Equine sarcoids: cryosurgery vs live BCG vs BCG cell-wall preparation — POSSIBLE

In horses with sarcoid tumours eligible for local therapy, how do cryosurgery, live BCG, and BCG cell-wall preparation compare for complete tumour regression?

Shelf #128 · gate-verified and approved by the developer

POSSIBLE: In the one randomised trial, cryosurgery cleared every tumour it was used on — complete regression in 10 of 10 horses — against 6 of 10 with intralesional live BCG and 7 of 10 with a BCG cell-wall preparation, with no recurrence in cured horses over 3 to 40 months of follow-up. The only other comparative series, in which treatment was chosen by tumour size, site and appearance rather than randomised, points the same way but more weakly: success in 11 of 14 horses (79%) with cryosurgery versus 18 of 27 (67%) with local BCG vaccination. So the direction — cryosurgery at least as good as, and probably better than, BCG immunotherapy for tumours that can be frozen — is consistent, but it rests on one small 1986 trial of 30 horses plus a non-randomised series, and BCG regression in the trial was worse for larger tumours and limb sarcoids. Drafted Nov 10, 2026 (VetMed build, topic #128); all figures from abstracts fetched and verified at drafting.

Klein 1986: complete sarcoid regression 10/10 cryosurgery vs 6/10 live BCG vs 7/10 BCG cell-wall preparation

Prospective randomised clinical trial (record's own title wording)

Who: Horses: 30 horses with single or multiple sarcoid tumours of the skin, randomly divided into three treatment groups of 10 in a clinical trial setting; a further 11 horses whose tumour site or size precluded cryosurgery were treated outside the randomised comparison (see result).

Result: Complete tumour regression was obtained in all 10 cryosurgically treated horses, in 6 of 10 live BCG treated horses, and in 7 of 10 BCG cell wall treated horses. One live BCG and 2 BCG cell wall treated horses showed partial tumour regression of more than 50% of the tumour area. None of the cured animals showed tumour recurrence 3 to 40 months following treatment. Regression after BCG immunotherapy appeared to correlate with size (larger tumours worse response) and localization of the sarcoid (less favourable results in the limb). In the 11 horses not eligible for random allocation, treated with BCG cell wall vaccine except for 1 treated with live BCG (in 4 cases combined with cytoreductive surgery), 8 animals showed complete tumour regression and 3 animals did not respond.

Watch out: Small, single trial from 1986: 10 horses per arm, so the gap between 10/10 and 6–7/10 is compatible with considerable uncertainty. The record establishes random allocation and a prospective design in its title and abstract, but no blinding of outcome assessment is stated or indexed — regression was judged clinically. The 11-horse non-randomised group was prognostically unfavourable (site/size precluded cryosurgery) and must not be pooled with the randomised arms.

Klein WR, Bras GE, Misdorp W, Steerenberg PA, de Jong WH, Tiesjema RH, Kersjes AW, Ruitenberg EJ. Equine sarcoid: BCG immunotherapy compared to cryosurgery in a prospective randomised clinical trial. Cancer Immunol Immunother. 1986;21(2):133-40. PMID: 3633215. Registry ID: none in the record. MeSH: Animals · Antibodies, Bacterial · BCG Vaccine · Cryosurgery · Female · Horse Diseases · Horses · Immunotherapy · Male · Skin Neoplasms

Martens 2001: success 79% cryosurgery vs 67% BCG vaccination in a non-randomised sarcoid series (excision arms 82% and 71%)

Evaluation study — comparative case series, treatment selected by tumour features (not randomised)

Who: Horses: 95 horses with sarcoids treated in a clinical (referral) setting; the type of treatment was selected on the basis of the size, location and clinical appearance of the tumours, and the choice between conventional and laser excision was empirical.

Result: A successful outcome was obtained in 11 of 14 (79 per cent) of the horses treated by cryosurgery, 18 of 27 (67 per cent) treated by BCG vaccination, 18 of 22 (82 per cent) treated by conventional excision, and 20 of 28 (71 per cent) treated with a carbon dioxide laser. The probability of local recurrence after excision was significantly higher for large sarcoids and sarcoids which had previously failed to respond to treatment. In 10 of the 31 horses with remaining sarcoids, some or all of the untreated sarcoids were observed to regress spontaneously.

Watch out: This is not a randomised comparison: clinicians chose the treatment from the tumour's size, site and appearance, so the arms are not comparable at baseline and the percentages cannot be read as treatment effects. It is carded as supportive, same-direction context for the randomised Klein trial only. Spontaneous regression of untreated sarcoids in 10 horses is a further reason uncontrolled sarcoid series overstate any treatment.

Martens A, De Moor A, Vlaminck L, Pille F, Steenhaut M. Evaluation of excision, cryosurgery and local BCG vaccination for the treatment of equine sarcoids. Vet Rec. 2001;149(22):665-9. PMID: 11765322. Registry ID: none in the record. MeSH: Animals · BCG Vaccine · Cryosurgery · Female · Horse Diseases · Horses · Laser Therapy · Male · Neoplasm Recurrence, Local · Skin Neoplasms · Treatment Outcome

Synthesis: cryosurgery ahead on the only randomised evidence; BCG remains an option where freezing is not feasible

Synthesis

Who: Synthesis of the cards above: Klein 1986 (30 horses randomised to cryosurgery, live BCG or BCG cell-wall preparation) and Martens 2001 (95 horses, treatment chosen by tumour features, clinical setting).

Result: Both comparisons put cryosurgery numerically ahead of BCG immunotherapy for complete regression (10/10 vs 6/10 and 7/10 randomised; 79% vs 67% non-randomised), and no cured horse in the randomised trial recurred within 3–40 months. But the randomised evidence is one small trial, BCG outcomes worsen with tumour size and limb site, and the trial's own non-randomised arm shows BCG cell-wall treatment can still clear tumours (8 of 11) in horses whose sarcoids cannot be frozen — which is the population in which the choice is usually real.

Watch out: Neither card establishes blinded outcome assessment, and sarcoids can regress spontaneously (Martens 2001), so uncontrolled 'it worked' reports for any local sarcoid therapy should be discounted. Excision results (82% conventional, 71% laser in Martens) are outside this shelf's question and are not randomised either.

Synthesis of Klein WR et al. PMID: 3633215 and Martens A et al. PMID: 11765322. Registry IDs as on the individual cards.

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