Evaluation of excision, cryosurgery and local BCG vaccination for the treatment of equine sarcoids.

Ninety-five horses with sarcoids were subjected to three types of treatment: surgical excision (conventional or carbon dioxide laser), cryotherapy or local BCG vaccination. The type of treatment was selected on the basis of the size, location and clinical appearance of the tumours. The choice between conventional and laser excision was empirical. 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. For both excision methods, rigorous measures were taken to avoid autoinoculation and to ensure a wide margin of normal skin. 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.     

Initial experience with high dose rate brachytherapy of periorbital sarcoids in the horse

Periorbital sarcoids are a common condition in the horse and are difficult to treat due to their location and invasive nature. Radiotherapy is considered the gold standard treatment, and high dose rate brachytherapy (HDRB) may represent a safer and more effective method of delivering radiotherapy in the standing sedated horse. The objective of this retrospective clinical case series study was to describe the response rate and safety of HDRB for the treatment of periorbital sarcoids in the horse. Horses and ponies referred for HDRB treatment of confirmed periorbital sarcoids were eligible for inclusion in the study. Sarcoids were confirmed via clinical diagnosis and biopsy. Horses were given 2 fractions of 12.5 Gy per fraction, delivered a week apart, under standing sedation via a novel HDRB technique. Eight horses with periorbital sarcoids were treated with HDRB under standing sedation. A complete response occurred in all cases. No significant acute adverse effects were noted after treatment and the cosmetic result was excellent, with permanent epilation and leucotrichia the only long‐term sequelae. Follow‐up was available for between 10 and 12 months after treatment. The major limitation of this study is the lack of long‐term follow‐up and the small case numbers. It was concluded that HDRB appears to be an effective and safe method of treating periorbital sarcoids in the horse. Long‐term follow‐up is required to determine the risk of recurrence of treated lesions.     

Partial orbital rim resection, mesh skin expansion, and second intention healing combined with enucleation or exenteration for extensive periocular tumors in horses

Ocular and periorbital sarcoids and squamous cell carcinoma are common in equine practice. Extensive involvement of periorbital tissues often necessitates removal of the globe if the function of the eyelids can not be maintained with tumor removal alone. This report describes a modification of the standard enucleation or exenteration technique for cases in which there is insufficient skin to achieve primary closure following complete surgical excision. The caudal portion of the dorsal orbital rim is protuberant; partial excision with an osteotome facilitates skin closure by decreasing the size of the wound. Mesh expansion of skin via multiple rows or parallel stab incisions can also be used as an adjunct to facilitate closure. Four horses underwent enucleation or exenteration using the orbital rim resection and mesh skin expansion techniques for extensive periocular tumors that were unresponsive to prior treatments. Follow-up intervals ranged from 6 to 42 months and no horses had tumor regrowth.     

Treatment of periocular and non-ocular sarcoids in 18 horses by interstitial brachytherapy with iridium-192

Treatment of the equine sarcoid has posed a significant challenge to clinicians for years and many different methods have been tried with varying success, including ionising radiation. The aim of this study was to review the efficacy of iridium-192 interstitial brachytherapy for the treatment of eight periocular sarcoids and 15 non-ocular sarcoids on 18 horses. All the periocular sarcoids and 13 of the 15 non-ocular sarcoids were treated successfully.     

Clinical observations on the use of BCG cell wall fraction for treatment of periocular and other equine sarcoids

Clinical observations on the use of BCG cell wall fraction in oil for treating seven horses with periocular sarcoids and five horses with sarcoids in other regions are described. Therapy was successful when used for periocular or solitary and smaller sarcoids. For sarcoids previously treated with cryosurgery, therapy appeared to be less efficient. A horse with a sarcoid on the stifle developed a septic gonitis due to necrosis of the sarcoid tissue adjacent to the joint. Sarcoids of the axilla appeared to be more aggressive than sarcoids at other locations and did not respond favourably to this form of therapy.     

Successful treatment of equine sarcoids with cisplatin electrochemotherapy: a retrospective study of 48 cases

Reasons for performing study: Sarcoids are the commonest form of equine skin tumour. Several therapeutic measures have been described but none is considered to be universally effective. Electrochemotherapy (ECT) is a new anticancer therapy that utilises electrical field pulses to induce increased cell membrane permeability to antitumour hydrophilic drugs, such as cisplatin. The increased intracellular concentration of the drugs has a significant therapeutic benefit. The procedure has not been previously reported in a large number of horses. Objective: To validate ECT as a novel alternative treatment for equine sarcoids. Methods: A retrospective study evaluating the efficacy of cisplatin ECT in the treatment of equine sarcoids was performed. Electrochemotherapy treatments were applied under general anaesthesia at 2 week intervals with or without prior excision or debulking. Electric pulses were directly applied to the lesions following intra‐tumoural injections of an aqueous solution of cisplatin. Results: One‐hundred‐and‐ninety‐four sarcoids on 34 horses, 2 ponies, 11 donkeys and one mule were treated with ECT. The 4 year nonrecurrence rate was 97.9% for animals (47/48) and 99.5% (193/194) for tumours. When ECT was used as a single treatment, a significant influence of tumour size (ρ= 0.55) on the number of treatments required for cure was shown. When prior surgery was performed, there was a significant influence (P<0.001) of the excision quality (complete or incomplete) and the healing mode (closed or open wound) on the number of treatments. The most common adverse effect was a slight oedematous reaction for lesions located on thin skin regions. Conclusion and clinical relevance: Results demonstrate that ECT, with or without concurrent tumour debulking, is an effective alternative for treatment of equine sarcoids.     

Equine Sarcoids. A Clinical and Epidemiological Study in Relation to Equine Leucocyte Antigens (ELA)

Associations between clinical parameters of sarcoids and the equine leucocyte antigen system (ELA) were analysed for 120 Swedish horses. Median age of affected horses was 5.2 years, and the majority presented with solitary tumors between 2 and 5 cm in diameter and ventral abdomen was a predilection site. Clinical signs first appeared at a median age of 3.5 years, and sarcoids at different locations first appeared at different ages. Lesions at different sites differed in size, and multiple tumors, early onset, long duration, and older age all had an association with large size. Clinical manifestations of sarcoids and the association between certain ELA-specificities and early onset (A5) and increased recurrence rates after surgery (W13), in addition to increased prevalence (A3W13), strengthen further that some horses are inherently predisposed to sarcoid growth. Unassociated with any clinical parameters, one third of the untreated horses became free of sarcoids due to “spontaneous” regression, perhaps as a result of immune responses against the tumors. Seventy percent of the horses were treated (mostly by excision), and large size was the main parameter promoting treatment. Excision had no significant effect on possibly remaining sarcoids. Recurrence rate after first treatment was about 35%, with the majority of tumors recurring within 4 months. Early onset, long duration, large size, and localization to distal limbs all appeared to increase risk of recurrence. Early treatment, performed under general anesthesia in recumbency which permits wide excision and measures to avoid autoinoculation, significantly reduced recurrence rates.     

Successful treatment of equine sarcoids by topical aciclovir application

Based on the anecdotally reported eradication of a sarcoid using aciclovir cream, the curative potential of this ointment was investigated in 22 sarcoid-affected horses referred to the Equine Clinic Tillysburg, Austria, between 2006 and 2009. Sarcoid disease was diagnosed by clinical examination and bovine papillomavirus types 1 and 2 from intact skin and tumour tissue. As nine horses had more than one lesion, a total of 47 sarcoids were treated by daily topical application of aciclovir 5 per cent cream for a period of two to six months; in four horses, surgical tumour ablation was performed before treatment. Disease parameters, including the tumour type, number, location and size, were recorded before and after aciclovir therapy. All 47 (100 per cent) of the sarcoids responded to treatment, with complete tumour regression observed for 32 (68 per cent) lesions and no recurrences reported thus far. Incomplete resolution was observed for 15 (32 per cent) lesions, probably due to their thickness. Aciclovir is proposed to be routinely used for the treatment of mild-type sarcoids and as an adjuvant therapeutic agent in combination with surgery.     

BCG treatment of periocular sarcoid

Twenty-six horses and five mules with periocular sarcoids were treated with intralesional injections of a purified bacillus of Calmette and Guerin (BCG) cell walls in oil suspension. All sarcoids were cured and the horses and mules remained free from recurrence of sarcoid during the two-year follow-up period.     

Bovine papillomavirus DNA in neoplastic and nonneoplastic tissues obtained from horses with and without sarcoids in the western United States

OBJECTIVE: To determine the incidence of bovine papillomavirus (BPV) type 1 or 2 in sarcoids and other samples of cutaneous tissues collected from horses in the western United States. ANIMALS: 55 horses with sarcoids and 12 horses without sarcoids. PROCEDURE: Tissue samples (tumor and normal skin from horses with sarcoids and normal skin, papillomas, and nonsarcoid cutaneous neoplasms from horses without sarcoids) were collected. Tissue samples were analyzed for BPV-1 or -2 DNA, using a polymerase chain reaction (PCR) and restriction fragment length polymorphism. The PCR products from 7 sarcoid-affected horses were sequenced to evaluate percentage homology with expected sequences for BPV-1 or-2. RESULTS: Most (94/96, 98%) sarcoids contained BPV DNA. Sixty-two percent of the tumors examined had restriction enzyme patterns consistent with BPV-2. Thirty-one of 49 (63%) samples of normal skin obtained from horses with sarcoids contained BPV DNA. All samples subsequently sequenced had 100% homology with the expected sequences for the specific viral type. All tissues from healthy horses, nonsarcoid neoplasms, and papillomas were negative for BPV DNA. CONCLUSIONS AND CLINICAL RELEVANCE: Bovine papillomaviral DNA was detected in essentially all sarcoids examined. There appears to be regional variation in the prevalence of viral types in these tumors. The fact that we detected viral DNA in normal skin samples from horses with sarcoids suggests the possibility of a latent viral phase. Viral latency may be 1 explanation for the high rate of recurrence following surgical excision of sarcoids.     

BCG emulsion immunotherapy of equine sarcoid

Of 61 horses with sarcoids treated with intralesional injection of a double emulsion incorporating inactivated bacillus Calmette Guérin organisms, 36 (59 per cent) showed complete regression and 11 (18 per cent) showed partial regression. The majority of cases required only one treatment. Not all sarcoids were responsive to this therapy; those not responding were usually large or on horses with multiple sarcoids.     

Expression of a transforming gene (E5) of bovine papillomavirus in sarcoids obtained from horses

OBJECTIVE: To determine expression of a transforming gene (E5) of bovine papillomavirus in sarcoids, other tumors, and normal skin samples collected from horses with and without sarcoids. SAMPLE POPULATION: 23 sarcoids and 6 samples of normal skin obtained from 16 horses with sarcoids, 2 samples of normal skin and 2 papillomas obtained from horses without sarcoids, and 1 papilloma obtained from a cow. PROCEDURE: Protein was extracted from tissue samples collected from horses and incubated with agarose beads covalently coupled to Staphylococcus aureus protein A and an anti-E5 polyclonal antibody. Following incubation, proteins were eluted from the beads and electrophoresed on a 14% polyacrylamide gel and transferred to a polyvinylidene difluoride membrane. The E5 protein was detected by use of western blot analysis, using a chemiluminescence detection system. RESULTS: All 23 sarcoids had positive results for expression of E5 protein. Quantity of viral protein appeared to vary among sarcoids. All other tissues examined had negative results for E5 protein. Highest expression for E5 protein was observed in biologically aggressive fibroblastic variants of sarcoids, compared with expression in quiescent tumors. CONCLUSIONS AND CLINICAL RELEVANCE: This study documented that activation and expression of the E5 gene is evident in sarcoids obtained from horses. These data support the conclusion that infection with bovine papillomavirus is important in the initiation or progression of sarcoids in horses. Treatment strategies designed to increase immune recognition of virally infected cells are warranted.     

The efficacy of intratumoural 5-fluorouracil for the treatment of equine sarcoids

OBJECTIVE: To document the efficacy of intratumoural injections of 5-fluorouracil for the treatment of equine sarcoids. DESIGN: A prospective study that included 13 horses and one donkey. PROCEDURE: Sarcoids were confirmed by histological examination and treated with intratumoural 5-fluorouracil every 2 weeks. If the sarcoids did not resolve after seven treatments, treatment was considered a failure. All cases were re-examined 6 months after treatment commenced and owners were telephoned 3 years after commencement of treatment to report on tumour recurrence. Outcome comparisons were performed to determine the effect of previous treatment, tumour size and tumour location on sarcoid resolution. The efficacy of intratumoural 5-fluorouracil was compared with other previously documented treatments of equine sarcoids. RESULTS: Sarcoids smaller than 13.5 cm3 were significantly (P = 0.032) more likely to resolve with treatment than larger sarcoids. Sarcoids that were not responsive to previous therapies were significantly (P = 0.007) more likely to recur after 3 years than sarcoids that had not been treated prior to this study. In this study, there were similar rates of resolution in cases with mutiple tumours (66.6%) when compared to cases with single tumours (60%). The numbers in this study were too small to properly evaluate the effect of tumour location on the success of treatment. Intratumoural 5-fluorouracil appeared to have resolved sarcoids in 9 of 13 cases (61.5%) as determined by follow up conversation with the owners 3 years after the initial treatment. CONCLUSION: The use of intratumoural 5-fluorouracil compares favourably with other treatment modalities for sarcoids, with a long term successful resolution rate of 61.5%. Owners should be warned that resistant sarcoids and sarcoids larger than 13.5 cm3 have a poorer prognosis for resolution and more aggressive therapeutic options should be considered.     

Carbon dioxide laser as a surgical instrument for sarcoid therapy--a retrospective study on 60 cases.

The objective of this retrospective clinical study was to evaluate the carbon dioxide laser in the treatment of single and multiple sarcoids in 60 animals (44 horses, 13 donkeys, 2 mules, and 1 pony). Only animals that had been operated on 6 mo or more ago were included. Recurrence, new manifestation rate, and cosmetic outcome were determined. Recurrence was observed in 23 (38%) individuals. Animals with new sarcoid manifestation with or without recurrence of a sarcoid were observed in 35 cases (58%). Cases of scar tissue formation and, rarely, leukotrichia were observed. Animals presented with multiple sarcoids were more predisposed to recurrence. Donkeys showed a significantly lower recurrence rate than horses.     

Management of equine sarcoids: 1975-93

Treatment options for equine sarcoids are briefly reviewed and the results of a retrospective study of 63 cases of equine sarcoid (66 lesions) treated by clinicians from the Rural Veterinary Centre, Camden, Australia from 1975 to 1993 presented. Five different treatments were employed in the management of these 66 lesions, including surgical excision alone or in combination with cryotherapy, radiotherapy, immunotherapy and tumour transfer to a subcutaneous site on the neck. The majority of cases were treated with surgical excision alone (18/66), excision followed by cryotherapy (31/66) and immunotherapy (16/66), with success rates of 28%, 42% and 81% respectively. Success was defined as no sign of recurrence of the lesion at the time of follow-up, at least 6 months later.     

Management of equine sarcoids: 1975–93

Treatment options for equine sarcoids are briefly reviewed and the results of a retrospective study of 63 cases of equine sarcoid (66 lesions) treated by clinicians from the Rural Veterinary Centre, Camden, Australia from 1975 to 1993 presented. Five different treatments were employed in the management of these 66 lesions, including surgical excision alone or in combination with cryotherapy, radiotherapy, immunotherapy and tumour transfer to a subcutaneous site on the neck. The majority of cases were treated with surgical excision alone (18/66), excision followed by cryotherapy (31/66) and immunotherapy (16/66), with success rates of 28%, 42% and 81% respectively. Success was defined as no sign of recurrence of the lesion at the time of follow-up, at least 6 months later.     

Factors associated with the risk of developing sarcoid tumours in horses.

A retrospective case-control study was conducted to identify risk factors in horses associated with the development of the common skin tumours known as sarcoids. The study involved 503 sarcoid cases diagnosed (January 1980-December 1989) at New York State College of Veterinary Medicine and a similar number of controls (non-sarcoid cases). Data on age, breed and sex of cases and controls were obtained from computerised records. Multiple logistic regression analysis was used to identify risk factors. Separate data were obtained for the same 10-year period from the Veterinary Medical Data Program to determine the proportional morbidity rate at different veterinary colleges in North America. Appaloosa, Arabian and Quarter horses were at a higher risk of developing sarcoid tumours than were Thoroughbred horses. Standardbred horses had a lower risk of developing sarcoids. Geldings were at a higher risk of developing sarcoids in comparison with stallions. There was no significant difference in the risk of developing sarcoids between stallions and mares. The risk of developing sarcoid increased with age up to 15 years and then declined. The proportional morbidity rate of sarcoids among the veterinary colleges ranged between 0 and 14 per 1,000 cases, with an average of 6 per 1,000.     

Evaluation of Locally Injected Mycobacterium Cell Wall Fraction in Horses with Sarcoids

A reformulation of Mycobacterium cell wall fraction immunotherapeutic can be used to successfully treat sarcoids in horses. Sarcoids are reported to be the most common equine skin tumors with tumor type and location influencing the choice of treatment. Wide surgical excision is curative for many tumors, but may not always be feasible. Previous studies have reported sarcoid regression after injection with mycobacterial cell wall immunotherapeutics. A new formulation of the Mycobacterium phlei cell wall fraction immunostimulant (Immunocidin Equine) was used to treat cutaneous tumors in horses. Equids with skin tumors diagnosed as sarcoids were enrolled in the study. Sarcoids were injected at the initial visit with Immunocidin Equine and subsequently at approximately 2-week intervals. Of 17 cases, nine cases were completely resolved at the end of the study period evaluation or at the time of final follow-up (52.9%). Three cases were reported as improved (smaller), but not resolved (17.6%). Three cases were discontinued from the study as the respective masses were growing larger or not resolving (17.6%). One case (5.8%) with two masses had resolution of one mass, whereas the other tumor had a small regrowth 5 months after the last treatment. One case (5.8%) was lost to follow-up. All cases had mild to moderate swelling of the injection site, and some cases had discharge after the second, third, or fourth injections. No serious systemic side effects or complications were encountered during the study.     

IRIDIUM-192 INTERSTITIAL BRACHYTHERAPY OF EQUINE SARCOID

Twenty-three equine sarcoids in 22 horses were treated, using an afterloading technique, with iridium-192 (¹⁹²Ir) interstitial radiation therapy. Previously unsuccessful treatment in 14 horses included surgical excision, cryosurgery, hyperthermia, and nonspecific immunotherapy. Twenty tumors were located in the skin of the head, and three were in the skin of the extremities. Before implantation, surgical debulking was done in six tumors, and hyperthermia (43°C, 30 min) was done in three tumors. Total implantation time varied from 4 to 14 days to give radiation doses of 52–93 Gy. The criteria for assessment of therapy were tumor response, tumor-free incidence at one year, and complications. Follow-up times ranged from six to 41 months (mean, 20 months). All tumors of the head and two tumors of the extremities had complete response to therapy. One sarcoid of the extremity had partial response to treatment. Tumor recurence was seen in the head of one horse. Of 16 horses followed for one year, the tumor-free incidence was 94% (15/16). Complications were severe local necrosis in two horses and deep infection in one horse. It was concluded that ¹⁹²Ir interstitial brachytherapy was an effective treatment of recurrent and difficult-to-manage equine sarcoid.     

A pilot study on the use of ultra-deformable liposomes containing bleomycin in the treatment of equine sarcoid

The efficacy of a novel topical liposome-encapsulated preparation of bleomycin (Bleosome) was studied in 118 clinical cases of equine sarcoid and efficacy was compared with two other standard conventional treatments, tazarotene and 5-fluorouracil (5-FU) as well as with the Bleosome in combination with each of these two conventional treatments. Treatments were arbitrarily assigned. Fifty-two of the 118 sarcoids (44%) were resolved after 12 months but there were significant differences between treatment groups with the combinations of either 5-FU and bleomycin, or tazarotene and bleomycin resulting in significantly superior resolution of 77 and 78% of the lesions, respectively. The preliminary results suggest that bleomycin in a liposomal carrier may be a useful treatment modality for superficial, diffuse and verrucose sarcoids. The treatment process was simple, and outcomes were functionally and cosmetically excellent. Liposome-encapsulated bleomycin is economic compared to radiation and other treatment options and can be applied effectively by the owner under guidance. Further studies with different administration protocols and higher concentrations of bleomycin are warranted.