By Julian Barker
This article first appeared in the June 2001 issue of the NGS Journal.
One small problem in gerbils is almost never discussed. That is seizures, or as they are more commonly called, fits. These seizures usually result from some form of stimulation, for example, excessive handling, being placed in a new cage or tank.
There are two main types of seizure. The first and less serious involves the gerbil freezing. It will appear to simply stare into space whilst standing low on all four legs. If picked up the gerbil will appear floppy and lacking in normal muscle control. This may last for no more than a minute or two, although it can last longer. The more severe type of seizure will involve the gerbil twitching with a series of violent muscular contractions that will last a few seconds, but rarely longer than half a minute. This more violent type of fit will usually lead to a period of about ten minutes when the gerbil will appear to be suffering from the first type of seizure. Although you will probably not notice it, scientists have discovered that in the days following a fit a gerbil will be more active than usual.
Both types of fit are usually harmless. Fits that cause damage or are in other ways serious are extremely rare. The warning signs of problems are if the gerbil does not come out of the first type of fit for an excessive period of time, or in the case of the second type, if the jerking goes on for more than a minute, if there are repeating bouts of fitting without the gerbil seeming to recover there is probably a cause for the fits such as brain injury.
If none of these occur then simply leave your gerbil in a quiet dark place for a few hours for it to fully recover. If there are danger signs there is probably little you can do. However, remember that these problems only happen in an extremely small proportions of gerbils that suffer seizures.
Most gerbils that have seizures are very young. Five or six weeks old is typical. In nearly all cases the tendency to fit reduces as the gerbil ages. Whilst fitting in juvenile gerbils is common, in adults it is fairly unusual unless they started seizures when young. Notwithstanding this almost all gerbils that fit will grow out of it.
Interestingly, there is evidence that at least some gerbils inherit the tendency to fit from their mothers. Whether this is inherited genetically, or whether it is the result of some maternal behaviour that is copied by offspring and triggers seizures later in life is not fully established, although there is evidence showing that both probably influence the susceptibility to fits. Regardless of the mode of transmission, scientists have managed to breed strains that are more likely to fit and those that are less likely to, so it is a good idea not to breed from any gerbil that suffers from seizures.
Scientists have studied the differences between seizure prone gerbils and those that are more resistant to seizures. They have found that seizure prone gerbils spend far less time in social activity, including scent gland marking, and aggressive behaviour than non-sezure prone gerbils.
Scientists have also looked at whether colour affects the tenancy to fit. The scientists used strains bred for seizures so their results may not be significant for your gerbils, but they found that when compairing Golden Agouti, Argente Golden and Black gerbils, that Argente Golden ones suffered shorter seizures and that the seizures were less severe.
So why are scientists so interested in these seizures in gerbils? Gerbil seizures are very similar to the epileptic fits suffered by humans and other mammals. They even respond to the same drugs. Because it is possible to breed strains that are very prone to having fits, and because such strains can be encouraged to suffer seizures more or less to order, these gerbils are an important part of epilepsy research aimed at understanding the causes of epileptic seizures and the treatments that can prevent them.
There are some suggestions that fitting may have an evolutionary advantage in that it may confuse predators, however I am sceptical about this myself.
The important thing to remember is that seizures in gerbils are rarely a serious problem. Simple peace and quiet will usually promote a quick recovery, and when not fitting, susceptible gerbils will act the same as any other gerbil.
EPILEPSY AND BEHAVIOUR OF THE MONGOLIAN GERBIL: AN ETHOLOGICAL STUDY: Cutler, M.G., Mackintosh, J.H., 1989, Physiology & Behavior, 46(4), 561-6
INFLUENCE OF COAT COLOR GENES ON SEIZURE BEHAVIOR IN MONGOLIAN GERBILS.: Gray-Allan, P., Wong, R., 1990, Behaviour Genetics, 20(4), 481-485
EFFECTS OF FOSTERING ON SEIZURE ACTIVITY IN THE MONGOLIAN GERBIL: Kaplan, H, 1981, Developmental Psychobiology, 14(6), 565-70