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| You may wonder what this waffle has got to do with Cardigan history.
Well, people, being people, will lay blame when an issue is poorly understood and works on their emotions and maybe their hip pockets. PRA in Cardigans is one such issue. I find some people still become defensive when the subject is mentioned. Others do not know what I am talking about. Therefore, I will explain the problem faced by our Cardigan breeders of the 1960�s as best I can. When PRA was first recognised in Australian Cardigans it must have been horrifying for the breeders. Suddenly they are confronted with puppies going blind and no record of such a disease in the breed. It is distressing to know that a beautiful puppy that you had bred was going to go blind, to say nothing of the anguish felt by the new owners of the pup. Cardigan breeders were faced with a disease that could destroy our lovely breed. The disease was not observed in Cardigans in Britain until the 1960�s, where apparently one in four dogs tested was found to be affected. When or where the mutation to cause the disease occurred, who knows? But it meant the emerging breed in Australia was terribly unlucky. Our timing couldn�t have been worse; just before the disease was observed in the UK, we started to bring Cardigans to Australia!! Of the dozen or so original Cardigans to come to Australia, only about 3 were clear of the disease; 4 were later proven to be carriers and the other 6 or 7 were suspect. The breeders of the day banded together and set out to learn about the disease and eliminate it from their breed. We owe these dedicated people a very great debt. They succeeded in their aim to eradicate PRA from our Cardigans. Until recently the only options available to breeders with PRA in their lines was to either do a test mating to check that a dog that might have PRA in its background was not a carrier of the disease, or to completely avoid lines with any hint of PRA in the background. Neither approach was ideal, test mating is time consuming and expensive and potentially results in PRA affected animals. Avoiding affected lines could mean that some outstanding animals could not be used and that the available �gene pool� was narrowed. This itself could lead to a different set of problems. In the 1960�s these were the only options available. Following is a report from �The Advisory Panel on Heritable Abnormalities� - a panel formed with the cooperation of breeders, specialist vets, both in Sydney and England, The NSW Welsh Corgi Club and The Cardigan Welsh Corgi Association of NSW. PROGRESSIVE RETINAL ATROPHY The disease, P.R.A., has been given wide publicity in recent years, and has been the subject of a careful study by a group known as "The Advisory Panel on Heritable Abnormalities". This Panel was appointed during the latter part of 1966, through a joint resolution of the Welsh Corgi Club of N.S.W. and the then newly-formed Cardigan Corgi Association of N.S.W. The formation of such a standing committee had been recommended by a sub-committee of the Corgi Club, which began preliminary investigations some months beforehand. These investigations began as a result of a claim by some Cardiganshire breeders that P.R.A. was affecting the breed, and several blind dogs were known to exist. Every week in many pure breeds and even in mongrel breeds, puppies are born which are destined to become slowly but surely blind. They are suffering from P.R.A., an incurable, hereditary, but thankfully painless, condition, which is also known as "night blindness". The term "night blindness" has been used because, in the early stages of its development, it is often in the evening or at night that the owner first notices signs of defective sight in the dog. Loss of night vision is followed by gradual loss of day vision, and ultimately total blindness. P.R.A. was given much publicity in 1938 when it was established that the Irish Setter was subject to the disease. A great deal of work was done on the condition, and its transmission, and as a result it was established that the disease was of an hereditary nature, and transmitted by a recessive gene. During the next 20 years the condition was spread very widely through the breed, entirely by the use of carriers for breeding purposes�refraining from breeding with blind dogs did not prevent its spread. Eventually the breed was saved from complete disaster by the implementation of a test-mating and registration programme carried out by the Kennel Club of England. Although never in as serious a position as the Red Setter, the Cardiganshire Corgi is confronted by a similar set of circumstances, and it is hoped that the test-mating and registration scheme devised by the Advisory Panel will prove as helpful to the Cardigan as the Kennel Club's scheme was for the Red Setter. The test-mating scheme is based on the assumption that the condition is transmitted by a recessive gene as was the case in the Red Setter. This assumption is, in turn, based on the results of test matings, pedigree information of blind dogs and the advice of genetic and veterinary experts in this country and in England. To date there is no concrete evidence of the second form of P.R.A. which has the same end result�total blindness�but which is transmitted by a dominant gene, and usually affects the dogs later in life than is the case with the recessive form. This does not mean that it does not exist in the breed, only that it has not been detected with any degree of certainty. The following report was compiled by the Advisory Panel at the end of about twelve months' investigation, breeding test and consultations with the various experts listed in the acknowledgements. It was circulated among the members of the two Clubs concerned, and was favourably accepted by Dr. K. Barnett of Cambridge University, a world authority on the subject. At this point of time the report and proposed registration scheme�details of which may be obtained by contacting the Panel through either of the Breed Clubs mentioned above are being considered by the Governing Council of the R.A.S. Kennel Control, for implementation on a Kennel Control level, in conjunction with the Australian Veterinary Association. If this should eventuate, the scheme will be able to operate on a wider basis than at present, and will result in the faster elimination of the disease from the breed than is possible at the present moment. WARREN HASTINGS. A Report on the Effect of Progressive Retinal Atrophy on the Cardigan Welsh Corgi in Australia PROGRESSIVE Retinal Atrophy (P.R.A.), also known as Progressive Retinal Dystrophy, is a wasting disease of the light sensitive retina of the eye. Its incidence was first observed in the Cardigan Corgi in Australia some eighteen months to two years ago. The study of the extent and effect on the breed was undertaken by an investigating sub-committee of the Welsh Corgi Club of N.S.W. This sub-committee was later to be replaced by the jointly constituted Advisory Panel responsible for the compilation and issue of this report. The members of this joint panel were drawn from the abovementioned club and the then newly formed Cardigan Welsh Corgi Association and was officially titled "The Advisory Panel on Heritable Abnormalities". The disease, P.R.A., is known to have occurred in many pure breeds of dog for 50 years or more, and has also been observed in mongrel breeds. Until its discovery in the Cardigan Corgi in Australia, however, investigating authorities were not aware of its incidence in this breed, and have only recently included the Cardigan in their study of the disease. The incidence of P.R.A. in Cardigans is fairly widespread with known cases of the condition being recorded in England and America as well as Australia, the three countries with any significant breeding stock. Based on pedigree and genetic factors, it is likely that there are affected Cardigans in New Zealand also, but this has not been confirmed. Progressive Retinal Atrophy is a type of blindness which becomes increasingly worse and ends in total blindness. The first symptoms are often noticed in poor light or at night and consequently the term "night blindness" has come into use. Progressive retinal atrophy is a term indicating that it is the light receptive layer of the eye which wastes away progressively and never recovers. The condition is bilateral (i.e., occurs in both eyes) and it is non-painful. There being no form of treatment, total blindness is inevitable. SYMPTOMS The two most obvious symptoms of P.R.A. occur in a dog in which the disease is well advanced. The pupil is dilated to the maximum opening giving the eyes a "glassy-staring" look. There is also a green, or less commonly an orange, glow from the eyes in certain lights due to the dilated pupil and shiny surface of the tapetum lucidem in the back of the affected eyes. These two symptoms occur to a lesser degree in dogs having the disease in its early stages, the amount of dilation and reflection depending on the progress of the disease. In addition to these two symptoms, the Veterinarian can also make use of the following factors in diagnosing the disease. The pupillary reflex to light which, besides being slow, is also incomplete, but may persist to some degree until late in the progress of the disease. By use of an ophthalmoscope, the narrowing of both the arteries and veins in the retina can be detected, the narrowing occurring uniformly along their length. Also the optic disc loses its normal pinkish-grey colour, becoming paler with progress of the disease until it eventually turns white. Owners of affected dogs have first become suspicious when the animal appeared unduly clumsy, bumping into objects in its path, particularly in strange surroundings. Subsequent examination of the dog has resulted in the discovery of the above symptoms. TRANSMISSION To date there is no indication that dietary or infective factors are involved in the transmission of the disease, there being no signs of inflammation or infection in the microscopic examination of eye sections taken from affected puppies. In all cases recorded the dietary conditions of the affected animals were such as to ensure a full and balanced supply of all vitamin and mineral requirements. It has definitely been established, however, that the disease is transmitted by a genetic factor, and this factor is now known to behave in a recessive manner (as summarised later in this report). RECESSIVE INHERITANCE The most important point to be remembered in connection with recessive inheritance is that for a dog to be affected by a condition inherited in this way, both parents must carry the defective gene. Equally important is the fact that although a dog may carry a gene for defective vision, it may not itself become affected, i.e., it is what is termed a "carrier", and is capable of producing progeny which will be affected whilst it remains quite normal. It is not uncommon in uncontrolled recessive conditions to find it by-passing one or two generations before re-appearing. Recessive inheritance leads to three different genetic conditions in the breed which are: (i) The Clear Dog This does not have P.R.A. and all its progeny will be clear provided they are the result of a mating to another clear dog. (ii) The Carrier This also shows none of the symptoms of P.R.A. and will have normal vision; however, it carries the genetic factor causing blindness and may pass this on to its offspring. (iii) The Affected Dog This animal has P.R.A. and all of its progeny will inherit the gene for P.R.A. in some form. INCIDENCE There are at least fifteen known cases of affected Cardigans in Sydney and surrounding districts, although several of them have now in the population, if the condition is recessive. If we place the Cardigan population of Sydney and surrounding areas at 200, then, using the conservative figure of eight affected dogs in 200, it can be shown that at least 35% of the population must be carriers to produce eight affected dogs. However, with the number of known affected dogs standing at fourteen, the proportion is likely to be much higher, and probably at least 50% of the Cardigans in this area are carriers. Although it is difficult to generalise the statements too much, it is likely that similar figures apply to the whole of the Cardigan Corgi population in this country. ERADICATION AND CONTROL There is only one way to eradicate P.R.A. from the breed. This is by a programme of test-mating and selective breeding. The test-mating procedure is used to identify carrier animals and establish which dogs and bitches are clear. Having done this only those dogs proven clear by such procedures should be used for further breeding. Carriers and affected animals should not be used for breeding unless special circumstances make it imperative that they should be used, in which case all progeny used for breeding should be then test-mated. Once proven clear stock is used consistently for breeding, there is no need to carry out further test-matings. There are three variations of the test mating procedure which can be applied for proving the genetic character of the dog. In listing them, reference will be made to test-mating a dog, however, the same applies to bitches which may be test-mated by similar means. Method 1�Male mated with affected Female This requires that the dog of unknown genetic condition be mated with a bitch affected with P.R.A. For a 95% probability that the carrier dog will be detected, at least five pups must be whelped and survive until 12 to 16 weeks of age. If none are affected then it can be said (with 95% certainty) that the dog is not a carrier. However, should one or more of the pups prove to be affected, then the dog is definitely a carrier. This method, whilst resulting in a litter of pups which must all be carriers, has the advantage of speed, especially when test-mating bitches. The alternative methods require much larger numbers of pups, and whilst five is not uncommon for a Cardigan litter, the larger numbers required by other methods would necessitate at least two or three litters. The alternative methods (2 and 3) would require at least 12 to 18 months to clear a bitch, against the much shorter time by this method. Method 2�Male mated with known Carrier Female In this case the dog of unknown condition is mated with a bitch known to be a carrier, either through previous test-matings, or by being the progeny of an affected parent. In order to obtain our 95% level of confidence in detecting the carrier by this method, at least 11 pups must survive to about 16 weeks of age and be found free of P.R.A. Again the occurrence of just one affected pup is sufficient to prove the dog a carrier. Method 3�Male mated with daughters of known Carrier or his own daughter Here at least 23 pups must be raised and examined to obtain our minimum level of 95% confidence in detecting the carrier animal. As with the previous two methods, detection of one affected pup is sufficient to indicate that the dog is a carrier. Of these three methods, Method 1 has the advantage of speed, whilst methods 2 and 3 can result in some clear pups, which, after detection by testing mating methods can, if of sufficient quality, be used for stud and show purposes. For test-mating to be effective as a means of controlling the spread of P.R.A. in the breed, it is necessary that definite diagnosis should be possible at an early age in dogs deliberately examined for this condition. As a result of studies made on litters of Cardigans here in Australia, we are confident that affected puppies can be detected by no later than sixteen weeks of age, and more usually by twelve weeks. Diagnosis is by way of ophthalmoscopic examination by an EXPERIENCED person familiar with the symptoms of the condition. RECOMMENDED PROCEDURE The following course of action is recommended as being the most effective and speedy in bringing the condition under control. Test-mating method No. 1 should be employed at the next season of each genetically indeterminate bitch (untested). The resulting pups should be raised to at least 12 weeks of age by the breeder or under the breeder's supervision. All pups in the litter should be presented for examination by an experienced veterinarian who is familiar with the symptoms of P.R.A. The first examination should be made at eight weeks of age, and all pups should be examined again at fortnightly intervals until at least 12 weeks of age, and older if requested by the veterinarian. In addition the dog being tested should be presented for examination also. At this stage it is recommended that the pups should be examined by either Mr. R. C. Ratcliffe, B.V.Sc., at the Gladesville Veterinary Clinic, or Mr. John Keep, Director of the Veterinary Clinic, Sydney University. Appointment to have the pups examined should be made by telephone prior to attendance at the Clinic. Breeders in other districts are advised to contact the Advisory Pane members through either the Welsh Corgi Club of N.S.W. or the Cardigan Welsh Corgi Association who will attempt to locate suitable veterinary examiners for the purpose. PANEL ACTIVITIES The first task confronting the Panel after its formation was the determination of the nature of the condition with which it had to deal. Although a number of affected dogs had been discovered and breeders generally agreed that P.R.A. existed in the breed, it was necessary to establish two factors beyond doubt. The first of these was to confirm that the condition was of an hereditary nature, and following this, the mode of inheritance involved. Careful examination of the pedigrees of the affected dogs, together with breeding tests, were sufficient to establish the hereditary nature of the condition. The second task of establishing the inheritance mode has been the longest and most difficult part of the Panel's activities. Although the indications that the condition was recessive have been steadily mounting for a long time, it is only recently that confirmation of this belief has been forthcoming from Dr. Bamett in England. In establishing the nature of the condition, electro-retinagram and pathology studies were made on a fourteen weeks old affected pup, the results of these tests being reported to Dr. K. Barnett at Cambridge University, and Mr. R. Bowden, the Director of the Small Animals Centre of the Animal Health Trust in England. Subsequently, a young affected puppy was sent to England for examination, and extracts from reports on this pup, received, from England, can be found appended to this report. As a result of these studies, the disease has been identified as the condition known as General Progressive Retinal Atrophy which is similar to that occurring in the Red Irish Setter, the miniature and toy Poodle and the Cocker Spaniel. However, Dr. Barnett is of the opinion that the condition occurring in Cardigans in England may be different from that occurring out here, and as yet is unable to make any statements on its inheritance mode in England. Note: - Dr Barnett's belief has since been proven to be incorrect. It is the same form of the disease in all our Cardigans world wide. |
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| A Register of Australasian Dogs & Imported Dogs/Semen Tested for PRA |
| A Little History |
| * History cont'd * The Present * Testing |
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| Introduction What is PRA? |
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| A Little History |
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