This criterion, called "backdoor", provides a mathematical definition of "confounding" and helps researchers identify accessible sets of variables worthy of measurement. Structure learning
While derivations in causal calculus rely on the structure of the causal graph, parts of the causal structure can, under certain assumptions, be learned from statistical data. The basic idea goes back to Sewall Wrights 1921 work on path analysis.
Pyometra or pyometritis is a uterine infection. Though it is most commonly known as a disease of the unaltered female dog, it is also a notable human disease. It is also seen in female cattle, horses, goats, sheep, swine, cats, rabbits, hamsters, ferrets, rats and guinea pigs. Pyometra is an important disease to be aware of for any dog or cat owner because of the sudden nature of the disease and the deadly consequences if left untreated. It has been compared to acute appendicitis in humans, because both are essentially empyemas within an abdominal organ. Signs and symptoms
The most obvious symptom of open pyometra is a discharge of pus from the vulva in a female that has recently been in heat. However, symptoms of closed pyometra are less obvious. Symptoms of both types include vomiting, loss of appetite, depression, and increased drinking and urinating. Fever is seen in less than a third of female dogs with pyometra. Closed pyometra is a more serious condition than open pyometra not only because there is no outlet for the infection, but also because a diagnosis of closed pyometra can easily be missed due to its insidious nature. Bloodwork may show dehydration and/or increased white blood cell count. X-rays will show an enlarged uterus, and ultrasound will confirm the presence of a fluid filled uterus. Cause
The risk of developing pyometra differs between dog breeds. Pyometra is a result of hormonal and structural changes in the uterus lining.