Dermoid sinus is a hereditary skin condition that can affect Rhodesian ridgeback puppies, generally along the line of their spine from the neck to the tail along the spinal column. The sinus itself is a drainage structure formed in tube shapes, which can potentially grow hair follicles but not necessarily. When the coat sheds hair, the natural response of the body is to push dead, shed hair out of the skin, as sebum builds up beneath the follicles to expel it.
However, some drainage sinuses are not actually tubular but in fact hollow, leaving no space for the sebum and debris to exit, which in turn can cause abscessing and swelling in the area of the affected sinus. Ultimately, this can cause to rupturing of the skin in order for the abscesses to drain, which can be very painful and even potentially fatal.
Dermoid sinus generally develops along the ridgeback’s signature ridge, and does not affect ridge-less dogs of the breed.
Because dermoid sinus is a hereditary condition, careful breeding and management is necessary for all breeders dogs of the breed, in order to ensure that potential litters stand the best possible chance of being born healthy.
Puppies born with the condition are often euthanized, although it is possible to perform an operation to remove the problematic dermoid sinus in order to eradicate the problem, which then allows the pups to be sold as pets (but not for breeding) and so, to live an otherwise normal life.
In order to curb the spread of the condition across the Rhodesian ridgeback breed and ensure that only healthy puppies remain in ongoing breeding programmes, Rhodesian ridgeback breed organisations and advocate strongly advocate for screening of breeding stock prior to choosing a mating match, in order to improve the health of the breed as a whole.
In this article, we will look at dermoid sinus in the Rhodesian ridgeback in more detail, including how the condition can affect dogs, and how to find out your own dog’s status. Read on to learn more.
There has been a lot of debate over the last couple of decades regarding how the heredity of the condition works-initially, it was thought to be an autosomal dominant disorder, but more modern research indicates that the condition occurs due to multiple gene mutations rather than just one.
This means that the exact combination of genes responsible for the condition have not been fully mapped, and so there is no DNA test in place to diagnose the condition prior to breeding.
Ridgebacks without the breed’s signature ridge do not suffer from the condition. However, the ridge itself is part of the breed standard, and so pups born without the ridge cannot be registered for breeding or showing in the UK, something that is again the source of some debate when it comes to the balance between breed standards and breeding for health.
Even ridgebacks that have the signature ridge and are themselves totally healthy can potentially produce affected puppies, and dogs with the ridge have both an elevated chance of being affected by dermoid sinus themselves, and also, passing on the condition to their puppies, even if they themselves appear healthy.
Whilst some cases of dermoid sinus can be easily identified by examination, not all problematic dermoid sinuses have openings on the skin’s surface, and this makes some presentations of the condition harder to diagnose.
For this reason, a veterinary surgeon that is experienced in recognising and diagnosing the problem should perform a thorough examination of the dog in order to identify their status. This generally involves using a catheter to probe the sinus itself in order to inject radiographic contrast dye, and then performing an X-ray.
MRI imaging and computed tomography (CT scanning) can also diagnose the problem, although these methods of diagnosis are generally significantly more expensive.
When it comes to breeding Rhodesian ridgebacks, affected dogs should never be bred from, and yet breeding from only unaffected stock with the ridge does not guarantee healthy puppies either.
This means that based on current knowledge of the condition, eliminating dermoid sinus from the breed’s gene pool entirely would involve breeding only dogs without the ridge, however, the fact that a lack of the ridge means a failure of the breed standard makes this course of action unlikely.
Additionally, the fact that the ridge itself is a breed standard feature means that even if ridge-less pups were accepted into the breed standard in future, there are so few genetically different ridge-less dogs of the breed left compared to the general population that there are unlikely to be enough dogs left to become the foundation of a new breeding programme without leading to dangerous levels of inbreeding.