This book “Diagnostic Veterinary Ultrasonography: Principles and Practices” is intended for the beginner-ultrasonographers in the veterinary and animal Sciences, particularly for those veterinarians who are involved in providing services to large and pet animals. In India, ultrasonography of animals is hampered by PC & PNDT act, a law that prohibit sex diagnosis in human. Under this act, there is strict regulation for the movement of ultrasound machine at farmers doorstep. This regulation also covers ultrasound imaging by veterinarians in India. The authors collected data from cases from animals presented for clinical diagnosis. Images were self-generated, using several machines viz portable and fixed ones having color Doppler and 3D facilities. Basic principles of ultrasonography have been explained along with a special chapter on physics of ultrasonography. The reader will learn where to place probe for obtaining images of various organs. Normal images of various organs and abnormal changes in diseases have also been provided for comparison. Age related developmental changes and dimensions of various organs have also been covered. Various species viz cattle, buffalo, sheep, goat, bitch etc., have been covered. Images of different organs viz., kidney, liver, spleen, gall bladder, urinary bladder, reproductive organs have been shown. This will help the learner to go ahead with imaging of these organs and will get help in comparing their images with the images given in this text.

Ultrasound is important tool for diagnosis and research that can be compared with other tools like radio-immunoassays. This has become an important tool applicable to farm and pet animals. Ultrasound uses high-frequency sound waves to produce images of soft tissues and internal organs. Electric current is applied to crystals in the transducer, producing vibrations characteristic of the crystals and resulting in sound waves. The sound beams that pass through the tissues are quite thin and a thin “slice” of tissue is sampled. The two dimensional image produced by ultrasound resemble to histological section. The sound waves are propagated or reflected by various tissues in different ways depending on their thickness and composition. The transducer receives those reflections and converts into electric signals and produces an echo on the ultrasound screen. Grey - scale is the term used for monochrome monitors on which a number of grey shades are distinguishable between black and white and constitute the image of reflected portion of tissue. Non-ecogenic (non echoic) tissues like fluids do not reflect sound waves and appear black on the screen. The echogenic tissues, having dense consistency, appear white as they reflect most portion of sound beam. Sometimes the artifacts create problem in the real image of the organ. These artifacts are created by certain tissues that cause bending or back and forth bouncing or blocking of sound beams. For imaging the reproductive tract of the domestic animals, B-mode (brightness modality), real time scanners are used. The amplitude of returning beams is reflected in the brightness of the dots on the screen. B-mode modulates brightness of the dots or pixels on the screen of echo displayer. The echo signals are presented as brightness of pixel corresponding to the amplitude of signal. The picture should be adjusted for clear display. In B-mode display the time-base brightness should be reduced just below the threshold of visibility so that even the smallest echoes could be visible.

Ultrasonography is the process of obtaining images of an area, organ or tissue with the help of ultrasound beam that can be displayed on a screen. Such images can be recorded on videocassettes or printed on a thermal paper. Ultrasonography in veterinary practice is a revolutionary step for diagnosis of various ailments and to assess normal physiological functions of the body organs of domestic animals. Ultrasonography is considered a wonderful tool particularly for the study of reproductive functions viz. follicular dynamics, pregnancy diagnosis and abnormalities of contents of tubular tract. In 1980, Palmer and Driancourt reported for the first time, real time ultrasonography for diagnosis of pregnancy in the mare. This report generated considerable interest among veterinarians and scientists about ultrasonography and this new discovery contributed significantly towards understanding of functioning of the uterus and ovaries of mare (Chevalier and Palmer, 1982; Ginther, 1983; Ginther and Pierson, 1984a & 1984b), cows (Pierson and Ginther, 1988, Reeves et al., 1984) and other species (Buckrell, 1988; Driancourt, 1991). The ultrasonography is fast replacing the age-old procedure of rectal palpation of genital tract for pregnancy diagnosis (Pieterse et al., 1990). This technique has been used and advocated for the use in the academics and field practice.

Most of ultrasound machines are designed for imaging with a particular resolution linear and convex transducers. These machines can be used for general purpose for abdominal, obstetrics, gynecological, small parts, urology and cardiac applications. Most of the machines have standard measurement software viz. distance, area, volume, circumference, and obstetrical gestational age measurement for BPD, HC, AC, FL, GS, CRL, AD and FW. Assessment of probes: One should examine the probe whether it is linear array or curved (convex) array. The probe should also be checked for its frequency. These days multi-frequency probes are supplied with the ultrasound-machine. These multiple frequencies could be 2.0 to 5.0 MHz with centrally fixed frequency of 3.5 MHz. The frequencies could be 4.0 to 7.0 (5.0 MHz setting), 5.0 to 9.0 MHz (7.5 MHz setting). The area and depth covered by various frequencies should be known. Before setting the ultrasound machine, one should make sure of all the auxiliary devices for the machines. These are Thermal video printer, Ultrasound gel, Biopsy needle, image saving devices (USB device or internal saving mechanism), wire, Uninterrupted Power Supply etc. Identifying and knowing the main system: One should note down the name and model of ultrasound machine as these are quoted in all the documents published with the ultrascan images generated on that particular machine. It is written on one side of front panel. On the front panel, there are various knobs for proper setting. One should locate the auxiliary power switch of the machine to begin with. Generally, there is power indicator on the machine that shows light on when power button is pushed to on position. The auxiliary power switch may also have indications of its ON and OFF positions, may be marked with 0 and 1 or other symbols. As shown in the figure below, there are various operating buttons on the operating panel. These might vary from Machine to Machine.

In order to evaluate the correct status of the organs their correct disposition within the body becomes very essential. Although one cannot see the organs beyond the skin, but appropriate knowledge of the topography of the organs can act as a glass covered watch wherein one can see from outside the arms and the dial of the watch. Horse Heart: The heart is placed in the middle mediastinum of the thoracic cavity with its long axis directed caudo-ventrally. Three fifth of the heart lies on the left of median plane while two fifth is on the right of the median plane. The base is placed dorsally, with its highest point at the junction of the dorsal and middle thirds of dorso-ventral diameter of the thorax. As a whole it lies opposite to second intercostal space/third rib to sixth rib/sixth intercostal space. The apex of the heart lies in the center of the last segment of the sternum about half inch from the sternal part of the diaphragm. Heart is directly related to the lateral thoracic wall at the cardiac notches formed in the lungs. The left surface of the heart extends from third to sixth rib in the lower third of chest while the right surface extends from third to fourth intercostal space.

The affections of abdominal cavity incidence wise are on the top followed by thoracic cavity. Both these affections lead to high morbidity and heavy mortality losses. Most thoracic affections produce almost similar clinical signs but abdominal affections can show different clinical signs. Radiography and ultrasonography play an important role in differentiation and confirmation of various affections. Radiography is an important diagnostic tool for both thoracic and abdominal diseases in small animals but for large animals it is more useful for thoracic affections as compared to abdominal affections. In large animals, the use of radiography is limited up to the ventral aspect of the abdomen only i.e. for diagnosis of diseases of reticulum, diaphragm and sternebrae. In thoracic cavity, there are numerous diseases that need to be differentiated. Pneumonia, lung cyst, lung abscesses, pleuritis and pleural effusions are some important diseases apart from presence of foreign bodies. In such a situation, radiography can play an important role as an aid in the diagnosis of various affections. Similarly ultrasonography has also played a major role in the diagnosis of abdominal diseases in small animals such as dogs and newborn calves especially in the field of G I tract and urinary system. The ultrasonography is advantageous over radiography in the sense that internal anatomy of the soft organs can be better known and studied by ultrasonography as compared to radiography. It is also considered to be extremely safe for both the patient and the operator.

General Instructions The monitor of ultrasound machine should be placed at the eye-level. The daylight should not be too bright. The setting of the machine should be done to obtain best picture on the screen. There are various knobs on the machine to set contrast and brightness. There are three other knobs that are used to set near gain, far gain and overall gain. There is also a brightness bar (help-bar) on the screen with different brightness areas. These knobs should be turned clockwise or anti-clockwise, so that all the areas on the help bar (brightness bar) are visible. Transrectal Procedure In cattle, trans-rectal ultrasonography is done in a way, similar to rectal examination done for palpation of genital organs. Following steps are suggested for proper procedure 1. Properly restrain the animal. 2. Evacuate the feces from the rectum. 3. Select a transducer of proper frequency (the linear array transducer of 5.0 MHz frequency is useful for general purpose in bovines, however for detailed examination of early conceptus and small follicles, a transducer of 7.5 MHz can also be used. Some transducers have range of these frequencies in single-equipment. Such transducers of switch-able frequency are found more useful.

Failure to accurately diagnose ovarian function is said to be one of the reason for poor reproductive efficiency in this species. The information regarding ovarian function can be gathered either by observing the reproductive behavior of the animal, status of reproductive hormones or palpation of ovaries per rectum for the presence of cyclic or pathological structures. However, due to poor expression of estrus signs behavioral observations poorly reflect the accurate information about ovarian function in buffaloes. Similarly, palpation per rectum does not provide reliable diagnosis since the CL is frequently embedded deep in the ovarian stroma of buffalo ovary and findings vary due to its subjective nature. Furthermore, measurement of hormones requires sophisticated laboratory procedures/ instruments for making a correct diagnosis. Therefore, real time ultrasonic examination is a better alternative to ascertain reproductive status of buffaloes and for devising suitable strategies to optimize fertility of this species (Sharma, 2003). However, it is important to mention that information gained from ultrasound must be used in conjunction with reproductive history of the animal, palpation of genital tract, and other diagnostic procedures rather than in isolation.

The recent availability and use of ultrasonography in veterinary science has revolutionized the study of bovine reproduction. The information- gathering capabilities of this technology are much higher than those of conventional rectal palpation. Ultrasonic imaging has provided new insights into the complex biology of various reproductive processes such as folliculogenesis and early fetal development. With the pressure on agricultural land, due to ever increasing human population, the grazing grounds for animals are fast squeezing and as a result more and more animals are being stall-fed. This practice has adversely affected the availability of essential nutrients to the animals and their reproductive efficiency. The problem is graverin small states, where pressure on land is more to accommodate the expanding developmental and commercial activities of the national capital situated next door. The routine applications of ultrasonography include evaluation of animals for pregnancy, twinning, cyclic structures on ovaries, uterine and ovarian pathologies etc.

The ultrasonography is based on echo-principal i.e. reflection of sound waves. The ultrasound waves, commonly termed as ultrasound beam is generated from the pizzo-electric crystals, under electric stimulation. The sound beam travels and strike to the organs/tissues on its way and get either reflected or reabsorbed by these structures. The reflected beam is received back by the transducer, which are processed and displayed on the monitor of ultrasound scanner. The display of signal is in form of shades of grey scale i.e. from bright to black picture. If these sound beams strike to organ such as bone, then major part of the beam is reflected and it appears bright (white) on screen. If the sound waves strike to fluid, these get absorbed and are not reflected back, therefore, the image of fluid appears as black on the screen. Other organs appear in between black and bright white. In fact, the reflected sound beam is not proportionate to frequency and velocity of emitted ultrasound beam. The strength of ultrasound beam (grey scale) or brightness of the image depends upon the acoustic impedance of organ or tissue. In simple term acoustic impedance is the capacity of tissue or organ to reflect or absorb these sound beams that again depends upon density or composition of these structures. The reflection of sound beams also depends upon, the angle at which the ultrasound beam strikes the structure on its way. The distance of the organ from the transducer also affects image brightness.

Ultrasonography in goat is becoming popular in the field of reproduction and replacing the other old-age techniques, viz. abdominal ballotment, recto- abdominal probes, X-rays and radioimmuno-assays. The reasons are numerous such as unsatisfactory results, hazardous effects to animal, operator or environment, high cost, long delay in diagnostic results and requirement of sophisticated labs. The ultrasound system has low operating cost and does not need special labs as it can be done at farm itself. Ultrasonography is considered safe to the animal and the operator and provides quick and reliable results. The popular opinion about ultrasonography is that it is noninvasive imaging system and is rapid, safe and practical means of diagnosis of pregnancy and reproductive disorders in sheep and goat. The B-mode real time ultrasonographic system particularly portable system is popular among researcher and practitioners. In goat, B-mode real time ultrasonography was used in 1971, using 5 MHz frequency transducer. A transducer of switchable frequency from 7.5 to 5.0 is more popular in small ruminant research and practice.

Ultrasonography in sheep is becoming popular in the field of reproduction and replacing the other old-age techniques, viz. abdominal ballotment, recto- abdominal probes, X-rays and radioimmuno-assays. The reasons are numerous such as unsatisfactory results, hazardous effects to animal, operator or environment, high cost, long delay in diagnostic results and requirement of sophisticated labs. The ultrasound system has low operating cost and does not need special labs as it can be done at farm itself. Ultrasonography is considered safe to sheep and the operator and provides quick and reliable results. The popular opinion about ultrasonography is that it is noninvasive imaging system and is rapid, safe and practical means of diagnosis of pregnancy in sheep. The B-mode real time ultrasonographic system particularly portable system is popular among sheep breeders. In sheep, B-mode real time ultrasonography was used in 1971, using 5 MHz frequency transducer. A transducer of switchable frequency between 7.5 to 5.0 is more popular in sheep practice. Transrectal Procedure in Sheep The procedure is similar to goat, but sheep remain quite during transrectal ultrasonography than goat. Following are some of the steps to obtain good quality image:

Introduction Ultrasonography is well-established technique in human sciences, particularly for diagnosis of pre-natal defects of fetus. In veterinary sciences, this technique is emerging an important tool. This tool is being employed in the small animal practices, particularly bitches for diagnosis of various reproductive disorders and estimation of gestational status. In the past, veterinarians had limited assistance for assessing reproductive status of this animal. Pregnancy diagnosis in a bitch was possible either with the use of X-rays or transabdominal palpation, but that too at an advanced stage of gestation. These methods could provide information either about presence of pups in vitro, or their number, but assessment of fetal viability was not accurately predicted with these traditional methods. With the use of X-rays, there was always risk of harmful effects on the health of mother and fetus. As far as reproductive disorders are concerned, most of them remained either undiagnosed due to the lack of proper access to the internal organs or were diagnosed with a guess. Diagnostic ultrasound is a valuable alternative imaging system that can provide more accurate information about the canine pregnancy and reproductive disorders in comparison to traditional methods.

The Liver The liver is a large and an irregular organ of the body, which extends from the sixth to the eleventh intercostal space. It extends much more caudally on the right side as compared to the left side. Its most caudal part is the caudate lobe whose small portion is visualized encircling the right kidney dorsally at the eleventh intercostal space. The liver of a dog is divided into various lobes namely the left lateral, left medial, quadrate, right medial, right lateral and the caudate lobes which are not identifiable ultrasonographically, except when f luid is present in the abdomen. Otherwise, the position of the different liver lobes can only be approximated. The gallbladder is located to the right of the midline between the quadrate and the right medial lobes of the liver. Proper preparation of the animal is important to obtain images of abdominal orgnas including that of liver. It is better to keep animal off fed for at east six hours prior to ultrasound scanning. This will avoid interference of gases and solid contents of the gastrointestinal tract. If stomach is taken as landmark of scanning then enough fluid should be given prior to scanning to get good images of stomach. The liver can be easily visualized on one side of stomach. One should be liberal in applying good amount of gel over transducer and body for better image of liver.

Ultrasonographic images of stomach are required to diagnose ingestion of any abanormal materials by dog. When content of stomach are dry or there is gas in stomach then, it is difficult to get proper image of stomach. Offering water to animal or oral administration of water with the help of syring is also helpful in getting the images of content of stomach. Some time, while doing ultrasonography, movement of contents of stomach can be visualized. Stomach can be images between liver and spleen. The size depends upon contents or intake of food by dog. For proper image of gastrointestinal tract including stomach, there should not be gas in GIT. One should remember that ultrasound beam does not travel in gas. The best medium of ultrasound beam is liquid. Scanning Technique If possible, fasting for 12 hours is good to diminish the amount of gastrointestinal gas. However, non-fasted dogs, when offered water may show adequate image quality. The water may be administered in quantity of 15 ml per kg of bodyweight. Removing the stomach gas using an orogastric tube has been recommended tto enhance the visualization of lesions of the stomach, however, this is not in practice in India.

Ultrasonography in bull is helpful in diagnosis of problems of testis and accessory glands. This can also be used in assessment of development of these organs. Such developmental assessment, when combined with endocrine data, is useful to know age of puberty, sexual development and dimension of these organs. The ultrasonographic images and data are available for testis, bulbourethral gland, prostate and seminal vesicles in the bull. Ultrasonography of testis of bull can be useful to assess developmental changes, testicular dimensions and pathological conditions of the testis viz. tumors, lesions, abscess etc. Epididymis can also be examined for change in lumen, inflammation, granuloma etc. The accessory sex glands can be better viewed in ultrasonographic scanning to assess their dimensions, normal developmental changes and alterations in their morphology. Before, ultrasonography is undertaken, one should thoroughly revise the knowledge of sectional anatomy and location of these organs. Testis Location: The testis, in the bull, is located in the scrotum. In abnormal conditions, the testis might be retained in the inguinal canal or abdomen. Before, ultrasonography, location of the testis should be assured. For this, the testis should be palpated to assess their pliability and rule out adhesions with the scrotal wall. In normal condition, the testis should be freely movable in the scrotum, soft of palpation and both the testis should touch the bottom end of scrotum.

Real time ultrasonography provides means to directly image the reproductive tract. An extensive amount of information can be gained from even a single examination, including determination of ovarian (luteal or follicle detection) and uterine status, detection and monitoring of ovarian and uterine pathology, monitoring the post-partum mare, detection of twins, prediction of ovulation, fetal growth and development and determination of sex of fetus. When first introduced the use of ultrasonography was primarily limited to early pregnancy diagnosis only, with advancement of knowledge and interpretive skills, the diagnostic ultrasonography has a much more application in reproduction. Some of the applications are discussed in this lecture. Procedure The procedure and precautions for intrarectal ultrasonographic examination are similar to those for rectal palpation, and no additional restraint is required. The transducer should be protected by the examiner’s hand to prevent trauma to the rectal wall, and the transducer should be well-lubricated. Care should be taken to avoid fecal material attaching to the transducer. After evacuating fecal material from the rectum, the probe is introduced and moved across the reproductive tract in the following pattern: uterine body, right uterine horn, right ovary, right uterine horn, uterine body, left uterine horn, left ovary, left uterine horn, uterine body then cervix. Good contact must exist between the transducer and rectal wall. Air in the rectum or a gas or fluid-filled loop of bowel will result in a distorted image. To minimize scanning errors, principally those of omission, it is recommended to conduct the same scanning procedure during each examination.

Corpus luteum, one of the biological clock of the estrous cycle and pregnancy, is known foremost for its production of progesterone that blocks the pituitary release of gonadotrophins and prepare the uterus for pregnancy. The ovarian follicle wall consists of granulosa cell and theca cells vascularised and luteinize after ovulation to from a corpus luteum. Corpus luteum is temporary steroid- producing gland undergoes marked structural and functional changes far a short time span during its development functional life and regression. During estrous cycle, the corpus luteum undergoes an initial period of growth (metestrus), followed by a period of maximal function (diestus) and finally by a period of regression (proestrus) preceding the next ovulation (Robert, 1986). The most prominent cell in the CL is the large luteal steroidogenic cell. Ultrasound imaging has been used to detect and measure the corpus luteum throughout the estrous cycle and corpus luteum has been characterized during pregnancy and non pregnancy. Changes in corpus luteum diameter as detected by ultrasonography are highly correlated with progesterone production. A high correlation has been found in the ultrasonographic detection of bovine corpora lutea (Lean et al., 1992) and between luteal tissue area measured ultrasonographically and plasma progesterone concentration (Bergfelt et al., 1989).

This paper primarily considers the general principles of ultrasound and instrumentation and its application in camel reproduction. Ultrasound waves are mechanical pressure waves similar to audible sound waves and must have a medium in which to audible sound waves and must have a medium in which to propagate. The “frequency” (f) is the number of high- or low- pressure regions crossing each area of tissue each second. The frequencies of the sound waves used in medical ultrasound are much higher than the human audible range (20 to 16000 Hz); hence the waves are called ultrasound. Ultrasound instrumentation The gray scale imaging equipment uses only time delay and echo amplitude information in creating the image. Most equipment contains the same basic building- block circuits; transmitter, receiver, display and scan converter. Transmitter The first circuit building block, the transmitter circuit produces either a high- amplitude, short- duration voltage shock pulse or a driving voltage waveform. Then an output control attenuates the amplitude of the shock pulse or the driving voltage wave form before it is applied to the transducer.

Mammary glands are important part of body which synthesize and store the milk in between milkings or suckling by the calf. Therefore it attains prime importance in any dairy animal. However, it has received little attention in buffaloes till now. Buffalo presents several unique characteristics in terms of milk production, length and shape of teats and arrangement of duct system in the mammary glands. Development of udder may be related to milk production and the knowledge of changes in its structure in relation to different physiological stages may also have practical implication. Transducer Selection and Preparation of Scanning Preparation of the site to be imaged will enhance the quality of the image. Therefore, any loose hair and dirt must be clean off. Ultrasound gel is applied to the area of interest. The gel acts as a coupling agent to prevent air from trapping between the transducer and skin. A 7.5 MHz transducer is ideal for imaging the teats. A 5.0 MHz transducer provides an adequate image. The mammary gland should be scanned with a 5.0-7.5 MHz transducer to give adequate penetration. All structures should be scanned in cross section and longitudinal planes.

Ultrasound is mainly used for reproductive purposes in bovine, now days it is also used for other applications. Ultrasound is an excellent tool for diagnostic imaging in large animals because it is portable, easy to use in the field, produces results at the time of the examination. It is totally non-invasive. Palpation of a gland can only detect certain levels of abnormality. Ultrasound can give an actual perception of mammary health, a picture of the inside anatomy and pathology. Tumors, scarring, stones, trauma, hematoma formation and level of damage due to mastitis can all be evaluated by this technique. Other diagnostic tools are still primary diagnostic tools, ultrasonogram gives yet another dimension to the hard to diagnose case. It will also allow a better estimate of treatment prognosis to aid in deciding whether to cull or treat a dairy animal. Congenital anomalies at initial stages of the mammary gland development during gestation may result into presence of supernumerary teats or less number of external teats, in place of usual presence of four teats in buffaloes. Hence, cases with two / three / five or six teats are often encountered in the f ield.

Congenital anomaly of newborn buffalo calves is quite common in new born calves. Most common encountered are atresia ani, rectovaginal fistula etc. Sometimes, developmental defects interfere with physiological processes viz. in urination and defecation. Therefore, such cases, if not corrected well in time can cause death of the patient. In the present report, few newborn calves were brought to the veterinary clinic with the following abnormalities: Agenesis of Urogenital System Without Anus Five newborn buffalo calves were brought to the veterinary clinic with the complain of not passing urine and feces. There was no visible external genitalia and anal opening. At the site of vulva, there was only an impression of vulvar lips and below it, a cord like structure was hanging. There was an impression of round structure below the skin; in some cases it was outside giving appearance of scrotum which was located in between the two thighs. On ventral side of abdomen, preputial sheath was not present, therefore, it was very difficult to decide about the sex of the calves and site of external preputial-orifice. There was an indication of both sexes, but organs were not developed, therefore it was difficult to decide about the sex of the calves. In some cases, impression of the anal sphincter was visible but there was no visible external anal opening. There was slight deviation of the tail from its base also. Intake of milk was normal. Abdomen was distended bilaterally. Respiratory rate was higher than the normal with slight discomfort .Heart rate was elevated. Blood picture revealed increased total blood cell count with neutrophilia. Radiography of the abdomen showed distended urinary bladder at the floor of pelvis indicating formation of the urogenital system without development of the external opening. Barium meal study revealed marking of gastrointestinal tract and stagnation of the barium up to the rectum.

Ultrasonography has an importance place in human practice and veterinary f ield especially in canine practice. Since many years two dimensional ultrasound has been used for scanning purposes both in human and animal practice. But the scenario has changed in human practice with development of three dimensional technology and later four dimensional ultrasonography has developed which shows movements of the objects being scanned especially in the case of fetuses. Nowadays it has been common to use these advanced technology in the human practices. Yet these technologies are in the childhood stage in the veterinary field. High cost of 3D/4D ultrasound equipment, operational difficulties in non sedated animals & lack of specific knowledge about the operation of volume scanning hinder the use of this technology in the veterinary field. Better understanding of the different application of these technologies can be made to use in research areas for the better understanding of the abnormalities, post therapeutics as well in the diagnosis of the diseases Principle of Three Dimensional and Four Dimensional Ultrasonography Sound waves of frequency higher than human audible frequency usually ranges from 2-13 MHz are used in ultrasonography. Depending upon on depth of tissue from the scanning surfaces frequency is selected. Three dimensional ultrasonography gives three dimensional images of the volume being scanned .it works on the same principle of 2D ultrasonography but ultrasonographic beams are sent different angles to get three dimensional image of object being scanned. Volume information is obtained either directly using 2D array probe or by reconstructing three dimensional volume from a series of continuous or non- continuous 2D images by using software (Fenster and Downey, 2000). An advancement of 3D technology is 4D ultrasound. Four dimensional ultrasound adds the fourth dimension as time and gives a dynamic real-time 3Dultrasonography of the concerned organ with a continuous volume image acquisitioned rendering process. (Khurana and Dahiya, 2004).

In Doppler imaging, the reflections are from circulatory vessels, while in 2D ultrasonic image the reflection is from a tissue(s) or organ(s) In 2D ultrasound strength of reflection in B-mode depends upon density of the organ.On other hand the reflection in Doppler imaging depends upon direction of the circulation. If circulaltion is coming towards transducer, the signal will be strong, while it looses its strength while flowing away from the transducer. As shown in the diagram, the position of transducer on curved surface decides the strength or amplitude of signal. If it is positioned on curve end from where circulation is coming, the signal will be of higher amplitude, but when position is changed to other end of curved surface, where circulation is going down the amplitude of signal will decrease accordingly and is shown in reverse direction. Principle of Doppler Movement of blood in vessels is detected, which is depicted by color in some ultrasound machines. The flow coming towards transducer is shown above baseline, while flow going down i.e. away from transducer is shown below baseline. If position of transducer is changed from where the arterial flow is going away from transducer then, the arterial flow will be shown below baseline and venous flow that is coming towards transducer will be shown above baseline. Some machine shows red and blue color of the flow. The red color shows flow coming towards and blue color shows flow going away from transcer. A beginner ultrasonographer may think that the red color is from artery and blue is from vein. This is not true, this shows direction of flow. Since ultrasonic image of flow in Doppler is formed from series of pulses returning from vessels, the magnitude of pulse changes with variation in flow. A stationary flow will not show any height of magnitude.

Diagnostic techniques are routinely used for diagnosing different surgical conditions. The most frequently used imaging techniques in veterinary practice are radiography and ultrasonography. Radiography and ultrasonography are not suitable for each organ in large animals. In small animals most organs are suited to ultrasound images except bones and gascontaining structures such as lungs etc. Bone and gas reflect ultrasound and do not allow the sound waves to form image therefore radiography gives better diagnostic images for these organs. The liver, spleen, kidneys, prostate, gravid uterus and fluid containing organs like urinary bladder, gall bladder and major blood vessels can be better imaged with ultrasound. In buffaloes in surgical section important clinical conditions relate to urinary and digestive systems, mammary gland and perineal area. 1. Urinary System: In bovine, the cases of obstructive urolithiasis are commonly observed. These types of cases are more common in bullocks and in buffalo calves. In these cases radiography is not so useful. Sonography can be tried to take the image of ruptured urethra in bullock and can be compared with radiography. Due to ruptured urethra there will be accumulation of urine in the s/c tissue of prepuce. Due to fluid density the image will be radioopaque and will appear white and no detail of the organ can be seen. The ultrasonogram (USG) will show images of glans penis and its coverings. Different diameters of urethra and a point of rupture just behind to glans penis can be make out. Due to obstruction, The B.calves either will pass drop wise urine or there will be complete stoppage of the urine. These cases can also be easily diagnosed by ultrasonography.

Ultrasonography of the GI tract presents problems and challenges for the sonographer. Sonography of the GI viscera was once throught to be impossible because of artifacts created by gas within the lumen but with the technical advancement in the ultrasonography now the problem has been solved. If the animal is kept of feed and adlib water is given to the dog with I/v fluid than ultrasonography becomes helpful in the diagnosis of gastrointestinal tract disorders. Other conditions such as esophageal carcinomas can also been diagnosed by ultrasonographic endoscopy. in human beings. The normal ultrasonography of the liver, kidney, stomach & spleen in dogs has been standardized and its use in evaluation of pathological lesions has been reported but ultrasonographic evaluation of oesophagus & intestine, both in normal animals and diseased conditions is yet to be established. Therefore normal ultrasonography of the oesophagus & small intestine in dogs and the importance of diagnostic capability of ultrasonography in diagnosis of pathology of these organs have been compiled.

Veterinary ultrasonographer has to write report of ultrasonography in different animals. The proper ultrasound report writing is the moral duty of the vet ultrasonographer. The accuracy of diagnosis must be ensured. The poor resolution/quality of machine may lead to erroneous diagnosis. Therefore, veterinarian must ensure good quality of machine and proper diagnosis. The report might be different in different animals e.g. report writing about uterus will be different in bitch, cows, buffaloes, camel, horse, goat and sheep. However following might be guidelines in writing ultrasound report of uterus. fetus, endometrium Uterus: Position of uterus, contents in the uterus, shape and size in initial pregnancy and infections, appearance of myometrium, thickening of uterine layers, presence or absence of fluied/pus/masses, left and right horns and their contents. Observations on the images of uterine fluid and its echoicity, membrane appearance in pregnant animals. Special attentions should be paid to endometrium. Endometrium: Appearance and thickness; any growth on the surface of endometrium. Images of retained portion of placenta can be ascribed in the cases of retained placenta. Ovary: Ovaries are scanned to assess cyclic structures, size, shape, its Position/ location and internal echo pattern of follicles. This echo pattern will indicate whether follicle is normal, cystic or with any other abnormalities of follclular f luid. Ultrasound reports also include shape and size of corpus luteum. In cows and buffaloes, presence of cavity, looseness/compactness of luteal cells are also mentioned.

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