Yorkshire Terrier Color Dilution Alopecia: Case Reports and MLPH Genetics

SamMy Yorkie’s coat has gone thin and patchy along her back. Could it be something genetic?

Elena MarshIt could be, or it could be something else. Veterinary case reports have described a coat-color-linked hair loss in Yorkies since 1988, but several common conditions look identical.

SamI’ve seen DNA kits that test for “dilute.” Would one of those just tell me the answer?

Elena MarshIt tells you something real, but less than the box suggests. LABOKLIN, a major test lab, states that no known genetic factor predicts which dilute dog will lose hair.

SamSo what is actually known about Yorkies specifically, and what is still guesswork?

Elena MarshGood question. The Yorkie record has two halves, clinical case reports and DNA surveys, and the interesting part is how little they overlap.

Bottom line: Color dilution alopecia (CDA) has been described in Yorkshire Terriers in case reports since 1988, including a 10-dog pathology study from the University of Naples (1995), and the dilution gene MLPH has separately been found in the breed: the d1 variant in 7 of 40 Yorkies sampled in Brazil and the d3 variant in one Yorkie genome. But none of the Yorkie CDA cases we could verify was ever genotyped for MLPH, so the disease and the gene have not yet been tied together in the same Yorkie in the published record. In practice that means two things. If you test, choose a test that covers all three known variants (d1, d2, d3), because d1-only results can miss d3. And treat any result as risk information, not a diagnosis: no genetic factor is known that predicts which dilute dog develops CDA. Thinning hair in a Yorkie needs a veterinary work-up first; diagnosis and treatment belong to your veterinarian or a board-certified veterinary dermatologist. There is no cure, only management.

The science behind CDA, compressed into one section

If you have read about color dilution alopecia in other breeds, this paragraph is the recap; if you have not, it is the minimum you need. According to the OMIA entry for canine MLPH-related dilution, “MLPH-related color dilution predisposes to a skin disease termed color dilution alopecia.” The MLPH gene makes melanophilin, one of the proteins that moves pigment granules (melanosomes) inside pigment cells. When both copies are defective, pigment clumps instead of spreading evenly, black looks blue-grey and brown looks Isabella or lilac, and in some dogs the clumped pigment weakens the hair shaft in the dilute areas. Three causal variants are known: d1 (c.-22G>A), reported by Drögemüller and colleagues in 2007; d2 (c.705G>C), reported by Bauer and colleagues in 2018; and d3 (c.667_668insC), reported by Van Buren and colleagues in 2020. Inheritance is autosomal recessive. OMIA notes that in dilute dogs with white spotting, only the pigmented skin is affected. Being dilute does not mean a dog will lose hair, and risk differs enormously by breed: a 1990 Cornell study found hair loss typical of CDA in 42 of 57 blue or fawn Doberman Pinschers, whereas OMIA describes dilute Weimaraners as “rarely or never affected.” There is no treatment that reverses the follicle defect; care is aimed at the skin and at secondary infection. Everything below is about where the Yorkshire Terrier sits within that picture, which turns out to be an unusual place.

A trail of Yorkie case reports from 1988 to 2022

SamIf vets have written about this in Yorkies for decades, isn’t the cause settled?

Elena MarshThe clinical side is well documented: a Naples team examined 10 affected Yorkies by electron microscopy in 1995. But the MLPH gene had not been identified, so nobody could test it.

The Yorkie literature on this condition is short but spans more than three decades, and reading the three reports we discuss below in order is the clearest way to see what has, and has not, been established.

1988, the Veterinary Record. Ferrer, Durall, Closa and Mascort published “Colour mutant alopecia in Yorkshire terriers.” We were able to confirm the bibliographic record but not the text, so we will not summarize its case numbers or findings. Its significance here is chronological: it shows the condition was being recognized in the breed nearly twenty years before the first causal MLPH variant was described.

1995, University of Naples “Federico II.” Roperto and colleagues carried out clinical laboratory work and light-microscope, electron-microscope and X-ray microanalysis studies on skin biopsies and hair from 10 Yorkshire Terriers with CDA. Three findings stand out. Biochemistry showed “a marked melanin reduction in hair from affected areas.” Histology placed melanin clumps “mainly” in the basal cells of the epidermis and inside the hair bulb and shaft. Scanning electron microscopy showed “holes and bulges scattered in the hair shaft,” which is a structural explanation for why the coat breaks rather than simply falling out. The abstract does not report ages at onset or the dogs’ exact coat shades, so we do not either.

2022, a single case from Portugal. Magalhães and Pinto described a 1-year-old female Yorkshire Terrier brought to a clinic in Matosinhos for a second opinion on her poor coat. The owner mentioned that the dog’s father had a similar coat. The examination found “extensive areas of hypotrichosis and alopecia, affecting only dark-haired regions,” mainly along the back, the neck and the outer surface of both ears. It is published as a diagnostic exercise, a teaching format, and is the weakest of these three as evidence, but it is also the most recent and the most clinically detailed.

The OMIA bibliography lists two further Yorkie reports, by Miller (1991) and Lowenstein (1995); both also predate the identification of MLPH, and we do not summarize them here.

Put side by side, these reports agree on the essentials: the hair loss tracks the darker, dilute-pigmented coat, and the microscopic picture matches CDA as described in other breeds. That is a consistent clinical story. It is not, however, a genetic one, and the next section explains why that distinction matters for a Yorkie owner more than for most.

The measurement no Yorkie case report has made

SamSo nobody checked whether those affected Yorkies carried the dilution variant?

Elena MarshNot in any report we could verify. The 1988 and 1995 papers predate the 2007 discovery of d1, and the 2022 case had neither a biopsy nor a genetic test.

In the Doberman Pinscher, dilute dogs were among those used to track down the gene in 2005, and a separate study had already measured how often blue and fawn dogs lose hair. For the Yorkie, each piece of the story exists, but the pieces were collected from different dogs.

The 1988 and 1995 papers were written before any MLPH variant had been identified, so genotyping was impossible. The 2022 Portuguese case was diagnosed by trichogram, a microscope examination of plucked hairs. The authors noted that “it would also be possible to carry out histopathological analysis … and even genetic tests from a blood sample,” then stated plainly that “Histopathology was not performed in this case.” No genetic test was reported either.

That leaves a specific, checkable gap: we found no published report of a Yorkshire Terrier with CDA whose MLPH genotype was determined. This is not the same as saying the gene is not involved. The clinical and microscopic findings fit MLPH-related CDA closely, and OMIA lists the Yorkshire Terrier among breeds with a recorded dilution phenotype or variant. It means that when someone tells you “Yorkie CDA is caused by d1” or “by d3,” they are extrapolating from other breeds.

The extrapolation is complicated by a broader uncertainty. The UC Davis Veterinary Genetics Laboratory notes that “the known variants d1, d2, and d3 do not account for all color dilution in some breeds such as Doberman Pinscher, French Bulldog, Italian Greyhound, and English Bulldog.” Van Buren’s group, who described d3, wrote that “additional variants are likely” and that “this fact must be taken under consideration when performing genetic testing and counseling.” The Yorkie is not on the UC Davis list of problem breeds, but with no genotyped CDA cases in the breed, nobody has been in a position to check.

What DNA surveys have found in Yorkshire Terriers

SamHas anyone at least measured how common the dilution variants are in Yorkies?

Elena MarshIn one small sample. A Brazilian hospital genotyped 40 Yorkies for d1: 7 carriers, none with two copies. A genome database also found one Yorkie carrying d3.

There are two population-level data points, and both need careful handling.

Brazil, 2021: d1 in 40 Yorkies. Caramalac and colleagues randomly selected 40 dogs of each of three breeds (Dachshund, Miniature Pinscher and Yorkshire Terrier) from patients at the veterinary hospital of the Federal University of Mato Grosso do Sul and genotyped them for d1 by PCR-RFLP. For the Yorkies the genotype frequencies were:

• D/D (no copy): 0.825
• D/d (one copy, a carrier): 0.175, which is 7 of the 40 dogs
• d/d (two copies): 0
• d1 allele frequency: 0.088

The authors found no statistically significant difference in genotype frequency between the three breeds (p = 0.252). Five dogs in the study had hair loss at blood collection, four Dachshunds and one Doberman; none was a Yorkie. Only d1 was tested, so a Yorkie carrying d2 or d3 would have been counted as D/D. Forty dogs from one hospital in central-western Brazil cannot stand in for Yorkies in the United States or the United Kingdom, and zero d/d dogs in a sample of 40 does not mean d/d Yorkies do not exist. We found no published d1, d2 or d3 frequencies for American or British Yorkie populations.

Genome database, 2020: d3 in one Yorkie. When Van Buren and colleagues searched the Dog Biomedical Variant Database Consortium collection of 804 dog and 9 wolf genomes, the d3 variant was present in seven genomes, all with a single copy: four indigenous dogs, one Tibetan Mastiff, one Yorkshire Terrier and one wolf. Across that whole multi-breed collection, the allele frequencies were 0.054 for d1, 0.0025 for d2 and 0.0045 for d3. Those are pooled figures across more than 140 breeds, not Yorkie figures, and one heterozygous dog does not make d3 a “Yorkie variant.” What it does establish is that d3 exists in the breed, which is why OMIA lists the Yorkshire Terrier under d3.

So the genetic side shows two different dilution variants present in Yorkies, while the clinical side shows a Yorkie disease that looks like MLPH-related CDA. That combination is what turns test selection from a detail into the main practical decision.

Choosing a D-locus test in the US or UK: why coverage matters more than price

The first decision is whether a test reports all three variants. A d1-only test on a Yorkie that carries d3 will report it as if that copy were normal. Here is what providers stated on their own pages when we checked them on 5 October 2026 (prices change; confirm before ordering).

• Wisdom Panel (US). Its traits page lists separate results for Dilution (d1), Dilution (d2) and Dilution (d3) in the MLPH gene; d1 is labelled a “linkage test.” On the US site, Premium was $127.99 on sale (regular $159.99) and Essential $95.99 (regular $119.99); sales tax was not shown. In the UK, Wisdom Panel UK listed Premium at £108.74 on sale (regular £144.99), but we could not load a UK traits page to confirm that the same three variants are reported there.
• Embark (US). The Breed + Health test was shown at $139 (regular $159), with Breed ID at $109 and free US shipping. Embark’s Color Dilution trait page names MLPH and cites the 2007, 2018 and 2020 papers that described d1, d2 and d3; it does not spell out variant-by-variant reporting in words, so confirm with Embark if d3 matters to you.
• LABOKLIN (UK). The D-Locus D1 test and the separate D2/D3 rare-variants test are each £48.00 including VAT for the first colour test, with each additional colour test on the same dog £24.00; turnaround is listed as 1 to 3 weeks, from a cheek swab or EDTA blood.
• UC Davis VGL (US). An archived November 2025 version of its dilute page states the test “can detect all three known variants of the MLPH gene.” The live page did not load when we checked, so we are not quoting a current price.

One detail on the LABOKLIN UK pages deserves attention from Yorkie owners in particular. The D2/D3 page says the lab “will only perform the test for the variant that is relevant to your breed. Either d2 or d3,” and its d3 breed list names the Chihuahua, Pumi, Mudi and Italian Greyhound, not the Yorkshire Terrier. Yet the same page lists the Yorkshire Terrier among “breeds known to be affected by CDA.” If you order from a lab that selects variants by breed, ask in writing whether d3 will be run for a Yorkie before you send the swab.

Two further points apply whichever provider you use. First, the result is a genotype, not a prognosis. LABOKLIN’s German website states that “no genetic factor is known so far that distinguishes between dilute animals with and without symptoms of CDA” (our translation). Second, a lab’s commentary is not the last word on the biology. LABOKLIN UK writes that dilution “is just a colour” and that “there is no evidence that CDA is caused by dilution,” while OMIA states that MLPH-related dilution “predisposes” dogs to CDA. Both are consistent with the core fact: CDA appears in dilute dogs, but which dilute dog gets it cannot be predicted from the gene.

Reading the coat: the pattern vets look for, and the conditions that mimic CDA

SamHow would a vet tell CDA apart from the other reasons a small dog loses hair?

Elena MarshMostly from the pattern and the microscope. In the 2022 Yorkie, loss hit only dark-haired areas, and the differentials included demodicosis, ringworm and hypothyroidism.

The distribution of hair loss is the first clue. In the 2022 case, the alopecia was confined to dark-haired areas. LABOKLIN’s German page makes the same general observation: areas with strong eumelanin are more affected than lightly pigmented areas. OMIA adds that in dilute dogs with white spotting, white areas stay normal.

Both the AKC and the Royal Kennel Club describe the adult Yorkie as dark steel blue and tan. The AKC standard notes that “puppies are born black and tan” and lighten as they mature, and the Royal Kennel Club standard (last updated April 2025) specifies “dark steel blue (not silver blue).” These are descriptions of appearance for showing and registration; a standard color name is not a genotype, and nothing in this article should be read as a claim about what produces the breed’s steel blue. The practical point is narrower: a normal maturing coat change in a Yorkie is not, by itself, a sign of disease, which is one more reason to judge hair loss by its pattern and by testing rather than by shade.

The Portuguese clinicians listed demodicosis, dermatophytosis (ringworm), hypothyroidism, alopecia X and color dilution alopecia as the main differentials from the clinical picture alone. Hair loss along the flanks has another lookalike: seasonal flank alopecia. In a 2024 Dutch study of Rhodesian Ridgebacks, 3 of 24 affected dogs and 1 of 12 controls carried one d1 copy, none carried two, and the authors found no difference between the groups. That condition typically regrows within 3 to 8 months and recurs seasonally, which is not how CDA behaves; note, though, that only d1 was analyzed.

How CDA is confirmed:

• Trichogram: plucked hairs under the microscope, looking for clumped pigment and damaged shafts. This is how the 2022 Yorkie was diagnosed.
• Skin biopsy: shows pigment clumping in the follicle and, often, in the epidermis. According to OMIA’s summary of Welle and colleagues (2009), 22 of 29 dogs with clinical signs of “CDA/BHFD” (CDA or the related black hair follicular dysplasia) had clumped melanin in the epidermis as well as the follicle and hair shaft, whereas dilute dogs without disease had it only in the follicle and hair shaft.
• Excluding the alternatives: skin scrapings for mites, fungal testing and thyroid testing, as your veterinarian judges appropriate.

On timing, CDA “typically manifests between 4 months and 3 years of age,” according to Christen and colleagues (2021), although a Korean series in Kim and colleagues (2005) included dogs from 3 months to 10 years old. Treat that range as a guide, not a prediction for an individual dog.

From first appointment to specialist, and the insurance question in between

In the United States, the usual path is your primary-care veterinarian, then referral to a board-certified veterinary dermatologist if the diagnosis is uncertain or skin infections keep returning. The American College of Veterinary Dermatology states that there are more than 400 ACVD board-certified veterinary dermatologists worldwide and runs a public “Find a Veterinary Dermatologist” directory. In the United Kingdom, referral to a dermatology service is arranged through your own practice; ask your vet who they refer to. Bring any DNA result to the appointment, along with what you know about the coats of the dog’s parents. The 2022 Portuguese owner’s remark that the father “had a similar fur appearance” is exactly the kind of detail a dermatologist will want.

Insurance is where timing matters most, because CDA is chronic and the costs come from recurring skin infections rather than a single procedure.

• US example: Embrace states it covers “hereditary and congenital conditions … when not pre-existing at the time of enrollment.” Nationwide states that “pre-existing conditions are not covered.”
• UK example: Animal Friends says pre-existing conditions are not covered and that a condition can count as pre-existing if it “was first noticed before your policy start date or within the waiting period,” even if you never took the dog to the vet. ManyPets sells a dedicated plan and says it covers “most pre-existing conditions (but not all of them).”

The common thread is that thinning hair noticed before cover starts can be excluded. If you are buying a Yorkie puppy, arrange cover early and read the hereditary and pre-existing clauses before you sign. In England, Lucy’s Law has banned commercial third-party puppy sales since 6 April 2020, so buyers deal directly with the breeder or adopt from a rescue, and licensed breeders must show puppies with their mothers where they were born. That visit is a chance to ask whether either parent has had coat problems and whether the breeding dogs have been D-locus tested with d3 included.

Living with a Yorkie that has CDA

SamIf my Yorkie is diagnosed, will her coat ever grow back?

Elena MarshDon’t count on it. In the 2022 Yorkie case, topical treatment controlled the scaling and folliculitis, but the bald areas showed no regrowth. Skin care is the realistic goal.

There is no cure for CDA, and nothing in the published Yorkie record shows regrowth after treatment. What the record does show is that the secondary problems can be controlled. In the Portuguese case, seborrhea and folliculitis “were quickly controlled” with topical treatment, while “the alopecic areas remained and no signs of hair regrowth was observed.” OMIA describes the severity as “highly variable”: mildly affected dogs show some hair loss but are otherwise healthy and may need no therapy, while severe cases develop extensive hair loss and generalized folliculitis.

Treatments aimed at regrowth have little support. In a single 2009 Canadian Veterinary Journal case report of a blue Doberman crossbreed, oral melatonin given for three months produced no improvement. One case proves little either way, but it is a reason not to buy supplements in the expectation of a full coat. Any medication, shampoo regime or supplement should be chosen and dosed by your veterinarian.

Day-to-day care is mostly protective. Philipp and colleagues (2005) described the exposed skin of affected dogs as “often dry and scaly as well as sensitive to sunburn or extreme cold.” For a toy breed whose standard caps weight at seven pounds, that means thinking about sun on bald patches in summer and warmth in winter, gentle grooming that does not break fragile hair, and prompt veterinary attention when the skin looks inflamed or infected.

For breeders, the most defensible step is to test breeding dogs for all three variants and to keep records of coat condition in adult dogs and their relatives. That is also how the gap described above will eventually close: a single published Yorkie with confirmed CDA and a known MLPH genotype would add more to the breed’s evidence base than another survey of healthy dogs.

Frequently asked questions

Q. Do Yorkshire Terriers get color dilution alopecia?
Case reports describe it in the breed, including a 1988 Veterinary Record report, a 1995 University of Naples study of 10 affected Yorkies and a 2022 case from Portugal. How often it occurs is unknown; no incidence study in Yorkies was found.

Q. Has CDA in a Yorkie been linked to a specific MLPH variant?
Not in any report we could verify. The 1988 and 1995 studies predate the discovery of the variants, and the 2022 case was not genetically tested. The d1 and d3 variants have been found in Yorkies, but in different dogs from the reported cases.

Q. Which DNA test should I use for a Yorkie?
One that reports d1, d2 and d3. A d1-only test can miss d3, which has been found in the breed. If a lab chooses variants by breed, ask whether it will run d3 for a Yorkie.

Q. If my Yorkie tests d/d, will she lose her coat?
Not necessarily. No genetic factor is known that predicts which dilute dogs develop CDA. A d/d result is risk information, not a diagnosis.

Q. My Yorkie is losing hair. Is it CDA?
It may be something else entirely. Demodicosis, ringworm, hypothyroidism and alopecia X are among the conditions that look similar. Please see your veterinarian, who can confirm or rule out CDA with a trichogram or skin biopsy and refer you to a veterinary dermatologist if needed.

Q. Can CDA be cured?
No. Management focuses on skin care and treating secondary infection under veterinary supervision. In the 2022 Yorkie case, the bald areas did not regrow even after the skin infection was controlled.

References

• Ferrer L, Durall I, Closa JM, Mascort J (1988). Colour mutant alopecia in Yorkshire terriers. Veterinary Record 122(15):360-361.
• Roperto F, Cerundolo R, Restucci B, Vincensi MR, Caprariis D, Vico G, Maiolino P (1995). Colour Dilution Alopecia (CDA) in Ten Yorkshire Terriers. Veterinary Dermatology 6(4):171-178.
• Magalhães TR, Pinto FF (2022). Color dilution alopecia in a Yorkshire. Brazilian Journal of Veterinary Pathology 15(3):181-184.
• Caramalac SM, Caramalac SM, Babo-Terra VJ, Ramos CAN, Palumbo MIP (2021). PCR-RFLP molecular confirmation of color dilution alopecia in dogs in Brazil. Journal of Veterinary Diagnostic Investigation 33(5):984-986.
• Van Buren SL, Minor KM, Grahn RA, Mickelson JR, Grahn JC, Malvick J, Colangelo JR, Mueller E, Kuehnlein P, Kehl A (2020). A Third MLPH Variant Causing Coat Color Dilution in Dogs. Genes 11(6):639.
• Drögemüller C, Philipp U, Haase B, Günzel-Apel AR, Leeb T (2007). A noncoding melanophilin gene (MLPH) SNP at the splice donor of exon 1 represents a candidate causal mutation for coat color dilution in dogs. Journal of Heredity 98(5):468-473.
• Bauer A, Kehl A, Jagannathan V, Leeb T (2018). A novel MLPH variant in dogs with coat colour dilution. Animal Genetics 49(1):94-97.
• Philipp U, Hamann H, Mecklenburg L, Nishino S, Mignot E, Günzel-Apel AR, Schmutz SM, Leeb T (2005). Polymorphisms within the canine MLPH gene are associated with dilute coat color in dogs. BMC Genetics 6:34.
• Miller WH Jr (1990). Colour Dilution Alopecia in Doberman Pinschers with Blue or Fawn Coat Colours: A Study on the Incidence and Histopathology of this Disorder. Veterinary Dermatology 1(3):113-122.
• Welle M, Philipp U, Rufenacht S, Roosje P, Scharfenstein M, Schutz E, Brenig B, Linek M, Mecklenburg L, Grest P, Drogemuller M, Haase B, Leeb T, Drogemuller C (2009). MLPH Genotype—Melanin Phenotype Correlation in Dilute Dogs. Journal of Heredity 100(Suppl 1):S75-S79.
• Verschuuren MUMY, Schlotter YM, Leegwater PAJ (2024). Investigation of the association of the MLPH gene with seasonal canine flank alopecia in Rhodesian Ridgeback dogs. Canine Medicine and Genetics 11:5.
• Christen M, de le Roi M, Jagannathan V, Becker K, Leeb T (2021). MYO5A Frameshift Variant in a Miniature Dachshund with Coat Color Dilution and Neurological Defects Resembling Human Griscelli Syndrome Type 1. Genes 12(10):1479.
• Kim JH, Kang KI, Sohn HJ, Woo GH, Jean YH, Hwang EK (2005). Color-dilution alopecia in dogs. Journal of Veterinary Science 6(3):259-261.
• Perego R, Proverbio D, Roccabianca P, Spada E (2009). Color dilution alopecia in a blue Doberman pinscher crossbreed. Canadian Veterinary Journal 50(5):511-514.
• OMIA:000031-9615 — Coat colour, dilution, MLPH-related in Canis lupus familiaris (dog). Online Mendelian Inheritance in Animals, Sydney School of Veterinary Science (accessed 2026-10-05).
• LABOKLIN — D-Lokus d1 (Dilution, Farbverdünnung), Leistungs-ID 8136 / D-Lokus (seltene Varianten d2, d3), Leistungs-ID 8636 (accessed 2026-10-05).
• UC Davis Veterinary Genetics Laboratory — Dilute (D Locus/Blue) [dog]. Wayback Machine snapshot 2025-11-08.

About the author

Elena Marsh

Editor & writer (not a veterinarian)

A writer with a molecular-biology background and a lifelong dog and cat owner. Not a veterinarian — she translates peer-reviewed genetics research and primary data into plain language, always as information rather than diagnosis.