The Coat
The coat is an excellent way to get an overall impression of how the rats are doing on a particular diet. It reacts relatively quickly to changes as the rats shed and grow new hairs, known as moulting. Hairs shed and regrow at different rates depending on where they are located. The head has the shortest moult period at about 4 weeks, this increases as you move along the rat with the lower back having the longest moult period of around 8 weeks.
This means that besides the first few moults (which you can often see as a line of newer fur travelling along the rats body, or moult mark) most rats don’t have an obvious time where they are moulting as different hairs fall out of sequence with each other. Instead the moult as the new hair is ready to replace the old hair.
It takes a large amount of nutrients to provide all the new hairs and if a rat doesn’t have enough to create the new hair it cannot push the old one out, meaning the rats fur is older than it would ideally be, waiting until it has enough to moult out as normal. This is known as being “stuck in moult”.
When judging your rats coat condition first of all give them a quick stroke, this tidies up the fur a little bit and gives a more reliable look than whatever mischief the rat has recently been up to. The stroking can also be used to get a feel of the rats fur, smooth and shiny fur feels like stroking silk (even in a coarser buck your hand still glides well), a rat that is excessively greasy feels sticky, a dry coat feels fluffy or rough. Once you’ve felt have a good luck, both from above and a side profile, paying particular attention to the fur over the rump.
This means that besides the first few moults (which you can often see as a line of newer fur travelling along the rats body, or moult mark) most rats don’t have an obvious time where they are moulting as different hairs fall out of sequence with each other. Instead the moult as the new hair is ready to replace the old hair.
It takes a large amount of nutrients to provide all the new hairs and if a rat doesn’t have enough to create the new hair it cannot push the old one out, meaning the rats fur is older than it would ideally be, waiting until it has enough to moult out as normal. This is known as being “stuck in moult”.
When judging your rats coat condition first of all give them a quick stroke, this tidies up the fur a little bit and gives a more reliable look than whatever mischief the rat has recently been up to. The stroking can also be used to get a feel of the rats fur, smooth and shiny fur feels like stroking silk (even in a coarser buck your hand still glides well), a rat that is excessively greasy feels sticky, a dry coat feels fluffy or rough. Once you’ve felt have a good luck, both from above and a side profile, paying particular attention to the fur over the rump.
Positive Signs
- Glossy sheen – this is harder to see on rexes and other fur types as their fur texture often presents a matt look (rex, velvet) or can even give a greater shine (satin / lustrous) but a healthy looking rat should have a shine to their coat and once your familiar with different coat types you can get a good feel for it. It should not go so far as the coat looks greasy or wet (unless the rat is satin/lustrous), stroking them will help with this as a good shiny coat is dry feeling not sticky or slick.
- Short neat fur – in some varieties it is normal to have a longer coat e.g. roans, however generally a rats fur should not be excessively long and straggly. It should be shorter over the head and shoulders and be slightly longer over the body but shouldn’t look excessively spiky or fluffy. Guard hairs will naturally be proud of the standard fur in all varieties that have them.
- Soft smooth feel – the coat should feel smooth and soft, this varies significantly from bucks to does, with does having a far softer coat. A bucks coat naturally becomes coarse with increased testosterone (so normally starts changing around 12-13 weeks old and is at its most coarse when hormones peak around 9 months) however a bucks coat will not feel dry or overly greasy when it is stroked, it should flow well under the hand even if a texture can be felt.
Negative Signs
- Dull coat – where a coat lacks shine but doesn't look or feel dry it can be due to a few things. The first thing to eliminate is that there isn't a coat type causing the effect. The next is to look to the diet, a dull coat is commonly caused by a lack of oil or protein in the diet. A lack of oil means that each hair doesn't have the healthy coating of oil it needs to shine, it normally is obvious before more the skin or coat feels dry or dandruff occurs. A lack of protein affects the coat by delaying the natural moult process, meaning the fur is relatively older than it should be. A dull coat can also be caused by a lack of grooming, which can be due to illness or the rat feeling under the weather. Assistance (e.g. brushing the rat) alongside medical attention can really help in this case. A coat can also get dull just before a moult is due, however shouldn't stay this way for long. A dull coat can also be caused by environmental factors such as a lack of humidity in the air, or even stress in the cage. It can be a sign that something is not quite right, either with diet or health. I would always look to eliminate the first two issues before investigating further.
- Dry coat – A dry coat looks dull, but also feels dry to the touch, often the skin underneath or tail will also feel and look dry. It is fairly normal to see white or orange flakes of dandruff in a dry coat. This is often related to dull coat, being a typical step where oil levels in the diet or humidity levels are too low. It can also be a sign that other parts of the diet are off, sometimes protein levels are too high or low, or a rat is allergic or does not get on well with certain elements of its diet (some proteins like sunflower seeds or peanuts are common causes as is too much lactose e.g. from cow’s milk, note many rats are not affected by these issues). I typically start looking into oil content in the diet and check the humidity in the room then tweaking protein and finally looking at higher risk ingredients
- Long straggly coat – This is where hairs in the coat fail to moult out when they are ready, looking long and scruffy. This typically affects guard hairs along the rump most frequently and these hairs are often loose. Lightly pinching them between finger and thumb and gently pulling often sees them come out (should not feel any resistance, if you do they are still attached). This is a sign that they are ready to, but not able to moult. This can be another progression of a dull coat, this time if too little protein is continued for a while.
- Dandruff – This is a sign of dry skin, much like in humans some rats are more prone to it than others It is worth knowing that in bucks the flakes can be coloured orange by the buck grease present on their skin. This condition can be confused with lice, these are small orange rods (the lice themselves, they will generally be moving very slowly along the hair shaft) and small white dots (the eggs, are relatively well stuck to the hair shaft Rats with lice often have out of condition, dry looking and scruffy coat so it is worth checking for this as a precaution as it is easily treated with ivermetcin based products) If you have ruled out lice then the first port of call here is to try adding oil into the diet, then looking into protein balance In some cases this issue can also be caused by a lack of rat personal hygiene, this is more common in older bucks, especially those with HLD. This is mainly due to difficulties grooming themselves and can be helped by using a soft bristled brush to brush them (particularly there rump and hard to reach areas) a couple times a day. It is also well worth having their urine tested for protein content, as it can also be linked to kidney degeneration.
- Greasy coat – this is where on stroking the coat it feels damp, sticky or greasy. It is more common in bucks where the coat may also have a yellowish or orange hue from the buck grease. Whilst it is normal for adult boys to have some orange residue on their skin it should not make there coat feel or look wet. Typically this can be a sign that they have too much, or more often, an imbalance of oils in their diet.
- Rusting – This is where the coat appears to noticeably brown. It normally happens in patches however it’s not abnormal for a rat to have a good proportion of its body covered. As with many coat conditions it is generally more common around the rump area where the fur is older, but also not uncommon on the belly too. It is generally only apparent on dark self-rats like black, Russian blue and mink, as other colours do not show up the change of hue as effectively (note if you suspect rusting on a pale rat look at staining later on). Whilst rusting is a normal part of ageing it can also be down to a copper deficiency, genetic predisposition and over exposure to sunlight. It is always worth checking for a copper deficiency first, as this can be improved and whilst the rusting itself isn’t necessarily harmful copper is responsible for a variety of jobs as well as producing pigment, all of which are important to the rat’s well-being.
Coat related issues that are not "condition" related
- Old Buck Coat – this is where a bucks coat begins to loose guard hairs around its “saddle” area, spreading to the rump. It shows up particularly well in agouti based rats as the loss of guard hairs removes a lot of the darker pigments in its coat, in extreme cases giving an almost hooded effect of true agouti on a sandy brown base. It seems to affect those rats who have had higher levels of testosterone through their lives, so your typical “stud bucks” more than those lower ranking rats and typically occurs any time after they have gone through their peak testosterone phase (around 6-9 months or so). Most old boys will show signs of this as they age which is why it is often associated with old age (hence the nickname) though in reality it can be seen in relatively young rats and doesn’t seem to be linked with overall lifespan. Once this starts there is little that will improve or delay it, though I have found that a small increase in protein can sometimes appear to improve it in the short term, however this may not be good for long term kidney health so I would take it alongside other issues.
- Barbered or chewed coat – this is where a rats coat appears normal but sits unevenly with shorter patches or even small bald spots. On parting the fur you can see it has been trimmed short. This is typically caused by a cagemate or the rat themselves barbering. A rat will typically barber itself on the wrists and forearms and sometimes chest and inner legs. A rat is typically barbered around the head and neck, though sometimes chew marks are evident along the back and rump where a rat has been over zealous in its grooming. This is usually a nervous habit from the rat doing the barbering and whilst there are things worth trying (identifying the source of the rats stress and reducing it) often it is a very difficult habit to break.
- Scabs, bites and scratches – these may make the coat lie unevenly or be revealed on parting the coat to check skin health. These don’t really come under a condition guide but it can be worth looking at a dietary intolerance (see dry coat) once mites and in cage squabbles have been eliminated, though more often there can be a skin infection and a vet visit is needed.
- Staining – this is generally more obvious on pale rats and typically shows itself as red flecked hairs, or a pinkish hue normally around the shoulder area and face. This comes from when the rat grooms itself. A rats salvia (and tears) contain a red pigment called porphyrin. Most of the time when grooming there is not sufficient to stain the coat, but where a rat grooms frequently or something is upsetting its internal health it can produce excessive porphyrin and so stain more obviously. If the rat shows any other signs of ill health it is well worth getting them checked out with the vet. You can also get Porphyrin crusting around the eyes and nose, this is generally a sign the rat is unwell.