Immunocidin

Sarcoid is the most common skin tumour of the horse and lesions commonly occur around the eye in close association with vital periorbital structures. They can be very problematic to deal with. Immunotherapy is one well recognised treatment modality.

Generally this has involved BCG or various other bacterial proteins injected intra lesionally. BCG has been used historically either in its lypophilic (live/viable) form or in crude or purified derivatives from capsular proteins.

The latest iteration of immunotherapy in the treatment of sarcoid is Immunocidin®. This allows for treatment of a wider range of facial and periocular lesions.

Immunocidin® is a relatively new material, produced by NOVAVIVE, USA. Immunocidin Equine has regulatory approval in the U.S. and Canada for the treatment of equine sarcoid tumours.

It is a purified protein derivative of a Mycobacterium and as such, it acts in much the same way as the previous BCG cell wall extracts. However, it is very purified and therefore, it does have a slightly more predictable effect with less risk of systemic side-effects.

It also has the benefit of not having to be placed intra lesionally; thus we can treat a much wider range of facial or other lesions with it. In contrast to other forms of the live BCG Bacillus and the crude capsular protein derivatives, no pre-medication is required.

Treatment consists of 2-6 injections delivered ideally at 2 week intervals depending upon the response .
The aim is to create an immunological response; this can result in quite dramatic swelling of the treated area. When this involves periorbital structures, the periocular swelling can be dramatic and sometimes even concerning, especially to those not used to using the material.

It is advised that the eye is fully examined prior to the use of Immunocidin, including staining the eye with fluorescein.
A follow up should be performed 24-96 hours post treatment to assess the degree of swelling. At this point NSAID’s can be instigated but the use of steroids should be avoided as these can reduce the efficacy of the Immunocidin®.

Immunocompromised patients, for example patients with PPID may also respond sub-optimally.

As the tumour tissue sloughs, draining sinus tracts can also develop; this is completely normal. These tracts can take 6-12 months to resolve. Very occasionally marked sublesional swelling can develop and is composed of pockets of pus and necrotic cellular debris that have yet to burst out.

The key to successful treatment with immunotherapy is persistence and optimising the impetus achieved once the immune system responds. This can be daunting when there is a large amount of swelling present and possibly also the presence of necrotic, sloughing and discharging tissue.

The team of veterinary consultants at EMS will guide you through the whole process, advising on when to perform the treatments.

Follow ups can be made at any time throughout the treatment. Follow ups are recommended at the time of the first treatment to assess needle placement, then 24-96 hours later and then at 2 weeks just prior to the subsequent treatment and then again 24-96 hours post treatment and so on.

CASE 1 EXAMPLE:

This series of images show the response of the sarcoids to treatment with Immunocidin.

In case 1 there is a multifocal complex of sarcoids within the upper and lower lids and lateral canthus. Immunocidin was chosen as the most appropriate therapy as it does not need to remain intralesionally and can be safely distributed throughout all of the lesions at this difficult site.

Image 1. the eye after 2 injections done at 2 weekly intervals. There is minimal inflammation present from the needle placement and the lesions have not started to respond yet.

Image 2. the eye 72 hours after the 3rd procedure. There is significant swelling within the upper eyelid, increased ocular discharge and a small amount of swelling within the lower lid. The epidermis is starting to show signs of an immunological response with serum exudate and superficial sloughing.

At this point the immunological response that has started needs to be maximised and the impetus continued.

The degree of swelling here was not enough to prevent or delay the 4th treatment performed 2 weeks later.

Image 3. the eye one week after the 4th treatment. The response is now well underway and the neoplastic cells are sloughing and coming away. This can be a difficult time for owners but it is a normal part of the process. At this point the eye was continued to be monitored but the 5th treatment was delayed.

Image 5. a close up of the sarcoid tissue sloughing away.

Image 6: 2 months later. A scar remains at the treated site but no active sarcoid remains.

CASE 2 FOR IMMUNOCIDIN 146431

Image 1. There is a family of small nodules within the lateral aspect of the upper lid along with fairly extensive occult change running through the whole of the upper lid.

Image 2. 48 hrs after second treatment. There is extensive swelling of the upper lid with marked ocular discharge. This swelling remained so that the 3rd treatment was delayed.

Image 3. 3 weeks after 2nd treatment. There has been a focal area of tissue necrosis and subsequent slough. At this point the 3rd treatment was administered.

Image 4. 1 week after 3rd treatment. The tissue necrosis and sloughing continues.

Image 5. 2 weeks after 3rd treatment. There is a very prominent immunological response occurring over the whole site of the upper lid. Further treatment was put on hold.

Image 6. 3 weeks after 3rd treatment. The area of slough has increased and it was not deemed viable to do a 4th treatment at this point and given the large immunological response it may also not be necessary.