Canine neonatology · Practical synthesis
A striking posture that is often reversible, but still requires a complete examination before the label is accepted.
Key point. A “swimmer” puppy cannot bring its limbs underneath the body: they splay laterally and the puppy moves with paddling motions. Signs are commonly recognised at 2–3 weeks, when littermates begin to stand. A non-slip surface, careful positioning and early rehabilitation can be very useful, but pain, fracture or luxation, orthopaedic deformity, neurological or neuromuscular disease and systemic illness must first be excluded. Any chest flattening or breathing abnormality changes the urgency.
For breeders, foster carers and owners. Diagnosis, limb support and the rehabilitation programme must be tailored and supervised by a veterinarian.
1. A locomotor syndrome of very young puppies, not an automatic diagnosis
Swimmer puppy syndrome (SPS), also called flat-puppy syndrome, describes an early failure to position the limbs underneath the trunk and bear weight. The limbs abduct, the sternum remains against the floor and attempts to move resemble swimming. The puppy is usually alert and interested in its surroundings; pain is not an expected feature.
In the largest published cohort, an international questionnaire study of 115 dogs, the median age at first signs was 14 days. All four limbs were involved in 48.7%, hindlimbs only in 35.7% and forelimbs only in 11.3%. A flattened chest was reported in 58 puppies. These figures describe submitted cases and do not estimate prevalence in the general puppy population. [3]
A useful first step. Compare the puppy with littermates of the same age, record a few attempts to stand on a high-traction surface, and arrange an examination. Video helps monitor change; it does not replace an orthopaedic, neurological and respiratory assessment.
2. Typical signs — and findings that do not fit
| Observation | Compatible with SPS | Suggests another cause or complication |
|---|---|---|
| Age and course | Recognised before 4 weeks, often when littermates start walking. | Sudden onset after normal walking, trauma, rapid deterioration or loss of an acquired function. |
| Posture | Laterally splayed limbs, persistent sternal recumbency and paddling movements. | Fixed rotation or angulation, a luxated joint, shortening, swelling or painful asymmetry. |
| Mobility | Passive range often preserved; active movements are present but ineffective. | Pain, marked stiffness, abnormal reflexes, tremors, progressive weakness or paralysis. |
| General condition | Alert puppy that seeks the teat and maintains temperature with the litter. | Hypothermia, anorexia, diarrhoea, dehydration, hypoglycaemia, infection or growth failure. |
| Chest | Mild flattening may accompany prolonged sternal recumbency. | Clearly depressed sternum, asymmetry, dyspnoea, cyanosis, fatigue, regurgitation or coughing. |
Kittens can show a similar pattern, but the feline literature is largely limited to case reports and small series. Most outcome data therefore come from dogs, and extrapolation should be stated. [9]
3. Chest flattening and pectus excavatum: the problem is not limited to the legs
Persistent sternal positioning may flatten the chest; conversely, a primary thoracic deformity may prevent normal positioning. The sequence cannot always be determined. Pectus excavatum is a dorsal deviation of the sternum. Its severity is not assessed by appearance alone: respiratory effort, nursing and exercise tolerance, auscultation and, where appropriate, radiography or further imaging all matter.
Dr Xavier Lévy’s recent teaching materials emphasise that vertebral and frontosagittal radiographic indices can document deformity and help guide treatment. A 2026 report of two American Akita littermates documented thoracic flattening, mild pectus and rightward cardiac displacement; improvement after physiotherapy, active positioning and an external thoracic splint does not turn two cases into a universal protocol. [7]
| Situation | Useful assessment | Practical consequence |
|---|---|---|
| Mildly flattened chest, normal breathing | Clinical examination, standardised images, weight monitoring and close recheck. | Reduce continuous sternal pressure and monitor shape. |
| Depressed sternum or asymmetry | Thoracic radiographs with appropriate measurements; echocardiography when clinically indicated. | Distinguish a flexible deformity that may respond early from a more complex abnormality. |
| Dyspnoea, cyanosis or fatigue | Immediate stabilisation, imaging and cardiorespiratory assessment. | An emergency; oxygenation and respiratory safety take priority over locomotor rehabilitation. |
| Severe or persistent deformity | Surgical/neonatal referral and follow-up imaging. | External remodelling or specialist correction may be considered while the chest remains malleable. |
4. Confirm the pattern and exclude conditions requiring different treatment
No blood test or genetic test confirms SPS on its own. Diagnosis is clinical and by exclusion. The veterinarian observes attempts to stand on suitable flooring, evaluates every joint, the spine, tone and reflexes, checks for pain and deformity, examines the chest and reviews weight, temperature, hydration and nursing ability.
| Category | Conditions to exclude | Clues and targeted tests |
|---|---|---|
| Orthopaedic/traumatic | Fracture, congenital or traumatic luxation, angular limb deformity, arthrogryposis, elbow, tarsal or patellar abnormality. | Pain, asymmetry, crepitus, fixed restriction; targeted radiographs. |
| Neurological/neuromuscular | Brain or spinal malformation, neuropathy, myopathy, neuromuscular-junction disorder or early neurodegeneration. | Abnormal reflexes, age-adjusted postural deficits, dysphagia or progressive weakness; specialist work-up. |
| Systemic/metabolic | Sepsis, hypoglycaemia, hypothermia, dehydration, anaemia or nutritional imbalance. | Depression, poor nursing, static weight, digestive or respiratory signs; individualised tests. |
| Thoracic | Pectus excavatum, aspiration pneumonia, congenital heart disease or diaphragmatic hernia. | Dyspnoea, murmur, cyanosis, cough or regurgitation; thoracic imaging and cardiac assessment if indicated. |
Normal blood results do not exclude every differential, and a mild muscle-enzyme increase may simply reflect effort or immobility. Tests should answer a clinical question rather than form an identical “large panel” for every puppy.
5. Unknown aetiology: association is not proof of cause
Published hypotheses include delayed muscle development, mechanical factors, floor traction, growth rate, litter size and familial predisposition. No single explanation fits every case. Older suggestions that herpesvirus, “over-rich milk”, a glycogen defect or a high-protein maternal diet routinely cause the syndrome have not been established.
In a Labrador colony followed for seven years, 16 of 436 puppies were affected. They came from smaller litters and were heavier at 10 and 28 days, with no birth-weight difference; pedigree analysis suggested a genetic component but identified neither a causal ancestor nor a causal variant. The findings concern one population and do not justify a commercial genetic test or a universal exclusion rule. [2]
The international 115-dog cohort also found smaller affected litters but detected no effect of the studied maternal diets on the number of affected puppies or recovery time. Recurrence in some related litters was observed, as were unaffected litters from the same breeding dogs. A shared environment may also contribute. [3]
Interpret cautiously. An affected puppy may be larger, similar in size or smaller than its littermates. Monitoring the weight trajectory is useful; starving a puppy, diluting formula or giving calcium/vitamin supplements without an indication does not treat SPS and can create an emergency.
6. Safe measures while arranging a diagnosis
- Provide genuine traction. Use clean, dry, stable, non-abrasive flooring on which the pads can grip. A smooth pad or tightly stretched cloth may worsen splaying.
- Vary position. Under supervision, without obstructing breathing or nursing, help the puppy rest laterally rather than continuously on the sternum; soft rolls may stabilise the posture.
- Measure rather than guess. Identify the puppy, weigh on the same scale, record nursing, ambient conditions, breathing and motor progress, and keep short videos.
- Arrange the examination. Urgency depends on associated signs, but early assessment benefits from tissue malleability and may prevent fixed deformity.
- Protect the skin. Check elbows, carpi, tarsi, sternum and abdomen; clean and dry without irritating products.
Avoid forcing a joint, painful massage, tight tape directly on the skin, complete limb immobilisation, improvised chest corsets or starting a “bone” supplement without a diagnosis.
7. Rehabilitation and limb support: guide movement rather than restrain the puppy
A programme generally combines environmental modification, gentle movement, positioning the limbs beneath the body, assisted weight-bearing and active movement. Sessions are short and repeated, stopping at any fatigue, chilling, pain or respiratory difficulty. Frequency and progression depend on age, limbs involved, chest shape and concurrent disease.
Devices that bring the limbs closer together — figure-of-eight bandages, soft hobbles or loose loops — have been described, but comparative efficacy and safety have not been established in controlled trials. A September 2026 case using a “loose-loop technique” recovered rapidly, yet multiple interventions were introduced together, the tape had not been validated in neonates and the report concerned one puppy. [6]
| Component | Aim | Safety check |
|---|---|---|
| High-traction surface | Allow push-off without lateral sliding. | Clean, dry, no loops that trap claws, and renewed regularly. |
| Assisted lateral recumbency | Reduce constant sternal pressure and vary loading. | Never obstruct nose, mouth, chest or access to the dam. |
| Gentle passive movement | Maintain range and prepare active support. | Within a physiological axis, without pain or force; taught by a professional. |
| Assisted standing/walking | Teach limb placement beneath the centre of gravity. | Soft ventral support, brief sessions, temperature watched, stop before fatigue. |
| Limb support | Limit abduction while allowing steps. | Position and width set by the veterinarian; skin, warmth, colour, swelling and comfort checked very frequently. |
| Thoracic orthosis | Remodel a flexible chest in selected cases. | Imaging-based indication; must never impair ventilation, circulation, nursing or growth. |
It is encouraging that 93% of dogs in the 2023 cohort received physiotherapy and owners very commonly perceived improvement. However, that retrospective study did not demonstrate shorter recovery with physiotherapy: spontaneous improvement, selection and diverse techniques preclude a causal conclusion. [3]
8. Weight, nursing and nutrition: address true excess without creating deficiency
Initially weighing each puppy daily, plotting an individual curve and comparing growth velocity with littermates is more informative than a single weight. If a very heavy puppy in a small litter is growing rapidly, the veterinarian may organise nursing access and activity, but growth must not be restricted arbitrarily.
- Check that the affected puppy can reach the teat without exhausting itself or aspirating milk.
- Review any milk replacer: species-appropriate complete product, concentration and hygiene according to instructions.
- Assess the dam’s body condition and diet without abruptly changing a complete lactation food.
- Do not add calcium, vitamin D, B vitamins, trace elements or extra protein “just in case”: small series using multiple treatments do not prove that supplements caused recovery.
9. Follow-up and prognosis: usually favourable, never guaranteed
In the 115-dog survey, puppies stood and walked unaided at a median age of 4.5 weeks, and signs had disappeared or almost disappeared by a median age of 6 weeks. Among 100 dogs already older than 12 weeks when data were collected, 97% had completely or largely recovered. Three dogs failed to recover, all with reported joint or bone abnormalities. [3]
These results are reassuring but cannot promise recovery. They came from retrospective questionnaires covering cases born between 1972 and 2021, with video available for a minority and heterogeneous treatment. Reports from 2024 and 2026 also show that older puppies or puppies with thoracic involvement may improve, sometimes with residual deficits. [5] [7]
Record at each recheck
- weight and nursing quality;
- ability to adduct each limb, rise, stand and then walk;
- joint range, pain, skin lesions and the effect of any support device;
- chest shape, respiratory rate and effort;
- comparable photographs/video on the same surface.
No progress, relapse after removing support, or any atypical sign calls for a new examination rather than mechanically repeating the same protocol.
10. What should be done for the litter and future breeding?
- Examine the whole litter on a high-traction surface: multiple puppies may be affected to different degrees.
- Correct slippery flooring immediately and record floor material, temperature, litter size, weights and growth velocity.
- Keep pedigrees and report related cases; familial recurrence warrants review with the veterinarian and breed club.
- Do not automatically blame the dam, sire or diet. No causal mutation or universal inheritance pattern has been validated.
- When cases recur, seek a reproduction consultation before another mating: weigh related cases, other congenital anomalies, environment and overall genetic value.
What the breeder contributes. Weight curves, dated videos, a diagram of the whelping area, flooring details, previous litter sizes and pedigree turn an isolated impression into an analysable case record.
11. Practical questions
Should I wait a week to see whether the puppy recovers?
No. Spontaneous improvement is possible, but waiting without an examination may allow thoracic or joint deformity to progress and may delay diagnosis of another disease. Improve traction and arrange prompt assessment.
Can I tape the legs together?
Not without veterinary demonstration and follow-up. A device that is too tight, high, low or left too long may injure skin, nerves and circulation or prevent useful movement. Puppies grow rapidly, so fit must be checked frequently.
Is a non-slip surface enough?
It is essential and may immediately improve grip, but it does not replace examination or an individual plan. A luxation, neurological disorder or severe pectus will not be corrected by flooring alone.
The puppy is the largest in the litter. Should milk be restricted?
Not arbitrarily. Rapid growth and small litters are associated with SPS in some studies, but smaller puppies are also affected. The veterinarian must preserve growth needs while correcting genuine overfeeding.
Is swimmer puppy syndrome inherited?
A familial predisposition is plausible in some lines, including one Labrador colony, but no causal gene or general inheritance rule is established. Document cases and request reproductive advice when related or repeated cases occur.
Will a flat chest become normal without treatment?
It may improve as weight-bearing and position improve, but a depressed sternum, dyspnoea or asymmetry warrants imaging. The opportunity for correction is greater while the chest remains malleable.
Is the prognosis always good?
It is favourable in most typical cases recognised early, but depends on concurrent malformations, breathing, joint integrity and the true diagnosis. A small proportion retain deficits or fail to recover.
Mobility and chest
When is specialist input useful?
Chest deformity, abnormal breathing, diagnostic uncertainty, several affected puppies or no progress: targeted assessment helps tailor imaging, limb support and rehabilitation. Dr Xavier Lévy: CRECS near Toulouse, Bordeaux Sud, and FR/EN guidance coordinated with your attending veterinarian.
12. References and scope
This article prioritises Dr Xavier Lévy’s personal material available in his private database: Advanced techniques in gynaecological surgery (March 2026) and Pediatric surgery in dogs and cats, used for specialist evaluation and correction of pectus excavatum. Detailed surgical protocols and treatments are not reproduced on this public page. Sébastien Lecocq’s institutional veterinary thesis (2007) was read in full for historical context; older hypotheses were checked against recent primary studies.
- Lecocq S. Les affections juvéniles du chien : application au diagnostic raisonné du 15e jour au 3e mois. Veterinary doctoral thesis, École nationale vétérinaire de Lyon, 2007. Full text consulted in the personal database.
- Tomihari M et al. Factors contributing to the swimmer puppy syndrome found in Labrador retrievers. BMC Veterinary Research, 2022;18:120. Single-colony cohort: 16 cases among 436 puppies; association with smaller litters and early weight gain, no causal variant identified. Full text.
- Rumpel L et al. A questionnaire-based investigation of the swimming puppy syndrome: 115 dogs. Frontiers in Veterinary Science, 2023;10:1233277. Largest available cohort, but retrospective owner questionnaire subject to selection and recall bias. Full text.
- Nganvongpanit K, Yano T. Prevalence of swimming puppy syndrome in 2,443 puppies during the years 2006–2012 in Thailand. Veterinary Medicine International, 2013:617803. Retrospective clinical study. Full text.
- Anatolitou AA et al. A successful outcome in four puppies with swimmer puppy syndrome. Veterinary Research Communications, 2024;48:4029–4036. Four cases, combined interventions, one residual deficit after early discontinuation. DOI.
- Kroker L. Rapid functional recovery in a Golden Retriever puppy with swimmer puppy syndrome following early conservative management including loose-loop technique: a case report. Frontiers in Veterinary Science, 2026;13:1907404. Single case; tape and method were not comparatively validated. Full text.
- Talavera-López J, Hernández-Rubio E, Soler M. Swimmer puppy syndrome, pectus excavatum, and cardiac dextroposition in two American Akitas: management and successful long-term outcome. Veterinary Research Communications, 2026;50:481. Two cases with imaging and follow-up. Full text.
- Verhoeven G et al. Swimmer syndrome in a Devon Rex kitten and an English Bulldog puppy. Journal of Small Animal Practice, 2006;47:615–619. Two cases. DOI.
- Gomes LCVM et al. Swimming puppy syndrome in cats. Acta Scientiae Veterinariae, 2015;43:109. Limited feline case series; canine extrapolation should be declared.
- Karcher DE et al. A modified technique for treating swimmer puppy syndrome. Veterinární Medicína, 2018;63:161–167. Support technique described without a comparative trial. DOI.
Dr Xavier Lévy makes his knowledge freely available to improve care. This article helps prepare the consultation; it cannot replace examination of the puppy, its chest and the litter.