Rats can lose their hair for several reasons; they may have a parasitic infestation in which case the resulting scabbing or drying of the skin can cause the hair to fall out; they may have an allergy causing contact dermatitis; they may be on the wrong diet, as too much protein has the side effect of hair loss, or they may be ‘barbering’, or over grooming themselves.
If a rat over-grooms itself this is called ‘barbering’ and it results in hair loss in very precise places, as the barbering is a behavioural thing, very much a habit and can be for comfort or because the rat it bored. Most of the time this behaviour will be very noticeable as the rat becomes very absorbed in the habit and will tend to indulge in it at odd moments or sometimes for hours on end. It involves the ‘scissoring’ movements common in normal grooming, but taken to excess. If the rat is self-barbering, the most common areas for hair loss are the front legs and stomach, in other words, the most easily accessible places.
Sometimes in a group of rats one is a barber and also does it to other animals. When this is happening, the incidence of baldness on the other animals is mostly on the head, face, neck and shoulders. The patches are randomly shaped and are not harmful; most rats don’t mind being barbered and unless the rats are intended for show there is no real need to do anything about it, although giving the rats more to do in terms of toys or a larger habitat might minimise it. It’s a bit like a human nail biter, though; an easy habit to pick up, not so easy to break! If the patches are as above and there are no accompanying scabs or scratches, the reason is almost always barbering.
Parasites causing hair loss
If your rat has scabs on its skin, or it is scratching uncontrollably, it may well have mites or lice. Theses parasites do not cause the hair to drop out in themselves, but the constant scratching will damage the hair, causing it to break, drop out and fail to regrow. There are many washes and treatments for lice and mites and in very bad cases the vet will probably administer invermectin; this is available on prescription only, can be expensive but is the treatment of choice for mites. Some fungal infections can cause hair loss; in particular the ‘ringworm’ effect where the hair falls out in a circle. There is no worm involved in ringworm despite its name and a treatment with an anti-fungal wash will usually clear it up with no permanent damage to the coat.
Some bedding has very high quantities of volatile oils – spruce and cedar woodchip or sawdust being the worst – and rats are often allergic to it. If this seems to be the problem a change of bedding will often do the trick. Like the parasite problem, the hair loss is not directly caused by the allergic reaction, but by the ceaseless scratching that the dermatitis causes. If the affected rat likes bathing – and many do – a bath in a proprietary shampoo will give quick relief until the skin starts to recover. Unless the scratching and scabbing has caused scarring, the hair will regrow to its previous quality very quickly. It is best to avoid bedding which may cause allergies and go for a neutral paper or something similar.
Allergies are not always from bedding, rats can also be allergic to certain foods. It is not an easy task to identify what this might be unless a new food has been introduced at around the same time as the allergic reaction. It may require the rat to be taken back to a diet of brown rice to clear the system, after which one foodstuff at a time can be reintroduced until the reaction recurs.
The effect of diet on hair loss
Many owners feed their pet rats a diet far too high in protein, thinking that they are doing the best for the animal. This is not in fact the case, as a diet too high in protein can cause scabbing and hair loss around the neck and shoulders particularly. A fatty diet will do the same although ironically a diet too low in fatty acids will also cause scabbing and hair loss. Nutrition is a bit of a minefield and it is difficult to remember the difference between fats and fatty acids although in fact they are not the same things at all. Bearing this in mind, it is better to stick to a proprietary rat food, such as can be obtained in a pet shop or animal feed shop.
Plenty of fresh fruit and vegetables to bulk the diet out and provide as many fresh vitamins as possible is also a good plan and a vitamin supplement should also be given; good practice for any small caged animal. This reason of hair loss is often quite difficult to pin down, as the owner is convinced that their pet is well nourished because it has ample food and is well cared for. This is one of those times when less is certainly more and feeding a diet lower in protein and fat will soon show a marked improvement with hair loss being minimised very quickly. To help the rat through the regrowth period, a conditioning shampoo would be a great help.
Rats suffer from hair loss when under stress, whether from nervous barbering or simply loss of condition generally. If the rat goes off its food from the stress of loss of a cage mate, a move, the introduction of another rat into the group, bullying or any other reason, the diet will become unbalanced and hair loss will result. If the rat is stressed and its immunity drops, then it could fall victim to opportunistic infections of the skin, which will also result in hair loss.