Topic:Chemotherapy
Chemotherapy in horses involves the use of chemical agents to treat neoplastic conditions by targeting and destroying cancer cells. This therapeutic approach is adapted from human oncology and is applied to equine patients to manage various types of tumors, such as lymphoma and sarcoids. The administration of chemotherapy in horses requires careful consideration of dosage, administration routes, and potential side effects due to the differences in metabolism and size compared to other species. Common chemotherapeutic agents used in equine medicine include cisplatin, doxorubicin, and cyclophosphamide. This page compiles peer-reviewed research studies and scholarly articles that explore the pharmacokinetics, efficacy, and safety of chemotherapy protocols in horses, as well as their impact on equine health and welfare.
Comparison of perioperative versus postoperative intratumoral administration of cisplatin for treatment of cutaneous sarcoids and squamous cell carcinomas in horses. To determine the benefits of reducing the interval between surgical cytoreduction and intratumoral administration of cisplatin. Methods: Randomized clinical study. Methods: 70 horses with 89 incompletely resected T2- and T3-stage sarcoids (n = 64) and squamous cell carcinomas (25). Methods: Horses were given 4 intratumoral treatments of cisplatin at 2-week intervals. The first treatment was given at the time of, or immediately after, surgical resection for horses treated in accordance with the perioperative protocol (group 1). Horses in group 2 were treated with cisplatin after the skin healed...
Clotrimazole, ketoconazole, and clodinafop-propargyl as potent growth inhibitors of equine Babesia parasites during in vitro culture. The antifungal agents clotrimazole (CLT) and ketoconazole (KC) and the herbicide clodinafop-propargyl (CP) inhibit growth of Plasmodium sp., Toxoplasma sp., and Trypanosoma sp. In the present study, we evaluated these drugs against the in vitro growth of the equine protozoan parasites Babesia equi and B. caballi. Clotrimazole (IC50: 2 and 17 microM), KC (IC50: 6 and 22 microM), and CP (IC50: 450 and 354 microM) were effective growth inhibitors. Interestingly, intraerythrocytic KC-treated Babesia sp. were observed to be in immediate contact with the plasma fraction of the blood in electron micr...
Growth inhibitory effect of triclosan on equine and bovine Babesia parasites. We evaluated the growth inhibitory effect of triclosan, which has recently been reported to inhibit the growth of Plasmodium species and Toxoplasma gondii, on bovine and equine Babesia parasites in in vitro cultures The growth of Babesia bovis and B. bigemina was significantly inhibited in the presence of 100 microg/ml of triclosan, while B. caballi and B. equi were susceptible to as low as 50 microg/ml. Babesia bigemina and B. caballi were completely cleared as early as on the first and second day of the treatment, respectively. These parasites did not exhibit any growth in the subsequent fiv...
Comparison of the efficacy of local treatment of equine sarcoids with IL-2 or cisplatin/IL-2. Local interleukin-2 (IL-2) is effective in a number of experimental animal models and in veterinary and human cancer patients without discomforting side effects. The primary goal of this study was to compare the therapeutic effects and side effects of the local intratumoral administration of five or ten low doses of IL-2 with those of a combination of cisplatin and a single high dose of IL-2 in the treatment of equine sarcoids. The therapeutic effect (complete and partial regression) of local cisplatin together with a single high dose of IL-2 was significantly better than the combined effect o...
Evaluation of the field application of PCR in the eradication of contagious equine metritis from Japan. The effectiveness of the polymerase chain reaction (PCR) as a field application test for the eradication of contagious equine metritis (CEM) was evaluated. Seven-thousands five-hundred and thirty-four genital swabs were collected from 4,026 Thoroughbred broodmares and stallions in Japan to test "high risk" horses as well as for general surveillance testing from 1998 to 2001. Bacterial isolation as well as PCR testing of original specimens and cultured specimens was performed for detection of Taylorella equigenitalis from genital swabs. As a result, T. equigenitalis was detected in 12 mares and...
Chemotherapy of surra in horses and mules with diminazene aceturate. During June-July 2000, an outbreak of surra occurred on an equine breeding farm in Khonkaen Province, Thailand. Forty-two percent of pregnant mares aborted or gave stillbirth and 40% (19/47) of horses and 10% (1/10) of mules died from surra. In August 2000 Trypanosoma evansi were detected in the remaining animals (28 horses and nine mules) on the farm by blood smear and/or the haematocrit centrifuge technique. All animals were treated with diminazene aceturate at 3.5 mg/kg body weight by intramuscular injection on days 0 and 41 of the study. Blood samples of eight randomly selected horses and ...
[Treatment of equine sarcoids with cisplatin in arachid oil: a useful alternative?]. At the Department of Equine Sciences at Utrecht University a study was performed on the treatment of sarcoids with the cytostatic drug cisplatin. Fourteen horses with 23 sarcoids were treated in the period 2000-2001. Complete regression was seen in 78% of the tumours. No systemic side-effects were encountered. Although treatment was easy to perform, the ALARA (As Low As Reasonably Achievable) principle should be followed when using cytostatics.
Periocular neurofibrosarcoma in a horse. A periocular neurofibrosarcoma was debulked and treated with intralesional cisplatin in a 5-year-old Thoroughbred mare. The horse presented with a 1-year history of a large slowly progressing subcutaneous mass over the right supraorbital process. The mass was surgically debulked, and intralesional cisplatin (1.0 mg/cm3) was injected in 3 doses at 2 weeks, 5 weeks, and 8 weeks postoperatively. No recurrence was noted over a 15-month follow-up period. Histopathology of the mass indicated neurofibrosarcoma.
Electrochemotherapy of horses. A preliminary clinical report. Sarcoids are skin spontaneous tumours detected in horses. It can be cured by chemotherapy by using cisplatin. A multisequence treatment must be performed. Problems are present due to the poor diffusion of the hydrophilic product in the tumours. Electropulsation is known to drastically enhance the effect of antitumoral drugs in vivo. Taking into account the very successful results of the group in Ljubljana (Slovenia), we started a research clinical program where electropulsation was applied after local cisplatin injection. The size of sarcoids is large (several centimeters). A specially designe...
Animal type melanoma: a report of a case with balloon-cell change and sentinel lymph node metastasis. Animal type melanoma is a rare histopathologic variant of melanoma characterized by sheets and nodules of heavily pigmented epithelioid melanocytes that involve the entire thickness of the dermis. This human neoplasm mimics melanocytic neoplasms seen in gray horses and laboratory animals; thus, is termed animal type melanoma. It is quite rare and, with only a few reported cases, its biological behavior is not well understood. We report an example of animal type melanoma on the back of a 27-year-old man. The lesion showed areas of melanoma in situ, which ruled out the possibility of metastatic ...
Equine orbital neoplasia: a review of 10 cases (1983-1998). The clinical manifestations, laboratory findings, and survival times of 10 horses with orbital neoplasms are reported. In all cases, orbital neoplasms were malignant and locally invasive with no defined surgical circumscribed edges. It was often difficult to identify the primary cell type of the neoplasia in histologic specimens due to the poorly differentiated, anaplastic nature of the majority of cases. All except one horse were eventually euthanized 2 mo to 5 y after diagnosis due to poor response to treatment, metastasis, or unrelenting orbital neoplasia. Mean survival time increased with ...
Alternative approaches to control of cyathostomes: an African perspective. Cyathostomes are common nematode parasites of horses, donkeys and mules in developing countries. These equids usually work on a daily basis and this includes transportation of goods, crops and people. Stress, associated with work, and limited nutrition often result in a loss of condition, and cyathostomid nematodes may, then, cause clinical disease. Because anthelmintics are not always accessible or affordable in many parts of Africa, or there may be anthelmintic resistance to current remedies, management practices are often used as an adjunct to chemotherapy. This paper discusses some current...
Successful treatment of an equine preputial fibrosarcoma using 5-fluorouracil/evaluation of the treatment using quantitative PCNA and Ki67 (MIB 1) immunostaining. (case report). An 18-month-old cross-bred Fjord pony colt presenting a fibrosarcoma of the prepuce with severe infiltrative growth, was treated by topical application of 5-fluorouracil. Biopsies were taken before and after a treatment period of 2 months. As a control, preputial tissue from a healthy horse was biopsied. Tissue sections were stained immunohistochemically for Proliferating Cell Nuclear Antigen (PCNA) and Proliferation related factor--Ki67 (MIB1). Using computerized quantitative image analysis of these sections, Mitotic index (PCNA), Growth Fraction (Ki67) and total nuclear area percentage of th...
Intralesional and topical chemotherapy and immunotherapy. Surgery is the mainstay of treatment for equine tumors. Conservative treatment approaches which preserve function and appearance are increasingly used in clinical practice. This article covers the principles and applications of two conservative treatment modalities including local chemotherapy and immunotherapy. The therapeutic benefit of local chemotherapy is based on the direct drug delivery to tumor tissue, i.e., topical and intratumoral administration of cytotoxic agents in slow release formulation. This treatment modality is very effective for cutaneous tumors and does not result in any p...
Signs of sympathetic denervation associated with a thoracic melanoma in a horse. Sympathetic denervation in a 20-year-old, gray, Thoroughbred-Percheron gelding was manifested by cutaneous hyperthermia and sweating over the right side of the body, demarcated by a line from the withers to the elbow and extending cranially. There was cutaneous hyperthermia over the right side of the head, but other signs of Horner's syndrome (sweating, ptosis, miosis, enophthalmos) were not present. The pattern of cutaneous hyperthermia and sweating was consistent with sympathetic denervation localized to the cervicothoracic ganglion, and thoracic radiographs revealed increased density in the...
Comparison of intratumoral administration of cisplatin versus bleomycin for treatment of periocular squamous cell carcinomas in horses. To compare therapeutic benefits of intratumoral administration of cisplatin and bleomycin for squamous cell carcinoma of the eyelids in horses. Methods: 25 horses with 27 T2-stage periocular squamous cell carcinomas. Methods: Horses were treated 4 times at 2-week intervals with a slow-release formulation of cisplatin (1 mg/cm3 of tissue) or bleomycin (1 IU/cm3 of tissue). A two-stage design was used to minimize the sample size in each treatment arm. Results: The local control rate at 1 year for lesions treated with cisplatin was 93 +/- 6%, and with bleomycin was 78 +/- 10%. Difference in local...
Control of Babesia equi parasitemia. Infection of horses with the hemoprotozoan Babesia equi has been reported in southern Florida, US Virgin Islands, part of Asia, Russia, India, the Middle East, Europe, Africa, Australia, South America, Central America, Mexico, Philippine Islands and some Caribbean islands. The restrictions placed on the international movement of infected horses has refocused attention on potential methods to control or eliminate infection. Don Knowles here discusses the primary chemotherapeutic compounds that have been used; the current knowledge concerning immune responses that potentially contribute to contr...
Serum can inhibit reversal of multidrug resistance by chemosensitisers. The purpose of this study was to evaluate to what extent the ability of various chemosensitisers (CS) to reverse P-glycoprotein-associated multidrug resistance (MDR) is reduced when tested in physiological serum protein concentrations. Utilising drug sensitivity and accumulation assays, the CS were tested in medium containing 10% fetal bovine serum and in 100% horse or human serum. Two RPMI 8226 human myeloma sublines were used which express different levels of P-glycoprotein. The CS were tested at various concentrations, including clinically achievable blood levels. When using the CS at high ...
Equine piroplasmosis an update on diagnosis, treatment and prevention. Two haemoprotozoan parasites, Babesia caballi and Babesia equi, can cause equine piroplasmosis. Due to the presence of potential tick vectors in areas so far unaffected by equine babesias, import and export regulations often require the serum testing of animals for evidence of infection. Although the complement fixation test (CFT) has been recommended for detecting the presence of antibodies to Babesia spp., it has been demonstrated to have several disadvantages, including false-positive results and low sensitivity for detecting latent infections. An enzyme-linked immunosorbent assay (ELISA) m...
Equine Cutaneous Lymphoma: A Case Report. Résumé- Les commémoratifs, les symptômes, l'histologie et la réponse au traitement d'un cheval de 15 ans atteint de lymphome cutané sont décrits. La jument présente de multiples nodules cutanés depuis 11 ans. Un diagnostic de lymphome cutané est poséà l'examen histologique de biopsies réalisées 2 fois à 4 ans d'intervalle. Des marquages immunihistochimiques identifient ces cellules comme appartenant à la lignée T. Ceci est la première description du marquage immunophénotypique d'un lymphome cutané chez le cheval. La jument a été traitée par des glucorticoïdes intralési...
Topical use of 5-fluorouracil for treatment of squamous cell carcinoma of the external genitalia of horses: 11 cases (1988-1992). Ten horses with histologically confirmed squamous cell carcinoma (SCC) and 1 horse with presumptive SCC of the external genitalia were treated with a combination of surgical debridement and topical administration of 5-fluorouracil, or with topical treatment alone. Tumor remission was obtained in all horses except 1 in which owner compliance was deficient, and no recurrences have been reported. Topical use of 5-fluorouracil as a chemotherapeutic agent for treatment of genital lesions of SCC in horses should be considered as a viable alternative to radical surgical excision.
Perioperative intratumoral administration of cisplatin for treatment of cutaneous tumors in equidae. Twenty-seven horses (and 1 mule) with 32 histologically confirmed cutaneous tumors were studied to evaluate the effects of intratumoral injection of cisplatin initiated at the time of surgery. As a result of surgery, 9 of the wounds were closed primarily (5 sarcoids, 4 carcinomas) and 23 were left open to granulate (16 sarcoids, 6 carcinomas, 1 hamartoma). Chemotherapy consisted of 4 treatment sessions of intratumoral injection of cisplatin in purified sesame oil at 2-week intervals. The first treatment session was administered intraoperatively. A controlled-release formulation of cisplatin in...
Leishmaniasis disseminated by Leishmania braziliensis in a mare (Equus cabalus) immunotherapy and chemotherapy assays. Cutaneous disseminated lesions caused by Leishmania sp. were found in a pregnant mare (Equus cabalus) from a rural city in the State of Rio de Janeiro, Brazil. Before delivering, treatment was undertaken by immunotherapy followed by chemotherapy. Histopatology and serology were performed during treatment, as well as the biochemical characterization of the parasite (L. braziliensis) that was isolated from one of the lesions.
Intratumoral chemotherapy with cisplatin in oily emulsion in horses. Twenty horses with 30 lesions were studied to evaluate the effects of intratumoral chemotherapy with cisplatin in sesame oil on equine sarcoids (n = 19), squamous cell carcinomas (n = 7), and squamous cell papillomas (n = 4). Treatment consisted of 4 sessions of intratumoral cisplatin chemotherapy at 2-week intervals. A controlled-release formulation of cisplatin in sesame oil was used to limit drug egress from the injection site. Mean dosage per session was 0.97 (+/- 0.17, SEM) mg of cisplatin/cm3 of tumor tissue treated for tumor volumes ranging from 10 to 20 cm3. Dosage tended to be slightl...
[A liposomal form of diamidine: reduced toxicity]. The cultures of Nuttalia eque mainly develop in the reticuloendothelial organs and so in treatment of nuttaliosis in horses and the Nuttalia carriers diamidine, an analog of imidocarb or imidozoline, was used encapsulated in liposomes. The liposomes were prepared with a modification of the phase inversion method (the lipids were dissolved in a mixture of freon-11 and chloroform). The content of the organic solvents in the preparation, as evidenced by gas liquid chromatography, was less than 0.2 per cent. The main fraction consisted of particles 1.5 to 2.5 microns in diameter. The tests on anim...
Equine helminth infections: control by selective chemotherapy. A programme of selective anthelmintic therapy was used in a herd of 31 horses. Faecal egg counts were done during the months of September, November, January, March, May and the following September. Horses with greater than or equal to 100 eggs per gram (epg) were treated with ivermectin, and those with less than 100 epg were not treated. The criteria for adequate internal parasite control in the herd was a median herd faecal egg count of less than or equal to 100 epg. Effectiveness of selective therapy was assessed by faecal egg count after nine months of treatment and was determined to be ade...
Immune-mediated hemolytic anemia in a horse. An 18-year-old Quarter Horse gelding was determined to have immune-mediated hemolytic anemia after detection of autoagglutination of RBC spherocytosis as well as a positive direct Coombs test result. A lack of response to treatment with corticosteroids necessiated the administration of cyclophosphamide and azathioprine. The anemia resolved after treatment with chemotherapeutic drugs.