Imaging the Neonatal Foal. Equipment. Neonatal foals. 5 or 7.5 MHz linear array 10 MHz linear array. Abdomen Thorax Musculoskeletal system

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1 Imaging the Neonatal Foal Leanne Begg BVSc DipVetClinStud MS MACVSc Dip ACVIM RANDWICK EQUINE CENTRE Equipment 5 or 7.5 MHz linear array 10 MHz linear array Neonatal foals Abdomen Thorax Musculoskeletal system 1

2 Small intestine Peritoneal fluid Bladder Kidneys Umbilical remnants Abdomen Indications Colic Distended abdomen Patent urachus Sepsis to evaluate umbilicus Renal disease Small Intestine Distension Motility Wall thickness - normal < 3mm in foal Intussusception donut 2 concentric rings with central core 2

3 Lawsonia intracellularis (older foal) Thickened small intestinal wall Hypoalbuminaemia Elevated fibrinogen Ill thrift Rhodococcus equi (older foal) Respiratory form multiple abscesses GIT form diarrhoea, illthrift,, thickened small intestine, can be hypoalbuminaemic Leucocytosis, neutrophilia, hyperfibrinogenaemia Polysynovitis immune complex deposition Uveitis immune complex deposition Peritoneal Fluid Uroperitoneum creatinine >2x peripheral blood Haemoperitoneum smoke swirling pattern Ascites Abdominocentesis (teat cannula!) 3

4 Bladder Identify rupture as usually collapsed with irregular shape Defect can be identified Can still contain urine if small defect Kidneys Size Cortical and medullary echogenicity Abnormal pelvic dilation Presence of perirenal oedema Umbilical remnants Umbilicus along ventral midline cranial to liver and caudal to bladder All 4 structures can be imaged in normal foal up to 4 to 8 wks of age 4

5 Umbilical remnants Umbilical vein follow cranially along ventral midline to liver; should be <1cm diameter Umbilical arteries travel either side of urachus caudally and branch to run caudally and dorsally to bladder; <1cm diameter Umbilical remnants Urachus courses from umbilical stump to apex of bladder; lumen should not be visible even if patent; if can view = infection Combined view of 2 arteries and urachus just caudal to stump; ET view should be < 1.5 x 2.5 cm Urachal remnants Enlarged vessels Hypoechoic to anechoic cores suspect infection Gas shadows anaerobic infection Thickened walls more chronic infection 5

6 Treatment Medical if leucocytosis, neutrophilia, hyperfibrinogenaemia,, one internal umbilical remnant structure is affected (BS ABS) Surgical if septicaemia, septic joints, multiple infected structures in umbilical remnant Patent urachus 7do Thorax Pleural effusion rarely occurs Interstitial disease most common Looking for pleural thickening = comet s tails Consolidated lung Identifying peripheral abscesses (Rhodococcus infection in older foal) 6

7 Indications Septic foal that suspect pneumonia Auscultation of thorax harder to assess in foals Radiography is ideal imaging tool Echocardiography Congenital cardiac defects Pericarditis Endocarditis Indications Murmur, although PDA present normally up to 4 days (continuous or systolic) Hypoxaemia unresponsive to O 2 Severe congenital cardia defects, R to L shunts, may not have murmur! 7

8 Fractured ribs Disruption of cortical surface of bone and surrounding oedema Concurrent haemothorax Musculoskeletal Septic arthritis echogenic particles and fibrin strands in joint fluid Anechoic fluid adjacent to and under the periosteum in early osteomyelitis Later see loss of cortical bone structure Musculoskeletal Gastrocnemius rupture large areas of fibre disruption and haematoma formation 8

9 Masses Distinguished by US appearance: Abscesses Haematomas Cysts Soft tissue masses Abscesses Cavitated areas containing sonolucent, hypoechoic or echogenic debris Foreign bodies appear as echogenic to hyperechoic masses, usually casting an acoustic shadow Haematomas Sonolucent loculated fluid Echogenic material may be seen if clots are present 9

10 Cysts Large cavity of sonolucent fluid with or without distinct septation Acoustic enhancement of far wall Unusual in foals Soft tissue masses Homogeneous appearance Can be complex pattern of echogenicity,, if lots of fibrous tissue US guidance for biopsy Hernias Umbilical or scrotal Useful to tell if gut has herniated through Motility and wall thickness of herniated gut evaluated If gut compromised, will have thickened wall and decreased motility 10

11 Eyes Examining intraocular and retrobulbar structures Frequency of beam inversely proportional to wavelength (=depth of penetration) 10 MHz (ideal) 5 MHz Sector scanner with small head (footprint) Eyes See anterior cornea, anterior lens capsule, posterior lens capsule, retina-choroid choroid-sclera May see iris, corpora nigra, ciliary body, optic nerve, orbital fat, muscles. Anterior and posterior chambers, lens and vitreous are normally anechoic Eye 11

12 Indications Opacity (cornea, aqueous humor,, lens, vitreous humor) ) prevents ophtho exam Evaluation of intraocular masses Examination for foreign body (>1mm and metal easier to see than glass or organic material) Looking at retrobulbar structures Foals Trauma retinal detachment Congenital cataracts might preclude ophtho exam Technique Sedation Through eyelid Transcorneally regional nerve blocks required and topical anaesthetic (Alcaine( Alcaine) on cornea Sensory innervation by trigeminal nerve (V) Motor innervation by facial nerve (VII) 12

13 Technique Supraorbital (frontal) branch of V anaesthesia of top eyelid emerges from supraorbital foramen of frontal bone Auriculopalpebral branch of VII akinesia of top eyelid palpate as courses over zygomatic arch Ultrasound gel (avoid cellulose-based ones if putting on cornea) 13