Long and Short of Bad Backs

“Low to ground, long in body and short of leg” – AKC Dachshund breed standard

Basset in bronze (ca 1841) by Antoine-Louis Barye (1795-1875)

Few studies are quickly explained with 3 graphs, this is one of them. It also neatly illustrates one problem associated with arbitrary exaggeration of certain traits.

Interested in determining how relative back length is related to Intervertebral disc extrusion risk the authors looked at a population of dogs directed to the Royal Veterinary College-Small Animal Referral Hospital.

A total of 710 dogs were recruited into the study; for each dog a set of 10 breed defining measurements were taken and each dog was also given a body conditioning score:

• cranial length
• head width
• eye width
• neck length
• neck girth
• chest girth
• chest width
• body length
• height at the withers (HW)
• height at the base of tail
• back length (BL)
• body weight
• body conditioning score (BCS)

The dogs were then divided into non-IVDE and IVDE positive and the numbers were crunched.

The authors identified 3 factors associated with increased IVDE risk: 1) back length to height ratio 2) skeletal size and 3) body conditioning score. For each of these factors miniature dachshunds were the most severely affected.

 Long Backs

For the longest miniature dachs the IVDE risk becomes near certainty.

For all breeds as BL:HW increases the risk increases.
doi:10.1371/journal.pone.0069650.g001

  Smaller Dogs Bigger Problems

The smaller the dog the greater the risk for IVDE.

Miniaturization is a risk factor across all BL:HW ratios and smaller dogs experience greater risk.
doi:10.1371/journal.pone.0069650.g003

  Fat Whack a Back

Obesity is the 3rd factor associated with increased risk but we can’t blame the breeders for this. Depressingly, around half the dogs in this study were overweight. I say depressingly and not surprisingly because surveys with populations in Australia and USA have found similar rates of obesity.

Body conditioning score over 5 is considered overweight. doi:10.1371/journal.pone.0069650.g002

This study should be mandatory reading for all breeders and judges.

REFERENCE

Packer RM, Hendricks A, Volk HA, Shihab NK, & Burn CC (2013). How long and low can you go? Effect of conformation on the risk of thoracolumbar intervertebral disc extrusion in domestic dogs. PloS one, 8 (7) PMID: 23894518