Topical treatment of equine sarcoids with imiquimod 5% cream or Sanguinaria canadensis and zinc chloride - an open prospective study.

BACKGROUND: Equine sarcoids are the most prevalent skin neoplasm in horses worldwide. Although several treatments are available, none are consistently effective and recurrence is common. OBJECTIVES: To evaluate the efficacy and safety of topical imiquimod 5% cream and Sanguinaria canadensis + zinc chloride for treatment of equine sarcoids and investigate possible systemic effects on distant untreated sarcoids. ANIMALS/TUMOURS: Twenty-five client-owned horses with a total of 164 tumours were included in the study. Fifty-seven tumours were treated and 107 tumours were left untreated. METHODS AND MATERIALS: Skin biopsy samples were collected from a minimum of one tumour per horse and the rest were diagnosed based on clinical appearance as likely sarcoids. Imiquimod 5% (A) was applied three times weekly, while Sanguinaria canadensis + zinc chloride (X) was applied every fourth day after a six day daily initiation phase. Treatment continued until clinical remission or for a maximum of 45 weeks, with a long follow-up period (mean 34 months). Skin biopsy samples of sarcoid lesions were re-taken before treatment termination and at follow-up if the owner gave consent. RESULTS: Complete remission was recorded in 84.4% (A) and 75.0% (X) of the tumours. Relapse was recorded in 7.3% (A) and 21.4% (X). Spontaneous remission was observed in 1.9% of untreated tumours. No systemic effect on untreated tumours was detected. During treatment varying degrees of local inflammatory reaction were common. CONCLUSIONS AND CLINICAL RELEVANCE: Both treatments were considered effective and safe. Smaller tumours responded more favourably to treatment. Relapse rate was low and not observed in sarcoids with repeat biopsies before treatment termination.

Genome-Wide Association Study of Insect Bite Hypersensitivity in Swedish-Born Icelandic Horses.

Insect bite hypersensitivity (IBH) is the most common allergic skin disease in horses and is caused by biting midges, mainly of the genus Culicoides. The disease predominantly comprises a type I hypersensitivity reaction, causing severe itching and discomfort that reduce the welfare and commercial value of the horse. It is a multifactorial disorder influenced by both genetic and environmental factors, with heritability ranging from 0.16 to 0.27 in various horse breeds. The worldwide prevalence in different horse breeds ranges from 3% to 60%; it is more than 50% in Icelandic horses exported to the European continent and approximately 8% in Swedish-born Icelandic horses. To minimize the influence of environmental effects, we analyzed Swedish-born Icelandic horses to identify genomic regions that regulate susceptibility to IBH. We performed a genome-wide association (GWA) study on 104 affected and 105 unaffected Icelandic horses genotyped using Illumina® EquineSNP50 Genotyping BeadChip. Quality control and population stratification analyses were performed with the GenABEL package in R (λ = 0.81). The association analysis was performed using the Bayesian variable selection method, Bayes C, implemented in GenSel software. The highest percentage of genetic variance was explained by the windows on X chromosomes (0.51% and 0.36% by 73 and 74 mb), 17 (0.34% by 77 mb), and 18 (0.34% by 26 mb). Overlapping regions with previous GWA studies were observed on chromosomes 7, 9, and 17. The windows identified in our study on chromosomes 7, 10, and 17 harbored immune system genes and are priorities for further investigation.

Intramuscular administration of sodium benzylpenicillin in horses as an alternative to procaine benzylpenicillin.

The aim was to supply information about the possibility of replacing the procaine salt with the sodium salt for benzylpenicillin IM treatment in horse in order to diminish the risk for procaine adverse effects. In a crossover study eight horses were given 15 mg/kg sodium benzylpenicillin (Na-pc) twice daily or procaine benzylpenicillin (control) once daily IM for four days. The half-life of Na-pc was 1.9h, peak concentration was 14,600 ng/mL reached after about 23 min. Trough plasma concentration was 281 ng/mL and protein binding 62.8%. The fT>MIC for Staphylococcus aureus was 63% and 100% for Streptococcus equi subsp. equi and Streptococcus zooepidemicus, indicating an adequate antimicrobial therapy. However, Na-pc cannot be recommended from a welfare point of view since the horses showed more pain related behaviour and more pain and swelling compared to the control treatment.

The effect of cryotherapy on oral mucosa: a study in healthy volunteers.

Oral cryotherapy causes local vasoconstriction, which reduces blood flow and reduces the cytotoxic damage to the oral mucosa, has been shown to reduce oral mucositis after intense cytostatic treatment. The main object of this study was to investigate the effect of oral cryotherapy on the temperature in the oral mucosa, the level of proinflammatory cytokine interleukin-6 (IL-6) in saliva and the effect on blood pressure in healthy volunteers, before and after 1 h of cooling the oral cavity with crushed ice. Twelve healthy volunteers [mean age 32.4 (SD 13.2) (20-56) years] were treated with oral cryotherapy in the form of crushed ice. Temperature measurements were performed in the oral mucosa using infrared thermograph following a flowchart protocol. Blood pressure (BP) was measured with a sphygmomanometer. Saliva was analysed for inflammatory cytokine IL-6, using an enzyme-linked immunosorbent assay (ELISA). All participants fulfilled the cooling session. The temperature in the oral cavity decreased significantly (mean 12.9 °C, p < .002). The systolic BP was marginally but significantly higher after cooling (~5 mmHg, p = .019). We could not detect any differences in cytokine IL-6 levels before and after oral cooling. We conclude that cryotherapy during 1 h lowers the mucosal temperature as much as ~12.9 °C, which explains the significant protective effect against mucosal damage by cytostatic drugs. The cooling caused no increase in IL-6 levels. Systemic blood pressure was marginally increased.

The same ELA class II risk factors confer equine insect bite hypersensitivity in two distinct populations.

Insect bite hypersensitivity (IBH) is a chronic allergic dermatitis common in horses. Affected horses mainly react against antigens present in the saliva from the biting midges, Culicoides ssp, and occasionally black flies, Simulium ssp. Because of this insect dependency, the disease is clearly seasonal and prevalence varies between geographical locations. For two distinct horse breeds, we genotyped four microsatellite markers positioned within the MHC class II region and sequenced the highly polymorphic exons two from DRA and DRB3, respectively. Initially, 94 IBH-affected and 93 unaffected Swedish born Icelandic horses were tested for genetic association. These horses had previously been genotyped on the Illumina Equine SNP50 BeadChip, which made it possible to ensure that our study did not suffer from the effects of stratification. The second population consisted of 106 unaffected and 80 IBH-affected Exmoor ponies. We show that variants in the MHC class II region are associated with disease susceptibility (p (raw) = 2.34 × 10(-5)), with the same allele (COR112:274) associated in two separate populations. In addition, we combined microsatellite and sequencing data in order to investigate the pattern of homozygosity and show that homozygosity across the entire MHC class II region is associated with a higher risk of developing IBH (p = 0.0013). To our knowledge this is the first time in any atopic dermatitis suffering species, including man, where the same risk allele has been identified in two distinct populations.

Evaluation of LHP® (1% hydrogen peroxide) cream versus petrolatum and untreated controls in open wounds in healthy horses: a randomized, blinded control study.

BACKGROUND: Treatment and protection of wounds in horses can be challenging; protecting bandages may be difficult to apply on the proximal extremities and the body. Unprotected wounds carry an increased risk of bacterial contamination and subsequent infection which can lead to delayed wound healing. Topical treatment with antimicrobials is one possibility to prevent bacterial colonization or infection, but the frequent use of antimicrobials ultimately leads to development of bacterial resistance which is an increasing concern in both human and veterinary medicine. METHODS: Standardized wounds were created in 10 Standardbred mares. Three wounds were made in each horse. Two wounds were randomly treated with LHP® or petrolatum and the third wound served as untreated control. All wounds were assessed daily until complete epithelization. Protocol data were recorded on day 2, 6, 11, 16, 21 and 28. Data included clinical scores for inflammation and healing, photoplanimetry for calculating wound areas and swab cytology to assess bacterial colonization and inflammation. Bacterial cultures were obtained on day 2, 6 and 16. RESULTS: Mean time to complete healing for LHP® treated wounds was 32 days (95%CI=26.9-37.7). Mean time to complete healing for petrolatum and untreated control wounds were 41.6 days (95%CI=36.2-47.0) and 44.0 days (95%CI=38.6-49.4) respectively. Wound healing occurred significantly faster in LHP® wounds compared to both petrolatum (p=0.0004) and untreated controls (p<0.0001). There was no significant difference in time for healing between petrolatum and untreated controls. Total scores for bacteria and neutrophils were significantly (p<0.0001) lower for LHP® treated wounds compared to petrolatum from day 16 and onwards. Staphylococcus aureus and Streptococcus zooepidemicus were only found in cultures from petrolatum treated wounds and untreated controls. CONCLUSIONS: Treatment with LHP® reduced bacterial colonization and was associated with earlier complete wound healing. LHP® cream appears to be safe and effective for topical wound treatment or wound protection.

Pharmacokinetics and effects of cetirizine in horses with insect bite hypersensitivity.

Horses with insect bite hypersensitivity (IBH) have difficulty in completely avoiding allergens, so effective treatment options are required. A randomised, placebo controlled and double blinded field study was conducted to determine the pharmacokinetics and efficacy in reducing dermatitis of the antihistamine cetirizine given orally at 0.4 mg/kg twice daily for 3 weeks. The influence of protection blankets and stabling were also investigated. The estimated maximum plasma concentration (C(max)) and trough plasma concentration of cetirizine were 135 ng/mL and 18 ng/mL, respectively. There was no difference in dermatitis reduction between the treatment and placebo groups (P = 0.77). The findings indicated that cetirizine was of no apparent benefit in treating IBH at the dose rate tested. The use of blankets and stabling were shown to have favourable influence on the dermatitis (P < 0.05) and may be the preferred options to prevent this condition.

Skin-infiltrating T cells and cytokine expression in Icelandic horses affected with insect bite hypersensitivity: a possible role for regulatory T cells.

Equine insect bite hypersensitivity (IBH) is a seasonally recurrent, pruritic skin disorder caused by an IgE-mediated reaction to salivary proteins of biting flies, predominantly of the genus Culicoides. The aim of this study was to define T cell subsets and cytokine profile in the skin of IBH-affected Icelandic horses with particular focus on the balance between T helper (Th) 1, Th2 and T regulatory (Treg) cells. Distribution and number of CD4+, CD8+ and Forkhead box P3 (FoxP3)+ T cells were characterized by immunohistochemical staining in lesional and non-lesional skin of moderately and severely IBH-affected horses (n=14) and in the skin of healthy control horses (n=10). Using real-time quantitative reverse transcription-polymerase chain reaction, mRNA expression levels of Th2 cytokines (Interleukin (IL)-4, IL-5, IL-13), Th1 cytokines (Interferon-γ), regulatory cytokines (Transforming Growth Factor ß1, IL-10) and the Treg transcription factor FoxP3 were measured in skin and blood samples. Furthermore, Culicoides nubeculosus specific serum IgE levels were assessed. Lesions of IBH-affected horses contained significantly higher numbers of CD4+ cells than skin of healthy control horses. Furthermore, the total number of T cells (CD4+ and CD8+) was significantly increased in lesional compared to non-lesional skin and there was a tendency (p=0.07) for higher numbers of CD4+ cells in lesional compared to non-lesional skin. While the number of FoxP3+ T cells did not differ significantly between the groups, the ratio of Foxp3 to CD4+ cells was significantly lower in lesions of severely IBH-affected horses than in moderately affected or control horses. Interestingly, differences in FoxP3 expression were more striking at the mRNA level. FoxP3 mRNA levels were significantly reduced in lesional skin, compared both to non-lesional and to healthy skin and were also significantly lower in non-lesional compared to healthy skin. Expression levels of IL-13, but not IL-4 or IL-5, were significantly elevated in lesional and non-lesional skin of IBH-affected horses. IL-10 levels were lower in lesional compared to non-lesional skin (p=0.06) and also lower (p=0.06) in the blood of IBH-affected than of healthy horses. No significant changes were observed regarding blood expression levels of Th1 and Th2 cytokines or FoxP3. Finally, IBH-affected horses had significantly higher Culicoides nubeculosus specific serum IgE levels than control horses. The presented data suggest that an imbalance between Th2 and Treg cells is a characteristic feature in IBH. Treatment strategies for IBH should thus aim at restoring the balance between Th2 and Treg cells.

Cetirizine in horses: pharmacokinetics and pharmacodynamics following repeated oral administration.

The pharmacokinetics of the histamine H(1)-antagonist cetirizine and its effect on histamine-induced cutaneous wheal formation were studied in six healthy horses following repeated oral administration. After three consecutive administrations of cetirizine (0.2 mg/kg body weight, bw) every 12h, the trough plasma concentration of cetirizine was 16+/-4 ng/mL (mean+/-SD) and the wheal formation was inhibited by 45+/-23%. After four additional administrations of cetirizine (0.4 mg/kg bw) every 12 h, the trough plasma concentration was 48+/-15 ng/mL and the wheal formation was inhibited by 68+/-11%. The terminal half-life was about 5.8 h. A pharmacokinetic/pharmacodynamic link model showed that the maximal inhibition of wheal formation was about 95% and the EC(50) about 18 ng/mL. It is concluded that cetirizine in doses of 0.2-0.4 mg/kg bw administered at 12 h intervals exhibits favourable pharmacokinetic and pharmacodynamic properties without causing visible side effects, and the drug may therefore be a useful antihistamine in equine medicine.

Summer eczema in exported Icelandic horses: influence of environmental and genetic factors.

A cross sectional study was designed to estimate the prevalence of summer eczema (a chronic, recurrent seasonal dermatitis) in exported Icelandic horses and the influence of environmental and genetic factors on the development of the disease. Among 330 horses, which had been exported to Germany, Denmark and Sweden, 114 (34.5%) were found to have clinical signs of summer eczema. The prevalence was highest 2 years after export and the exposure to the biting midges Culicoides spp., was found to be the main risk factor for developing the disease. Genetic influence on the sensitivity for the disease was not established. It was concluded that exported Icelandic horses are predisposed for summer dermatitis and the fact that they are not introduced to the antigens of the biting midges early in live, due to it's absence in Iceland, is likely to explain the high prevalence of the disease after export.