Heat stress in sheep is rare but during hot weather it can occur if they are handled during the heat of the day. Signs include continuous panting/rapid breathing, weakness and ability to stand. If you see an animal struggling, moving them to a cool shaded area and wetting them in wool-less areas only with water or rubbing alcohol will help them cool down. Offering water in small amounts but not allowing them to gorge will also help recovery.
While in cattle we often recommend sprinklers to wet the backs of the animals, in sheep this can worsen the issues, due to air not being able to pass through wet wool.
On average a sheep drinks 4-8L of water a day but this can increase during hot weather, so ensure your stock have access to enough clean water.
Reducing heat stress will also help reduce the incidence of enzootic pneumonia. Outbreaks occur often after periods of stress involving mustering and yarding, and especially in dry, dusty conditions. Pneumonia is usually associated with a stress factor such as drenching, shearing, and transport- often this will come before an outbreak.
There is both an acute (causing sudden death) and a chronic version of this disease that shows up at the works with pleurisy (inflammation of the lungs). Enzootic pneumonia is caused by a combination of several viruses and bacteria, the virus (in NZ often a parainfluenza) usually causing the initial lung damage, allowing bacteria to colonize and damage the lungs. Two of these bacteria are a mycoplasma (notoriously hard to treat) and another called Mannheimia Hemolytica.
Symptoms of pneumonia include; loss of appetite, depression/lethargy, loss of condition, nasal discharge (white to yellow), increased respiratory effort, coughing and sudden death. Antibiotics may help animals survive the acute form of disease but the lung damage is often so severe by the time animals are seen that they are given too late.
Both heat stress and pneumonia are significant causes of production loss in sheep, by causing death, downgrading of carcasses, and decreased weight gain. At this point in time prevention is key.