Hereditary defect of dental enamel formation that produces a thin, irregular or absent adamantine layer. Affected teeth are yellowish-brown due to translucency of the dentin, suffer accelerated wear and may show sensitivity and cuspal fracture. It is the canine equivalent of human amelogenesis imperfecta and has been described in several breeds (Akita, American Akita, Italian Greyhound, Parson Russell Terrier, Samoyed). Molecular characterization is heterogeneous depending on the breed: the Italian Greyhound is caused by ENAM variants (PMID 23638899), the Samoyed by an SLC24A4 variant (PMID 29201383) and the Akita/American Akita by an ACP4 variant (PMID 30877375).

Limited data. Cases described in specific lines of Akita, American Akita, Italian Greyhound, Parson Russell Terrier and Samoyed. No reliable population frequencies by breed have been published.

- Thin, irregular or absent enamel from tooth eruption
- Yellowish-brown teeth due to translucency of the dentin
- Accelerated wear of cusps
- Sensitivity and pain when chewing hard foods
- Risk of fracture and pulpitis due to dental exposure
- Normal calcification of dentin and root

Canine familial enamel hypoplasia (FEH) has been described in series from several breeds since the end of the 20th century. Molecular characterization is heterogeneous depending on the breed: the Italian Greyhound is caused by ENAM variants (PMID 23638899), the Samoyed by an SLC24A4 variant (PMID 29201383) and the Akita/American Akita by an ACP4 variant (PMID 30877375), all of them analogous to autosomal recessive human amelogenesis imperfectas. The diversity of genes involved reflects the heterogeneity of human amelogenesis imperfectas. The exact chronology of the findings is not published in a consolidated form.

- Screen breeding animals of affected breeds when a molecular test is available
- Do not cross two identified carriers
- In the absence of a test, do not repeat crosses that have produced puppies with enamel hypoplasia
- Dental restorations improve quality of life but do not correct the cause

Differentiate from environmental enamel defects (dystrophy due to high fever, trauma, calcium-fluorosis, distemper in puppies) by distribution and family history. Involvement is symmetrical and generalized in genetic forms. The genetic test must be chosen according to the breed (ACP4 in Akita/American Akita; ENAM in Parson Russell Terrier and Italian Greyhound; SLC24A4 in Samoyed); a negative result does not rule out other amelogenesis imperfectas. Coordinate management with a veterinary dentist in affected animals.

1. Hytönen MK, Arumilli M, Sarkiala E, et al. (2019) Canine models of human amelogenesis imperfecta: identification of novel recessive ENAM and ACP4 variants. Hum Genet 138:525-533. PMID: 30877375
2. Gandolfi B, Liu H, Griffioen L, Pedersen NC. (2013) Simple recessive mutation in ENAM is associated with amelogenesis imperfecta in Italian Greyhounds. Anim Genet 44:464-467. PMID: 23638899
3. Pedersen NC, Shope B, Liu H. (2017) An autosomal recessive mutation in SCL24A4 causing enamel hypoplasia in Samoyed and its relationship to breed-wide genetic diversity. Canine Genet Epidemiol 4:11. PMID: 29201383
4. Nicholas FW, Mellersh C, Lewis T. (2018) Letter to the editor regarding an autosomal recessive mutation in SCL24A4 causing enamel hypoplasia in Samoyed. Canine Genet Epidemiol 5:4. PMID: 29744112