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Computed axial tomography (CAT or CT scanning)
amount of radiation passing through the body in each view. The information is processed by a computer to produce a series of cross-sectional images of slices of the body. These individual images can be combined into a final three-dimensional image, similar to the way single slices of bread can be combined to create a loaf. A typical scan takes approximately 45 minutes to an hour. CT scanning has been used in human medicine for the last 20 years. It was first introduced into the veterinary
In 1993, the faculty at the University of California, Davis, School of COMPUTED AXIAL Veterinary Medicine enlisted the help TOMOGRAPHY of a UC Davis mechanical engineering (CAT OR CT SCANNING) graduate student to design a special large animal patient table for CT scanby Laurie Fio and ning. This table fits over the existing Philip D. Koblik, DVM, human table and is linked so that the CT computer controls movement of both MS, Dipl. ACVR tables. This is a unique solution to the size dilemma of horses and allows radiologists to position and move the paComputed axial tomography (CAT tient with a high degree of accuracy or CT scanning) is a sophisticated which is important when method of obtaining crosssectional images of various scanning areas of complex body parts which can be anatomy such as the dental arcades in a horse's combined and manipulated by special computer prohead. Without the comgrams to produce threeputerized control of the dimensional or volume rentables, the tables would dered images. Standard rahave to be moved manudiographs give a two-dially to reposition the pamensional representation tient and the location of the scanning area would of a selected part of the body have to be refigured with by passing x-rays through the body. The bones and each movement. The CT other tissues absorb some computer does all of this quickly and automatically. of the x-rays and the image With standard sized, that appears on film is what adult horses, only the head, passes through the patient. The final image is a superpart of the neck and the legs will fit in the opening imposition of all structures in the path of the x-ray of the CT scanner. The maj or clinical applications beam. Bones appear white, A foal under anesthesia being positioned in the CT scanner to of CT scanning in horses muscle and internal organs evaluate central nervous system disorders. is to evaluate teeth and are gray and air is black. sinuses and to evaluate The CT scanner uses a standard x-ray tube that is fixed in a field approximately ten years ago and complicated fractures of the lower large donut shaped apparatus. The anes- was exclusively used to scan dogs, cats limbs. The three-dimensional view prothetized patient is positioned inside the and other small animals. The equip- vides an aid to the radiologist to visucentral opening. The x-ray tube is then ment used was developed for human alize certain relationships of bones and rotated around the patient so that the practice and had definite limitations as fractures that might not be obvious in to the size of the patient that could be the standard two-dimensional view. Authors' address: California Center for Equine Health and Performance, School of Veterinary supported by the scanning table. Sev- Sometimes, it can be difficult to deterMedicine, University of California, Davis, CA eral veterinary colleges around the na- mine which direction a complicated 95616-8589
Volume 15 Number 12,1995
511
ported to be doing very well. Another horse was brought to the UC Davis VMTH because it showed pain when it attempted to open its mouth and was reluctant to eat. Standard x-rays of the skull were inconcluA cross sectional slice from a CT scan of the foot of a sive, but the CT scan foal.The arrow shows a defect in the bone. (1 - middle of this horse's skull phalanx, 2 - distal phalanx, 3 - hoof wall, 4 - digital revealed a complex cushion) fracture through the joint of the left side fracture has gone, the extent of the of the jaw where it joins with the skull. fracture and/or where its position is in The two-dimensional, cross-sectional relation to other fragments and body slices revealed the fracture, but the parts. three-dimensional representation A horse was brought to the UC showed the fracture in relation to the Davis Veterinary Medical Teaching jaw and further showed the position of Hospital (VMTH) because it had been v a r i o u s bone f r a g m e n t s . The showing undiagnosed neurological ab- three-dimensional view allowed a betnormalities for several months. The ter appreciation of the extent of the horse was exhibiting ataxia of the legs, injury. This fracture was too complimeaning an incoordination due to an cated to treat. inability to communicate messages In addition to valuable diagnostic from the brain to the legs. The horse capabilities for clinical use, the CT also developed a head tilt and showed scanner has also proven to be an imporsigns of pain below one ear. Standard tant tool for research. The UC Davis x-rays of the skull showed a bony thick- Equine Research Laboratory has funded ening (calcification) near the base of several studies utilizing the CT scanthe ear, but were very inconclusive as ner. One study by Dr. John Madigan to the origin and extent of the injury. and his associates involved evaluating The CT scan revealed a fracture of central nervous system disorders in the the stylohyoid bone which is part of the neonatal foal characterized by seizures, whole apparatus that helps horses swal- abnormal sucking reflexes, blindness low. There are se,veral nerves in this and motor dysfunction. These neuroarea which were also affected by the logic symptoms are often associated inflammation from the fracture. The with bacterial infection, prematurity, CT scan was used to further define the difficult births and their related probaffected area and to determine if there lems, and the syndrome called neonatal were any other related complications to maladjustment or "dummy foals." help develop a treatment strategy. It The nature of the circulatory or was decided to surgically remove a part pressure changes in the brain that conof the fractured bone. No post-surgery tribute to the abnormal neurologic signs, stabilization was necessary and the and lesions seen at necropsy, have failed horse recovered without complications to reveal the cause of these disorders. within four to six weeks. The horse is Treatment is often directed at reducing currently back to normal use and re- the increased pressure change on the
512
brain, but without the capability to monitor the effects of such treatment on intracranial pressure. The CT scanner is a valuable tool to evaluate central nervous system disorders because of its capability to reveal areas of damage, developmental abnormalities or the accumulation of fluid in the brain. The CT scanner is being used to further define and understand the nature of these diseases so that better treatment protocols can be developed. Another study by Dr. Andris Kaneps and his associates involved defining the development of bony ab-
Four three-dimensional reconstructions from the CT scans of a foars foot. The upper left and lower right corners show the side views. The upper right corner shows the view from directly above and the lower left corner is from the bottom of the foot.The wings of both sides of the distal p h a l a n x have fractures.
normalities in the heel region of the foot. These abnormalities have been seen as separate bony bodies closely associated with the wings of the coffin bone in lame foals two to four months of age. The goals of this study were to define the normal development of the foot and to determine the cause of these
JOURNAL OF EQUINE VETERINARY SCIENCE
VETERINARY
bony abnormalities. The CT scanner was used to identify lesions in the foot and associated structures that were not visible with a normal radiographic evaluation. Results from this study will help answer questions regarding the significance of these lesions in the growing foal and with further study, will determine their influence on the soundness of these horses as adults. The CT scanner is a powerful tool that has excellent diagnostic capabilities for complex problems of the skull and lower limbs, as well as valuable research applications. About the authoc Philip D. Koblik, D VM, MS, DipL ACVR, is a professor with the University of California, Davis, School of Veterinary Medicine Department of Surgical and Radiological Sciences. He received his veterinary degree from Colorado State University in 1977and then completed his residency in radiology and a master's degree in comparative pathology at UC Davis. In 1982, he was an assistant professor and head of large animal radiology and nuclear medicine at Tufts University School of Veterinary Medicine in Massachusetts. In 1985, he joined the faculty at UC Davis. Dr. Koblik is board certified with the American College of Veterinary Radiology (ACVR) and a member of the American Veterinary Radiology Society, American Veterinary Medical Association and the Society of Nuclear Medicine. He has served as a manuscript reviewer of several scientific journals, a member of the ACVR Alternate Imaging Committee, chairman of the ACVR Radiation Safety Committee, chairman of the ACVR Nuclear Medicine Committee, chairman of the ACVR Certification Examination Committee and president of the Society of Veterinary Nuclear Medicine. Dr. Koblik has over 50 articles published in scientific journals and travels internationally to share his research findings. His research interests include the use of computed axial tomography (CT scanning) and magnetic resonance imaging (MRI) for diagnostic radiology of the horse. This paper summarizes some of his research using CT scans funded by the UC Davis Equine Research Laboratory which receives funding provided by the Oak Tree Racing Association, the State of California Satellite wagering fund and contributions by private donors.
UMBILICAL CARE IN FOALS Stephen E. O'Grady, DVM, MRCVS Routine umbilical care in immediately postpartum foals and the materials used are still controversial. The umbilicus is treated to prevent bacterial contamination which may lead to an ascending infection resulting in an umbilical abscess and/or sepsis. Prevention of umbilical infection also relies on other parameters such as environmental hygiene, absence of uterine infection or placentitis, adequate passive transfer levels of immunoglobins and nutrition. Various methods of disinfection of the umbilicus have been used including various strengths of iodine, povidone iodine, gentian violet and Furazolidin spray. Frequency has ranged from a single treatment immediately post-foaling to multiple daily treatments extending up to five days. In human medicine, gentian violet (triple dye) and 4% Chlorhexidine appear to be the disinfectants of choice for the umbilicus; neither have gained widespread popularity in veterinary medicine. A different technique for umbilical cord treatment was used on two hundred-seventy foals born over a three year period on three different farms. All three farms had good foaling management, yet had previous histories of multiple cases of neonatal sepsis believed to originate from the umbilicus. Two farms were in South Africa and one was in the United States. Formerly, the farms had treated the umbilical cords on their foals with various forms of iodine over a two- to five-day period. The new protocol used
REVIEW
on these farms was as follows. The navel cord was allowed to detach from the mare naturally. The remaining umbilical stump was treated with povidone iodine or 2% to 3% aqueous iodine (tincture is very caustic to tissues and produces necrosis). A plastic human umbilical clamp (Unoplast) was then attached to the severed cord halfway from the end of the stump to the body wall. The clamp was left in place until the remaining stump detached by itself which usually takes seven to ten days. No further treatment was given, but the navel was observed daily for signs of heat, swelling or moisture. There appears to be no difference b e t w e e n the two d i s i n f e c t a n t s (povidone-iodine vs. aqueous iodine) with respect to drying efficacy or duration of stump attachment. Since changing to this regimen, there have been no umbilical abscesses or neonatal septicemia in the foals on these farms. Also of interest, there were no umbilical hernias seen in this group of foals. This method of treating the umbilicus in foals appears to prevent ascending infection, can be used as a routine therapy and may be useful on those farms with an increased incidence of umbilical abscessing or sepsis. REFERENCES: 1. Madigan J: Preventive measures for umbilical a b s c e s s e s in the foal. Proceedings 12th ACVlM Forum. 1994; 692-694. 2. Gladstone IM, Clapper L, et al.: Randomized study of six umbilical cord care regimens. Clinical Pediatrics 1988;27:127131. 3. Newman NW: Use of povidoneiodine in umbilical cord care. Clinical Pediatrics 1989;28:37.
Acknowledgement: The author would like to thank Rodney Clarkin, Stud Manager at Camargue Stud in South Africa for his contributions to this report.
Volume 15 Number 12,1995
513
In 1993, the faculty at the University of California, Davis, School of COMPUTED AXIAL Veterinary Medicine enlisted the help TOMOGRAPHY of a UC Davis mechanical engineering (CAT OR CT SCANNING) graduate student to design a special large animal patient table for CT scanby Laurie Fio and ning. This table fits over the existing Philip D. Koblik, DVM, human table and is linked so that the CT computer controls movement of both MS, Dipl. ACVR tables. This is a unique solution to the size dilemma of horses and allows radiologists to position and move the paComputed axial tomography (CAT tient with a high degree of accuracy or CT scanning) is a sophisticated which is important when method of obtaining crosssectional images of various scanning areas of complex body parts which can be anatomy such as the dental arcades in a horse's combined and manipulated by special computer prohead. Without the comgrams to produce threeputerized control of the dimensional or volume rentables, the tables would dered images. Standard rahave to be moved manudiographs give a two-dially to reposition the pamensional representation tient and the location of the scanning area would of a selected part of the body have to be refigured with by passing x-rays through the body. The bones and each movement. The CT other tissues absorb some computer does all of this quickly and automatically. of the x-rays and the image With standard sized, that appears on film is what adult horses, only the head, passes through the patient. The final image is a superpart of the neck and the legs will fit in the opening imposition of all structures in the path of the x-ray of the CT scanner. The maj or clinical applications beam. Bones appear white, A foal under anesthesia being positioned in the CT scanner to of CT scanning in horses muscle and internal organs evaluate central nervous system disorders. is to evaluate teeth and are gray and air is black. sinuses and to evaluate The CT scanner uses a standard x-ray tube that is fixed in a field approximately ten years ago and complicated fractures of the lower large donut shaped apparatus. The anes- was exclusively used to scan dogs, cats limbs. The three-dimensional view prothetized patient is positioned inside the and other small animals. The equip- vides an aid to the radiologist to visucentral opening. The x-ray tube is then ment used was developed for human alize certain relationships of bones and rotated around the patient so that the practice and had definite limitations as fractures that might not be obvious in to the size of the patient that could be the standard two-dimensional view. Authors' address: California Center for Equine Health and Performance, School of Veterinary supported by the scanning table. Sev- Sometimes, it can be difficult to deterMedicine, University of California, Davis, CA eral veterinary colleges around the na- mine which direction a complicated 95616-8589
Volume 15 Number 12,1995
511
ported to be doing very well. Another horse was brought to the UC Davis VMTH because it showed pain when it attempted to open its mouth and was reluctant to eat. Standard x-rays of the skull were inconcluA cross sectional slice from a CT scan of the foot of a sive, but the CT scan foal.The arrow shows a defect in the bone. (1 - middle of this horse's skull phalanx, 2 - distal phalanx, 3 - hoof wall, 4 - digital revealed a complex cushion) fracture through the joint of the left side fracture has gone, the extent of the of the jaw where it joins with the skull. fracture and/or where its position is in The two-dimensional, cross-sectional relation to other fragments and body slices revealed the fracture, but the parts. three-dimensional representation A horse was brought to the UC showed the fracture in relation to the Davis Veterinary Medical Teaching jaw and further showed the position of Hospital (VMTH) because it had been v a r i o u s bone f r a g m e n t s . The showing undiagnosed neurological ab- three-dimensional view allowed a betnormalities for several months. The ter appreciation of the extent of the horse was exhibiting ataxia of the legs, injury. This fracture was too complimeaning an incoordination due to an cated to treat. inability to communicate messages In addition to valuable diagnostic from the brain to the legs. The horse capabilities for clinical use, the CT also developed a head tilt and showed scanner has also proven to be an imporsigns of pain below one ear. Standard tant tool for research. The UC Davis x-rays of the skull showed a bony thick- Equine Research Laboratory has funded ening (calcification) near the base of several studies utilizing the CT scanthe ear, but were very inconclusive as ner. One study by Dr. John Madigan to the origin and extent of the injury. and his associates involved evaluating The CT scan revealed a fracture of central nervous system disorders in the the stylohyoid bone which is part of the neonatal foal characterized by seizures, whole apparatus that helps horses swal- abnormal sucking reflexes, blindness low. There are se,veral nerves in this and motor dysfunction. These neuroarea which were also affected by the logic symptoms are often associated inflammation from the fracture. The with bacterial infection, prematurity, CT scan was used to further define the difficult births and their related probaffected area and to determine if there lems, and the syndrome called neonatal were any other related complications to maladjustment or "dummy foals." help develop a treatment strategy. It The nature of the circulatory or was decided to surgically remove a part pressure changes in the brain that conof the fractured bone. No post-surgery tribute to the abnormal neurologic signs, stabilization was necessary and the and lesions seen at necropsy, have failed horse recovered without complications to reveal the cause of these disorders. within four to six weeks. The horse is Treatment is often directed at reducing currently back to normal use and re- the increased pressure change on the
512
brain, but without the capability to monitor the effects of such treatment on intracranial pressure. The CT scanner is a valuable tool to evaluate central nervous system disorders because of its capability to reveal areas of damage, developmental abnormalities or the accumulation of fluid in the brain. The CT scanner is being used to further define and understand the nature of these diseases so that better treatment protocols can be developed. Another study by Dr. Andris Kaneps and his associates involved defining the development of bony ab-
Four three-dimensional reconstructions from the CT scans of a foars foot. The upper left and lower right corners show the side views. The upper right corner shows the view from directly above and the lower left corner is from the bottom of the foot.The wings of both sides of the distal p h a l a n x have fractures.
normalities in the heel region of the foot. These abnormalities have been seen as separate bony bodies closely associated with the wings of the coffin bone in lame foals two to four months of age. The goals of this study were to define the normal development of the foot and to determine the cause of these
JOURNAL OF EQUINE VETERINARY SCIENCE
VETERINARY
bony abnormalities. The CT scanner was used to identify lesions in the foot and associated structures that were not visible with a normal radiographic evaluation. Results from this study will help answer questions regarding the significance of these lesions in the growing foal and with further study, will determine their influence on the soundness of these horses as adults. The CT scanner is a powerful tool that has excellent diagnostic capabilities for complex problems of the skull and lower limbs, as well as valuable research applications. About the authoc Philip D. Koblik, D VM, MS, DipL ACVR, is a professor with the University of California, Davis, School of Veterinary Medicine Department of Surgical and Radiological Sciences. He received his veterinary degree from Colorado State University in 1977and then completed his residency in radiology and a master's degree in comparative pathology at UC Davis. In 1982, he was an assistant professor and head of large animal radiology and nuclear medicine at Tufts University School of Veterinary Medicine in Massachusetts. In 1985, he joined the faculty at UC Davis. Dr. Koblik is board certified with the American College of Veterinary Radiology (ACVR) and a member of the American Veterinary Radiology Society, American Veterinary Medical Association and the Society of Nuclear Medicine. He has served as a manuscript reviewer of several scientific journals, a member of the ACVR Alternate Imaging Committee, chairman of the ACVR Radiation Safety Committee, chairman of the ACVR Nuclear Medicine Committee, chairman of the ACVR Certification Examination Committee and president of the Society of Veterinary Nuclear Medicine. Dr. Koblik has over 50 articles published in scientific journals and travels internationally to share his research findings. His research interests include the use of computed axial tomography (CT scanning) and magnetic resonance imaging (MRI) for diagnostic radiology of the horse. This paper summarizes some of his research using CT scans funded by the UC Davis Equine Research Laboratory which receives funding provided by the Oak Tree Racing Association, the State of California Satellite wagering fund and contributions by private donors.
UMBILICAL CARE IN FOALS Stephen E. O'Grady, DVM, MRCVS Routine umbilical care in immediately postpartum foals and the materials used are still controversial. The umbilicus is treated to prevent bacterial contamination which may lead to an ascending infection resulting in an umbilical abscess and/or sepsis. Prevention of umbilical infection also relies on other parameters such as environmental hygiene, absence of uterine infection or placentitis, adequate passive transfer levels of immunoglobins and nutrition. Various methods of disinfection of the umbilicus have been used including various strengths of iodine, povidone iodine, gentian violet and Furazolidin spray. Frequency has ranged from a single treatment immediately post-foaling to multiple daily treatments extending up to five days. In human medicine, gentian violet (triple dye) and 4% Chlorhexidine appear to be the disinfectants of choice for the umbilicus; neither have gained widespread popularity in veterinary medicine. A different technique for umbilical cord treatment was used on two hundred-seventy foals born over a three year period on three different farms. All three farms had good foaling management, yet had previous histories of multiple cases of neonatal sepsis believed to originate from the umbilicus. Two farms were in South Africa and one was in the United States. Formerly, the farms had treated the umbilical cords on their foals with various forms of iodine over a two- to five-day period. The new protocol used
REVIEW
on these farms was as follows. The navel cord was allowed to detach from the mare naturally. The remaining umbilical stump was treated with povidone iodine or 2% to 3% aqueous iodine (tincture is very caustic to tissues and produces necrosis). A plastic human umbilical clamp (Unoplast) was then attached to the severed cord halfway from the end of the stump to the body wall. The clamp was left in place until the remaining stump detached by itself which usually takes seven to ten days. No further treatment was given, but the navel was observed daily for signs of heat, swelling or moisture. There appears to be no difference b e t w e e n the two d i s i n f e c t a n t s (povidone-iodine vs. aqueous iodine) with respect to drying efficacy or duration of stump attachment. Since changing to this regimen, there have been no umbilical abscesses or neonatal septicemia in the foals on these farms. Also of interest, there were no umbilical hernias seen in this group of foals. This method of treating the umbilicus in foals appears to prevent ascending infection, can be used as a routine therapy and may be useful on those farms with an increased incidence of umbilical abscessing or sepsis. REFERENCES: 1. Madigan J: Preventive measures for umbilical a b s c e s s e s in the foal. Proceedings 12th ACVlM Forum. 1994; 692-694. 2. Gladstone IM, Clapper L, et al.: Randomized study of six umbilical cord care regimens. Clinical Pediatrics 1988;27:127131. 3. Newman NW: Use of povidoneiodine in umbilical cord care. Clinical Pediatrics 1989;28:37.
Acknowledgement: The author would like to thank Rodney Clarkin, Stud Manager at Camargue Stud in South Africa for his contributions to this report.
Volume 15 Number 12,1995
513