Lordosis in cats refers to two very different things depending on context, and the distinction matters. In everyday feline behavior, lordosis is the dramatic back-arching posture a female cat assumes during mating, a perfectly normal reflex. In veterinary medicine, lordosis describes an abnormal inward curvature of the spine that can signal congenital defects, metabolic disease, or structural problems in the chest and vertebrae. One is a sign that your cat is in heat; the other may require X-rays and a conversation with a veterinarian.
The Mating Posture
If you have ever seen an unspayed female cat flatten her front end to the ground, raise her hindquarters, and deflect her tail to one side, you have seen behavioral lordosis. This is a hardwired spinal reflex triggered by estrogen during the cat’s heat cycle. Pressure on the lower back or perineal region activates it almost mechanically, which is why a cat in estrus will sometimes drop into the posture when you stroke her back, even without a male present. The posture holds the pelvis at the correct angle for mating. Male cats do not display it.
The reflex is coordinated by circuits in the lower spinal cord and brainstem. Hormones set the stage, but the actual motor pattern runs on a fairly simple loop: sensory input from the skin and flanks feeds into spinal interneurons, which fire the muscles that arch the lumbar spine downward and elevate the rump. It is involuntary in the same way a knee-jerk is involuntary, though hormonal state determines whether the circuit is “switched on.” Outside of estrus, the same pressure on the back produces no lordosis response. This is why spaying, which removes the ovarian source of estrogen, permanently eliminates the behavior.
For cat owners who notice this posture for the first time, it can look alarming. The cat may vocalize loudly, tread her hind feet, and seem agitated. None of this is painful or abnormal. It is simply the full behavioral suite of estrus. If you are not planning to breed, spaying is the straightforward solution and also eliminates the risk of pyometra and reduces mammary cancer risk.
Pathological Lordosis of the Spine
The medical meaning of lordosis is completely different. A healthy cat spine has gentle natural curves, but when the inward curvature of the thoracic or lumbar region becomes exaggerated and fixed, that is pathological lordosis. Instead of a smooth, flexible arc, the spine dips noticeably inward when viewed from the side. In severe cases, this curvature compresses the chest cavity, crowds internal organs, and puts pressure on the spinal cord itself.
A documented case in the veterinary literature describes a cat with congenital thoracic lordosis spanning from the fifth to the thirteenth thoracic vertebra, accompanied by scoliosis and a flattened sternum.1PubMed Central. Congenital thoracic lordosis and scoliosis in a cat That kind of curvature is present from birth, caused by vertebrae that formed abnormally during fetal development. The degree of curvature in that case was severe enough to be measured at roughly 77 degrees using standard orthopedic assessment methods. Cats with milder congenital lordosis may live comfortably without any obvious signs, while those with more extreme curves can develop breathing difficulties, exercise intolerance, or neurological symptoms in the hind limbs.
Breeds With Higher Risk
Not all cats face the same odds of spinal or thoracic deformity. Bengal cats, for instance, appear to have a breed-related predisposition to thoracic wall abnormalities. A study examining thoracic wall deformities in Bengals found that lordosis, flat chest, and pectus excavatum (a caved-in breastbone) were all frequent findings among affected individuals.2PubMed. Thoracic wall deformity in Bengal cats – Morphological findings and results from a breeder questionnaire These deformities often overlap in the same cat, meaning a Bengal kitten with lordosis may also have a noticeably flattened or sunken chest.
Manx cats carry their own well-known genetic burden. The gene responsible for taillessness in the Manx also affects vertebral development more broadly, and spinal malformations are a recognized consequence. One reported case involved a 15-week-old Manx kitten with a vertebral malformation at T3 that caused progressive weakness and wobbliness in the hind legs due to spinal cord compression. That kitten underwent decompressive surgery and improved.3PubMed Central. Surgical management of vertebral malformation in a Manx cat While that particular case involved a single malformed vertebra rather than a long lordotic curve, it illustrates the broader principle: breeds selected for skeletal traits sometimes pay a price in spinal integrity.
Other breeds with shortened or kinked tails, or with extreme body proportions, may also carry elevated risk for vertebral anomalies, though published case series are less common outside Bengals and Manx cats. If you are buying from a breeder, asking about spinal screening in the breeding line is reasonable for any breed known to have skeletal quirks.
Flat-Chested Kitten Syndrome
Flat-chested kitten syndrome (FCKS) is a condition that shows up within the first few weeks of life and often involves lordosis as part of the picture. Affected kittens develop an abnormal dorsoventral flattening of the ribcage, meaning the chest looks squashed from top to bottom rather than rounded. A case report documented two 18-day-old domestic shorthair kittens that presented with breathing difficulty, a bluish tinge to their gums, heart murmur, abnormal lung patterns, and an obvious flattened thorax.4PubMed Central. Successful correction of flat-chested kitten syndrome in two littermate kittens These kittens also had abnormal crawling, which makes sense: if the chest is compressed and the spine is curving abnormally, normal locomotion is compromised.
The cause of FCKS is not fully understood. Proposed explanations include genetic factors, nutritional deficiencies in the queen during pregnancy, and abnormal positioning in utero. In mild cases, the chest may gradually reshape as the kitten grows, especially with supportive care such as gentle manual reshaping splints. Severe cases can be fatal if the compressed chest prevents adequate breathing or heart function. The condition is more commonly reported in certain breeds, with Bengals and Burmese mentioned in veterinary discussions, but it can appear in any breed including domestic shorthairs as the case above illustrates.
How Vets Diagnose Spinal Lordosis
A veterinarian suspecting lordosis will typically start with a physical examination, feeling along the spine for abnormal curves, tenderness, or muscle wasting. The posture of the cat at rest and while walking offers clues. Cats with significant lordosis often have a visible dip in the topline when viewed in profile, and those with concurrent neurological involvement may drag their hind feet, walk with a swaying gait, or have trouble jumping.
Standard X-rays are usually the next step. Lateral radiographs show the degree and extent of the curve clearly. Measurements like the Cobb angle, borrowed from human scoliosis assessment, help quantify how severe the curvature is. More advanced imaging comes into play when the spinal cord itself is at risk. One case involving fused vertebrae and an intervertebral disc herniation in a cat required MRI to reveal that a disc at the L1/L2 junction was pressing on the spinal cord from underneath.5PubMed. Chronic intervertebral disk herniation associated with fused vertebrae treated by vertebral lateral corpectomy in a cat In that case, the fused vertebrae at L2-L3 were sharing a single bony process on top, an abnormality that X-rays alone had picked up but that required MRI to fully characterize the disc problem beneath it.
CT scans are also used, particularly for surgical planning when vertebral anatomy is complex. The Manx kitten case mentioned earlier used both spinal X-rays and computed tomography to map the malformation before surgery.6PubMed Central. Surgical management of vertebral malformation in a Manx cat For most owners, the practical takeaway is that if your cat is showing back pain, gait changes, or a visible spinal curve, X-rays are the reasonable first diagnostic step and your vet may recommend advanced imaging depending on what those show.
Treatment Options for Structural Lordosis
Treatment depends entirely on how much trouble the lordosis is causing. A cat with mild congenital lordosis that moves around comfortably, eats well, and shows no neurological deficits may not need any intervention at all. The curvature is simply part of that cat’s anatomy, and monitoring over time is sufficient.
When the curve is severe enough to compress the spinal cord or compromise breathing, surgical options exist. Decompressive surgery, where bone is removed to relieve pressure on the cord, has been performed successfully in cats with vertebral malformations. The Manx kitten with spinal cord compression at T3 had a dorsal laminectomy without any metal stabilization hardware and still showed clinical improvement.7PubMed Central. Surgical management of vertebral malformation in a Manx cat In the case of the cat with fused vertebrae and disc herniation, a different surgical approach was used: a lateral corpectomy, which involves cutting into the vertebral body from the side to remove the herniated disc material pressing on the cord.8PubMed. Chronic intervertebral disk herniation associated with fused vertebrae treated by vertebral lateral corpectomy in a cat
For disc herniations specifically, whether or not lordosis is involved, the evidence in cats is surprisingly nuanced. A study comparing surgical and conservative management of thoracolumbar and lumbosacral disc herniations in cats found that conservative management, meaning cage rest, pain control, and physical rehabilitation, may be as effective as surgery regardless of the type of disc herniation.9PubMed Central. Outcomes of surgically and conservatively managed thoracolumbar and lumbosacral intervertebral disc herniations in cats That finding contrasts with the situation in dogs, where surgical decompression is more strongly recommended for severe cases. Cats seem to recover surprisingly well with time and supportive care, though the decision still depends on the individual case and how much neurological function has been lost.
For kittens with flat-chested kitten syndrome, early intervention with external splinting or gentle manual correction has been reported to help reshape the thorax during the growth period when the cartilage is still pliable. The two domestic shorthair kittens in the FCKS case report were described as successfully corrected, suggesting that early detection and treatment matter.10PubMed Central. Successful correction of flat-chested kitten syndrome in two littermate kittens Waiting too long allows the thorax to harden in its deformed shape, making correction much harder.
Telling Normal Posture From a Problem
Cats are flexible animals with a wide range of normal spinal postures. A cat stretching after a nap may temporarily arch its back inward in a way that mimics lordosis. A cat sitting with a slightly sunken lower back is not necessarily abnormal. What you are looking for as a warning sign is a consistent, fixed curve that does not change with position. If your cat’s spine always dips noticeably inward at the same spot whether the cat is standing, lying down, or walking, that warrants a vet visit.
Other red flags include changes in gait, reluctance to jump, hind-limb weakness, dragging of the toes, visible muscle loss over the back or hind legs, and any signs of breathing difficulty. In kittens, failure to gain weight, abnormal crawling, and a chest that looks flat rather than rounded should prompt early veterinary attention. FCKS in particular is time-sensitive because the kitten is still growing, and the window for conservative correction narrows quickly.
One common source of confusion is the “elevator butt” posture, where a cat raises its hindquarters dramatically in response to being scratched at the base of the tail. This is not lordosis in either the behavioral or pathological sense. It is a simple sensory reflex related to a concentration of nerve endings near the tail base. Some cats do it more than others, and it has no clinical significance unless the cat seems to be in pain when the area is touched, which could point to a flea allergy, skin infection, or sacral nerve issue rather than a spinal deformity.
Living With a Cat That Has Mild Lordosis
If your cat has been diagnosed with mild structural lordosis and the vet has ruled out spinal cord compression or progressive disease, the prognosis is generally good. Many cats with minor vertebral anomalies live full, comfortable lives. You may want to make some environmental adjustments: lower platforms and ramps instead of tall cat trees, padded resting surfaces, and keeping your cat at a healthy weight to reduce mechanical stress on the spine.
Periodic rechecks are worthwhile, especially in young cats whose skeletons are still maturing. A curve that is mild at six months could worsen during a growth spurt, or it could stabilize and remain static for life. Your vet can track this with occasional X-rays without putting the cat through anything invasive. Cats that develop new neurological signs at any point, such as sudden hind-limb weakness, loss of bladder control, or reluctance to move, need prompt re-evaluation even if the lordosis was previously considered stable.
Pain management is another area where cats are tricky. Cats are famously stoic and tend to hide discomfort, so you may not see obvious pain behavior even when the spine is causing problems. Subtle signs include decreased grooming (especially of the lower back and hind legs), sleeping more than usual, reduced appetite, and a preference for lying flat rather than curling up. If you suspect discomfort, a trial of veterinary-prescribed pain medication can sometimes reveal a cat that is suddenly more active and engaged, confirming that pain was present even though it was not obvious.
Breeding and Ethical Considerations
For breeders, the presence of lordosis in a kitten raises questions about whether to continue using that breeding line. Because congenital vertebral anomalies and thoracic wall deformities often have a genetic component, breeding a cat with known lordosis risks passing the trait to offspring. The Bengal breed’s elevated incidence of thoracic wall deformity, including lordosis, flat chest, and pectus excavatum, has been documented through both clinical reports and breeder questionnaires.11PubMed. Thoracic wall deformity in Bengal cats – Morphological findings and results from a breeder questionnaire Responsible breeders screen for these conditions and retire affected cats from breeding programs.
The genetics are not always straightforward. In Manx cats, the tailless gene is a dominant mutation with variable expression, and two copies are lethal in utero. One copy produces taillessness but also elevates the risk of spinal malformations along the entire vertebral column. This means even careful breeding cannot fully eliminate spinal problems in the Manx without abandoning the breed’s defining trait, a tension that breeds with extreme skeletal features frequently face. For buyers, asking a breeder whether any kittens in previous litters have had spinal or chest abnormalities is a reasonable and important question.