Strangles – managing an outbreak
Strangles is an endemic disease. Horses can be carriers, so all horses in a yard are often tested to identify which are a risk. A strangles test at vetting and prior to moving yards is advised. The commonest question, if it is a competition or livery yard, is whether, or when, the other horses on the yard can go off the yard to clinics or competitions.
First signs of an outbreak
A typical scenario is a young horse in a yard has a high temperature approximately 10 days after a new horse to the yard arrives next door. The sick horse develops a glandular swelling under the chin.
Immediate action
The vet should be called, both horses need to be isolated and barrier management put in place. These two should be tested and treated according to veterinary instructions. This is likely to include a guttural pouch wash. These tests revealed that the new horse is a carrier, and the more vulnerable young horse had been infected with strep…. Equi coci….
Yard management
The next issue is managing the other horses in this affected yard. It is important to understand the impact on business, reputation and horses’ health of a contagious disease. Couple with the power of social media, it is important to manage an outbreak very professionally. All liveries need to understand the importance of following the isolation procedures and act on veterinary advice.
The minimum policy is as follows:
- Check all horses’ temperatures daily once isolation starts
- Other horses on the premises can be ridden but should not compete or leave the premises until 2 weeks after isolation has begun
- No new horses should come onto the yard
- If a ridden horse is at all off colour, then it should stop ridden and fast work, no competing or leaving the yard.
There are three zones during an outbreak :
RED ZONE – any horses exposed to the carrier or with positive results
ORANGE ZONE – in contact but results of test not yet known or proven
GREEN ZONE – has been in contact but negative or has not been in contact. This zone is only achieved towards the end of the treatment and isolation period

Ben Mayes is a partner in Mayes & Scrine EVP, a six vet, RCVS PSS tier-2 100% equine practice offering 24 hour emergency cover with purpose built clinic facilities in Horsham, West Sussex. He is a member of BEVA Council and was the 51st president. He is also on the Advisory Board for the University of Surrey Veterinary School and vice-president of the Federation of European Equine Veterinary Associations (FEEVA).