Possible Effects of the Photoperiod on the Adrenal Gland
 
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  1998

Theories abound as to why ferrets appear to be prone to adrenal disease. If one were to scan the various discussions on this topic on the Internet, one would find the blame placed on a number of different causes. I've been involved in group discussions in which adrenal problems have been attributed to early neutering, Marshall Farms, environmental effects, inbreeding, or diet. There is another possible cause that has piqued my interest over the last year or so, and that is the effects of the abnormal lighting cycle to which we subject our ferrets.

Can we cure our ferrets simply by subjecting them to a more "normal" light cycle?

The light cycle, or photoperiod, is the amount of time a plant or animal is exposed to light in a 24 hour period. This can be daylight, but it can also be artificial light to which our ferrets are exposed by our desire to be able to see in our home at night and not stumble over chairs, assorted ferret toys and even our beloved ferrets. This is not an unreasonable desire, but it can subject our ferrets to 16 or more hours of "daylight" almost every day of the year.

In one issue of the "Ferret Adrenal/Insulinoma Mailing List," an Internet discussion group, Cathy Johnson-Delaney, DVM, speculated that adrenal disease may have some relation to the pituitary-adrenal feedback. The pituitary gland gets turned on due to a long photoperiod, and as a result, the adrenal is super stimulated and becomes hyperplastic [abnormal multiplication of cells] and eventually, neoplastic [a new growth of different or abnormal tissue, e.g. a tumor]. According to Dr. Johnson-Delaney, any tissue which is constantly stimulated over a long period goes hyperplastic, and the more cell cycles and stimulation, the greater the chance for neoplasia. This is particularly true with secreting tissue, such as the adrenal gland.

Dr. Judy Bell, former veterinarian for Marshall Farms, also theorizes that adrenal problems may be due to the abnormal light cycles to which we subject our ferrets. Dr. Bell has proposed testing light amounts and measurements of melatonin, and attempting to keep one's ferrets on an eight hour light cycle.

In relation to melatonin, Jerry Murray, DVM, says that melatonin directly and indirectly controls the hypothalamus-pituitary-adrenal/gonadal axis. During the longer days of spring and summer, the level of melatonin decreases and during the short days of fall and winter, levels increase.

These increases and decreases in melatonin levels cause the seasonal weight increase and decrease, begins and ends the estrus cycle and stimulates the hair follicles to grow hair or cause it to shed.

So what does all this medical talk mean? Can we cure our adrenal ferrets simply by subjecting them to a more "normal" light cycle? Dr. Cathy Johnson-Delaney says, "... most people agree that artificial light cycles can't cure adrenal disease once it's begun."

Also, Jerry Murray, DVM, says that increasing melatonin levels by using a short photoperiod will cause hair growth and weight gain. In the short term, this may look good, but one is not actually curing the ferret. As the photoperiod increases and melatonin levels decrease, signs of estrus and hair loss will re-occur and become progressively worse.

Dr. Murray says an artificially regulated photoperiod is best used in the following instances: After adrenal surgery, when surgery is too risky due to other health concerns, if the owner simply cannot afford surgery, or when the left adrenal has already been removed and the right adrenal has been debulked.

It is interesting to note that ferrets with adrenal problems will often go into temporary remission without any treatment. If you visited our shelter, you would have seen this in Flower, who was totally naked due to adrenal problems. She had a few tufts of hair on her head and on her legs, but was otherwise hairless. A short time later, Flower had spontaneously re-grown all of her hair except for a small spot near the base of her tail. She had received no treatment that would account for this.

The point being, it's often hard to determine if an experimental treatment is the reason for hair growth in ferrets, or if it was simply spontaneous like we saw in Flower. It's not unusual for ferret owners desperate for an answer to jump to conclusions by the results achieved on a few ferrets given an experimental treatment.

So, are we once again jumping to conclusions in hoping that a more natural lighting cycle is the answer? No one knows at this point in time. It's a pretty sure bet that it's not a cure, but a preventative measure at best. It seems that surgical removal is still the best cure for a diseased adrenal gland. The good news is that placing your ferrets in a more natural lighting environment cannot possibly be harmful, and there's no great expense involved. The biggest problem is the difficulty of keeping your ferrets in darkness or very low light levels during the very times you want them to be out and about with you.

 

© Copyright Mike Janke All Rights Reserved.
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