EYE CONDITIONS

All breeding dogs and bitches should have a specialist exam.

This article was written by Pamela Francis for the FLCV in 2010. Pam's work remains an up to date and relevant summary for people who are considering buying a Finnish Lapphund. If you would like to read about steps that breeders can take to reduce the chance of hereditary disease, refer to the club breeding guidelines 2017-2020.

 

prcdPRA (Progressive Retinal Atrophy)

As the name would suggest, this is a disease where the retinal tissue of the eye gradually dies over time, causing gradual blindness in the dog. The early symptoms in dogs are a loss of night vision, which gradually extends to a loss of day vision as well.

The age of onset varies amongst different dog breeds, but in the Finnish Lapphund it is quite late, with early signs often not appearing until 5 to 8 years of age.  There has not been a clinical diagnosis of PRA disease in Australia. Due to a DNA test being available (please read below), there should never be a case in the future.

prcdPRA is inherited through a simple autosomal recessive gene. What does this mean? Well, many traits in dogs (and humans too) are under the control of a pair of genes. With prcdPRA inheritance in Lappies, there are two varieties of this gene – the “Normal” gene and the “Abnormal” gene. The Abnormal gene is the one that causes the actual disease condition of PRA, but luckily, it is recessive to the Normal gene. This means that whenever it is paired up with a Normal gene, the Normal gene will mask the expression of the Abnormal gene and the dog will never develop the disease. It is only when the Abnormal gene is paired up with another Abnormal gene, with no Normal gene to keep a lid on them, that these genes are free to be expressed and so the disease develops.

So, in terms of genotype (gene pattern), there are three possible pairings of genes that a Lappie could carry and that are revealed by the DNA test:

 

  • Normal/Normal, known as Clear

  • Normal/Abnormal, known as a Carrier

  • Abnormal/Abnormal, known as Affected


Again, it is only this last pairing of genes that will cause PRA to develop.

Each parent contributes one of their pair of genes to their offspring, making up a pair in their puppies. As you can see from the above, as long as a puppy inherits at least one Normal gene from either of their parents, they will never suffer from prcdPRA disease. To make sure this always happens, breeders in Australia do only two types of mating. These are Clear x Clear (all resulting progeny will be classified as Clear by Parentage), or Clear x Carrier (each pup has a 50% chance of being Clear and a 50% chance of being a Carrier). This means that in Australia there are no Finnish Lapphunds produced which have the Affected genotype.

If you are purchasing a Finnish Lapphund pup to be a desexed pet, the possibility of your pup being a Carrier (from a Clear to Carrier mating) is totally irrelevant, because it will never develop the disease, (as it also carries the Normal gene). If you are looking to purchase a pup for breeding, you would need to keep in mind that a Clear puppy can be bred to either other Clears or a Carrier, whereas a Carrier puppy must be bred to a Clear dog to avoid PRA resulting in the puppies. 


Hereditary Cataracts (HC)

The lens of an eye is usually clear and focuses light on to the retina. A cataract is an opacity (cloudiness) in the lens, usually white, which scatters the light. The level of impact on vision can vary according to the size of the cataract (varying from a pinhead to the total lens) and its location on the lens.

There are many forms of cataracts with a variety of causes, which can be found in many dog breeds and cross-breeds. Cataracts may be in one eye (unilateral) or both (bilateral).  When they occur in both eyes of an individual, they are thought to most likely be inherited and are therefore called “hereditary” cataracts.

To explain cataracts a little better, a brief look at lens anatomy is needed. The lens consists of a core, called the nucleus, surrounded by an outer layer called the cortex, coated with a thin layer of cells around the whole lens called the capsule. The front surface of lens (closest to the outside of the eye) is called the anterior surface. The back surface (closest to the inner part of the eye) is the posterior surface.

 

A cataract can occur in any part of the lens.  They are named according to where in the lens they are found, so dogs can have the following types of hereditary cataracts (occurring in both eyes):


• posterior polar cortical
• anterior cortical
• equatorial cortical
• nuclear
• capsular

An anterior cortical cataract therefore occurs in the front (outside) cortex of the lens. Where does a posterior polar cortical cataract occur? Yes, on the back (posterior) cortex of the lens. The “polar’ part of the name means that it is located in the middle part of the lens, not at its top or bottom. (As the lens is tilted 90 degrees onto its side, in order to sit upright in the dog’s eye, the equators are actually at the “top” and “bottom” of the lens and the polar areas in the middle).

In Finland, as a result of examinations done by certified opthamologists (specialist eye vets), three types of hereditary cataracts have been found in Finnish Lapphunds.  Data gathered from the years 2007 to 2011 shows the incidence for each type of cataract is as follows:

 

Anterior Cortical                   18 with condition 1.22% of total FInnish Lapphunds tested

Posterior polar Cortical        26 with condition  1.77% of total FInnish Lapphunds tested

Nuclear                                   02  with condition  0.14% of total Finnish Lapphunds tested.


(Source:  Koiranet at http://jalostus.kennelliitto.fi/frmTerveystilastot.aspx?R=189&Lang=en)

​Another term used in describing cataracts is that of the “punctuate” cataract.  In this case, the word “punctuate” refers to the size of the cataract.  It means it is very small, just a pin prick. If a dog has a punctuate cataract in one or both eyes, it will most likely gain an eye certificate, with a recommendation for a recheck in six months.  Small opacities like this may not be inherited and may not develop further, but if they have grown bigger on subsequent eye examinations and develop in both eyes, then they should be assumed to be inherited.

Unfortunately, the genetic inheritance of hereditary cataracts in Finnish Lapphunds is not currently known or understood, although there is now research underway at Helsinki University. Consequently, although there are genetic tests available for HC in other breeds, this is not the case for Lappies. It appears from the research conducted so far, that HC found in Lappies has a different mode of inheritance than that in these other breeds which have test available.  As a result, these tests are not applicable to Lappies and cannot genetically determine whether a Lappie does or does not have HC, or whether it carries the condition.

Breeding stock should have their eyes checked and cleared by an ophthalmologist registered with ACES (AVA-ANKC Australian Canine Eye Scheme). This needs to be done prior to mating and thereafter at least every two years, so that the current status of the dog’s eye health is known. Any affected dogs can then be withdrawn from the breeding pool. This is not a fool proof way of ensuring eye diseases are not produced in offspring, but is the best method currently available.

Hereditary cataracts in the Finnish Lapphund usually appear after the first year, although there have been some isolated cases of juvenile cataracts in the breed. In Finland, it is the most common of all the eye conditions to impact on the breed in its native country.


To June 2009, there were no recorded cases in Australia, out of 27 Lappies for which eye test data is currently available.
The Lapphund Club of Finland advises not to breed with Lappies diagnosed with posterior polar cataracts or anterior cortical cataracts.


Retinal Dysplasia (RD)

There are three forms of retinal dysplasia, which are all types of abnormal development of the eye's retina, present at birth. There are two layers in the retina and if these do not form or gel together properly, damage to the inner surface of the retina results. While these conditions may be hereditary, they can also be the result of a viral infection or some other event prior to birth.

The three types of RD are listed below, along with their effects on a dog’s eye sight and breeding recommendations from the Lapphund Club of Finland.

Type 1- Focal or Multi-focal (MRD)
Effect on vision- Very small localized areas of folding in the retinal layer. Small blind spots which are probably not noticed by the dog.
Breeding recommendation- Lapphund Club of Finland advises that dogs with MRD may be bred from, providing their mate is clear of MRD.

Type 2- Generalized (GRD)
Effect on vision- Large areas of defective retinal development. Large holes in the visual field.
Breeding recommendation-Lapphund Club of Finland recommends not breeding with affected dogs.

Type 3- Retinal detachment
Effect on vision- The two retinal layers do not come together at all. Total blindness.
Breeding recommendation- Lapphund Club of Finland recommends not breeding with affected dogs.

Many breeds and cross breeds exhibit retinal dysplasia, but this condition is very rare in the Finnish Lapphund breed; as of December 2012, only 0.78% of Lappies tested in Finland over the past five years have been diagnosed with MRD and only 0.20% with GRD.


PHTVL/PHPV

These two conditions, Persistent Hyperplastic Tunica Vasculosa Lentis (PHTVL) and Persistent Hyperplastic Primary Vitreous (PHPV), are congenital eye anomalies, which affect the lens of the eye. When the eye is developing in utero, a system of blood vessels coats the lens, feeding the eye structure during its development. In normal development, these blood vessels break down prior to birth and disappear without a trace, but in these conditions the blood vessels remain beyond birth and can interfere with the dog’s sight.

There are various levels of these conditions which can be diagnosed, from Grade 1through to Grade 6. There will generally be no impairment to vision with Grade 1. In grades 2 to 5, there is increasingly poor vision. A Grade 6 condition means there is a total cataract across the lens and the dog is completely blind.

The condition is known to be hereditary in other breeds, but no research has been done regarding Finnish Lapphunds. The incidence in the breed is very low, being 1.32% in the test results in Finland five years prior as of December 2012. As of December 2012, there were no recorded cases in Australia, according to ACES data, out of the 64 Lappies included in that data.​

The Lapphund Club of Finland advises that only dogs with a Grade 1 or 2 may be bred from. They recommend that any dog diagnosed with a Grade 3 to 6 form of PHTVL/PHPV should be excluded from breeding.


Persistent Pupillary Membrane (PPM)

The pupillary membrane covers the puppy’s pupil during its foetal development. Normally, this membrane completely dissolves before the puppy is born, but sometimes small strands of the membrane can still persist. They can disappear by the time the puppy is 4 to 5 weeks old, but if they don’t, the puppy is said to have PPM (Persistent Pupillary Membrane).

The strands of membrane can be attached to different points of the eye and this will determine how the dog’s vision is affected:

Type of PPM- Strand from iris to iris (coloured part of the eye)
Effect on vision- No problems caused, generally disappearing eventually on their own.
Breeding recommendation- Lapphund Club of Finland advises that affected dogs may be bred from, providing their mate is clear of PPM

Type of PPM- Strand from iris to lens
Effect on vision- Can cause minor cataracts and minor effect on vision.
Breeding recommendation-

Type of PPM- Strand from iris to cornea
Effect on vision- May damage cornea and pup could be born blind.
Breeding recommendation-

It is not known if this condition is hereditary in Lappies. The current incidence in Finland i 2.38% in the test results five years prior as of December 2012. To December 2012, there were no recorded cases in Australia, according to the data available from ACES (64 Lappies).


Testing for Eye Conditions

The only genetic test presently available for eye conditions in Finnish Lapphunds is that for prcdPRA. There are no other genetic tests for hereditary cataracts or other eye conditions. The only way to control the other eye conditions listed above is firstly, to ensure that dogs to be used for breeding have a specialist eye examination before being used. This first examination will rule out retinal dysplasia, PHTV/PHPV and PPM. Continuing bi-annual eye tests will then warn the breeder if hereditary cataracts appear in breeding stock.

 

 


 

© 2018 Finnish Lapphund Club of NSW Inc

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