When the uterine muscles contract, they constrict the blood supply to the tissue of the endometrium, which, in turn, breaks down and dies. These uterine contractions continue as they squeeze the old, dead endometrial tissue through the cervix and out of the body through the vagina. These contractions, and the resulting temporary oxygen deprivation to nearby tissues, are thought to be responsible for the pain or cramps experienced during menstruation. Compared with non-dysmnenorrhic individuals, those with primary dysmenorrhea have increased activity of the uterine muscle with increased contractility and increased frequency of contractions. Diagnosis
The diagnosis of dysmenorrhea is usually made simply on a medical history of menstrual pain that interferes with daily activities. However, there is no universally accepted standard technique for quantifying the severity of menstrual pains. There are various quantification models, called menstrual symptometrics, that can be used to estimate the severity of menstrual pains as well as correlate them with pain in other parts of the body, menstrual bleeding and degree of interference with daily activities. Further work-up
Once a diagnosis of dysmenorrhea is made, further workup is required to search for any secondary underlying cause of it, in order to be able to treat it specifically and to avoid the aggravation of a perhaps serious underlying cause. Further work-up includes a specific medical history of symptoms and menstrual cycles and a pelvic examination. Based on results from these, additional exams and tests may be motivated, such as:

Gynecologic ultrasonography
Laparoscopy

Management
Treatments that target the mechanism of pain include non-steroidal anti-inflammatory drugs (NSAIDs) and hormonal contraceptives.
Sudden acquired retinal degeneration syndrome (SARDS) is a disease in dogs causing sudden blindness. It can occur in any breed, but female dogs may be predisposed. Approximately 4000 cases are seen in the United States annually. Characteristics
Symptoms include sudden permanent blindness, but may occur more slowly over several days, weeks or months, dilated pupils. Pupillary light reflexes  are usually reduced but present; the slow phase mediated by melanopsin in retinal ganglion cells is retained. Other symptoms commonly seen are similar to those seen with Cushings disease and include increased water consumption and urination, weight gain, confusion, restlessness, behavioral changes and lethargy. These symptoms may develop over a few months preceding the onset of SARDS. Clinical signs and disease progression vary markedly among individual animals, depending on the number and type of hormones that are increased, the degree of hormone elevation, and the age of the dog.Some owners notice a more obvious "eye shine" in photographs due to the dilated pupils and retinal atrophy creating what is described as a "hyper-reflective tapetum". Causes
The cause of SARDS is considered to be idiopathic and the veterinary community is divided as to its cause, but the most common hypotheses on the causes of the disease possibly include autoimmune disease, or exposure to toxins. Autoimmune disease as a cause is controversial because some studies have supported the presence of antiretinal autoantibodies in dogs with SARDS, but others have failed to show a link.