombosis. The dog was euthanased due to poor prognosis. Necropsy findings were of a poorly differentiated invasive sarcoma of the skeletal muscle of the proximal right hindlimb, thrombosis of the aorta and right external iliac artery and secondary renal glomerulopathy. Immunohistochemistry of the neoplastic tissue indicated angiosarcoma based on expression of CD31 and factor VIII-related antigen. Thrombosis was considered likely to be due to systemic hypercoagulability because of the presence of altered flow characteristics and endothelial damage in the vascular tumour bed. Aortoiliac thrombosis, paraparesis and hindlimb ischaemia are unusual sequelae of angiosarcoma in the dog.     

Repair of a proximal diaphyseal femoral fracture in a calf, using intramedullary pinning, cerclage wiring, and external fixation.

Repair of a comminuted, spiral oblique, proximal diaphyseal femoral fracture in a 7-day-old calf was achieved by use of an intramedullary pin, cerclage wires, and external fixator. Six stainless steel wires were used for full cerclage to secure a long butterfly fragment and multiple incomplete and complete nondisplaced fragments to the femur in order to create 2 principal fragments. Axial alignment and resistance to bending was provided by a round, double-pointed, end-threaded intramedullary pin (6.35 mm in diameter), which was inserted in a retrograde fashion. A type-1, double-connecting-bar external fixator, using 4 round pins (4.8 mm in diameter), was used to provide supplemental stabilization against shear and torsional forces. At 45 days after surgery, healing at the fracture site was seen on radiography of the limb, and the external fixator was removed. Eight months after surgery, the calf had a normal gait.