Growth and development of kittens

Rat kittens are born as small underdeveloped ‘pinkies’, approximately 2.5cm – 3cm long. They are blind, deaf and naked but certainly not dumb. One of the first signs of their arrival is the high-pitched ‘eeping’ that occurs every time their hold on one of their mothers nipples is disturbed. At birth the doe cleans up the babies, and using her teeth snips off the umbilical cord and placenta, which make a nutritious meal. She should then settle down to nurse the babies. If her milk comes in immediately the babies will quickly develop a white crescent shape on the left of their abdomen. This is called a ‘milk band’ and is the milk in their stomachs, clearly visible through their translucent skin. Sometimes it may take a few hours of suckling before the milk begins to flow properly. So long as your doe is nursing her litter there is really no need to disturb her. Although a doe only has 12 teats she is quite capable of raising much larger litters so long as she is provided with excellent nutritional support.

It is sensible to check on progress 2-3 hours after labour commences (as one would expect labour to be completed in this time, and uterine inertia, or similar problems need to be responded to quickly. At this point one can remove any dead babies and make sure that the doe is not bleeding heavily. She can then be left to settle to nurse the litter. Occasionally a doe will refuse to have anything to do with her new babies. This is usually due to a hormonal deficiency and Oxytocin may help if given quickly. One practical solution that may help is to place the doe and kittens into a ‘show’ tank. Often there is nothing that helps to resolve this rejection and unless a foster mother is found the babies are likely to die. Hand rearing babies who have not suckled at all (and have therefore not received any colostrum) is an extremely difficult task, and most will die.

Initially the doe will spend almost all of her time nursing her new babies. She may only leave the nest for very short periods and this is completely normal. She may also seem not to eat a great deal for 24 hours after the delivery. This is due to the large meal of afterbirths that she has consumed. Some does will also eat any dead babies. When you can coax her off the nest for some tasty food you can take a look at the babies, count them and check them for injury or congenital defects (very rare). You can really begin handling the babies from day one, though at this stage they will easily lose heat and such sessions should be kept very short.

From day one it is possible to tell a number of things about the kittens (though it may take a little practice to get it right!)

Gender - From birth, bucks are distinguishable from does by the longer gap between their anus and urethra. In does this gap is very short, especially in the newborn. Both sexes have a black dot where the cord was attached, and neither have visible nipples at this stage.

Ear set - Within a day or two of birth you should be able to clearly see the ear-flap folded over and adhered to the baby’s head. In a top-eared rat the flap is folded from top to bottom diagonally, like the corner of a folded handkerchief. In a dumbo the flap is folded from back to front. When the ears unfold at around 3-4 days the difference becomes very obvious.

Rex/smooth - Rex kittens are distinguishable from birth as they have curly whiskers.

Eye colour - From birth it is possible to tell which babies will have black eyes and which will have pink/red/ruby eyes. The eye is seen as a slight bulge under the sealed eyelid. A black eyed rat has a visibly black bulge, though diluted black eyed rats (blue, mink etc) usually have a paler black bulge than blacks and agoutis. Ruby/pink eyed rats generally have very little colouration under the eyelid at birth.

By day two the skin of dark coloured babies will begin to darken whilst paler babies will remain pink much longer. Markings on dark rats become clearly visible over the first 5-6 days.

By day three any bruising and discolouration from the birthing process will have gone.

By day four the digits are formed and you will even see nails developing.

By the end of the first week colours are more easily distinguishable, except on very pale babies who will still look pink. In the darker colours agoutis can be differentiated from blacks by looking at their tummies. Blacks are darkening all over while agoutis have pink bellies. Markings will be clearly visible on darker varieties. Mum may begin to spend longer periods outside of the nest. Her own food intake will begin to noticeably increase.

By the end of the second week the babies have grown considerably and are now fully mobile. Their eyes will open around day 14. They will be fully furred and even the paler colours are clearly distinguishable now. The nipples on does will be very visible (while bucks have none) so sexing at this age is quite simple. From this stage they will begin to leave the nest, and also begin to eat solid foods. Weaning takes about 2-3 weeks and most litters are no longer nursing at all by 5 weeks. Each day seems to bring almost visible growth and physical dexterity increases as the babies gradually become baby acrobats. It is very normal at this time for the babies to engage in a good deal of play fighting and romping around the cage, accompanied by plenty of loud squeaking! At five weeks the bucks should be separated from their sisters and mum. Very soon after this they will become sexually mature enough to impregnate their sisters. It is also normal for kittens of this age to become a little flighty (especially girls), which may have some hormonal influence as they approach their first heat. This behaviour will quickly settle with continued gentle handling and re-assurance.

It is best to handle babies daily and allow them to experience a variety of social environments and noises (such as music, TV and hoover). Ideally, they should be handled by children and other people who are not their main human carer. All these things will help them to cope with the huge change of leaving their mum, most of their siblings and all that is familiar when they are six weeks plus.

The environment the family live in can be changed in line with their needs and development. Whilst in the nest they are best kept in a cage with easy access, narrow bar spacing (or no bars e.g. a duna or aquarium). Whatever the cage used they need to be kept draft free, with plenty of nesting material (I use Ecopetbed and Safe bed). Some people use an igloo for the nesting area. I prefer not to use any cage furniture – but allow the doe to construct her own nest to her own requirements. Some does seem to prefer to nest in a small hollow, others build huge impressive ‘dens’. It is best not to include hammocks tubes etc in the cage until the kittens are mobile, as they can easily be carried around the cage attached to a teat, and one left in a hammock or tube can be easily missed by mum and quickly perish.

From about two and a half weeks the babies have the need to practice and improve their climbing skills, and if in a tank this is the time to move them into a narrow barred cage. By three weeks the babies are agile and able to make full use of a cage, hammocks, toys and a gravity water bottle. Try to design your cage so that there is somewhere for mum to escape to that (at least initially) the babies can’t get to. She will also need plenty of ‘time out’ as the demands of her brood increase. By around three and a half weeks the kittens will be large enough to go into a mesh cage (such as Michelangelo) if that is the type of cage you use. Kittens at this age can vary a lot in size so do make sure that the smallest in the litter are too large to squeeze through the holes in the mesh.

With good nutrition kittens will moult into their shiny coats between 5 and 7 weeks. Inadequate nutrition or major stress at this point can delay this process.