Gross and histopathological evaluation of umbilical outpouchings in pigs.

Clinical presentations of umbilical outpouchings (UOs) in pigs cover a variety of pathological manifestations. Pigs with UOs often do not reach the abattoir as they die due to complications or are euthanized for welfare concerns. The primary objective was to characterize the gross appearance of UOs in pigs with respect to the different types of pathological manifestations. Also the association between the pathological manifestation and presence of a wound on the UO was evaluated. Pigs (in different age groups, n = 444) with an UO were sampled in Denmark from different locations (two herds and at an abattoir) and examined post mortem. Tissue samples from animals with an enterocystoma or internal umbilical proliferations were collected for histological and immunohistochemical characterization. Hernia umbilicalis was the most frequent cause (72%, n = 320) of the UOs. It was the only diagnosis in 57% (n = 254) of the pigs, and in 15% (n = 66) of the pigs the hernia appeared in combination with other manifestations. Thus, 28% (n = 124) of the pigs were diagnosed with an enterocystoma, internal umbilical proliferations, subcutaneous abscess/ fibrosis or another diagnosis, presented alone or in combination. The distribution of diagnoses varied in the different age groups. Overall, 38% (110/291) of the pigs presented a wound on the UOs post mortem. The age of the pigs confounded the relation between the pathological manifestation and the presence of a wound. The odds that an UO had a wound were lower among pigs with a subcutaneous abscess/ fibrosis compared to pigs diagnosed with an umbilical hernia or enterocystoma (OR, 0.3; 95% Cl, 0.1-0.7). The odds of wounds were higher among weaners (OR, 4.3; 95% Cl 2.3-8.3) and finishers (OR, 6.5; 95% Cl, 3.4-12.7) compared with piglets from the farrowing unit. The area of wounds ranged from 0.03 to 78.5 cm2 and increased with age (P < 0.001). Histologically and immunohistochemically the enterocystomas and internal umbilical proliferations seemed to be lined with mesothelial cells and both had a content comparable with mesenchymal embryonic connective tissue. However, only the cavities of the enterocystomas were also lined with mesothelial cells. In conclusion, UOs in pigs are caused by complex pathological conditions with hernia umbilicalis as the dominating diagnosis. Knowledge clarifying the different pathological manifestations causing an UO and the presence of wounds on the UOs is essential for future prevention strategies.

Survival of pigs with different characteristics of umbilical outpouching in a prospective cohort study of Danish pigs.

Umbilical hernia and other conditions clinically evident as umbilical outpouchings (UOs) affect the welfare and economy in Danish pig production. The objectives of the current study were to characterize the associations between 1) time of detection of the UOs and the odds of dying before scheduled slaughter; 2) time of death, irrespective of the cause, and clinical signs of the UOs, i.e. general condition, size, reducibility, form and skin-color of the UOs; and 3) occurrence of wounds on the UOs and clinical signs: general condition, size, reducibility, form and skin-color. A cohort of Danish conventional pigs with UOs (n = 255) were followed from the detection of an UO until spontaneous death, euthanization or slaughter of the pig. The pigs were clinically examined once a month, and when pigs with an UO died spontaneously, were euthanized or slaughtered, the causes and date of death were recorded. The effects of the clinical manifestations on overall survival were assessed using a Cox proportional hazards model. In total 57 % of the pigs died spontaneously or were euthanized before slaughter. The median age of spontaneous death or euthanasia was 85 days. The UOs were detected at different ages, with half of the pigs (52 %) detected in the farrowing section. No significant association was found between death before scheduled slaughter and the time of detection. Three different clinical manifestations were found to have a prognostic value for overall survival until slaughter, i.e. skin-color of the UO, a general condition of the pig and the size of the UO. An interaction was present between the size and the skin-color of the UO. Wounds on the UO were the most frequent complication resulting in euthanasia (37 %). The odds for developing a wound on the UO were higher for pigs in a general bad condition compared to pigs in a good condition (OR, 5.4; 95 % CL 2.5-11.3), and for pigs with an UO large in size compared to pigs with a small UO (OR, 4.8; 95 % CL 3.0-7.5). The identification of prognostic clinical signs in pigs with an UO is useful in the assessment and decision-making in relation to the future prospects of pigs with UOs.

Duroc boars have lower progeny mortality and lower fertility than Pietrain boars.

In pig production, Pietrain and Duroc lines are often used as terminal sire lines to produce crossbred slaughter pigs. The objective of this study was to identify the differences in paternal fertility and mortality during the suckling period of crossbred progeny from Pietrain and Duroc terminal sire lines. In total, 87 purebred Duroc boars and 68 purebred Pietrain boars were used as terminal sires to produce 1,823 crossbred Duroc litters (D-litters) and 1,705 crossbred Pietrain litters (P-litters) in two production herds. The sows were crosses between DanBred Landrace and Yorkshire (F1). All boars were kept at the same artificial insemination (AI) station, and all semen doses were produced in the same laboratory. The experiment was balanced according to herd, boars, and time, with approximately 13 sows from each herd mated to each boar within each breed. The results showed higher fertility expressed as litter size at birth in P-litters compared with D-litters led to 0.5 higher total number born (TNB) for P-litters (P = 0.0076). However, piglet mortality including number of stillborn piglets was lower in D-litters compared with P-litters (P < 0.0001), and 5 d after farrowing, the average litter size in P-litters ranged 0.4 below the litter size in D-litters (P < 0.027). At 21 d after birth, mean litter size in P- and D-litters were 14.5 and 14.9 piglets per litter, respectively (P < 0.015). This indicated that Pietrain progenies were weaker than Duroc progenies, and it was concluded that use of Duroc boars as the terminal sire line led to lower piglet mortality. In the two herds, the mean piglet mortality rate including still born piglets ranged from 19.5% to 23.6% and from 17.6% to 19.1% in P- and D-litters, respectively.