Y chromosome (kroh-muh-sohm): One of the Y chromosomes’ genes, the SRY (sex determining region Y), makes a protein that triggers embryonic development as a male

Yawning: An involuntary deep, open-mouth inhalation often accompanied by stretching which cats do when bored, relaxed, irritated, stressed, waking up or seeking attention

Yeasts: Microscopic, single-celled fungi that reproduce by budding and although  bacteria commonly cause inner ear infections in cats, yeasts can also be the cause

Yellow fat disease: Also called Feline pansteatitis causes inflammation and discoloration of body fat and is associated with eating large amounts of unsaturated fatty acids found in foods such as tuna and other oily fish

Yohimbine ( yoh-him-been): A drug used to reverse the sedative effects of Xylazine, particulary after emesis is successful


Zona pellucida (zoh-nuh puh-loo-si-duh): A transparent, non-cellular layer or envelope of uniform thickness surrounding an oocyte (egg)

Zoomies: The act of running around erratically, also known as Frenetic Random Activity Periods (FRAPs), may occur to release pent-up energy, after defecating and as a symptom of hyperthyroidism

Zoonosis (zoo-ah-nuh-seez): An infectious disease that can be transferred between species from people and animals and from animals to people

Zoonotic disease (zow-uh-naa-tuhk): Another term for zoonosis, such as rabies, ringworm and Q fever

Zoophobia (zoh-uh-foh-bee-uh): An abnormal fear of animals, which when related to cats is known as ailurophobia

Zygote (zai-gowt): A fertilized egg cell that results from the union of a female egg or ovum with a male sperm