13 March 2026

Settle® immunotherapy was one of the treatment approaches assessed in a research abstract presented at the 2025 Bain Fallon Memorial Lectures in Australia and published in SciQuest. The abstract, “Pregnancy results after antibiotic and non-antibiotic medication for positive uterine cultures”, was authored by E. Barter (Hunter Equine Centre), S. Manning and A. Shephert.

The study evaluated the prevalence of uterine bacterial infections in Thoroughbred broodmares during the 2024 breeding season and assessed the effectiveness of various treatments on pregnancy outcomes. A total of 2,947 uterine samples were collected, yielding 329 positive cultures, with pregnancy outcomes recorded for 231 mares. The most common bacteria were Escherichia coli (E. coli) and beta-hemolytic streptococcus (BHS). Non-antibiotic treatments included systemic Settle and intra-uterine hydrogen peroxide, dimethyl sulfoxide (DMSO), and iodine. Pregnancy rates were 45% for E. coli-positive mares and 54% for BHS-positive mares. For BHS-positive mares, systemic Settle (OR* 1.2) and intra-uterine DMSO (OR 2.1) were associated with increased pregnancy results, whereas hydrogen peroxide and penicillin were not. In E. coli-positive mares, gentamicin susceptibility was associated with higher pregnancy outcomes (OR 2.6), while cefazolin, hydrogen peroxide, DMSO, and iodine were not.

Overall, systemic Settle, administered 12–24 hours prior to cover or, in some cases, post-cover as a follow-up treatment, showed a positive trend for improving pregnancy outcomes in BHS-positive mares, suggesting potential benefit.

Settle is manufactured using the NovaVive Mycobacterium cell wall fraction (MCWF) technology. It is an antibiotic alternative that is regulator-approved as an aid in the treatment of equine endometritis caused by Streptococcus zooepidemicus, the hardest to treat cause of the disease. When administered into a mare, Settle stimulates her immune system to fight an infection. It is approved and sold in the USA, Canada, Australia and UAE.

Settle is backed by extensive scientific research. It is compatible with hormones and other conventional treatments and it is safe when administered with natural breeding or artificial insemination.

It is interesting to note that the Australian Veterinary Association launched Australia’s first nationally endorsed Antimicrobial Prescribing Guidelines for Horses in September, 2025 as a guide to best practices in the field. In its chapter about endometritis, the Guidelines refer to Settle:

Bacterial extracts, such as Mycobacterium phlei cell wall extract (Settle), have been used to enhance the innate humoral immune response by decreasing pro-inflammatory cytokines and increasing anti-inflammatory cytokine production. Mares treated with this product had reduced immune cell infiltration into the uterus, mimicking the immune response of a resistant mare. This immune stimulant can be administered to the broodmare as part of the routine breeding management of the mare to normalise the immune response to breeding.

*Note: OR = odds ratio

About NovaVive Inc.

NovaVive is a private company founded in July, 2014. The Company has an advanced veterinary immunotherapeutic platform based on mycobacterium cell wall fraction (MCWF) technology with 5 regulator-approved products. One formulation has been developed as an anticancer therapy in dogs and horses. Other formulations have demonstrated the capability of reducing the reliance on antibiotics in the treatment of bacterial diseases of horses and cattle or effectively treating viral equine respiratory disease.