Summer this year in the UK has been particularly hot; we have experienced a heat wave for the first time in almost a decade. The hot days between roughly the tenth of July and the fifteenth of August are known as the Dog Days, so called because they are under the astronomical influence of the Dog Star (canicula in Latin, hence the French “canicule”, sometimes also used in English), also known as Sirius. Greek and Latin poets, starting with Homer and Hesiod, sang of the effects of the parching heat on the environment and people:
When the golden thistle blooms and the chirping cicada
Sits in a tree and pours down its shrill song
Continuously from under its wings, it is the season of exhausting heat,
Then goats are fattest, wine is at its best,
Women are most lustful, but men are weakest,
Because Sirius dries up the head and the knees,
And the skin is parched by the burning heat.
[Hesiod, Works and Days 582-588]
To the Greeks, women were wet and men dry. The heat of the Dog Days caused both men and women to become drier; this brought positive effects to women, who became more like the ideal male, but weakened men. That weakness, however, was not a morbid state; it was not an illness.
Medical texts composed in later antiquity described a disease called seiriasis, which was an inflammation of the meninges accompanied by a burning fever. Its name evoked the Dog Star Sirius, although the physician Soranus of Ephesus suggested that the origin of the word seiriasis might be slightly more complex:
Some people state that the disease is called ‘seiriasis’ after the star [Sirius], because of the fever; but others state that it is thus called after the sunken forehead, because among farmers ‘seiros’ is the name of a hollow object in which they put and keep seeds. [Soranus, Gynaecology 2.55]
Soranus, and other medical writers, recommended the application of various ingredients to the forehead as treatment for the illness: egg yolk mixed with rose oil, the leaf of the heliotrope, grated colocynth, the skin of melon, or the juice of nightshade with rose oil. Most of these products, available in mid-summer, were thought to be cooling, and therefore effective in the treatment of fevers: opposite is a cure for opposite. The heliotrope, however, was not known as a cooling drug. The therapeutic principle at play here seems to be that of homeopathy (similar is a cure for similar): the heliotrope, the plant that follows the heat of the sun, is a remedy for a burning fever.
An altogether more colourful remedy for seiriasis is recorded in Pliny the Elder’s Natural History:
The inflammation of infants which is called seirasis is improved by the bones that are found in dog excrement, worn as amulets. [Pliny the Elder, Natural History 30.135]
Bone shards are sometimes found in dog poop, and these might be what Pliny was referring to here. This ingredient was most certainly chosen because of the perceived link between seiriasis and the Dog Star Sirius. One can only imagine the despair that would lead the sleep deprived parents of a sick child to put their trust in such an amulet.