Objective Successful disease management requires effective surveillance. Slaughterhouse inspections provide opportunities to efficiently collect regular disease data from many animals across large areas. Toxoplasma is a cat‐borne parasite that causes reproduction failure in sheep, although it is not visually detectable at slaughterhouses. Macroscopic sarcocystosis is a disease of sheep that is visually detectable at slaughter and is caused by parasites that share a similar biology with Toxoplasma. We investigated if sarcocystosis could act as a proximate measure for Toxoplasma exposure in sheep to facilitate its efficient surveillance at large scales. Design/methods We compared the presence of macroscopic sarcocystosis to Toxoplasma serostatus at the animal and farm levels. Results At the animal level, we found a weak association between Toxoplasma seropositivity and sarcocysts in the oesophagus (OR = 1.76 [95% CI: 1.17, 2.65; McFadden'sR2 = 0.01]) but no association between Toxoplasma seropositivity and sarcocysts in skeletal muscles. At the farm level, the seroprevalence of Toxoplasma was strongly associated with oesophageal sarcocystosis prevalence (OR = 28.59 [95% CI: 13.07, 62.57; McFadden'sR2 = 0.34]) but less strongly associated with sarcocystosis prevalence in skeletal muscles (OR = 7.91 [95% CI: 1.24, 50.39; McFadden'sR2 = 0.02]). Conclusions For Toxoplasma surveillance in sheep at the farm level, routine slaughter inspection and recording of macroscopic oesophageal sarcocystosis could be a reliable and efficient proximate measure. The monitoring of oesophageal sarcocystosis may be a useful passive Toxoplasma surveillance tool for guiding the timing and location of other Toxoplasma detection methods to facilitate the management of Toxoplasma impacts within the sheep industry.