Bovine blood products may alter antibiotic activity in canine keratitis
Bottom line
Version 1
A new Frontiers in Veterinary Science study suggests that bovine blood products used on the eye can change how well common topical antibiotics work against bacteria isolated from dogs with infectious keratitis. Researchers tested 30 canine corneal isolates — Staphylococcus pseudintermedius, Streptococcus canis, and Pseudomonas aeruginosa — against 17 ophthalmic antibiotics, both alone and in the presence of bovine serum or plasma. They found that the blood products had their own antimicrobial activity and could either raise or lower antibiotic minimum inhibitory concentrations depending on the drug-pathogen pairing. The paper adds a pharmacology wrinkle to a treatment approach many clinicians already use to support corneal healing in melting ulcers and severe keratitis. (frontiersin.org)
Why it matters: For veterinary teams, the takeaway isn't that serum or plasma should be avoided, but that adjunctive blood-based therapy may not be pharmacologically neutral. Infectious keratitis can progress quickly and already sits at the center of antimicrobial stewardship concerns in ophthalmology, where tear-film proteins, inflammation, and concurrent serum therapy may all influence drug performance. In practice, this study supports being more deliberate about antibiotic selection, culture and susceptibility testing, and dosing schedules when blood products are part of the plan. (pmc.ncbi.nlm.nih.gov)
What to watch: The next question is whether these in vitro effects translate into measurable differences in clinical outcomes, and whether treatment timing or product choice can reduce unwanted antibiotic interactions. (frontiersin.org)
Key facts
- Study type
- In vitro study
- Journal
- Frontiers in Veterinary Science
- Sample size
- 30 canine corneal isolates
- Pathogens tested
- Staphylococcus pseudintermedius, Streptococcus canis, and Pseudomonas aeruginosa
- Antibiotics tested
- 17 ophthalmic antibiotics
- Interventions
- Bovine serum and plasma
- Main finding
- Blood products had intrinsic antimicrobial activity and changed antibiotic minimum inhibitory concentrations
- Clinical context
- Dogs with infectious keratitis
Version 2
A new in vitro study is putting a closer lens on a familiar ophthalmology tool: blood-derived eye drops. In Frontiers in Veterinary Science, investigators reported that bovine serum and plasma can directly inhibit common canine keratitis pathogens and also alter the activity of topical ophthalmic antibiotics, sometimes improving susceptibility and sometimes reducing it, depending on the organism-drug combination. (frontiersin.org)
That matters because blood products are commonly used as adjunctive therapy in dogs with severe corneal ulceration, especially when clinicians are trying to control collagenolysis and support healing. At the same time, bacterial keratitis remains an urgent, vision-threatening condition in veterinary ophthalmology, and antimicrobial resistance is an increasing concern. Recent reviews note that the ocular surface environment itself — including inflammation, tear proteins, and concurrent serum therapy — can shape how antibiotics behave at the cornea. (merckvetmanual.com)
In the new study, researchers evaluated 30 bacterial isolates from dogs with infectious keratitis: 10 Staphylococcus pseudintermedius, 10 Streptococcus canis, and 10 Pseudomonas aeruginosa. They measured minimum inhibitory concentrations for 17 ophthalmic antibiotics under control conditions and after exposure to bovine serum or plasma. The core finding was not a single uniform effect, but modulation: blood products showed intrinsic antimicrobial effects and changed MICs in ways that varied by both pathogen and antibiotic. (frontiersin.org)
The work also builds on earlier conference reporting from the same research group. In ACVO proceedings, the investigators framed bovine serum and plasma as potentially attractive options because of their antimicrobial and anti-collagenolytic properties, while also cautioning that concurrent use with antibiotics may influence susceptibility testing and treatment effect. A related indexed summary of the paper notes a practical implication: clinicians may need to think about which blood product they choose and how they sequence it with antibiotic drops, rather than assuming all adjunctive serum or plasma therapies behave the same way. (static1.squarespace.com)
Industry and expert commentary around veterinary ophthalmic stewardship helps explain why this study is likely to resonate. A 2026 review in Veterinary Ophthalmology described antimicrobial resistance as a growing challenge in bacterial keratitis and specifically highlighted concurrent serum therapy as one of the local factors that may substantially influence therapeutic response. AAHA coverage of that review also emphasized that ophthalmology clinicians are looking more closely at antibiotic-sparing and adjunctive approaches, particularly in difficult corneal infections. (pmc.ncbi.nlm.nih.gov)
Why it matters: For general practitioners, emergency clinicians, and ophthalmologists, this study is a reminder that supportive corneal therapies can interact with anti-infective therapy in clinically relevant ways, at least in vitro. If a dog with infectious keratitis is receiving bovine serum or plasma alongside frequent antibiotic drops, culture and susceptibility testing may become even more valuable, especially in nonresponders. It also reinforces a broader stewardship point: treatment failure may reflect not just resistance or poor compliance from the pet parent, but the biochemical environment on the ocular surface and the order or timing of therapies. (frontiersin.org)
The study doesn't answer whether these laboratory effects will consistently change healing time, globe salvage, or visual outcomes in practice. But it does provide a stronger rationale for protocol refinement, including closer attention to dosing intervals and product selection when blood-derived drops are used as adjuncts. Because infectious keratitis can worsen within hours to days, even modest shifts in effective antibiotic activity could matter in the sickest corneas. (pmc.ncbi.nlm.nih.gov)
What to watch: Expect follow-up interest in prospective clinical studies, along with more discussion of whether blood-product timing, formulation, or species source should be standardized in canine keratitis protocols. (openalex.org)