After studying in Frankfurt, Stuttgart, Munich and Düsseldorf (his lessons including riding and horse anatomy), Schreyer travelled with Prince Thurn and Taxis in 1848 or 1849 through Hungary, Wallachia and southern Russia. In 1855, he followed the regiment commanded by the prince as an artist-reporter assigned to cover the Crimean war. He did not go to the Crimea itself, however, but to the eastern reaches of the Danube, the Austrian army's field of action in the conflict. He visited Syria and Egypt in 1856 or 1859, and Algiers in 1861, mastering several Arab dialects and thoroughly immersing himself in Bedouin life. He settled in Paris until the outbreak of the Franco-Prussian war obliged him to leave. He then went to live in Kronberg, but occasionally returned to Paris. Schreyer was the court painter to the Grand Duke of Mecklenburg, exhibited at the Paris Salon and in other European cities, and held membership in the Amsterdam and Rotterdam Academies. A number of German and American museums own examples of his work.

Throughout his thirty-year-long career, Schreyer continued to paint snowy scenes of Wallachian, Moldavian and Russian peasants or soldiers and their horses, which he had seen in his youth. These were as much appreciated as his pictures of Algerian horsemen. Schreyer first showed the latter in violent action, but later painted them riding their way quietly over rough ground, alone or in small groups. The choice of subject matter is clearly inspired by Fromentin (some of the copies made at the time of Schreyer's pictures even bear Fromentin's name), but his figures are generally in close-up, not in the middle distance as is usually the case in Fromentin's pictures. The colour schemes are characteristic; white and red clothing, red bridles and harnesses, a pale blue sky filled with puffy clouds, and a brown, rust and ochre ground. At their best, Schreyer's pictures are painted with real verve and brio, at their worst, they are rather heavy repetitions of stock themes.