604


| Use of the more readily available higher- frequency transduc-


ers has been mentioned in the literature. Cook and Hassel ( 2014 ) described that ‘information can be gained even when a higher fre- quency probe’ is used. One conference proceeding described that the spleen, liver, kidneys, duodenum, large colon, small intestine, bladder and diaphragm could be imaged transcutaneously using the transrectal transducer (Bradecamp, 2007 ). Evidence- based informa- tion comparing the use of the transrectal transducer and abdominal transducer in transcutaneous abdominal ultrasonography would fa- cilitate critical decisions for equine colic patients in the field.


LITERATURE REVIEW


With a series of studies, our group set out to answer the ques- tions of how a transrectal transducer compares with an abdominal transducer for organ identification during transcutaneous abdomi- nal ultrasonography of clinically healthy horses (pilot project) and how they compare in ultrasonographic detection of abnormalities in horses presenting for colic. These are the first published studies to compare the transducers in organ identification and detection of abnormalities in equine abdominal ultrasonography. In the pilot study (Haardt et al., 2022 ), four veterinarians with


variable skill level performed abdominal ultrasonography on 12 clinically normal horses. Two horses were examined independently on both sides simultaneously by two randomly assigned veterinar- ians. Both recorded whether 10 organs expected to be visualised on abdominal ultrasonography were ‘identified’ or ‘not identified’ via ultrasonography in six standardised sextants to designate loca- tion along each side of the horse. This protocol followed the meth- odology described by Williams et al. ( 2014 ). The transducer used was randomly allocated, and then the pair would switch to the next horse and scan the other respective side of that horse with the opposite transducer. Fisher ' s exact tests or chi- squared tests (as appropriate) were used to determine if there was a difference be- tween transducers in identifying target abdominal organs. There was no significant difference in organ identification on


the right side of the abdomen and on the left side, the stomach, liver and kidney ( p = 0.014, p = 0.036 and p = 0.0146, respectively) were less likely to be detected with the transrectal transducer. There were no significant differences between the transducers in the detection of the spleen, colon, small intestine and urinary bladder on the left side. With the maximum depth of 10 cm for the transrectal transducer, the depth of organs was thought to be a factor in decreased organ identification on the left side. The left kidney is located medial to the 5–8 cm spleen (Reef, 1998 ) and the stomach is also located deeper within the abdomen, deep to the spleen. It is less clear why the left liver was less likely to be iden- tified using the transrectal transducer, but one hypothesis is that the narrow field of this transducer makes it more difficult to use surrounding structures such as the spleen and stomach to defin- itively identify the left liver lobe. Overall, the transrectal trans- ducer produces ultrasonographic images of sufficient quality to


TAN and HAARDT


allow organ identification similar to the abdominal transducer with the exception of a depth limitation that affects the visualisation of the left kidney, left liver and stomach. Limitations to the study were the lack of blinding to the transducer being used, the variable expertise of the ultrasonographers and the relatively low number of horses used. Following the pilot study, we decided to compare the detection


of abnormalities in horses presenting with colic using transrectal and abdominal transducers and fast localised abdominal ultrasonogra- phy of horses (FLASH) (Haardt et al., 2024 ). The FLASH protocol is simple to use for clinicians without extensive ultrasound experience and can be used in emergency settings to detect major abnormali- ties in horses with colic (Busoni et al., 2011 ). This makes FLASH the ideal protocol for use by general practitioners evaluating horses for colic in the field. Our hypothesis was that both the transrectal and abdominal transducers could detect free abdominal fluid and abnor- malities of the small intestine. We hypothesised that there would be significant differences in their ability to detect gastric conditions and left dorsal displacement of the colon. Horses over 1 year of age that presented to a referral clinic for


colic and transcutaneous abdominal ultrasonography were recruited over the study period of 2 months. Due to the emergent nature of the situation, horses were not clipped and the haircoat was instead soaked with alcohol. Horses were evaluated as usual by the attend- ing clinician using an abdominal transducer for abdominal ultraso- nography. Enrolled horses were simultaneously examined using the transrectal probe on the opposite side and the exam was concluded whenever the attending clinician completed their exam, to not delay diagnostics and treatment. Each ultrasonographer (all veterinary interns with equivalent ultrasound experience) completed a FLASH score sheet and recorded cine- loops. Redacted and randomised cine- loops were retrospectively analysed by board- certified equine specialists, who completed FLASH score sheets. These data were an- alysed using chi- square testing, paired- t - testing, Wilcoxon matched- pairs signed rank testing and Mann–Whitney testing depending on normality determined by Shapiro–Wilk testing. There were no significant differences in detection of free abdom-


inal and thoracic fluid, small intestinal pathology (distention, wall thickness and motility) or colon wall thickness using the transrectal and abdominal transducers. In fact, the transrectal transducer de- tected colon wall thickening (subjective assessment) in 5.6% of im- ages compared to 1.4% of images using the abdominal transducer. As predicted based on the pilot study, the transrectal transducer was less likely to detect the left kidney (and therefore nephrosplenic en- trapment and left dorsal displacement) and stomach (and therefore detection of gastric dilation). Detection of abnormal small intestine using FLASH is the best


predictor for surgical intervention (Busoni et al., 2011 ), therefore rapid diagnosis of small intestinal distention, abnormal wall thick- ness and abnormal motility using the readily available transrectal probe by general equine practitioners could lead to faster referral and improved survival rates. This is an important finding since oe- dema, distention and amotile small intestinal findings on abdominal


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92