An introduction to equine ultrasonography
Ultrasound technology has advanced in leaps and bounds over the last few years and this has had a huge positive impact on veterinary diagnostic imaging across all species. Ultrasonography has long been a key tool in the diagnostic investigation of equine musculoskeletal disorders, and slightly more recently has facilitated great advances in the field of equine reproduction.

As technology continues to develop the possibilities for the use of ultrasound as a diagnostic tool will expand, and increasing affordability of high quality equipment should help drive this. Below are some things to consider regarding the use of ultrasonography in equine practice, including its potential applications and the equipment required.

Indications
Musculoskeletal

Tendons and ligaments of the distal limb, e.g. SDFT core lesions



Pelvis, e.g. ilial wing fractures
Joints, e.g. meniscal injury in the stifle
 


Spine, e.g. cervical facet joints
 
Reproductive
Pre-breeding, e.g. uterus and ovaries
 


Pregnancy diagnosis, foetal sexing and twin management
Monitoring of the health of a pregnancy, e.g. CTUP measurements



Abdominal

Colic exam
• Assessment of abdominal organs, e.g. liver
 


Performing ultrasound-guided biopsies
Cardiac

Assessment of cardiac anatomy and function, e.g. investigation of murmurs



Investigation of episodes of ataxia/collapse
Ophthalmological

Investigation of globe disease, e.g. cataracts, retinal detachment 
Miscellaneous

‘Lumps and bumps’, e.g. haematoma vs. abscess
• Finding foreign bodies and sequestra
• Ultrasound-guided diagnostic and therapeutic procedures, e.g. thoracocentesis or injecting tendon core lesions
Equipment Required

Portable ultrasound systems are most suitable for ambulatory practice 

Cart based or mobile ultrasound systems are more commonly used for hospital use

Probes -

For distal limb musculoskeletal and ophthalmological purposes – a high frequency linear probe is required
For pelvic and abdominal scanning – a low frequency convex (curvilinear) probe is needed
Reproductive tract – rectal probe (linear)
Cardiac – low frequency phased array (sector) probe
‘Lumps and bumps’ – usually high frequency linear probe, though a low frequency convex probe might sometimes be required
Pros

Portability of equipment
Non-invasiveness
Low upkeep costs
Cons

Dependent on operator skill