The term “uterine dysplasia” is rarely used in veterinary literature. Specific congenital abnormalities described in cats include absence of one uterine horn, called aplasia, a unicornuate uterus and segmental aplasia. They are often found incidentally during spaying.
When to see a vet urgently
A congenital abnormality may cause no symptoms, but do not wait at home if there are signs of a possible uterine infection:
- pus-like discharge from the vagina of an unspayed female;
- a swollen or tender abdomen and a subdued cat;
- not eating, vomiting or rapidly deteriorating general condition;
- increased drinking together with obvious signs of illness.
Contact a vet immediately and find a vet near you.
Overview
Uterine dysplasia refers to structural or functional abnormalities arising during foetal development. In cats, these can include absence of a normal uterine cavity, abnormal uterine horns or abnormal development of the endometrium, the uterine lining. Owners often notice a problem only when a cat cannot become pregnant or carry kittens to term.
More precisely, the subject here is a congenital structural abnormality of the uterus. Aplasia means failure of a structure to develop, while hypoplasia means underdevelopment. In segmental aplasia, only part of a structure is absent. In a unicornuate uterus, one uterine horn is absent or replaced by a non-functional band of tissue. These findings do not all affect reproductive ability in the same way.
The uterine horns, cervix and part of the vagina develop from the same paired ducts during foetal life. A developmental disturbance can therefore affect different parts of this system. The ovaries may still develop normally. A congenital uterine defect is different from cystic endometrial hyperplasia, a condition that develops later and can also disrupt reproduction.
Causes
The main causes proposed for uterine dysplasia in cats include:
- congenital disturbances during foetal development
- hereditary factors, with genetic susceptibility in certain lines
- harmful factors during pregnancy, including infections, toxins and medicines
- hormonal disturbances in early foetal development
This list describes possible influences on development, but their causal relationship with uterine aplasia in cats has not been comprehensively established. Congenital does not automatically mean inherited: the abnormality is present from birth, but exactly how it arose may remain unknown. There is no confirmed general pattern of inheritance in cats.
Risk factors
The risk of dysplasia is greater in cats that:
- belong to lines with inherited reproductive system disorders
- were born to a mother who had an infection during pregnancy
- were exposed to toxins or medicines during foetal development
Information about risk factors for uterine developmental abnormalities in cats is limited. In an individual cat, it is generally not possible to conclude that the finding resulted from the mother's infection, medication or a particular exposure. Abnormalities in related cats may justify investigating heredity, but relatedness alone does not prove a specific genetic defect or inheritance pattern.
Main symptoms
Uterine dysplasia has no specific outward signs. It may be suspected because of:
- failure to become pregnant despite regular mating
- abnormal seasons, with infrequent, irregular or unusual cycles
- early miscarriages
- complications during birth
- unexplained infertility
Abnormal seasons are not an inevitable consequence of a missing uterine structure. Both ovaries may be present and functioning even if one uterine horn is absent. The cat may then show normal signs of being in season. A normal season therefore does not prove that uterine structure is normal either.
Infertility has many other causes. Mating timing, failure to ovulate, infections and acquired diseases of the uterus or ovaries can produce a similar situation. Investigation distinguishes failure to become pregnant from pregnancy loss or a problem during birth. An unsuccessful mating alone is not evidence of a congenital defect.
Complications and consequences
Uterine dysplasia can lead to:
- infertility
- inability to carry a pregnancy to term
- difficult births
- an increased risk of uterine infections, including endometritis and pyometra
The potential complications depend on the location and extent of the abnormality. Absence of one uterine horn does not always prevent pregnancy: pregnancies in a remaining, normally developed horn have been described in cats. However, such a case does not show that pregnancy or birth would be safe in every similar situation.
If a section of duct is closed, secretions can accumulate upstream and cause the structure to enlarge. Fluid accumulation and bacterial pyometra are different findings, and fluid alone does not establish infection. Conversely, a serious uterine infection can occur without visible vaginal discharge if secretions cannot drain. Deteriorating general condition helps determine how urgent treatment is.
Diagnosis at the vet
As there are no outward signs, uterine dysplasia may be detected through:
- abdominal ultrasound
- X-rays if developmental abnormalities are suspected
- histological examination of tissue samples when the uterus is surgically removed
- assessment of the history, including repeated pregnancy problems
The point about X-rays needs qualification: ordinary radiographs cannot confirm the entire uterine structure or the presence of every part. Ultrasound helps assess the uterus and ovaries, but the precise anatomy sometimes becomes clear only during surgery and tissue examination. An abnormal band of tissue may look different from a functioning uterine horn.
Assessing the ovaries and kidneys
When a uterine abnormality is found, the positions of the ovaries and the structure of the kidneys are also investigated. An ovary may still be present on the side with a missing uterine horn. Conversely, the kidney on that side may be absent. The presence of these organs cannot therefore be inferred from the uterus's appearance alone. Uterine abnormalities both with and without an associated kidney abnormality have been described in cats.
Ultrasound can examine whether the kidneys are present and assess other abdominal structures. Blood and urine tests complement the assessment of general health and possible other problems. If infertility is the concern, the vet may also investigate the stage of the reproductive cycle using hormone measurements or cytological examination of a vaginal sample. These do not replace structural investigation: they answer different questions.
An incidental finding
In a cat without symptoms, the abnormality may be discovered during routine spaying. The surgical report then records which part of the uterus was abnormal and what was found regarding the ovaries and kidneys. Keep these details for future veterinary visits. Without a precise description, the general term uterine dysplasia does not identify which structure was actually missing or abnormal.
Prevention
As uterine dysplasia is congenital, there is no specific prevention. However, risk may be reduced by:
- avoiding breeding from cats with inherited disorders
- ensuring good nutrition and care for a pregnant cat
- avoiding toxic medicines during pregnancy
- monitoring breeding animals' health through veterinary examinations
Good nutrition and avoiding harmful exposures support a pregnant cat's health, but have not been shown reliably to prevent these uterine abnormalities. Feeding cannot make an absent uterine horn develop after birth either. Breeding decisions require a precise diagnosis and an assessment of the cat's own health. An unknown inheritance pattern should not be presented as either a certain explanation or a guarantee that there is no inherited risk.
What it means for owners
Although uterine dysplasia is rare, it is a possible cause of infertility in cats. Owners planning to breed should consider the risks and seek veterinary investigation if a problem is suspected. When congenital abnormalities are found, spaying is generally recommended to avoid future complications.
Treatment and recovery at home
Treatment decisions depend on the nature of the finding, symptoms and any associated problems. Spaying may be chosen to avoid breeding from an animal with an abnormal reproductive tract or prevent related problems from developing. The aim is not to restore a missing structure to normal. If there is a severe uterine infection, treatment may require fluids and other measures to stabilise general condition as well as surgery.
Both ovaries must be identified separately during surgery: a missing uterine horn does not mean that the ovary on the same side is absent. Remaining ovarian tissue can cause signs of being in season later. Tell the vet if an already spayed cat develops clear signs of being in season again, and bring any previous surgical report.
During recovery at home, keep your cat indoors in a quiet space. Restrict jumping and boisterous activity for the period advised by the operating vet, and prevent licking of the wound with a collar or suitable recovery suit. Inspect the wound and monitor appetite and general condition. Increasing swelling, discharge or sudden deterioration are reasons to contact the practice.
Keep the surgical wound dry and do not apply anything without specific instructions. Do not clean a healing wound with alcohol or hydrogen peroxide, as these can damage tissue and delay healing. Give medication and attend follow-up according to the plan provided. If you cannot administer the medicines or your cat does not improve as expected, ask for clarification of the care instructions.
This material is for information and does not replace veterinary advice. Seek veterinary attention immediately when the first signs of illness appear.
Frequently asked questions
Can a cat become pregnant with only one uterine horn?
It is possible, and such pregnancies have been described in cats. The finding therefore does not automatically mean complete infertility. However, the possibility of pregnancy is not a reason to try breeding without investigating the abnormality and its associated risks.
Is a uterine developmental abnormality always inherited?
That cannot be assumed. A congenital finding indicates an abnormality arising during development, but its cause and inheritance may remain unknown. Family and investigation records can help assessment, but do not establish a particular genetic defect on their own.
Can a cat without symptoms otherwise be healthy?
Yes, the abnormality may be found incidentally. However, the structure of the other reproductive organs and kidneys should also be investigated. Further care depends on the actual findings, not simply a general name for the condition.
This article is for general information only and is not a guide to treatment. If you notice the first signs of illness, contact your vet.
Paw4care editorial team
Sources
- Female Genital Abnormalities of Animals, Merck Veterinary Manual, accessed 2026-11-03.
- Uterine aplasia in Felis catus, University of Sydney, OMIA, accessed 2026-11-03.
- Uterus unicornis and pregnancy in two feline littermates, JFMS Open Reports / PubMed, accessed 2026-11-03.
- Ragdoll Uterus/Kidney Project, University of Missouri, accessed 2026-11-03.
- Infertility in Female Cats, VCA, accessed 2026-11-03.
- Pyometra in Cats, VCA, accessed 2026-11-03.
- Surgical Discharge Instructions for Cats, VCA, accessed 2026-11-03.