The undercoat is often absent during shedding. The process results in normal hair loss known as shedding. Males behave the same way towards females while they are shedding their skin. In vaccinated sows multiplication of viruses and virus shedding are significantly reduced. Concurrent infection with HIV increases the frequency and duration of asymptomatic shedding. Transmission is believed to occur most frequently through the shedding of viral particles into saliva. Once full size, the frequency of shedding drastically decreases. This breed has little to no shedding. Consequently, this lifts the old skin from the new one allowing shedding to occur. A person with a viral disease is contagious if they are shedding viruses. The breed is renowned for its minimal shedding. Most sexual transmissions occur during periods of asymptomatic shedding. The presence of moisture aids in the shedding. Stress and use of corticosteroids precipitate shedding. Other plausible explanations include escape from predators, shedding parasites, or to gulp or expel air.