Further to your correspondence dated 25/3/15 the National Bull Terrier Council (Australia) (NBTCA) would like to proceed with a Litter Registration Limitation (LRL) for the Bull Terrier (Miniature) (BTM) in respect to Primary Lens Luxation (PLL).

The adoption of this LRL is seen as an essential measure for the further improvement in the health of the BTM and evidence that the NBTCA together with the Australian National Kennel Council (ANKC) take health and welfare of the breed and hereditary issues very seriously.

To comply with your Regulation Part 6 Clause 18:19 please refer to the information below for consideration of the National Health & Wellbeing Committee to introduce a LRL to ensure screening of PLL prior to animals entering the breeding program.

(I) Disease Description

PLL is a painful and potentially blinding inherited ocular condition. PLL describes the displacement of the crystalline lens from its normal position within the patellar fossa of the eye. This is caused when the zonular fibres which support the lens breakdown or disintegrate, causing the lens to fall into the wrong position.

Should the lens fall into the anterior chamber of the eye it may result in glaucoma and loss of vision in the eye through obstruction of the pupil or the filtration angle.

PLL is invariably bilateral, although a period of several weeks or months might separate luxation of the two lenses.

The condition is well documented to affect many breeds, particularly terrier and terrier-type breeds. In breeds that have been studied in depth the condition has variable age-of-onset of between three to eight years.

(ii) Severity of the Disease

PLL is considered to be a medium to highly severe disease*as untreated dogs will often become blind. When the lens collapses it causes a painful pressure to build in the eye

Treatment Options:

PLL is not considered a fatal disease but does greatly impact the health and quality of life of an affected dog. Although the disease is not fatal the severity of the pain, prohibitive cost of surgery, potential complications and difficulty of surgery in the BTM and cost of life long treatment often results in the dog being euthanized.

(iii) Mode of inheritance

The mode of inheritance is Autosomal Recessive as published in the following document:

http://benthamopen.com/contents/pdf/TOGENJ/TOGENJ-5-7.pdf

CLEAR: these dogs have two normal copies of DNA and no copy of the PLL Risk Allele. Our research has demonstrated clear dogs will not develop PLL as a result of the mutation we are testing for, although we cannot exclude the possibility they might develop PLL due to other causes, such as trauma or the effects of other, unidentified mutations.

CARRIER: these dogs have one copy of the mutation (Risk Allele) and one normal copy of DNA. Our research has demonstrated that carriers from have a very low risk of developing PLL. The majority of carriers do not develop PLL during their lives but a small percentage can or do.

This has been particularly noted for the Miniature Bull Terrier during our study and is also suggestive in the Lancashire Heeler. For Tibetan Terriers our study did not show any evidence to suggest that carriers will develop PLL.

For the Miniature Bull Terrier we estimate that between 2% and 20% of carriers will develop the condition, although we believe the true percentage is nearer to 2% than 20%. We do not currently know why some carriers develop the condition whereas the majority do not, and we advise that all carriers have their eyes examined by a veterinary ophthalmologist every 6- 12 months, from the age of 2, throughout their entire lives.

GENETICALLY AFFECTED: these dogs have two copies of the mutation (Risk Allele) and will almost certainly develop PLL during their lifetime. We advise that all genetically affected dogs have their eyes examined by a veterinary ophthalmologist every 6 months, from the age of 18 months, so the clinical signs of PLL are detected as early as possible throughout their entire lives. *

(iv) Statistical Information:

Worldwide: Bull Terrier (Miniature): 1184 clear, 1203 carrier, 189 affected

Australia: Bull Terrier (Miniature): 244 clear, 242 carrier, 16 affected

As you can see from these statistics it is important for the continued improvement in the health of the breed not only for the animals in the breeding program but for the sale of animals to the public that wish to have a Bull Terrier Miniature as their family pet.

(v) Desired Breeding Strategy

The initial indications from the research that has been completed indicates that removing carrier and affected BTM’s from gene pool and only using clear dogs will have a serious impact on the genetic diversity of the breed and may place the breed at risk of being affected by other hereditary diseases common to the breed.

To ensure improvement in any future breeding program it is the recommendation of the NBTCA that as a prerequisite for the registration of a litter on the ANKC Main Register both parents (Bull Terrier (Miniatures)) must be DNA tested for Primary Lens Luxation and at least one parent must be assessed as clear. This LRL should be introduced for all Bull Terrier (Miniature) litters born on or after the 1st January 2017.

Permissible matings would be as follows:-

Ø  Clear to Clear

Ø  Carrier to Clear

Ø  Affected to Clear:

Litters which do not meet the above requirements will only be able to be placed on the Limited Register and will be flagged not to be upgraded.

It is intended that carriers are not bred indefinitely but rather are gradually removed from the gene pool as the percentage of clear animal’s increases.

(vi) Conclusion

The NBTC supports the ANKC’s focus on health and well being as well as the approach to modern dog breeding principals and responsible ethical breeding.

As the DNA PLL test is the first available for our breed it gives us the opportunity

to create a controlled disease and breeding plan that will, over time, allow us to remove this painful ,blinding hereditary disease from our breed completely. Enabling breeders of today and the future to produce healthier pure bred puppies.

The DNA test is affordable and easily accessible to breeders everywhere in Australia and worldwide. There are DNA Testing Laboratories in most states and Orivet, Genomic Diagnostic and Petnetwork provide PLL testing locally within Australia. The testing process is non invasive, only a simple buccal cheek swab is required.

At present this DNA sample can be collected by either the dog owner, a licensed tester or a Veterinarian. The recommendation would be for these DNA samples to be completed by either a licensed tester or a Veterinarian. This would ensure the validity of the sample collected the microchip is verified and recorded on the official paperwork when the sample is being taken.

It should be noted that blood and semen samples may also be used to conduct the DNA PLL Test if required.

(vii) Further Information, References and Resources

Animal Health Trust - http://www.aht.org.uk/cms-display/genetics_pll.html

As per your correspondence please find attached a copy of the draft survey for your consideration, review and approval.