Folic Acid Study Further Discussion
Following the April 1996 presentation of our research paper concerning a possible role for high folic acid diet in the prevention of dermoid sinus in the Rhodesian Ridgeback, a great deal of comment and discussion has been generated, both on the Internet and in personal conversation. In addition to sensible, balanced opinions, there has been a good deal of misinformation, misinterpretation, assumption and extrapolation. Several of the points raised should be addressed.
THE AUTHORS ARE NOT QUALIFIED TO CONDUCT SUCH A STUDY ...
JGR is a specialist MD anaesthetist with a research PhD in aspects of canine physiology and pharmacology. FN-G is a university research pharmacologist / toxicologist of ten years standing. Both authors have designed and conducted many research projects and have published widely in the peer-reviewed literature. The design and conduct of this study was well within their capabilities.
THE AUTHORS MUST HAVE A VESTED INTEREST ...
As owners and breeders of RRs our only interest is in the welfare of the breed. Cost of the study was met from personal funds. There was no input of any kind from any outside agency or commercial company. The authors have no personal commercial interest in the matter.
THE STUDY DESIGN WAS FLAWED ...
The ideal study would be to preserve sinus-effected dogs and bitches and to subsequently breed them together repeatedly with and without high folate diets. All offspring would be culled. This might be ethically unacceptable, it would take a long time and would demand enormous financial resources.
The next best design would be a prospective randomised placebo controlled cross-over study with repeated matings of the same breeding pairs. Extensive preliminary enquiry amongst Australian breeders showed that placebo control was unacceptable and repeated matings of the same breeding pairs generally out of the question. The prospective, open, voluntary reporting design, as implemented, was the only viable option.
Given the results of this study the authors believe that any contemplated future study employing a placebo would be ethically unacceptable. It should be noted that the seminal human study (Lancet, July 1991) was terminated by its Overview Committee because its cumulative results clearly indicated the preventative effect of folic acid in relation to spina bifida in man and that further employment of the placebo group was therefore ethically unacceptable.
As 16% percent the incidence of sinus in the Australian study was much higher than is seen in our country. Our incidence is 2-3%. This has been achieved by selective breeding practices...
The Australian breeders who participated in this study are fully conversant with good breeding practice. We believe that the reported incidence of DS was true (why should it be over reported?). This may have resulted from respondents knowledge of the purpose of the study and acceptance of a guarantee of absolute confidentiality reinforced by the authors' medical and scientific qualifications. Breeders may publicly play down the incidence of problems within their litters to preserve the reputation of their kennels.
ALL YOU ARE DOING IS MASKING A BAD GENE ...
Our "perceived risk" figures are very important in this context. There was no correlation whatever between dermoid sinus incidence in litters produced from parents who were themselves unaffected whose own siblings were frequently, infrequently or not at all affected by DS. Given this result it would be impossible to totally "breed out the bad gene". Attempts to do so have had only limited success.
Our suggestion is: There is / are not a gene or genes uniquely present in certain RR individuals which expresses as DS in only those individuals who carry the "bad gene". Rather we hypothesize that all Ridgebacks, as part of the genetic makeup of the breed in its totality, have an inherently deficient ability to absorb, utilise or otherwise employ folate and the process of cellular synthesis in rapidly growing neuroectodermal tissues.
It may well be that the expression of this breed defect differs in intensity in different individuals. There may be genetic modifiers in certain individuals. It has to be remembered that all pups in a litter are not genetically identical. They are genetically similar. These are multi-ovular conceptions resulting in litter mates which are all different one from the other. Obviously some can handle folate better than others.
Our results indicate that Ridgebacks as a group need more dietary folate than other breeds. That a potentially lethal congenital condition can be substantially prevented by the simple expedient of a high vegetable folate diet for the brood bitch or, if this is impractical, the supplementation of her normal diet either continuously or before and during pregnancy with tiny amounts of an essential non-toxic water soluble B group vitamin indicates that all RR breeders should consider adopting one of these methods.
If a particular breeder has had no problem with DS it may not be entirely due to selective breeding. Such a person might like to calculate the folate content of their bitches' existing diet and might find that this content is already high. Lists of average folate contents of common footstuffs are available from all medical and public heath agencies who deal with the help of mothers and babies. It should be noted particularly that (a) if the bitch is not on a high natural folate diet supplementation must commence before the time of mating and be continued well into the pregnancy; (b) vegetable folate is destroyed by prolonged heat.
WHERE CAN I GET FOLIC ACID TABLETS FROM AND HOW MUCH DO THEY COST?
Folic acid tablets 5 mg (one brand is Megafol 5) are available from any pharmacy without prescription. Just tell the pharmacist what you want them for. They are quite cheap at $3 - $4 Australian per 100 tablets.
