Both sexes of gerbil have scent glands and they use them in the same way, to mark their territory, but this is far less important to the females. Males, especially in a large group, constantly mark by rubbing the scent gland on bits of furniture of the cage and can make it very sore, resulting sometimes in tumours. Although females can also suffer from scent gland tumours, it is far more common in males.
Where is the Scent Gland and what does it look like?
The scent gland on an adult gerbil is a hairless oval patch, slightly darker than the skin colour which is on the underside of the animal and runs along the midline of the body. It is easy for owners new to gerbil-keeping to mistake it for a healed wound or tumour, but it is meant to be there and nothing to worry about. Once you have identified the scent gland it is an easy matter to check on it once in a while when handling the gerbil, to make sure that it has not changed shape or colour and that it has no rough patches or bleeding. This may be the start of a tumour. Although females can develop scent gland tumours it is relatively rare. Males will scent mark far more if they are in a large group, so keeping a maximum of two males is the best idea.
Signs to watch out for
A scent gland tumour often starts as a rough spot, not unlike a skin tag. This irritates the gerbil, especially if it is scent marking a lot, and it may bite at it and try to remove it that way. This will cause a localised infection and so you will see not only excessive grooming or nibbling in the area of the scent gland, but also possibly bleeding and redness. On closer examination you may see a lump or rough patch. It is important to take the animal to the vet at this stage, as the tumour can easily be removed and the operation is usually very successful.
Diagnosis and Treatment
Gerbils are very healthy animals as a rule and most owners will never have to take them to the vet. When they do have to be taken, they tolerate it very well and usually do well following surgery. A scent gland tumour is in itself very easy to diagnose but the extent of it needs to be investigated before any intervention. The tumour is usually benign but just occasionally it is malignant and then it is important to remove it before it has a chance to spread to other organs. This is usually a situation where the tumour has to be deemed inoperable and the gerbil is euthanized. Where there has been no spread, or where the tumour is simply a benign adenoma, the removal is of the entire gland. If just the tumour is excised, the chance of recurrence is high. The gerbil does not need the scent gland as such – its loss has no impact on the physiology of the animal as a whole – and so recovery is complete. The only slight drawback is that tumours of the scent gland almost always occur on more elderly animals and so there is obviously a slightly increased risk involved with the anaesthetic and surgical procedure.
Surgery and recovery
A gerbil has an amazingly fast metabolism, so most vets use gas. This way they can adjust the dosage as the operations continues and there is no risk of either the animal waking up or of being overdosed. Usually the wound is closed with dissolvable stitches so there will be the minimum likelihood of the gerbil biting at them; this type of stitch does not ‘pull’ as much as removable stitches as the healing process starts and so irritate the animal less. If it does bite or lick at them as the wound heals, it will be later in the process and less likely to do damage. Even so, the animal will need to have a careful eye kept on it in the first few days after surgery, although a gas anaesthetic leaves the system very quickly, so should give no trouble.
Prevention of Scent Gland Problems
There is no real way of preventing the development of a tumour but it is true that males kept together in large groups do tend to scent mark more and the constant friction on the gland can cause local damage which may predispose to tumour formation. The best way, then, to avoid this issue is to keep males in groups of no more than two. Even in this case, it is far better to have two males from the same litter, as they will tolerate each other very well and will even mutually groom and socialise. If it is essential to introduce another male for some reason – if a single male is lonely, for example – the split cage method must be used or the gerbils will fight and this could be very serious. In the split cage system, the gerbils become used to one another’s smell gradually without actually being able to meet physically. It is vital to monitor the moment when the gerbils meet and regularly for a while, to make sure that the integration has been successful. It is considered impossible to introduce a single gerbil to an established group. The group will have bonded strongly and will simply refuse to accept the newcomer. This is almost certain to spark off excessive scent marking with all of the possible problems that can bring.