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|Spanglefish Gold Status Expired 18/11/2017.|
THE BASSET HOUND EYE IS...
A diamond configuration.............Originally, this shape was produced by huntsmen to ensure that, if the hound’s eye was caught in undergrowth, it did not rip but had some “give”. There are very few breeds where this diamond or lozenge shape occurs and great care must be taken by breeders to ensure that excessive skin/wrinkle is not produced resulting in a “loose” eye.
The first two undernoted conditions, although rarely occurring, may arise from time to time, due to excesses or looseness of skin around the head area, or from too much haw. The third condition is caused by a prolapse of the gland situated under the third eyelid.
These conditions are not unique to the Basset Hound as they are just as likely to be found in any pedigree breed or cross breed. It is useful, though, to know what they look like and what can be done.
Conformational defects may result in an inward-rolling of the lower and/or upper lids. Head conformation and structure as well as weight and amount of skin wrinkle also play an important role in this condition.
Breeders must look to conformation that minimizes the likelihood of occurrence of lid deformations. Canine lower lid entropion may be secondary to chronic conjunctivitis which sometimes turns out to be allergic. Other irritating causes may lead to spastic entropion.
In the older Basset Hounds, and some other breeds, the skin of the forehead may become flaccid leading to upper lid entropion.
Whenever lid deformation leads to irritation, surgical correction is usually necessary.
This condition is an outward rolling of the eyelid and in Breeds with loose skin the lower lid may droop thereby exposing conjunctiva, leading to chronic conjunctivitis. If chronic irritation is clinically noted, simple surgical correction of the temporal lower lid is indicated.
Hypertrophy/hyperplasia of the nictitans gland - Cherry Eye is a prolapse of the third eyelid gland. This is seen most commonly in younger dogs. It may present in one eye initially but the condition can become obvious in the other eye within a short period of time.
Cherry eye surgery is challenging in large breed dogs as these dogs often have a prolapsed third eyelid gland, and perhaps overly-wide third eyelids.
Prolapsed glands should be replace surgically. Keratoconjunctivitis sicca (Dry Eye) - KCS rarely but occasionally follows surgery. KCS is a lackof ability to produce tears resulting in dry eyes.
CONJUNCTIVITIS – Sometimes described as Pink Eye or Red Eye.
The conjunctiva and cornea are subjected continuously to noxious environmental agents such as wind, dust and pollen, and infectious agents such as viruses, bacteria, and fungi. For these reasons, the conjunctival sac is usually non-sterile. There are efficient defence systems such as the tear film, the reticuloendothelial system, and the replacement of the conjunctival epithelium. Inflammation of the conjunctiva (conjunctivitis) may have either non-infectious or infectious causes, although often both are involved. Frequently, one factor, such as irritating hairs, dust, or a virus, causes the initial damage, which enables bacteria, fungi, or yeasts to penetrate and colonize the conjunctival sac. Eye drops or ointments are usually the drugs of choice. Eye drops are watery solutions that must be applied every few hours, while ointments last longer and are usually only applied two to three times per day. Always consult your Vet so that any underlying cause may be investigated.
Be aware that the Basset Hound has a moderate amount of “haw” apparent, where the lower lid droops just a little to reveal a very slight amount of pink. Please do not confuse this with “Red Eye”.
PRIMARY ANGLE CLOSURE GLUACOMA (PACG)
Although we are giving this condition some prominence, very few Basset Hounds are actually affected. However, it is a very painful and blinding affliction which requires immediate attention. We therefore make no apology for the length of this explanation of PACG and what it might mean to your Basset Hound. For some time now, we have been investigating the incidence of this disease in the Breed, much of the time seeming to make no progress, but just recently we have started moving forward, albeit, slowly. It has not been an easy task as so few are affected.
Gonioscopy is a test to ascertain whether or not your Basset might be affected and must be carried out by a specialist. Initially, a referral should be obtained from your own veterinary surgeon to have testing done. Should you wish to breed from your hound, please seek out a specialist who is on the panel of BVA eye testers as they will report the outome to The Kennel Club for noting on your hound’s records – you can find a route to your nearest BVA Panellists at the end of this article. PACG is described as a Presumed Inherited Eye Disease (PIED). Once examined, a certificate of the eye examination is issued, by the specialist, in respect of PIED. If the examination findings are inconclusive it might be necessary for the animal to be re-examined, say within 6 months.
WHAT IS GLAUCOMA?
Glaucoma is an increase in fluid inside the eye, which leads to damage to delicate structures within the eye which may eventually lead to blindness following swelling of the eye. In its acute form glaucoma is painful but in all types it is the effect on sight through destruction of the optic nerve that represents its most important feature. Two forms of glaucoma are considered to be inherited in the dog: open-angle glaucoma (very uncommon) and angle closure glaucoma. The latter form is considered to be inherited in the Basset Hound. In angle-closure glaucoma, goniodysgenesis is characterised by non-differentiation of the pectinate ligament and a narrowed drainage angle and predisposes the “patient” to acute onset disease, usually in middle or old age.
WHAT TREATMENT IS AVAILABLE?
Treatment is often unsatisfactory but if the pressure can be kept within normal limits, the progression of the condition may be halted for considerable periods. Medical treatment, in the form of eye drops applied daily, is usually the first choice but surgical procedures are also available. These procedures are aimed at increasing the outflow of fluid from the eye, but there may be complications which require further surgery. Research continues into appropriate and successful methods of controlling this distressing condition.
IS GLAUCOMA INHERITED?
It is considered that there is a breed incidence of glaucoma in the Basset Hound and this is linked to abnormal drainage angle formation. Work in other breeds (and humans) has shown that abnormal drainage angle anatomy is inherited and that severe forms of abnormality predispose to glaucoma development.
CAN MY DOG BE TESTED FOR THIS CONDITION?
Yes. Fortunately, the goniodysgenesis can be identified at an early age by gonioscopy, and as such, predisposed animals may be taken out of breeding programmes. However, this is not always a good idea as it may restrict the gene pool. Very careful breeding of an affected to an unaffected hound may result in unaffected puppies. Such a breeding programme should be left to the really experienced breeder.
Contact should be made with an Eye Specialist, via your own Veterinary Surgeon in the first instance. A few drops of local anaesthetic are applied to the corneas of the eyes to be examined and than a special type of contact lens is applied to the eye, permitting examination of the drainage angle of the eye, with either an opthalmoscope or a camera. Please be guided by your Vet, but bear in mind that the Basset Hound is a very slow maturing dog and this includes the head area. It may be a good idea to ensure that your hound is fully mature before having this type of testing done.
The problem facing breeders and eye panellists is that we cannot at the moment predict with any certainty what degree of goniodysgenesis places a dog at significant risk of developing the clinical disease. The eye test allows only two categories – affected or unaffected (which in reality is a pass or fail). An objective method of assessing the angle is difficult and has led to apparent inconsistencies. The object of the investigations under way is to arrive at a practical, consistent method of diagnosis and to be able to give rational breeding advice.
To put this into perspective there are very few known cases of Angle Closure Glaucoma currently in the Basset Hound, and it is very easy to have your dog tested for the condition. It is recommended by the veterinary profession that a hound can be tested as early as 6 months of age. However, experts in the breed advise that the eye is not fully mature at this age and perhaps this should be borne in mind. It should be pointed out here that the pre-disposition does not mean that your dog will develop Glaucoma, in fact it is really quite unlikely bearing in mind the numbers currently known in the breed. However, it is known that pre-disposed animals may pass the condition on to their pups. It is rare, but there.
ANATOMY OF THE EYE AND THE DRAINAGE ANGLE
The drainage angle (or iridocorneal angle) is formed by the iris and cornea. Aqueous (fluid) drains through this angle into the veins around the eye. Impairment of drainage leads to an increase in pressure, as aqueous continues to be formed at the same rate. In the dog, abnormality of the pectinate ligament (which spans the angle) can lead to impaired drainage. This abnormality can be detected by looking at the drainage angle through a goniolens and is often termed goniodysgenesis.
THE FUTURE – A POSITIVE MOVE FORWARD
Ongoing research into PACG in the Basset Hound by a University team in the USA looks to be moving forward at a fast pace since the team were awarded a generous grant in November, 2011. We are very excited about the work carried out, on the Basset Hound, by this team.
The team wants to identify dogs which are prone to develop the disease, therefore they would like to have some kind of a genetic marker that allows them to determine which dogs are carrying the recessive gene. It is possible that once the gene is identified, future generations may have genetic testing performed and the breed could be rid of this form of glaucoma in five to six years.
Blood samples from the dogs participating in the new study will be drawn by authorised vets and sent to the lab. All of the dogs will remain with their owners, regardless of where they are located.
One of the biggest challenges facing the study is a low number of samples. Some breeders aren't eager to admit they have the glaucoma in their bloodline and may hesitate to participate in the study. It may be that the research team will appeal to draw more interest nationally or even internationally.The genetic markers for Primary Angle Closure Glaucoma (PACG) should be identified by the end of the two-year grant period. From there, the lab can take the study findings and quickly adapt it to human PACG. To quote from the team "We would know where to look for the gene, so identifying it in humans could really take less than a year”. What a tremendous result that would be!
Anomalies in the results of testing by Gonioscopy, as is currently carried out, do exist, because different examiners may interpret the extent of the abnormality in the eye differently. This may result in possible inconsistencies in test results, although the specialists do try to meet a specific standard with the information to hand. Because the extent of the abnormality in any particular dog is subject to individual interpretations, the Animal Health Trust are seeking a more objective measurement which may prove to have some predictive value.A slightly different method of testing looks as though more accurate results may emerge, but, as with most successful projects – it all costs a lot of money! High Resolution Ultrasound Scanning (HRUS) is highly recommended by the research team. As mentioned earlier, very few Basset Hounds actually contract this disease and therein lies an obstacle. Quite a number of affected animals will be required so that research may be carried out to identify genetic mutations. It may be that a world wide appeal will eventually go out to Basset Hound owners whose hounds actually have this disease, who will willingly allow access to vital information and permit essential tests to be carried out.
The bottom line is......this is a painful and blinding condition. It is not a time bomb waiting to go off, but it is a caution to be aware that it may happen, albeit to only a few.
**An up to date list of BVA Eye Panellists can be found at http://www.bva.co.uk/canine_health_schemes/Eye_Scheme.aspx then click on eye panellists.
We thank eye specialist, John Mould, BA, BVSc, DVOphthal, FHEA, MRCVS, for giving us so much of his time to provide help and advice and for channelling us in the direction of being aware of Primary Angle Closure Glaucoma. He has given us a useful insight into this painful disease and without his help we would still be struggling to move this undertaking forward.