Dr. van Haeringen Laboratorium B.V.

H350 Ridge disposition (Dermoid sinus)


The breed-defining dorsal ridge in Rhodesian Ridgeback dogs is the result of a ~ 133,000 base pair duplication on chromosome 18 (Ridge allele). This duplication is absent in dogs without a ridge. The ridge trait is inherited in a dominant fashion, a single copy of this duplication results in appearance of a ridge. Dogs with two copies of the duplication are indistinguishable from dogs with one copy of the Ridge allele, but are at substantially greater risk for the development of dermoid sinus, a neural tube defect that is caused by incomplete separation of tissue layers during development. Affected dogs develop an inappropriate connection between the dermal surface and the spinal cord. This growth can become infected and lead to the development of abscesses and sepsis. In many cases, dermoid sinus can be fatal.

Test specific information



Symptoms will develop at a young age. Within a few hours to a maximum of several weeks after birth, the characteristics that go with these genetic effects will become visible.

Turnaround time

The Turnaround Time (TAT) depends on various factors, such as the shipment time of your sample to the test location, the test method(s) and whether the tests are performed completely or partially by a Partner Lab or Patent owner.

The TAT of tests performed at our facilities is normally 10 working days after receipt of the sample at the testing laboratory (VHL, VHP or Certagen). For tests performed by a Partner Laboratory (so-called "partner lab test") or patent owner, the TAT is at least 20 working days after receipt of your sample. Because the shipment time to our Partner Labs or patent owner may vary due to factors we cannot influence, the mentioned 20 working days are therefore an estimate.

Sometimes it is necessary to re-run your sample. We call this a retest. In that case, the TAT will of course be extended.

Location of disease or trait

This disease is present in the entire body, but causes main effects in the internal organs such as stomach, intestinal tract, liver and / or kidneys. In a number of cases, the disease affects one major internal organ.

Breed dependence

This DNA test is available for the following breeds: Rhodesian Ridgeback, Thai Ridgeback Dog. Additional information is available in the Frequently Asked Questions (FAQ).

Sample type

For this DNA test we accept the following materials: Blood EDTA, Blood Heparin, Semen, Tissue, Swab. Please contact Dr. Van Haeringen Laboratorium if you wish to submit other material as listed.


An animal can be free and has in that situation two healthy alleles. When used in breeding this animal will not become ill due to the disease. It cannot spread the disease in the population.

An animal can be carrier and has in that situation one healthy and one disease allele. When used in breeding 50 percent of the offspring will receive the disease allele. Carriers will also become ill.

An animal can be affected and has in that situation two disease alleles. When used in breeding all offspring will also receive the disease allele. Affected will also become ill.


This genetic factor is inherited in an autosomal, dominant, mode. This means, that the individual can be free of the mutation (homozygote normal), affected (homozygous affected) or carrier (heterozygous affected). Both carriers and affected individuals will show symptoms of the mutation.

Severity of Disease


Code H350

Ridge disposition (Dermoid sinus)

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