Goodbye twisted legs
In January 2014 it came to my attention that angular limb deformity, also called Pes Varus/Valgus, could be a rising problem among miniature dachshunds. This condition appears as one or two legs twisting either inwards (varus) or outwards (valgus). Symptoms vary from mild to extreme, ranging from no impairment to the dog’s quality of life right through to extreme cases that can be corrected by surgery.,
Pes Varus is not included on the internationally recognised LIDA list of heritable diseases for miniature dachshunds and, consistent with this, it is reported in the scientific literature as being caused by trauma to the growing leg sometime in the first year of life. That is, there is injury to the growth plate that lies between the upper and lower leg bones. This results in one limb bone ceases growth while the other continues, leading to an angular limb.
With the incidence seemingly on the rise, I was keen to find out how many miniature dachshunds were affected and published a ‘Notice to all dachshund owners’ calling for any dachshund owners having this condition to contact us. This was promoted on our twitter feed, of some 1800 followers at the time, as well as being prominent on the home page of the website. Thankfully for the breed there was no deluge of responses; in fact while it attracted a lot of interest, no one came forward to say their dog had the condition. Despite this we were aware this condition had occurred in some of the pups we have bred, becoming apparent to owners around the one year age mark. We were beginning to suspect there might be some heritable genetic basis.
What I’ve found
I set about getting more information on the condition from the scientific literature. Trauma was the most commonly cited cause, but I was not entirely satisfied.
Next I re-examined the reported cases we have had over the years. I found it to be 1%. One pup in 100 pups would grow on to exhibit a degree of deformity in their first year. Incidentally, as an aside, this rate of 1% eclipsed any other health conditions reported to us, including the popular notion of bad backs (IVDD) at 0.16% (being a similar rate for human back disk surgery), and the much-publicised Progressive Retinal Atrophy (PRA) being 0% (noting the dogs we have bred are under 12 years of age).
Back to Pes Varus, in studying our data I found no evidence of any genetic link. That is, the pups who went on to be afflicted were as widespread genetically as it comes. There was no coincidence of two afflicted pups from the one litter. There was no pattern with any given breeding pair. There was no link to any individual breeding dog.
This information told me that the condition is not likely to be heritable; that is, these events were genetically random.
Conversely, if I had found that there was a familial link then this would have told me that for that family of dogs there was in fact an hereditary factor at play. A separate ball game to the random occurrence in the global dwarf dog population. In the event of such a case arising, there would be indeed be something about the genetics of that family predisposing them to the condition. Within that family resides some multiple gene combination that sees them have more fragile growth plates than the general population.
A clear answer
I have just come across a new chapter in an internationally renowned veterinary text book titled Mechanisms of Disease in Small Animal Surgery. The chapter is titled Canine Angular Limb Deformities and clearly explains this condition (1). The chapter is authored by Professor of Orthopaedic Surgery Dr Denis Marcellin-Little, who is a world leading researcher in canine orthopaedics. The following information is taken from this chapter.
Angular limb deformities are common in dogs, being most common in dwarf breeds. Angular limb corrective surgery accounts for about 1% of all orthopaedic problems of dogs.
Examples referred to in the article are the basset hound and Yorkshire terrier, although the condition can arise in any dwarf dog regardless of whether they are purebreed or crossbreed (interestingly, as an aside, the dachshund is not directly referred to in the article).
Dr Marcellin-Little explains that dwarf dogs have a genetic makeup that leads to variable growth of their leg bones. This usually leads to symmetrically deformed limbs; in other words, the dachshund breed as we know it.
Dwarfism occurs through the premature closure of the part of the limb bone that is responsible for bone growth. As a result most dwarf dogs have some degree of angulation in their limbs, which Dr Marcellin-Little notes as ‘expected’: “Breeders and owners of chondrodystrophic [dwarf] dogs anticipate a certain degree of curvature in the limbs of their dogs and they may not seek medical care to treat the consequence of these deformities unless the dogs are limping consistently.’ (1)
He goes on to state: ‘Angular deformities occur as a result of injuries, most often injuries to the growing long-bone physes [growth plate] but also as a result of fracture malunions…These deformities account for 1% of all orthopaedic problems of dogs, and may include valgus [outwards] or varus [inwards] angulation of variable severity.’
The article describes the need for vets to appropriately grade the severity of the condition, since not all are serious enough to warrant surgery. Treatment decisions for limb deformity are complex and range from conservative management to corrective osteotomies. It is noted that splinting is not recommended with no positive results to the deformity and bad side effects in the form of muscle loss and skin abrasion.
Breeder’s role in reducing Pes Varus
There are four ways a breeder can help reduce Pes Varus.
First, never breed with a dog showing any signs of a health condition – be it Pes Varus or a skin condition, the rule is the same. It’s the breeding mantra.
Second, when a breeder is alerted to one of their past puppies developing the condition (and this holds true for any health condition) they need to examine their breeding records afresh. Does this new case bring to light some familial pattern – some link between relatives that was perhaps not uncovered before?
Third, in the event you need to assist a birth you must NEVER pull on the puppy’s legs. For a normal backwards presentation, with rear legs appearing first, gently apply pressure with each contract behind the hips. For a breech presentation with the rump-first, use a little finger to gently untuck each leg such that the hips are no longer splayed and puppy can slip out.
And fourth, provide good handover information to ensure new owners are briefed on the current 1% incidence rate of Pes varus among dwarf legged breeds and crossbreeds and how this risk can be reduced through minimising undue stresses to the developing limbs (see below).
Owner’s role in reducing Pes Varus
Owners can reduce the risk of their puppy developing Pes Varus/Valgus by minimising stresses to their developing legs. This would include such things as not letting puppy jump on the hind legs excessively, not taking puppy for overly long walks and avoiding puppy climbing stairs or jumping from one level to another.
For owners with children, puppy should not have their legs pulled, puppy fallen on and so forth.
For elderly people or movement impaired people, a tiny puppy can easily get underfoot (and provide a tripping hazard to boot).
Have your dog in an area not accessible to the public. For example, your courageous dachshund should not have access to the public pathway to your front door or electricity meter. They will bark at delivery people, the meter reader, tradespeople and any other stranger coming to your home. The stranger does not know they are highly unlikely to bite, so your dog’s behaviour of protecting your home might result in a stranger taking some protective action of their own.
Is a dwarf dog for you?
In light of this research and other scientific literature on this topic, it is a fact that leg curvature inherent to dwarfism can become exaggerated through trauma during the growing months of life.
When deciding if a dog with dwarfism is suitable, bear in mind that at this point in time there is a 1% chance your dog could develop this condition – although there are ways you can reduce the risk, as discussed above.
What if your dog shows signs?
People facing angular limb deformity in their pet dog should refer their vet to the reference cited here (1). It is extensive and covers assessment guides, conservative management, surgical management right through to post operative management.
Current understanding of the ‘how, when and why’ of Pes Varus can see a reduction in its strike rate. Breeders and owners hold the key here.
As a final thought, although this article has focused on a negative aspect of the dachshund I must finish by saying the mini dachshund is possibly the healthiest of all purebred dogs. That’s certainly our experience for the dogs we have bred (see article Health in the miniature dachshund). By way of comparison, albeit an extreme one, 30% of all dalmatians are born deaf in either one or both ears. (2)
(1) Canine Angular Limb Deformities, D. Marcellin-Little, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA.
In: Mechanisms of Disease in Small Animal Surgery, 3rd Ed., Bojrab M.J. and Monnet E. (Eds.). Publisher: Teton NewMedia, Jackson, WY, USA (www.tetonnm.com/). Internet Publisher: International Veterinary Information Service, Ithaca NY (www.ivis.org), Last updated: 4-Feb-2016; A5697.0216