Study finds limits in ESR method interchangeability for dogs and cats

A newly published Animals study is putting a finer point on how veterinary teams should interpret erythrocyte sedimentation rate testing in small animals. In the July 24, 2026 paper, researchers compared the manual Westergren method with the automated MINI-PET system in dogs and cats and found that the methods were comparable only within limits, not as simple substitutes for one another, with anemia emerging as an important complicating factor. The study also reported that healthy cats had significantly higher ESR values than healthy dogs across both methods. (mdpi.com)

That matters because ESR has had an uneven history in veterinary medicine. In human diagnostics, Westergren remains the reference technique under international standardization guidance, but in dogs and cats the test has been used far less often, in part because the manual method is slow, labor-intensive, and less convenient for routine clinic workflow. A recent review in Animals described renewed interest in ESR after the arrival of automated veterinary analyzers, especially MINI-PET, which can use the same EDTA tube already collected for CBC analysis and return a result in minutes rather than relying on a traditional manual setup. (pubmed.ncbi.nlm.nih.gov)

The new paper builds on that revival rather than starting from scratch. Earlier canine work found MINI-PET could provide ESR results from standard K3-EDTA blood tubes with shorter turnaround time and lower operational burden, while feline research published in 2024 similarly explored automated ESR as a possible inflammatory marker in cats. Additional studies have looked at ESR behavior in canine inflammation, routine clinical practice, leishmaniosis, and preanalytic issues such as storage time and temperature. Together, those studies have helped move ESR from a largely historical parameter toward something more usable at the point of care, even if its exact place in practice is still being defined. (pubmed.ncbi.nlm.nih.gov)

What the new study appears to add is a more direct comparison between the reference-style manual approach and the in-clinic automated platform across both dogs and cats, including anemic individuals. Based on the abstracted article details available through the journal index, the authors set out specifically to test comparability, not just convenience, and their conclusions point away from treating the two methods as interchangeable. That distinction is important: method comparison studies in both veterinary and human medicine often show that automated ESR systems can track the reference method reasonably well overall while still diverging enough at certain value ranges, or in certain patient groups, to affect clinical interpretation. (mdpi.com)

Industry context has been moving in the same direction for several years. DIESSE, the manufacturer behind MINI-PET, introduced the platform to veterinary medicine as an in-clinic ESR analyzer for dogs, cats, and horses, positioning it around ease of use and workflow efficiency. Independent academic reviews have echoed the operational upside, especially the ability to test from routine EDTA samples without needing extra blood volume, something that can matter in cats and small dogs. But those same reviews also emphasize that ESR is influenced by red cell characteristics and plasma proteins, which means species differences, anemia, and other hematologic variables can complicate interpretation. (diesse.it)

Why it matters: For veterinary professionals, this is a practical validation story, not just a methodology story. If a clinic is considering ESR as an adjunct inflammatory marker, the attraction is clear: fast in-clinic testing, no extra sample, and another data point that may complement CBC findings and, in some cases, other markers such as CRP or fibrinogen. But the downside is equally clear from the broader literature and this new comparison: ESR is not a plug-and-play biomarker. It is affected by anemia and erythrocyte properties, and now there is fresh evidence that automated and Westergren values in dogs and cats should not be assumed to mean the same thing on a one-to-one basis. For practices, that argues for method-specific reference use, consistency in platform when trending a patient, and caution in overinterpreting isolated results. (mdpi.com)

There is also a broader clinical pathology takeaway. Veterinary medicine has been steadily reassessing older, lower-cost inflammatory markers as point-of-care tools improve, but validation remains the gating issue. The new paper doesn't suggest ESR is ready to replace better-established markers. Instead, it supports a narrower, more realistic use case: ESR as an accessible adjunct that may help frame inflammation when interpreted alongside signalment, hematology, and disease context. For pet parents, that likely won't change the visible clinic experience much, but for teams in general practice and referral settings, it could shape whether ESR becomes part of the routine diagnostic toolkit or remains a niche add-on. (pmc.ncbi.nlm.nih.gov)

What to watch: The next step is likely not another basic comparability paper, but outcome-focused work, including stronger species-specific reference intervals, clearer adjustment for anemia, and prospective studies showing whether automated ESR meaningfully improves case triage or monitoring when used with other inflammatory markers in dogs and cats. (mdpi.com)