sunnuntai 31. maaliskuuta 2024

The latest whippet LTV statistics from Finland (2014 - 2/2024)

Short introduction: LTV (Lumbosacral transitional vertebrae) is congenital, hereditary vertebral anomaly. It can not be caused by a trauma. It's not a disease, but this spinal anomaly can predispose to conditions such as qauda equina syndrome. Even a dog with LTV0 can develop the aforementioned syndrome, but it's more likely if the dog has abnormal LTV-area. You should note that LTV classification is developed to tell how genetically severe the abnormality is, not how severe it is for the dog itself. LTV0 is completely normal LTV area and LTV4 indicates that either the last lumbar vertebra is "changed" to be a part of the sacrum or the first vertebra of the sacrum has "changed" to be the last lumbar vertebra. The most recent knowledge about LTV suggests that LTV1 and LTV4 are most likely asymptomatic, while LTV3 tends to have symptoms more often (However, you have to remember that not all larger abnormalities are combined with symptoms, or symptoms may show up in older age when the dog reaches its senior years). Therefore, if the classification were to reflect the most likely severity from the dog's perspective, the classification would be LTV0, LTV1, LTV4, LTV2, LTV3. 

If you're not familiar with the subject, please check out these my earlier texts about LTV. First one explains what is LTV and why we should be interested about it. The second one demonstrates that it's impossible to determine a dog's LTV result based solely on its phenotype traits, such as its overline, angluations or lenght of loin. The only reliable method to assess whether a dog's LTV area is normal is using X-ray (or MRI or CT scans).

Finnish Kennel Club's general breeding advice, what comes to LTV, is that you can use all numbers of the scale, but dog has to be symptom-free, and LTV1-4 should be combined with LTV0. Although, due to high prevalence of LTV1 changes in whippets, Whippet-Harrastajat ry (Finnish whippet breed club) has consulted the FKC's vet experts and we have permission to combine LTV1+ LTV1. Please note, that these are just recommendations and there are no registration limitations, so you can combine even LTV4 to LTV4 if you want. If dog has LTV0, but is has symptoms, it should not be used for breeding. We have to keep in mind, that closed gene pool has its challenges, so we should be careful when ruling the dogs out from breeding - this should be kept in mind also when talking about spinal issues as well. 

Now, let's delve into the statistics. All data (which means results of official health tests) is gathered from Finnish Kennel Club's (awesome!) open database, Koiranet. In this collected dataset, there are dogs from 187 different breeder from different countries and offspring from 302 different sires and 356 different dams. 

Enjoy the reading!

Number of official x-ray examinations

Currently 773 whippets has been examined for LTV. The number of examinations increased until 2020/2021, but since then there has been a slight decrease in examination numbers. The breed club had reimbursement program, where dog's owner was received a small cash they sent their dog's spine examination report. However, the tax authority decided that this would be taxable income for the dog's owner. Due all the burocracy and administrative burden, breed club decided to end their refund program in January 2023. It's difficult to say how much this has affected and whether it has connection with the decreased number of x-ray examinations.

However, an increasing number of sires and dams are examined for LTV, which is delightful and provides us with more data about the inheritance. 

The following charts show the development of examination numbers by the birth year of the dog. The number of examined dogs is also compared to annual registrations. The examined dogs were born between 2006 and 2023. 33,9 % of the registered whippets in Finland have been examined for LTV. Whippets born (and registered) between 2013 and 2023, 20,8 % have been x-rayed. 

The following table lists the litters registered between 2014 and 2/2024, showing the percentage (%) of parents with some LTV results. The parents could have been examined after the litter was born. Since 2018, more than half of the litters have either one or both parents examined for LTV.

Examination results

"Full set of spine examinations" includes scans for LTV (lumbosacral transitional vertebrae), SP (spondylosis) and VA (vertebral anomalies). If you take your whippet to be x-rayed, it's more likely that there is some vertebral change on the spine than that the spine is completely normal. 

As you can see, there is quite high prevalence of LTV1-4 results. Although, the amount of larger changes has decreased and the amount of LTV0's has increased since the first time I made summary about LTV-situation in 2018. On the first summary, 17 % of the dogs had LTV2-4, 46 % had LTV1 and just 37 % had LTV0. 
Following table presents the distribution (%) of LTV results, sorted by birth year. Number of examined dogs in parantheses below bith year. At this point, I'd like to remind you, like one of the earlier charts showed us, since 2018 more than half of the litters have had one or both parents tested for LTV. 

Prevalence of VA changes has stayed on aboutish the same level through whole time since 2018. Most common reason for VA1 result for whippet seems to be (this is not a strict fact, just a gut feeling based on the many spine examination results which I've seen) extra pair or underdeveloped extra pair of ribs. There has been also a few block vertebrae and some other changes, but those are not a common finding.

Spondysosis situation has stayed also on the same level since 2018.

Parents of LTV examined dogs

425 LTV examined whippets have one or both parents examined for LTV as well. This covers 163 different combinations.

Following chart shows what kind of LTV results these examined parents have. As you can see, majority of the litters meet the recommendations of the FKC and the breed club. 

Combinations and what they have produced

All the following charts are about those 425 different LTV examined dogs, which have their parents examined for LTV as well. At this point I have to remind you, that now group sizes are starting to be quite small and this affects the reliability of the statistics. To obtain more reliable results, we still need to get more dogs to be x-rayed.

When other parent is LTV0, so the combination is either LTV0 + LTV0-4 or LTV0 + unexamined, this increases the proportion of LTV0's and decreases the proportion of LTV changes in the offspring.

When viewing the combinations where an unexamined dog is mated with LTV1-4, the number of LTV changes in the offspring increases. Seems like when pairing LTV2-4 with unexamined dog, it produces more and bigger LTV changes in the offspring, than when pairing LTV1 with unexamined dog.

When both parents have some LTV change, the proportion of LTV0's decreases and the proportion of LTV abnormalities increases in the offspring. There are no combinations of  LTV2-4 + LTV2-4 in the dataset, so in all these combinations, other parent is LTV1.

Here was the summary for this time, It seems like it is possible to influence the number of LTV changes with breeding choices. Is it necessary to panic about the LTV situation on our breed? I think that no. Is it important to pay a attention to it? Definitely yes.

Hopefully you enjoyed reading.

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