It’s not uncommon for litters of kittens to have size variations. There are a few possible reasons why one kitten may be smaller than its littermates:
Prematurity
If a kitten is born prematurely, before the full 63-65 day gestation period, it may be significantly smaller than kittens born at term. Premature kittens have not had as much time to develop and grow in the womb. They are often underweight and weaker than other kittens in the litter.
Illness or Genetic Defect
Certain illnesses or genetic conditions can inhibit a kitten’s growth in the womb. Kittens with birth defects affecting bone development or organ function may be undersized. Viral infections during pregnancy, such as feline panleukopenia, can also cause stunted growth.
Low Birth Weight
Even kittens born at full term can have low birth weights. If the mother cat was malnourished or ill during pregnancy, kittens may be born smaller. Large litter sizes can also result in some kittens getting less nutrition in the womb and having lower birth weights.
Failure to Thrive
In some cases, a newborn kitten is normal sized but then fails to grow at the same rate as littermates. This “failure to thrive” could be caused by illness, a congenital defect, or inadequate access to milk.
Maternal Neglect
If the mother cat rejects or does not properly care for a kitten, it may become dehydrated and underweight. Lack of grooming and attention from the mother can impair a kitten’s health and growth.
Competition for Milk
Kittens often have to compete for access to the mother’s milk supply. In large litters, smaller or weaker kittens may have trouble competing with bigger siblings for nursing time. This can result in the smaller kitten getting less milk and poorer nutrition.
What to Do
Here are some tips if you have a kitten that is significantly smaller than its littermates:
- Weigh the kitten daily and track weight gain. Normal kittens gain about 4-8 oz per week.
- Supplement with bottle feeding if the kitten seems to have trouble nursing.
- Keep the kitten warm and hydrated since small kittens have difficulty regulating body temperature.
- Have the kitten examined by a vet to check for any medical issues.
- Ensure the kitten can access a “milk bar” for uninterrupted nursing time.
With dedicated care and attention, many undersized kittens are able to thrive and catch up to their littermates over time. However, some may continue to be smaller than average throughout life due to premature birth or congenital conditions. As long as the kitten is healthy and developing well, size difference alone is not necessarily a cause for concern.
Typical Kitten Growth Rate
To understand why one kitten may be smaller, it helps to know the average growth rate for newborn kittens:
| Kitten Age | Average Weight |
|---|---|
| Birth | 3.5 oz (100 g) |
| 2 weeks | 7 oz (200 g) |
| 4 weeks | 14 oz (400 g) |
| 6 weeks | 1 lb (450 g) |
| 8 weeks | 1.5 lbs (680 g) |
| 3 months | 2 lbs (900 g) |
| 6 months | 3.5 lbs (1.6 kg) |
Kittens should double their birth weight by around 2 weeks old. They gain about 4-8 oz per week from weeks 3-8. After 8 weeks, kittens continue to gain weight but at a slower pace. If one kitten lags behind this normal growth rate, it indicates an issue.
Risks of Being the Smaller Kitten
Undersized kittens may face the following risks:
- Hypothermia due to inability to regulate temperature
- Dehydration from inadequate nursing
- Malnutrition without supplemental bottle feeding
- Greater susceptibility to illness
- Developmental delays
- Higher mortality rate
The first few weeks are the most critical time. With dedicated care and nursing, many small kittens can catch up and overcome their shaky start.
Is the Small Kitten Getting Enough Milk?
Signs that the smaller kitten may not be getting adequate milk:
- Weight loss or failure to gain weight
- Little interest in nursing
- Smaller belly after nursing
- Crying or meowing from hunger
- Weakness, lethargy, inability to stand
To help the kitten get more milk:
- Allow uninterrupted nursing time
- Gently massage the mother’s mammary glands to stimulate milk flow
- Try allowing the small kitten to nurse from just one or two nipples
- Supplement with bottle feeding after nursing
Is the Mother Cat Providing Adequate Care?
Signs of maternal neglect:
- Ignoring the kitten’s cries
- Failing to nurse or groom the kitten
- Showing aggression toward the kitten
- Pushing the kitten away from milk bar
If you observe signs of rejection or inadequate care from the mother toward a smaller kitten, consider stepping in to provide supplemental care such as:
- Bottle feeding with kitten milk replacer
- Keeping kitten warm with heated pad, incubator, or your body
- Gently massaging kitten with warm cloth to stimulate bowel/bladder
- Weighing daily and tracking weight
It may also help to temporarily separate the mother and kitten and reintroduce them slowly later.
Should You Supplement Feed the Small Kitten?
Supplemental bottle feeding is recommended if:
- The kitten is crying hungry after nursing
- Weight gain is inadequate or weight is being lost
- The belly does not feel full after nursing
- The kitten seems too weak or tired to nurse
Use a kitten milk replacer formulated for supplemental feeding. Feed after the kitten nurses for best results. It’s ideal to use a small pet nursing bottle. Feed slowly and gently, stopping if the kitten starts coughing or sputtering. The amount depends on age and weight, usually around 2-10 ml per feeding.
Providing Warmth for Undersized Kittens
Small kittens have difficulty regulating their body temperature. To prevent hypothermia:
- Keep kitten’s bed or box in a warm, draft-free spot
- Place heating pad under half the bedding on low setting
- Insulate bed or box with towels or blankets
- Use incubator designed for newborn kittens
- Tuck kitten inside your shirt for direct body warmth
Monitor the temperature to ensure the kitten does not overheat. Rectal temperature should be 95-99°F when the kitten is sleeping or resting.
Caring for a Premature Kitten
Here are some tips for caring for a premature kitten:
- Feed kitten milk replacer – they may lack suckle reflex
- Bottle feed every 2-3 hours, even overnight
- Stimulate bowel/bladder with warm cloth after feeding
- Keep kitten in incubator or other warm spot 24/7
- Weigh and track weight daily – aim for steady gains
- Have vet examine for any medical issues or special needs
Preemies have a higher risk of health problems. Patience and dedicated around-the-clock care in the early weeks gives them the best chance to thrive.
When to See the Vet
See a veterinarian promptly if the undersized kitten shows any of the following:
- Failure to gain weight for more than 1 day
- Weight loss or dehydration
- Difficulty breathing, coughing, or nasal discharge
- Fever, lethargy, vomiting, or diarrhea
- Crying non-stop and unwilling to nurse
- Abnormalities like cleft palate or leg deformities
Veterinary examination and testing can identify any health issues requiring treatment. The vet may recommend supplemental feeding tips specific to the kitten’s needs.
Long Term Outlook for Small Kittens
The long term outlook depends on the specific reason for the kitten’s small size:
- Prematurity: Prognosis is good with dedicated neonatal care in early weeks.
- Illness/defect: Depends on underlying condition – some kittens overcome problems and catch up.
- Inadequate nutrition: Can fully recover with consistent supplemental feeding.
- Low birth weight: May remain smaller than average but still healthy.
While challenging at first, most undersized kittens can go on to lead normal, healthy lives. With lots of TLC in their critical early weeks, they can defy the odds and thrive.
Should You Keep a Small Kitten Separate from the Others?
Factors to consider when deciding whether to separate an undersized or weak kitten from the litter:
- Risk of being pushed away or accidentally smothered by larger siblings.
- Needs more frequent feedings than the rest of the litter.
- Vulnerable to catching illnesses from the others.
- May benefit from supplemental feeding, warmth from incubator.
- Separation may cause stress and deprive kitten of learning social skills.
If possible, keep together but provide separated “milk bar” and bed in same room. Otherwise, separate for short periods each day and reunite when feeding and playing.
Advantages of Separating Kitten
- Allows focused care and feeding on kitten’s schedule
- Reduces risk of injury from rough play
- Prevents deprivation of milk access
- Lets you closely monitor eating and elimination
- Keeps kitten warm and stable without litter disruption
Disadvantages of Separating Kitten
- Isolation stress without littermates nearby
- Misses out on important social learning
- Harder for kitten to stay warm alone
- Mother’s milk production may decrease
- Requires more hands-on care from you
Weigh pros and cons based on the kitten’s age, condition, and needs. As kitten gets older and stronger, aim to reintegrate into the litter.
How to Help a Small Kitten Develop and Grow
Here are some tips to help an undersized kitten develop and grow optimally:
- Ensure kitten stays warm – they cannot regulate temperature well
- Bottle feed kitten milk replacer if nursing is inadequate
- Stimulate urination/bowel movements with warm cloth
- Give uninterrupted access to mother’s milk if possible
- Weigh daily and keep detailed records of weight gain
- Provide proper nutrition once weaned – high calorie kitten food
- Check for developmental milestones like crawling, walking, teething
- Give treatments or supplements as advised by your vet
- Give lots of affection and comfort – DON”T overlook stimulation
With dedicated supplemental care and monitoring in the first few weeks, many small kittens overcome early disadvantages and develop into strong, healthy cats.
Frequently Asked Questions
Why is my newborn kitten not gaining weight?
Possible reasons a newborn kitten may fail to gain weight normally:
- Not getting enough milk from mom
- Underlying health issue or birth defect
- Premature birth
- Inadequate care from mother cat
- Unsanitary living conditions
Weigh the kitten daily and track progress. Supplement feed if needed. Have a vet examine kitten to identify any medical problems requiring treatment.
How can I get a small kitten to eat?
Tips for getting a small, underweight kitten to eat:
- Bottle feed kitten milk replacer if not nursing well
- Hand feed wet kitten food warmed to room temp
- Choose calorie-dense, high protein foods
- Offer food frequently, like every 2-3 hours
- Gently rub food on kitten’s lips to stimulate appetite
Get advice from your vet on diet, feeding techniques, and supplements to help kitten gain weight.
Is my kitten supposed to be this small?
Kittens can vary in size, but extreme smallness could indicate a problem. Check kitten’s weight and growth rate compared to averages. Discuss any concerns with your veterinarian. With focused care, many undersized kittens can catch up developmentally.