Diseases and Disorder of Youngstock – Respiratory Conditions
(By Ed Lyall, BVetMed, CertEM (StudMed), MRCVS)
Young horses are like children where they have quite naïve immune systems meaning they can pick up viral and bacterial infections much easier that an adult horse. Many of these manifest themselves when the antibodies, derived from the mothers colostrum, start to disappear from the foal’s blood stream. The most common infections are respiratory infections; it is not unusual to see paddocks full of weanlings with crusty snotty noses on stud farms, they are usually caused by viruses.
There is little treatment for respiratory viruses in horses other than supportive care, ideally the youngsters affected should have their temperature monitored and non-steroidal anti-inflammatory drugs such as bute can be given to bring the temperature down to normal.
Any foal with a snotty nose and a high temperature should be monitored for the development of swollen painful glands under the jaw and around the base of the ear. If such swellings are present, tests should be performed to rule out strangles, the bacterial respiratory infection caused by Streptococcus equi. Young horses often have slightly enlarged glands where their immune system is learning to deal with all the pathogens that the horse is being exposed to on a daily basis. The difference is that strangles causes abscesses with the glands that are very painful to palpate. Any horse, and its contact companions, that are suspiciously looking as though it has strangles should be isolated until the results of the appropriate tests are through.
Rhodococcus equi is a bacterial disease that causes abscessation in the lungs of young foals. It is derived from inhaled environmental bugs and can affect multiple foals on the same property, typically from two months of age. Foals will be found to be dull and lethargic with reasonably high temperatures, severe cases will be breathing difficulty; blood samples will show elevation of white cell counts and more importantly elevation of fibrinogen levels.
The diagnosis is confirmed by ultrasound scanning the chest to find evidence of the abscesses. Treatment is with appropriate long term antibiotics.