Modified-Live Virus: A virus which has been modified to no longer produce a disease but still retain the ability to induce a protective immune response so that it can be used as a vaccine.

Molars: The posterior teeth of the dental arcade, with two on each side in the upper jaw and three on each side in the lower jaw in an adult with correct dentition.

Molera: Incomplete, imperfect, or abnormal ossification of the skull.

Mongrel: See Crossbred

Monorchid: A dog that has one testicle retained or hidden in its abdominal cavity. See Cryptorchid

Mottled: Pattern of dark roundish blotches on a lighter background. Color definitions may vary by breed. Always check the breed standard for the definitive color description.

Move: To gait a dog in a pattern prescribed by the judge.

Moving Close: When the hocks turn in and pasterns drop straight to the ground and move parallel to one another, the dog is moving close in the rear.

Moving Straight: Term descriptive of balanced gaiting in which angle of inclination begins at the shoulder, or hip joint, and limbs remain relatively straight from these points to the pads of the feet, even as legs flex or extend in reaching or thrusting.

Music: The baying of the hounds.

Mustard: Usually used to describe Dandie Dinmont Terriers, this color is like the color of the spice; i.e., a dull, highly saturated, brown-yellow. Color definitions may vary by breed. Always check the breed standard for the definitive color description.

Mutation: A change of the DNA sequence within a gene or chromosome of an organism resulting in the creation of a new character or trait not found in the parental type.

Mute: To run mute, to be silent on the trail; i.e., to trail without baying or barking.

Muzzle: (1)The forward, projecting part of the head of certain animals, such as dogs, including the mouth, nose, and jaws; the snout; (2)A leather or wire restraining appliance that, when fitted over an animal's snout, prevents biting and eating.

Muzzle Band: White marking around the muzzle.

Myiasis: Infestation of tissue by fly larvae.