Dog health conditions

Macadamia nut poisoning in dogs is caused by ingestion of a toxic dose of macadamia nuts. No other species of companion animals appear to suffer from this kind of toxicosis.

Mammary gland tumors (MGTs) result from the uncontrolled growth of mammary gland (breast) cells, which group together to form lumps in the mammary glands.

Mastitis is the inflammation of breast (mammary) tissue. Mastitis in dogs usually results from a bacterial infection and almost exclusively affects nursing mothers.

Mast cells are part of the immune system. Uncontrolled growth of these cells leads to mastocytoma, or mast cell tumors (MCTs), which are the most common type of skin tumor in dogs. These tumors commonly present as a lump in or under the skin.

Masticatory muscle myositis (MMM) is a condition in dogs where the immune system attacks the chewing muscles. Myositis is the term for inflammation of muscle tissue. The chewing muscles are on the top and sides of the head and are responsible for opening the mouth and chewing.

Megacolon in dogs describes abnormal dilation of the lower intestines, which prevents normal passage of feces. Megacolon is a rare condition in dogs, most commonly seen in geriatric patients.

Megaesophagus is a condition in which the esophagus is abnormally dilated (stretched) and lacks the muscle tone needed to move food into the stomach. Dogs may be affected from birth (congenital), or acquire the disorder later in life.

Melanoma is a tumor which develops from the cells responsible for skin pigmentation (melanocytes). Melanomas can be either benign or malignant and can be found on the skin, mouth, and eyes.

Meningitis is an uncommon, potentially life threatening condition that refers to inflammation of the meninges. Meninges are membranes that cover the brain and spinal cord. 

Inflammation of the middle and inner ear affect the parts of the ear that are behind the eardrum. In dogs, this form of inflammation is usually caused by bacterial infection, which most often spreads to these structures from the external ear.

Mothball poisoning is caused by close contact (ingestion, inhalation, or dermal exposure) with mothballs. 

Motion sickness (also known as car sickness) is when a dog shows signs of nausea and/or vomiting as a result of being in motion outside of their control.

Mushroom poisoning occurs as the result of ingestion of a toxic dose of a poisonous mushroom.

Myasthenia gravis (MG) is a disease which interrupts the way nerves communicate with striated muscles. Striated muscles control voluntary movement, such as those used to walk or change facial expression.