When Swimming Helps - and When it Hurts: A Veterinary Rehab Perspective

Swimming in Focus: While swimming is a powerful tool for cardiovascular conditioning without limb loading, it requires a careful assessment of the horse's individual movement patterns and injury history to ensure it supports, rather than hinders, postural rehabilitation.

In this new rehab series, we’ll break down common rehabilitation modalities—what they do well, where they can backfire, and how a veterinarian + rehabilitation team selects the right tool based on your horse’s injury, stage of healing, movement pattern, and job.

Modality spotlight: Swimming

Swimming became a popular option offered in equine rehab in the early 2000's, but the practice has been used by racehorse trainers for years prior. The primary reason race horse trainers use swimming is to "replace track work for horses with limb injuries and improve or maintain fitness." The downside of swimming include the possibilities of swimming-induced colic, skin infections, and even drowning.

Pools range from circular systems (continuous swimming) to “U”-shaped designs, to straight-line lanes where horses enter, swim forward, and exit without turning. Pool design matters because it can influence posture, turning forces, and how consistently a horse moves.

Pros of swimming

1) Cardiovascular conditioning without limb loading

Swimming can improve aerobic fitness while minimizing ground-reaction forces and concussion—valuable when you want conditioning but need to reduce impact on healing tissues.

2) Low-impact exercise

Because there is no stance phase against the ground, swimming reduces repetitive concussive forces compared with land work.

Cons of swimming

1) Epaxial dominance: why swimming can “build the wrong topline”

When a horse swims, they must stabilize the trunk against buoyancy and drag while generating propulsion—often in a posture that biases spinal extension. In practice, that frequently means the horse relies more on the epaxial system (the topline/extensor chain) and less on the abdominal/ventral support system.

• Epaxial muscles most likely to be over-recruited in swimming (topline/extensors):

• Longissimus dorsi (primary thoracolumbar extensor; stiffens/extends the back)

• Iliocostalis (rib/back extensor synergy; contributes to trunk rigidity)

• Multifidi (segmental spinal stabilizers; can “brace” when the horse is trying to stabilize a hollow posture)

• Thoracic/cervical portions of longissimus (linking neck-to-back extension strategies)

Why that matters:

Understanding Swimming Strategies: Not all horses swim the same way. As shown in Figure 4, Gaulmin et al. (2025) identified three distinct limb sequences (lateral, diagonal, and 4-beat) used by horses to maintain propulsion and balance. This mechanical variability is a key consideration in rehabilitation; if a horse shifts between these strategies, it may inadvertently load different muscle groups or joints, making it difficult to maintain a consistent, controlled therapeutic stimulus. Source: Gaulmin, P., et al. (2025). Description and Analysis of Horse Swimming Strategies in a U-Shaped Pool. Animals, 15(2):195. [CC BY 4.0]

If a horse already has a tendency toward a hollow back, poor thoracolumbar lift, or chronic inversion of the topline, swimming can reinforce that compensation pattern—stronger “bracing” muscles, but not necessarily better spinal control, core engagement, or swing through the back.

2) Neck: which muscles get over- vs under-developed

Swimming commonly encourages a head-up, neck-extended strategy (especially during entry and when the horse is working to keep the airway clear). Over time, that can bias muscle development toward dorsal extensors and away from ventral stabilizers.

• Neck muscles that tend to become overworked/overdeveloped (dorsal neck extensors + superficial “brace” muscles):

• Splenius (major head/neck extensor; commonly hypertrophies in horses that brace in extension)

• Semispinalis capitis (powerful head/neck extensor; contributes to a “high head/short neck” posture)

• Longissimus capitis / longissimus atlantis (dorsal cervical extensors; link the neck to the topline)

• Upper trapezius and related dorsal cervical fascia (supportive, can become hypertonic with chronic head-up carriage)

Neck muscles that tend to be undertrained/underdeveloped (ventral neck + deep stabilizers):

• Longus colli / longus capitis (deep cervical flexors; key for true cervical stability and “lifting” the base of the neck)

• Ventral cervical stabilizers (e.g., scalene group) (supportive role in controlled neck posture and ribcage mechanics)

• Functional abdominal sling involvement (not a neck muscle, but closely tied to whether the horse can lift the thorax and stabilize the neck/back chain appropriately)

https://video.wixstatic.com/video/7c92fc_326da47aaa864874b176408ccb2e279c/1080p/mp4/file.mp4

Biomechanical Analysis of the Swimming Gait: Notice the characteristic spinal extension and "head-high" carriage as the horse stabilizes against buoyancy. While this eliminates limb concussion, the intense hind-end propulsion and dorsal bracing (epaxial recruitment) seen here may be contraindicated for horses with kissing spine or SI dysfunction. Source: Grossi, I., et al. (2024). Characteristics of horse gait during swimming exercise in swimming pool. Journal of Equine Rehabilitation.

3) Biomechanics: inconsistency is common

Horses don’t all swim the same, and even the same horse may not stay consistent within a single session. That variability matters in rehab, where the goal is often to retrain reliable, repeatable motor patterns.

4) Injury aggravation risk—especially hind end and topline

Swimming is hind-end driven and can be demanding on pelvic and hindlimb structures. Swimming causes spinal extension and intense hindlimb propolsion; it can aggravate issues involving the lumbosacral region, SI region, ililopsoas injuries, hips, stifles, and hocks, or worsen symptoms in horses with chronic back pain patterns.

5) Respiratory risk (including aspiration)

Horses are not natural swimmers. Water inhalation is a recognized risk and can contribute to respiratory complications.

Which horses may benefit most from swimming?

Racehorses (Thoroughbreds and Standardbreds)

Cardiovascular development is non-negotiable but building it comes with repetitive high-speed loading on young or heavily used limbs. Swimming can support aerobic conditioning while reducing concussive load.

Speed/power athletes (including many barrel horses)

Similar logic: conditioning support with reduced concussion—if the horse’s topline, neck, and hind-end mechanics make swimming appropriate.

Which horses should generally avoid swimming?

Horses with neck pain or cervicothoracic dysfunction

If swimming reinforces cervical extension and dorsal bracing, it can flare pain and delay true postural rehab.

Horses with kissing spine or a history of back pain

If the horse already over-recruits the epaxial chain and struggles with thoracolumbar comfort, swimming can reinforce the exact strategy you’re trying to unwind.

Horses with SI/lumbosacral sensitivity or hind-end joint issues (stifle/hock/hip)

Swimming can be hind-end intense and mechanically inconsistent—often not ideal for these cases.

Swimming and Sport Horses

Swimming can be a useful tool for conditioning some athletes, but it often does not train the posture and movement patterns the majority of sport horses need under saddle. Swimming reinforces epaxial bracing and cervical extension which can aggravate many issues sport horses struggle with to include painful necks and kissing spine.

Bottom line

Swimming can be valuable—but it’s not automatically “safe” just because it’s low-impact. The decision should be individualized: What are we treating? What pattern are we trying to restore? What structures are most vulnerable in this horse? When those answers align, swimming can support conditioning. When they don’t, it can slow progress by stressing the wrong areas.

References:

• Steel, C.M., B.M. Bond, A.V. Morrice-West. 2019. Survey of trainers on the use of swimming exercise for Standardbred racehorses in Australia. Australian Veterinary Journal. 97(3):61-67.

• Santosuosso, E., R. Leguillette, T. Vinardell, S. Filho, S. Massie, P. McCrae, S. Johnson, C. Rolian, D. Florent. 2021. Kinematic analysis during straight line free swimming in horses: Part 1—Forelimbs. Frontiers in Veterinary Science. 8:752375.

• Santosuosso, E., R. Leguillette, T. Vinardell, S. Filho, S. Massie, P. McCrae, S. Johnson, C. Rolian, D. Florent. 2022. Kinematic analysis during straight line free swimming in horses: Part 2—Hindlimbs. Frontiers in Veterinary Science. 8:761500.

• Jones, S., S. Franklin, C. Martin, C. Steel. 2020. Complete upper airway collapse and apnoea during tethered swimming in horses. Equine Veterinary Journal. 52:352–358.

• Hobo, S., K. Yoshida, T. Yoshihara. 1998. Characteristics of respiratory function during swimming exercise in Thoroughbreds. Journal of Veterinary Medical Science. 60(6):687–689.

• Thomas, D.P., G.F. Fregin, N.H. Gerber, N.B. Ailes. 1980. Cardiorespiratory adjustments to tethered-swimming in the horse. Pflügers Archiv. 385:65–70.

• Adair, H.S. III. 2011. Aquatic therapy for conditioning and treatment of tendon and ligament injuries. Proceedings of the 57th Annual Convention of the American Association of Equine Practitioners (AAEP). 57:181–185.

• Swanstrom, O.G.L. 1973. Therapeutic swimming. Proceedings of the American Association of Equine Practitioners (AAEP) Annual Convention. (Atlanta, GA).

• Imahara, T. 1976. Swimming pool for horses. Experimental Report of the Equine Health Laboratory. 13:79–82.

• Gaulmin, P., F. Marin, C. Moiroud, A. Beaumont, S. Jacquet, E. De Azevedo, P. Martin, F. Audigié, H. Chateau, C. Giraudet. 2025. Description and Analysis of Horse Swimming Strategies in a U-Shaped Pool. Animals. 15(2):195. https://doi.org/10.3390/ani15020195 

• Grossi, I., G. Merluzzi, F. Beccati, M. Pepe. 2024. Characteristics of horse gait during swimming exercise in swimming pool. Journal of Equine Rehabilitation. 2:100012