A simple blood test that can tell a farmer whether a goat is pregnant—performed on the spot, next to the animal’s head, with results in minutes—has now been formally validated for use in goats, and the findings suggest it could reshape early reproductive management on dairy goat farms. The study, published in Veterinary Medicine and Science, evaluated the Alertys OnFarm Pregnancy Test (AOFPT), a lateral-flow assay originally developed to detect pregnancy-associated glycoproteins (PAGs) in cattle, and demonstrated that it performs with impressive accuracy when applied to goats from day 28 after mating.
Pregnancy-associated glycoproteins are inactive aspartic proteases produced exclusively by the placenta in ruminants. After secretion by trophoectodermal cells, these molecules migrate from foetal tissues and fuse with maternal uterine epithelial cells to form hybrid foeto-maternal trinucleate cells. PAGs become detectable in the peripheral blood of a pregnant animal around the time the extraembryonic membranes attach to the endometrium, coinciding with the migration of binucleate trophoblast cells that form the embryo-maternal syncytium. This makes them reliable biomarkers of both pregnancy status and fetoplacental function. Crucially, structural similarities—driven in part by N-glycosylation patterns shared among PAG proteins from cattle, sheep and goats—mean that antibodies raised against bovine PAGs cross-react with caprine and ovine isoforms. This cross-reactivity is what allows a commercially available bovine test to be repurposed for small ruminants.
The research team, led by Ayşe Merve Köse and Mehmet Can Kara of Hatay Mustafa Kemal University in Turkey, set out to answer a question that had remained open until now: how well does a rapid, whole-blood, on-farm lateral-flow test actually perform in goats during the earliest window of pregnancy? While the same test had already been validated in dairy cows and, in related work, in Awassi ewes, no prior study had evaluated a commercially available blood-based lateral-flow pregnancy test in goats. Earlier goat studies had relied on a visually read ELISA format, the Rapid Visual Pregnancy Test, which requires laboratory conditions and colour-change interpretation that is open to subjective error.
The study involved 85 clinically healthy, fertile Kilis does, five months post-partum, aged three to five years and weighing between 45 and 65 kilograms, kept by a producer in the Yayladağı district of Hatay province. Estrus was synchronized during the natural breeding season using an 11-day intravaginal progestagen sponge, followed at sponge removal by an intramuscular injection of 125 micrograms of d-cloprostenol and 500 IU of pregnant mare serum gonadotropin (PMSG). Twenty-four hours later, bucks were introduced to the flock, and does exhibiting estrus were mated by hand. Whole blood and serum samples were then collected from the jugular vein on days 21 and 28 post-mating.
The on-farm test was performed immediately after collection, following the manufacturer’s instructions, without any prior knowledge of each animal’s pregnancy status. EDTA-anticoagulated whole blood and a wash solution were applied sequentially to the test well; after a 20-minute incubation, the appearance of both a control line and a test line indicated pregnancy, while a control line alone indicated non-pregnancy. For comparison, serum progesterone concentrations were measured in the laboratory using an electrochemiluminescence immunoassay on a fully automated Roche Cobas E601 analyser, with concentrations of at least 1.5 ng/mL on day 21 considered indicative of pregnancy. Transabdominal ultrasonography was performed on days 35 and 42 using a 5 MHz convex probe, and the day 42 findings—based on visualization of a fluid-filled uterus, placentomes, a moving foetus and a foetal heartbeat—served as the gold standard.
The results tell a clear story about timing. On day 21, the AOFPT produced 14 false negatives and just 1 false positive, yielding a sensitivity of 79.4 percent, a specificity of 93.8 percent, a positive predictive value of 98.2 percent, and a negative predictive value of only 51.7 percent. Statistical agreement with the gold standard, measured by Cohen’s kappa, was 0.55—categorised as weak—with an overall accuracy of 82.14 percent. By day 28, however, the picture changed dramatically: the test produced zero false negatives and only 3 false positives, with sensitivity reaching 100 percent, specificity 81.3 percent, positive predictive value 95.8 percent, and negative predictive value 100 percent. Kappa agreement rose to 0.87, a strong level of agreement, with overall accuracy of 96.43 percent. The pregnancy rate in the flock, as established by the gold-standard ultrasound, was 81 percent.
The researchers explain the early false negatives by the biology of PAG secretion. In sheep and goats, PAG concentrations become detectable as early as days 17 to 18 after breeding and reach roughly 3 to 5 ng/mL around days 21 and 22, rising steadily as placentation progresses. Some does on day 21 simply had not yet accumulated enough circulating PAG to cross the detection threshold of the lateral-flow strip. By day 28, those concentrations had climbed well above the limit, which is why the test missed no pregnancies at all. The day 28 false positives—three animals—were more intriguing. Retrospective analysis of their progesterone profiles suggested that early embryonic death may have occurred: PAGs have a reported half-life of approximately 7.5 to 8 days, so after embryo loss, persistently elevated PAG concentrations can linger in the bloodstream and produce a positive result even though the pregnancy has ended.
The progesterone data reinforced the value of the PAG-based approach. Pregnant goats showed significantly higher serum progesterone than non-pregnant goats on both sampling days, with median values of 5.95 ng/mL versus 0.14 ng/mL on day 21 and 6.92 versus 0.84 ng/mL on day 28. Receiver operating characteristic analysis showed that progesterone on day 21 had an area under the curve of 0.958—a high-accuracy category—with an optimal cutoff above 4.19 ng/mL yielding 88.2 percent sensitivity and 87.5 percent specificity. But progesterone has a well-known weakness as a standalone pregnancy marker: elevated levels indicate a functional corpus luteum, not necessarily a foetus. Luteal cysts, pseudopregnancy, prolonged estrous cycles and early embryonic death can all keep progesterone high in a non-pregnant animal. Among the 16 non-pregnant does in the study, several maintained progesterone above 1.5 ng/mL for reasons consistent with these pathophysiological conditions. PAG testing sidesteps this problem, because the molecule is produced only by living placental tissue.
Ultrasonography remains the reference method for good reason—fetal heartbeats can be detected transabdominally in goats between days 27 and 35, and placentomes become visible around day 40—but the study’s authors point to its practical limitations. Transabdominal scanning demands trained personnel, expensive equipment and substantial time, which makes it difficult to scale on large dairy goat operations or for farmers with limited resources. During the study itself, two does that appeared to carry gestational sacs on day 35 lacked embryonic movement or heartbeat and were ultimately classified as non-pregnant on day 42, underscoring the importance of confirmatory criteria and the fact that early embryonic loss can occur between the test window and the ultrasound window.
That is precisely where the on-farm test earns its place, the authors argue. Because it is qualitative rather than quantitative, it cannot report exact PAG concentrations, fetal viability or litter size—limitations the researchers acknowledge explicitly. But it requires no laboratory, no specialized training and no costly equipment, and it delivers an answer while the farmer is still standing next to the animal. Early identification of non-pregnant does is arguably the more valuable half of the result: it allows prompt re-breeding, culling decisions, or selective management, and it lets producers direct nutritional resources toward does that are actually carrying kids. In cattle, the same test achieved 100 percent sensitivity and 100 percent negative predictive value at days 28 to 31 post-insemination, and in Awassi ewes it reached 95.6 percent sensitivity with a kappa of 0.859 from day 28 onward—benchmarks the goat results now match or exceed.
The study, approved by the Hatay Mustafa Kemal University Animal Experiments Local Ethics Committee, is described by the authors as the first comparative evaluation of serum progesterone measurement and the OnFarm Pregnancy Test against transabdominal ultrasonography for early pregnancy diagnosis in goats. Their conclusion is straightforward: from day 28 after mating, the test is a rapid, practical and effective tool for early pregnancy detection in goats, capable of improving reproductive performance and herd management in both dairy goat farms and large herds. Where a result is doubtful—false negative or false positive—the recommendation is to repeat the test or confirm with ultrasonography. For an industry in which profitability hinges directly on reproductive efficiency, putting laboratory-grade pregnancy diagnosis into a handheld strip that works in a field, at a pen-side, in twenty minutes, is a small technological shift with potentially large economic consequences.
Subject of Research: Validation of a blood-based lateral-flow pregnancy test (Alertys OnFarm Pregnancy Test) for early pregnancy detection in goats at days 21 and 28 post-mating
Subject of Research: Biology
Article Title: Validation of a Pregnancy-Associated Glycoprotein-Based Lateral Flow Assay for Early Pregnancy Detection in Goats
Article References: Kara, M. C., & Köse, A. M. (2026). Validation of a Pregnancy‐Associated Glycoprotein–Based Lateral Flow Assay for Early Pregnancy Detection in Goats. Veterinary Medicine and Science, 12(4), Article e71022. https://doi.org/10.1002/vms3.71022
Image Credits: AI Generated
DOI: 10.1002/vms3.71022
Keywords: goats, pregnancy-associated glycoproteins, lateral flow assay, early pregnancy diagnosis, serum progesterone, transabdominal ultrasonography, reproductive management, on-farm testing, Kilis goats, dairy goat farming, PAG biomarkers, veterinary diagnostics
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Harold Sullivan. (September 3, 2026). Lateral Flow Assay Detects Early Pregnancy in Goats. Scienmag. https://scienmag.com/lateral-flow-assay-detects-early-pregnancy-in-goats/
Harold Sullivan. “Lateral Flow Assay Detects Early Pregnancy in Goats.” Scienmag, 3 September 2026, https://scienmag.com/lateral-flow-assay-detects-early-pregnancy-in-goats/. Accessed 3 September 2026.
Harold Sullivan. “Lateral Flow Assay Detects Early Pregnancy in Goats.” Scienmag. September 3, 2026. https://scienmag.com/lateral-flow-assay-detects-early-pregnancy-in-goats/
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