Lexicon

Malignant Hyperthermia (MH) is also known as "Canine Stress Syndrome (CSS)". Affected animals exhibit symptoms such as high fever, muscle cramps/stiffness, or respiratory distress. Some affected animals appear healthy, but exhibit the above symptoms under stress.

The disease occurs in many breeds. The inheritance is autosomal dominant. It occurs when one or both copies of the gene (n/MH or MH/MH) are affected by the mutation.

Genetic Test: available in Shop

Malignant hyperthermia (MH) causes anesthesia- or stress-induced muscle rigidity with fever and respiratory distress. MH results in death of the horse in approximately 34% of cases.

The disease occurs in Quarter Horses and related breeds. The inheritance is autosomal dominant.

Genetic Test: available in Shop

The dog has black markings over the muzzle and face ("mask"). This colour pattern is caused by the Em allele of the extension locus.

See: Extension (Coat colour E-Locus Dog)

Merle coloured dogs show a pattern of darker and lighter patches which appears random. The eyes may be lighter or blue in colour.

The colour is caused by the M allele of the M locus. Homozygous animals (M/M) have severe health problems such as deafness, blindness and organ problems.

Genetic Test: available in Shop

Muscle Integrity Myopathy (formerly known as "PSSM2") is form of Exertional Myopathy (link in those words), in which the structure and/or function of the muscle is disrupted.  It is caused by hereditary predisposition and various environmental factors (age, feeding, husbandry). Typical symptoms can include unexplained lameness, muscle stiffness, difficulties with gait changes/coordination, reluctance to move, muscle atrophy and/or difficulty building muscle. Almost any breed of horse can be affected.
Six genetic variants that can disrupt muscle structure and/or function have been identified in horses. These predispose a horse to developing symptoms of exertional myopathy.

Muscle Integrity Myopathy Test: available in Shop

Mushroom is a coat colour unique to the Shetland Pony, where phaeomelanin (chestnut colour) is lightened to a light sepia shade. Mushroom can also slightly affect the coat colour of ponies with bay base colour.

The colour is inherited autosomal recessively. Animals with one copy of the mutation (N/mu) show no dilution. Only animals with two copies of the mutation (mu/mu) show the Mushroom dilution.

Genetic Test: available in Shop

MYH1 Myopathy is an autoimmune disease where a horse can have an immune reaction against its own muscle cells.  There are two clinical presentations of MYHM: 

Immune-mediated myopathy (IMM) and non-exertional rhabdomyolysis.

The tested genetic mutation is a risk factor for these conditions. The disease is incomplete autosomal dominant and occurs in Quarter Horses and related breeds.