Differences in canine serum N-glycosylation pattern during infection and pregnancy.

Diagnosis of inflammatory disorders during canine pregnancy is complicated by changes caused by pregnancy. The total glycosylation pattern of body fluids reflects cellular status in health and disease. The aim of the present study was to evaluate the overall canine N-glycan pattern in dogs with infection compared to pregnant dogs. Serum samples from ten dogs with pyometra (bacterial disease), ten dogs with canine infectious respiratory disease, CIRD (primarily viral disease), ten pregnant dogs (day 24-30) and nine healthy non-pregnant dogs were included. A method optimised for N-glycan quantification in canine serum, based on RapiFluor-labelling and subsequent glycan mapping by HILIC-UPLC-FLR-MS was used. The levels of the two dominating glycans, A2G2S2 and FA2, and six glycan groups were evaluated. No significant differences between pregnant dogs and dogs with pyometra were observed. In dogs with CIRD and in healthy non-pregnant dogs, the levels of terminally galactosylated and high mannose glycans were higher, while the levels of glycan A2G2S2 were lower, than in pregnant dogs. The present study provides new insight into the canine N-glycan pattern during infection and pregnancy. Serum N-glycans and N-glycan groups do not seem suitable as biomarkers to differentiate inflammatory changes due to pregnancy from those caused by infections.