Fading Kitten Syndrome: Causes, Symptoms, & Treatment

Fading Kitten Syndrome (FKS) is a condition that anyone who has bred kittens will be aware of. However, it is not a specific illness in the usual sense: rather, there a number of different conditions that can each result in a similar pattern of signs of illness in kittens. It is this pattern of signs that is known as Fading Kitten Syndrome.

What Is Fading Kitten Syndrome?

Fading Kitten Syndrome

Instead of being a specific diagnosis, “fading kitten syndrome” is a general term used when a young kitten falls ill, sometimes leading to death.

There is no specific definition of Fading Kitten Syndrome: in general, this describes any situation where one or more kittens in a litter, aged between birth and three months of age, falls ill, and sometimes dies. The first week of life is the main period of concern, with the period up to weaning (at around 3 – 4 weeks of age) the second most critical time.

An entire litter of kittens may be affected. If one kitten is affected, all littermates should be monitored especially closely. The “fading” process may happen over hours, or sometimes over days, sometimes starting with one kitten then spreading to affect the rest of the litter.

Regardless of the primary underlying cause, the general process of fading has common characteristics, including a falling body temperature, falling blood glucose due to lack of feeding, and general weakness. This leads to a lack of consciousness. Unless successful intervention takes place, the fading process concludes in the death of the kittens.

Identifying the early signs that this syndrome is developing is important so that prompt action can be taken.

What Are The Causes Of Fading Kitten Syndrome?

Person petting a cat who has been sick

Fading kitten syndrome occurs for a variety of reasons, including environmental, maternal, nutritional, and congenital problems.

Fading kitten syndrome has many possible causes, including:

  • Maternal issues. From dystocia (difficulties during kittening) to poor milk supply to poor mothering ability and direct trauma by a mother to her kittens, there are a number of ways that the mother can contribute to a kitten “fading”.
  • Congenital defects. Some kittens are born with anatomical anomalies that are incompatible with normal life. From cleft palates to internal hernias to heart defects to internal metabolic disorders or abnormalities of the immune system, there is a long list of possible problems. Often a kitten may appear to be normal on cursory examination, but as time passes, it becomes obvious that they are not thriving. A closer examination may identify an abnormality with the kitten’s body that explains what is happening. Any kitten that has an unusually low birth weight should be checked particularly carefully.
  • Environmental issues. If the surrounding conditions of young kittens are not ideal, this can lead to poor health that results in fading. Temperature (too high or too low), excessive humidity, too much stress (e.g. over-handling of kittens by owners or visitors, or too much noise), are all possible environmental factors.
  • Nutritional issues. If kittens are not fed correctly, malnutrition can lead to low blood glucose, weakness, hypothermia, and ultimately, fading.
  • Viral infections. Young kittens are often protected from common viral infections by antibodies from their mother’s milk. However, as the kittens grow older and are weaned (usually by 3 – 4 weeks of age), maternally-derived antibody levels in their bloodstream reduced. Without these antibodies, they may become unprotected until they are vaccinated. A wide number of viral infections can affect a litter of kittens, causing them to “fade” around the same time.  Examples include Cat Flu (herpes virus and calicivirus), Feline panleukopenia, Feline Coronavirus, and Feline Leukemia Virus.

Read More: Cat Vaccination Schedule

  • Bacterial infections. A wide number of bacterial infections can affect litters of kittens. These include respiratory infections, such as Bordetella Bronchiseptica, Mycoplasma, Pasteurella, and Streptococcus. Your kittens may experience gastrointestinal infections such as E Coli, Campylobacter, Enterococcus, and Clostridia, along with a number of other systemic infections that can cause generalised sepsis. Good hygiene in the home, especially in the kittening area and den, are the best way to prevent such problems.
  • Parasites. Kittens are commonly infected with roundworms (Toxocara) at birth, or soon after via their mother’s milk, and these can gather both in the intestines, as well as in the lungs, causing serious illness. A serious flea infestation can suck enough blood from kittens to cause anemia, which can also present as fading kitten syndrome. Other parasites such as protozoa (e.g. Giardia, Toxoplasmosis or coccidia) can also cause serious illness in a litter of kittens, again presenting as Fading Kitten Syndrome.
  • Neonatal isoerythrolysis. This is a specific issue that relates to blood type: just like humans, different cats have different blood groups. This condition can develop when a blood type A male cat is mated with a blood type B queen. The queen’s colostrum (first milk) will contain high levels of anti-A antibodies, and some of the kittens will have type A blood inherited via their father. When a type A kitten sucks, it will absorb the anti-A antibodies from the queen’s milk, and these will attack the kitten’s blood cells, causing haemolytic anaemia. Around 90 percent of non-pedigree cats may be type A, but some pedigree breeds (e.g. Persian, British Shorthair, and Devon Rex) may have around 50% type B cats. Cat breeders should check for this condition by stimulating newborn kittens to urinate onto a piece of cotton wool. Affected kittens will have dark red urine, due to blood pigment being passed in the urine. Ideally, the queen and sire should be blood-typed before breeding, and if this is not done, kittens should be blood typed at birth using blood from their umbilical cords. The problem can then be prevented by stopping a type A kitten from sucking a type B queen for the first 24 hours, after which it is usually safe to return them to their mother.

How Is The Cause Of Fading Kitten Syndrome Identified?

As with any illness, it’s necessary to carry out an investigation to make a specific diagnosis. This can involve a DVM veterinarian gathering a detailed history from the cat carer, carrying out careful physical examinations of affected kittens to identify common causes, taking samples for laboratory analysis (eg. blood, urine, faeces), and ultimately, perhaps carrying out autopsies of kittens that have died.

Treatment Options

Treatment of Fading Kitten Syndrome

Treating Fading Kitten Syndrome requires a combination of general supportive treatment and specific treatment of the syndrome’s underlying cause.

If the specific cause of Fading Kitten Syndrome can be identified, then specific treatment can be given (e.g. antibiotics for a bacterial infection, anti-parasite medication for worms or fleas, etc). However as well as this, there are general supportive treatments that are likely to be needed for all cases of Fading Kitten Syndrome.

  • Nutrition. Newborn kittens have very low body reserves to supply them with the energy that they need, so ongoing nutrition is essential, to avoid hypoglycemia (low blood sugar). Cat carers should ensure that queens have a plentiful milk supply, and that kittens are successfully latching on and suckling, resulting in plump, full abdomens. If there are issues in this area, supplementary feeding should be given using kitten milk formulas or feeding solutions that include dextrose. Fading kittens should be supplemented in this way if there are any suspicious that poor nutrition is an issue. The application of karo syrup to the gums is a simple way of rapidly boosting blood sugar levels in a fading kitten.
  • Hydration.  Dehydration leads to weakness and dullness, and can contribute to Fading Kitten Syndrome, so efforts should be made to ensure that all affected kittens are well hydrated. As well as ensuring that they are drinking plenty of milk, supplementary rehydrating fluids may be offered via a bottle, or under veterinary supervision, by tube feeding.
  • Warmth.  A low body temperature is a key part of Fading Kitten Syndrome. It’s critically important to keep neonatal kittens warm, so extra warmth (e.g. by using heating pads and infra-red lights) is essential in the kittening area, as well as in the first few weeks of life. This is important even for healthy kittens: when Fading Kitten Syndrome has been identified, it is even more important to boost the kittens’ chance of survival.

Frequently Asked Questions:

Can kittens survive fading kitten syndrome?

This depends on the cause. If treatment is given at the first sign of a problem (e.g. identifying and focussing on any kitten that fails to gain weight as fast as the other kittens), then the survival rate can be  boosted.

What are the symptoms of fading kitten syndrome?    

The four key signs of fading kitten syndrome are:

1. Low  Body Temperature (<99F or <37.2C). Affected kittens feel cold to the touch.
2. Lethargy. Fading kittens may be unresponsive, do not move around like healthy kittens, and cannot stand up properly.    
3. Vocalizing. Fading kittens may vocalise abnormally, crying or mewing in an unusual way.
4. Difficulty breathing. Fading kittens may make exaggerated breathing movements, or they may gasp.    

Do kittens die suddenly?

Some kittens may die suddenly, but more often, affected kittens will gradually fall ill, over hours or days.    

What is failure to thrive in kittens?

Failure to thrive  means that a kitten is not normally healthy. A healthy kitten should  be strong, active, suckling well, and behaving normally. Any kitten that does not fit this description could be said to be “failing to thrive”. Kittens that fail to thrive can go on to develop Fading Kitten Syndrome.

How do you save a dying newborn kitten?

The three key areas are warmth, nutrition, and hydration. The  safest option is to rush any dying kitten to your veterinarian so that these aspects can be addressed rapidly and professionally.

How can I save my lethargic kitten?

Veterinary help is essential to ensure that any underlying causes of the lethargy are properly addressed.

Why is my kitten sleeping all day?

Healthy kittens can  spend a lot of time sleeping, but this should be interspersed with periods of activity. If a kitten sleeps all the time, it’s safest  to have any excessively sleepy kitten checked out properly by a veterinarian.

Pete Wedderburn DVM

About Pete Wedderburn DVM

Dr Pete Wedderburn qualified as a vet from Edinburgh in 1985 and has run his own 4-veterinarian companion animal practice in County Wicklow, Ireland, since 1991. Pete is well known as a media veterinarian with regular national tv, radio and newspaper slots, including a weekly column in the Daily Telegraph since 2007. Pete is known as "Pete the Vet" on his busy Facebook, Instagram and Twitter pages, regularly posting information on topical subjects and real-life cases from his clinic. He also write a regular blog at www.petethevet.com. His latest book: “Pet Subjects”, was published by Aurum Press in 2017.

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