Diamond C Farm

01/13/2026

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Rhodesian Ridgebacks & Dermoid Sinus

Recently on a post about how we normalise extreme conformation. We asked people to give examples of animals with conformation that we normalise that we shouldn't. Rhodesian Ridgebacks & Dermoid Sinus was mentioned. For the purpose of this, we could also consider the Thai Ridgeback.

Lets investigate...

Rhodesian Ridgebacks are well known for their distinctive line of hair running along the spine — the dorsal ridge.
Fewer people realise that the same developmental abnormality that creates the ridge also predisposes these dogs to a condition called dermoid sinus.

What Is Dermoid Sinus?

Dermoid Sinus presents as a tubular skin indentation to variable degree into underlying tissues on the dorsal midline or cranial or caudal to the ridge, present from birth. A recent study stated there was a 'complex genetic basis for this condition'

These tunnels can:

➡️ remain shallow
➡️ extend deep into tissue
➡️ in the most severe cases (Category IV), connect directly to the spinal cord

How Common Is It?

In Sweden, 8–10% of Ridgebacks were reported affected, and prevalence was increasing (Salmon Hillbertz 2005). More recent data from Germany (12,700 puppies, 2001–2019) shows 2.53% prevalence, (litter with only ridged animals, prevalence was 2.81%.)

The Genetics — More Complex Than Once Believed

Historically, dermoid sinus was thought to be inherited in a simple way. As it was thought to be simple autosomal dominant mutation, one paper stated 'Because this disease is considered inherited in Rhodesian Ridgebacks, affected animals should not be bred.' However, research (see below) did more work to investigate the complexity of dermoid sinus.

The dorsal hair ridge in ridgeback dogs was found in a 2007 paper to be caused by a '133 kb duplication of three fibroblast growth factor genes FGF3, FGF4 and FGF19 and the ORAOV1 gene.' It stated that 'dogs homozygous for this copy number variation mutation have an increased risk of developing Dermoid Sinus (DS)'. They stated that 'further studies regarding the genetic complexity of DS and LTF will shed light on the biological complexity of these dermal lesions.'

Research (2022) did more work to investigate the complexity of this. It found:

✔ Inheritance of DS does not fit a simple autosomal recessive model
✔ The genetics of DS appear complex

How Serious Is It?

The welfare impact varies depending on the type of sinus:

🔴 Category IV (highest risk):

• Infection can spread to the spinal cord
• Causes severe pain, neurological disease, or paralysis
(In some dogs, these sinuses pe*****te through the vertebral lamina and Into the dura mater, predisposing the animal to infection and neurologic abnormalities.)
• May lead to death or euthanasia if not treated urgently
• One article stated 'Currently, it is the policy of some breeders to euthanase affected puppies shortly after birth' - we are unsure how common this occurs now.

🟠 Other forms:

• Recurrent infections
• Chronic pain and discomfort
• Need for surgical removal

📖 References

Prevalence and segregation analysis of dermoid sinus in Rhodesian Ridgebacks, Ottmar Distl, The Veterinary Journal, 2022.
https://www.sciencedirect.com/science/article/abs/pii/S1090023322000181

Universities Federation for Animal Welfare, Rhodesian Ridgeback, Dermoid Sinus
https://www.ufaw.org.uk/dogs/rhodesian-ridgeback-dermoid-sinus

Miller, Lisa & Tobias, Karen. (2003). Dermoid sinuses: Description, diagnosis, and treatment. Compendium on Continuing Education for the Practicing Veterinarian. 25. 295-300.

Salmon Hillbertz NH, Isaksson M, Karlsson EK, Hellmén E, Pielberg GR, Savolainen P, Wade CM, von Euler H, Gustafson U, Hedhammar A, Nilsson M, Lindblad-Toh K, Andersson L, Andersson G. Duplication of FGF3, FGF4, FGF19 and ORAOV1 causes hair ridge and predisposition to dermoid sinus in Ridgeback dogs. Nat Genet. 2007 Nov;39(11):1318-20. doi: 10.1038/ng.2007.4. Epub 2007 Sep 30. PMID: 17906623.

Salmon Hillbertz, Nicolette. (2007). The origin of the ridge and associated anomalies in Rhodesian Ridgebacks.

12/23/2025

🤔

🐴 The Muddy Horse: "YOU SEE DIRT. I SEE MY THERMAL COAT."
The visual focuses on a horse standing in a winter paddock, its coat matted with thick, dried mud "plates." An infographic overlay shows a cross-section of the hair: one side is clean and flat, while the other is mud-crusted, showing how the mud "tents" the hair to create a pocket of warm air against the skin.

YOU SEE DIRT. I SEE MY THERMAL COAT.

"Your grooming brush is stripping away my insulation. In the wild, mud isn't a mess—it’s a windbreaker. It seals my hair follicles against the biting cold and creates a barrier that parasites can't pe*****te. When you scrub me clean for the sake of a photo, you leave me shivering in the wind. Let me be 'dirty' so I can stay warm."

The Biological Reality: Horses utilize piloerection (the ability to fluff up their hair) to trap air. Dried mud acts as a physical sealant, reinforcing this air pocket and preventing the wind from "cutting through" the coat to reach the skin.

📰 FIELD REPORT: The Protective Crust
Angle: Dirt as a Functional Barrier.

[BIOLOGICAL EVALUATION] A horse's winter coat is a dynamic thermal system. When mud dries on the outer guard hairs, it creates a "shell" similar to a ceramic coating. This shell provides two critical unshown benefits: it prevents moisture (rain/snow) from reaching the dense, dry undercoat, and it acts as a "physical shield" against winter gnats and lice that struggle to navigate the hardened exterior.

THE ANATOMY OF THE WINTER "SHIELD"
1. Windproofing and Sealing
The Wind-Chill Factor: A clean, fluffy coat can be parted by a strong gust, allowing cold air to hit the skin directly. A mud-caked coat is "matted" into plates that deflect the wind like a suit of scale armor.

Thermal Retention: The mud acts as a secondary layer of insulation, helping to maintain a consistent skin temperature even when the external environment drops below freezing.

2. Waterproofing the Undercoat
The Shedding Effect: Dried mud often creates a "roofing" effect where snow or freezing rain sits on top of the mud layer rather than soaking into the skin. This keeps the skin dry, which is the single most important factor in preventing Rain Rot (a bacterial skin infection).

3. The Grooming Conflict
Removing the Oils: Over-grooming in winter can strip the natural sebum (skin oils) that provide waterproofing. When you brush off the mud, you often take these essential oils with it, leaving the horse more vulnerable to the elements.

THE "STEWARDSHIP" MANIFESTO
"Prioritize health over horse-show aesthetics."
Respect the "Gross" Look: A horse living outdoors in winter should look a bit rugged. That ruggedness is a sign that their natural defenses are working.

Targeted Grooming: Grooming should be limited to the areas where tack (saddle/bridle) will sit to prevent sores, leaving the rest of the body's "shield" intact.

🤝 Our Duty: Smart Winter Care
Coexisting with a "muddy" horse means knowing when to intervene and when to let nature take the lead.

The Action: The "Minimalist" Winter Protocol.

The "Tack-Only" Brush: Only remove mud from the girth, saddle, and bridle areas. Leave the mud on the flanks, back, and neck where it provides the most insulation.

Check for Skin Health: Instead of brushing, use your hands to "feel" under the mud. You are checking for heat, swelling, or bumps that might indicate an infection hidden beneath the crust.

The "Mud-Out" Shedding: Save the deep cleaning for the spring "shed-out." When the temperatures rise, the horse will naturally shed the mud and the winter hair together.

Provide a Dry Choice: Ensure the horse has access to a dry, bedded area. They should choose to be muddy, not be forced to stand in deep, wet muck that never dries.

A muddy horse is a horse that has successfully adapted to its environment. By leaving the "dirt" alone, you are respecting thousands of years of evolutionary wisdom that knows exactly how to stay warm when the mercury dips.

11/20/2025

The Equine Disease Communication Center is monitoring an outbreak of EHM that originated at the Women’s Professional Rodeo Association (WPRA) World Finals and Elite Barrel Race event Nov 5-9. To date, officially confirmed cases have been reported in the following states-