Guidance

Information for assistance with toxigenic Corynebacterium ulcerans animal index cases

Published 20 May 2026

Corynebacterium ulcerans is not reportable or notifiable in animals, but because of its zoonotic potential and public health concerns, Animal and Plant Health Agency (APHA) assist private vets with toxigenic Corynebacterium cases in pets. The UK Health Security Agency (UKHSA) and local Health Protection Teams lead with all human aspects of each case.

Treatment choice and management is the prerogative of the private vet based on clinical need and animal-owner needs, bearing in mind C. ulcerans is likely to be part of a mixed infection in clinical cases.

APHA advocates a minimum 3 week antibiotic course, with good clearance being observed with the use of a combined spiramycin, metronidazole product. Shorter courses of antibiotics may not achieve clearance.

A number of other antibiotics have also given good results and for pets that will not take oral medication, resolution of infection has been achieved using a long-acting injectable antibiotic to the equivalent of at least 3 weeks treatment.

Treatment can be longer than 3 weeks if the pet is slow to improve and is guided by clinical assessment(s).

Clearance swabs for treated toxigenic C. ulcerans cases

Clearance swabs should be 7 days after the completion of antibiotic treatment.  

In cases using long-acting 14-day antibiotic, clearance swabs are 7 days following the end of duration, (for example, 21 days after injection of a 14-day duration injection).

Swabbing of contact pets – pets in the same household

For households with other pets surveillance swabs from in-contact animals (cats and dogs) are recommended.

Pet cats and dogs in a household are usually considered as one epidemiological group – antibiotic treatment of contact pets could be commenced following swabbing. Alternatively, the vet and pet owner may decide to wait for the laboratory results. If one or more contact pets tests positive for toxigenic C. ulcerans it is advisable to treat them all (with coordinated antibiotic treatment).

Veterinary discretion should be used regarding swabbing to ensure minimal distress. If an animal cannot be swabbed safely with normal restraint, please contact APHA to discuss. APHA would not advocate for sedation to facilitate swabbing only. Ideally plan swabs early to mid-week to avoid postal delays during weekends.

Plain charcoal swab or a suitable bacteriology swab (for example eswab) labelled with pet id and swab location.

• oro-pharyngeal (throat) swab from each pet. Throat swabs are important as the bacterium can be carried in the throat of healthy animals.
• additional swabs of any exudative lesions and nasal discharge

Appropriate personal protective equipment (PPE) should be used by all staff handling animals for swabbing until a negative swab is achieved.

Typical PPE includes:

• eye protection
• disposable gloves
• apron or overall
• fluid repellent surgical face mask
• face guard

Where possible, these pets should be booked in at the end of a consulting session or wait in the car park to avoid mixing or close contact with other animals and people.

Samples submitted to APHA for bacterial examination will be reported in the normal way to the vet practice.

The cost of vet time, swabbing and any follow up treatments is the responsibility of the owners.

How to submit samples for bacterial examination

You can submit bacterial samples using the general submission form.

Complete all appropriate boxes (ignoring the farm related questions) and write at the bottom for C. ulcerans culture, pets name and if this is a post treatment swab or a first swab of a contact animal.

APHA will cover the cost of bacterial examination of C. ulcerans swabs sent to our APHA Starcross laboratory at:

APHA Veterinary Investigation Centre
Staplake Mount
Starcross
Exeter
EX6 8PE

Further information

Public health management of toxigenic C. ulcerans in companion animals guidance - appendix 2 includes information for vets and pet owners.