If the weather gets hot and wet, some animal diseases I am on the lookout for are facial eczema, enzootic pneumonia and flystrike. Facial eczema is a disease of ruminants and alpacas that eat enough of a specific fungal toxin found in the plant litter layer of pasture in late summer and autumn. Ideal conditions for the fungal growth are when night temperatures don’t fall below 14C and humidity is close to 100 per cent. Pastures grown in hollows and north-facing hillsides are more at risk. When enough toxin is eaten, there will be significant liver damage. Because of this the chlorophyll (the green pigment in green plants) eaten in greenfeed cannot be properly broken down and photodynamic pigments, which have a toxic reaction to light, build up in the blood. Where the skin is white and not covered with thick wool, sunlight will now cause severe burning. Prevention is much better than cure. So seek some advice if you are not familiar with this disease.
Enzootic pneumonia is a syndrome in sheep, especially hoggets, in New Zealand. The occurrence of enzootic pneumonia is influenced by many factors. A number of microbes can be involved. Parasitism and underfeeding have an influence, as do environmental conditions. If you are tossing and turning in bed because it is too muggy to sleep, and you have sheep under your care, then a little red flag should pop up. If you have to drive sheep in hot weather, do it in the early morning and avoid yarding for long periods. Co-ordinate events that need yarding with times the sheep are in paddocks near the yards. If the yards are dusty, dampen them down before the sheep arrive. The only mob pneumonias I have seen in cattle, apart from lungworm in weaners, is in neonatal calves in under-ventilated, damp, smelly sheds or where there is bovine viral diarrhoea immunosuppression.
Blowflies get up and get going for the year when ground temperatures rise over 12C. Wet summers are like Christmas for them. They are attracted to areas wet with diarrhoea, soaked with urine, and to weeping wounds and even footrot. They lay their eggs on wounds and in a day or two maggots start eating the surface of the host. All animals are at risk from flystrike, but sheep are the main target. Maggots don’t like being exposed to the sun and wool is an excellent hiding cover. Ideally sheep are shorn pre-summer. Some products for prevention or treatment are available in smallish amounts suitable for block holders.
David Haugh, Wellsford Vet Clinic