Questions and Answers

Risk Analysis

* “What is a risk analysis?”

Risk analysis is a mathematical computation of the percentage of risk derived from the cumulative contribution of ancestors in a particular disease process. Verified information regarding affecteds and producers of the diseases is entered into the database. The computer program then calculates the risk value of a disease for a particular dog or for a prospective mating. The computations are only as good as the amount of information in the database. The more complete the data; the better the analysis.

Risk analysis is now computed for seizures, PCD and PRA with recommendations for PSS. In addition, the results of published testings for hips, elbows, eye and heart are included. The names of owner, breeder or dog are not mentioned unless permission is received in writing to share information.

Effective May 11, 2004, wherever possible, copies of requested risk analyses will be sent to the owners of both dogs involved in each analysis.

* “Can you give a sample risk analysis and explain what the information is saying?”

Definitions of Terms
:
Autosomal – a chromosome that is not an X or Y (sex) chromosome. In other words, not sex linked.

Recessive - a mode of inheritance that requires genetic contributions from both parents.

Incomplete penetrance – the gene for the disease is present but is not expressed in all individuals in a litter (family) with the gene.

Modifier – a gene that modifies the expression of another gene

Inbreeding coefficient - The inbreeding coefficient is the total percentage of identical gene contributions from all ancestors common to both parents, not just one ancestor in particular.

S = seizures

SL = late onset seizures (after 3 1/2 years for bitches and after 4 1/2 years for males). The seizures in this category are also considered genetic but may be different than the earlier onset type.

PCD (primary ciliary dyskensia)/rhinitis (same disease)

PRA (progressive retinal atrophy)

PSS (portosystemic shunt)

OFA – Orthopedic Foundation for Animals. This is an open health registry for hip, elbow, patella, eye, thyroid, heart and Von Willdebrand's testing.

PennHip – This is a closed registry dealing with hip testing. It is based on the degree of laxity in the hips.

CERF – Canine Eye Registration Foundation. This is an open registry for eye testing.

Mode of inheritance for

Seizures: autosomal recessive with incomplete penetrance ( 2 to 3 modifiers)

PCD = autosomal recessive

PRA = autosomal recessive

The explanation of the numbers in the risk analysis is:

The first number is the percentage of the risk of being an affected. The second number is the percentage of risk of being a producer. Examples only: 1) a number written as S = 0 / 12 would mean that the animal in question has a zero % risk of being affected and a 12% risk of being a producer. 2) a number written as SL = 0 / 9 means that that animal has 0% risk of being affected and 9% risk of being a producer for late onset seizures.

In the case of a “what if” analysis, EACH pup has the risk percentage stated. For example, if you wanted to breed Stud Muffin to Doodles and the seizure risk were 3 / 45. It would mean that each prospective pup would have a 3% risk of being an affected and a 45% risk of being a producer.

PSS recommendations and testing codes:

The recommendation for PSS is based on the number of producers in a 6 generation pedigree. The values are
1) not enough information - meaning that there are no producers shown but there may be unreported data
2) testing recommended - where producers appear on only one side of the pedigree
3) testing highly recommended - where producers appear on both sides of the pedigree but there are few
4) testing mandatory - were producers appear on both side of the pedigree in profusion.
5) testing absolutely mandatory – were the number of producers is overwhelming or if one or both of the prospective parents are siblings of an affected.

As of May 1, 2005, we have added results of testings for Hips, Elbows, Eyes and Hearts, where published records are available or where owners can provide private test results.

The hip, elbows and eye certification information is based on published testing data - such as OFA and CERF.  In Europe, especially in Germany, heart testing is mandatory in breeding animals and a rating is given and published in their yearbook.  If any of these things are privately tested, I mark them as OK - which lets me know that the owners did test for these things but did not send them to OFA etc. (i.e. data is unpublished) but they must have documentation if asked. 

Explanation of the ratings is:
 
USA - Hips: E = excellent  G = good  F = fair.
Elbows: Normal

Europe – Hips: A = Free B = Under suspicion C = Light D = Middle E = Grave
Elbows: 0 is Free
 
Elbows = OFA rated elbows as Normal until recently when people can decide to allow the failed tests to be published.  You have to send in the information and pay a fee for diagnosis of the x-rays before it is entered into the published registry.
        Many people x-ray hips and elbows but do not send them to OFA.  Also, some people do PennHip instead, which has a different form of rating and is not published. 
         
Eye Cert - In the US a number is assigned if a dog passes the CERF eye test.  Information about eye diseases sent in by owners who did independent testing, has to be backed up with an examination certificate.  Some of the eye diseases that are reported, not including PRA, are retinal dysplasia, retinal folds, iris cysts, juvenile cataracts, old age cataracts etc.
 
Cardiac testing - The German year book lists the animal as having a rating of OB (no abnormality detected - OK) and MB (abnormality detected – did not pass).  I then add the age at which the last test was done = e.g. OB3 means it was last tested at 3y and was found to be OK for breeding. 

“No data available” generally means that there were no published test results or there was no documentation of private testing available.

What a risk analysis looks like and what it means

I am going to use 3 of my own breedings as examples. They are sequential breedings between 1987 and 1994 and show what happens with 2 diseases (PCD and PSS) which are in the risk analysis. I used the numbers that I would have seen years ago if the risk analysis was done pre-breeding.

Breeding #1 - Cinderblock to Fluffball (the names have been changed to protect the guilty….)
(3 males )

S = 0 / 6
SL = 0 / 0
PCD = 8 / 25
PRA = 0 / 0
PSS = testing recommended
Inbreeding coefficient at 10 generations = 11.60
Testings:
Hips – 1 normal, 3 rated OK
Elbows – no data available
Eye – no data available
Heart – 1 AF at 7y

The explanation and results of this breeding (3 males in litter) are as follows:

S = Risk of seizures is 0% for affected and 6% for a producer
No seizures in any puppy in this litter

SL = Risk of late onset seizures is 0 / 0
No late onset seizures in any puppy in this litter

PCD = Risk of being an affected is 8% and risk of being a producer is 25%
2 affecteds (the third pup in the litter had a 25% chance of being a producer)

PRA = 0 / 0 - No PRA in any puppy in this litter

PSS = testing recommended means that the risk values were low and producers appeared only on one side.
1 affected (the other two pups in the litter had a risk of being a producer.)
Since there is an affected and PSS is in most likelihood an autosomal recessive with incomplete penetrance, there is obviously information missing on one side of the pedigree and I found out later that there was incomplete data and what it was. The disease might have been misdiagnosed or incorrectly named (perhaps “fading puppy syndrome”?)

Inbreeding coefficient – the breed average is about 15% at 10 generations.

Testings: In this case, there was formal heart testing on a grandparent but I have not permission to share the information (this goes for breeding #2 also).

None of these pups were bred. As you can see, the numbers for seizures were low but the numbers for PCD were high and produced 2 affected puppies. PSS data appeared only on one side. The fact that there was an affected for PSS means that there was data missing from the other side or the data was beyond the 6 generation computation level. One part of the definition of a recessive is that the disease can skip generations. Complex recessives like seizures and PSS skip erratically.

Breeding # 2 - Cinderblock (also sire of Breeding #1) x Trickster (2 males / 1 female / 2 dead)

S = 0 / 7
SL = 0 / 0
PCD = 7 / 28
PRA = 0 / 0
PSS = testing absolutely mandatory
Inbreeding coefficient at 10 generations = 22.49
Testings:
Hips – no data available
Elbows – no data available
Eyes – no data available
Heart – no data available

S = 0% risk of being affected and 7% risk of being a producer - No pups in the litter were affected

SL = 0% risk of either affected or producer - No pups in the litter were affected

PCD = 7% risk of being affected and 28% risk of being a producer
No pups in the litter were affected although the sire was a producer
It will be never known if either of the two dead pups would have been affected.

PSS = A very high risk of producing both affected and producer
1 male affected

Inbreeding coefficient – this shows linebreeding above breed average

Testings – see note above about permission.

Neither male in this litter was bred. The bitch, Snookums, was bred to Boytoy in Breeding #3.
In this analysis the seizure numbers are still low but the PCD numbers have dropped slightly. They are, however, high but produced no affecteds. Of course, the question will always remain as to whether or not any of the dead pups would have had the disease. The PSS numbers have increased mainly because there was an affected produced by the sire of this litter. He produced a second affected here.

Breeding # 3 - Boytoy to Snookums ( 3 male / 6 females / 3 dead)
This breeding was done by a friend but the bitch was my breeding and shows a pattern, so it is included here.

S = 0 / 14
SL = 0 / 0
PCD = 2 / 30
PRA = 0 / 0
PSS = testing mandatory
Inbreeding coefficient at 10 generations = 19.14
Testings:
Hips – 1 OK, 1 producer of HD (in generation 6)
Elbows – 1 producer of UAP (in generation 4)
Eyes – no data available
Heart – 1 AF at 8years, 1 AF at 6years.

This litter contained 3 pups with PCD but no PSS or seizures. Notice that the risk of being a producer has increased. The risk of PCD has decreased slightly, as has PSS. The point is that the risk is still there. A decrease should not be ignored but should be given measured consideration. We don’t know what the 3 dead puppies would have had and none of this litter was bred.

The testings section in this breeding shows how submission of data will be shown for this category. Note that no names are listed and the data was obtained from open registries or I had written permission to include it.

You are now wondering what the hell I was doing. Well, hindsight is a wonderful thing. Back then we did not have risk analysis and PSS was considered congenital (as opposed to genetic) and routine testing by breeders was not known. There is a saying that goes “I did the best that I could until I knew better and then I did better.”

* Who can provide information on health issues for a specific hound and what is necessary to submit information?

Any breeder or owner of a hound may submit health or longevity information. The data needed are:

Registered name
Pet name
Date of birth
Parents

I may already have your dog in the database but this is a good way to verify my entries.

Optional information

Date of death
Cause of death (was a necropsy done? Do you have documentation?)
Any health issue during the hound’s lifetime (is documentation available?)
Tests results for hips, elbows, eyes, heart, and thyroid. If these results are not published, I will need documentation in the form of a certificate or a note from the veterinarian.

I am also collecting information on the following diseases for future use – Megaesophagus (genetic or acquired), FCE (fibrocartilagenous emboli), bloat and torsion (any type), lymphosarcoma, pneumonia (single occurrence, recurring or secondary to another health issue), OCD (osteochondritis dissicans).

All information will be kept confidential unless I have written permission to share that information. Please be specific as to what can or cannot be shared.

Information can be emailed, snailmailed or faxed. Please contact me at iwstudies@comcast.net .

This is a free service of the Irish Wolfhound Seizure Study.