American Bulldog — Myotonia (hereditary; OMIA-verified breed predisposition)

--- license: permission_granted topic_id: companion_breed_health_american_bulldog_omia2053_dog category: companion-breed-health title: "American Bulldog — Myotonia (hereditary; OMIA-verified breed predisposition)" lang: en source: "OMIA (Online Mendelian Inheritance in Animals, University of Sydney) breed-specific hereditary-disorder record, saved verbatim to source_file; C1 substring-verified. Pulled 2026-08-02 from local OMIA database dump." source_file: pdf-raw/breed-health/american_bulldog_omia2053_2053.txt date_parsed: 2026-08-02 tokens_estimated: 523 verification: method: substring_match claims: 9 passed: 9 date: 2026-08-02 recovered: false path: companion-breed-health/companion_breed_health_american_bulldog_omia2053_dog/01_companion_breed_health_american_bulldog_omia2053_dog.md source_document: "OMIA — Online Mendelian Inheritance in Animals (University of Sydney)" citation: authority: "OMIA — Online Mendelian Inheritance in Animals (University of Sydney)" title: "American Bulldog — Myotonia (hereditary; OMIA-verified breed predisposition)" url: "https://omia.org/OMIA000698/9615/" retrieved: "2026-08-02" ref: "OMIA breed-specific hereditary-disorder records (omia.org), derived from local OMIA database dump; dataset: https://doi.org/10.25910/2AMR-PV70" doc_type: "academic animal-genetics database (breed-specific disorder entries)" needs_review: false

American Bulldog — Myotonia (hereditary; OMIA-verified breed predisposition)

Source: first-hand OMIA (University of Sydney) breed-specific hereditary-disorder record, saved verbatim to source_file; every claim below is a C1 byte-substring of it.

Claims

• Breed: American Bulldog (Dog)
• Disorder:
• Mode of inheritance: Autosomal recessive
• Summary: Myotonia is a chloride channel disorder characterized by delayed skeletal muscle relaxation after contraction. Predominant signs include a stiff gait and skeletal muscle hypertrophy. Genetic tests are available for the miniature schnauzer and Australian cattle dog. Edited by Vicki N. Meyers-Wallen, VMD, PhD, Dipl. ACT
• Clin feat: Signs in miniature schnauzers include a stiff gait most pronounced at the onset of movement and during rapid changes in posture (turning quickly, falling), which may diminish with exercise. Other signs include severe skeletal muscle hypertrophy, difficulty rising, increased respiratory sounds, difficulty swallowing, and ptyalism beginning around 2 to 3 months of age. Associated superior prognathism may be a closely segregating trait (Gracis et al., 2000). Signs in the Australian cattle dog are similar, including skeletal muscle hypertrophy and generalized stiffness (Finnigan et al., 2007).brTwo French bulldogs reported by Shelton et al. (2024) presented with muscle hypertrophy, swallowing disorders, and gait abnormalities.
• Defect: yes
• Pathology: In affected dogs, skeletal muscle voltage-dependent chloride channels are unable to fully open at voltages near the resting membrane potential. There is a resultant delay in skeletal muscle relaxation after termination of the action potential, as depolarization is maintained longer than normal. Spontaneous triggering of action potentials independent of neuromuscular signaling induces frequent contraction and muscle hypertrophy (Rhodes et al., 1999).
• Prevalence: Of 372 Miniature schnauzers tested from the US, Canada, Europe and Australia, 78.5% were normal, 20.4% were carriers, and 1.1% were affected. All affected dogs initially identified had a common ancestor (Bhalerao et al., 2002).
• Control: Siblings of affected dogs and relatives of their parents should be tested. Breeding of affected dogs or carriers is discouraged.

Associated gene(s)

Derived from OMIA database dump (omia.xml, local); structured field, not verbatim prose. First-hand values below are verbatim substrings of the topic's pdf-raw/omia/<phene_id>.txt source file.

• Gene: Entrez Gene ID 403723 (no symbol in OMIA GeneSynonym) — OMIA Phene_Gene
• OMIA molecular-genetics note: By cloning and sequencing a very likely comparative candidate gene (based on the homologous disorder in himans, goats and mice), Rhodes et al. (1999) identified a causative variant [omia.variant:62]in the miniature schnauzer as a C to T substitution that changes the amino acid from threonine to methionine [p.T268M] in the <em>CLCN1</em> gene, which encodes the skeletal muscle voltage-dependent chl…

Evidence (references)

Derived from OMIA database dump (omia.xml, local); structured field, not verbatim prose. First-hand values below are verbatim substrings of the topic's pdf-raw/omia/<phene_id>.txt source file.

• 1981. Hereditary myotonia in the Chow Chow. Journal of Small Animal Practice — PubMed:PMID7289589 | DOI:DOI: 10.1111/j.1748-5827.1981.tb00629.x — OMIA Phene_Article / Article
• 1974. Three cases of myotonia in a family of Chows. Tijdschrift voor Diergeneeskunde — PubMed:PMID4536400 — OMIA Phene_Article / Article
• 1995. Myotonia in a cocker spaniel. Journal of the American Animal Hospital Association — PubMed:PMID8581546 — OMIA Phene_Article / Article
• 1998. Possible adult onset myotonic dystrophy in a boxer. Journal of Veterinary Internal Medicine — PubMed:PMID9560770 — OMIA Phene_Article / Article
• 1998. Myotonia associated with hyperadrenocorticism in two dogs. Australian Veterinary Journal — PubMed:PMID9862060 — OMIA Phene_Article / Article
• 1999. A missense mutation in canine ClC-1 causes recessive myotonia congenita in the dog. FEBS Lett — PubMed:PMID10452529 | DOI:10.1016/s0014-5793(99)00926-6 — OMIA Phene_Article / Article
• 1999. Congenital myotonic myopathy in the miniature schnauzer: An autosomal recessive trait. J Hered — PubMed:PMID10544501 | DOI:10.1093/jhered/90.5.578 — OMIA Phene_Article / Article
• 2002. Detection of a genetic mutation for myotonia congenita among Miniature Schnauzers and identification of a common carrier ancestor. American Journal of Veterinary Research — PubMed:PMID12371774 — OMIA Phene_Article / Article
• 2003. Detection of a genetic mutation for myotonia congenita among Miniature Schnauzers and identification of a common carrier ancestor (vol 63, pg 1443, 2002). American Journal of Veterinary Research — OMIA Phene_Article / Article
• 2007. A novel mutation of the CLCN1 gene associated with myotonia hereditaria in an Australian cattle dog. J Vet Intern Med — PubMed:PMID17552451 — OMIA Phene_Article / Article
• 2009. Myotonia congenita in a Jack Russell terrier. J S Afr Vet Assoc — PubMed:PMID19831273 — OMIA Phene_Article / Article
• 2000. Dental and craniofacial findings in eight miniature schnauzer dogs affected by myotonia congenita: preliminary results. J Vet Dent — PubMed:PMID11968937 — OMIA Phene_Article / Article
• (18 additional references in OMIA)

Comparative medicine (human OMIM)

Derived from OMIA database dump (omia.xml, local); structured field, not verbatim prose. First-hand values below are verbatim substrings of the topic's pdf-raw/omia/<phene_id>.txt source file.

• OMIM:160800 (type: trait) — OMIA Group_OMIM (via OMIA_ID)
• OMIM:255700 (type: trait) — OMIA Group_OMIM (via OMIA_ID)
• OMIM:118425 (type: gene) — OMIA Group_OMIM (via OMIA_ID)

verification_derived: method: derived_from_dataset source: "OMIA database dump (omia.xml, local); fields Gene/Variant/Article/OMIM" note: "Structured fields (gene, variant rsID/protein change, PubMed/DOI references, OMIM cross-link) extracted from OMIA dump and presented with first-hand values; not verbatim prose."