Thrombocytopenic purpura on an organic farm with pen mating: a case report on the re-emergence of an old disease.

BACKGROUND: Thrombocytopenia is an immune-mediated disease, which affects suckling piglets. Piglets are pale and inactive, show multiple hemorrhages and often die within days. Pathological examination reveals severe haemorrhages and oedema in several organs. Severe thrombocytopenia and elongated bleeding time characterize the disease haematologically.The sow produces antibodies against the thrombocyte antigens of the boar, which are present in the blood of the piglets. These isoimmune antibodies attack the platelets and megakaryocytes of the piglets, causing thrombocytopenia in succeeding matings of the same boar and sow. There is no known therapy against this condition. In the last few decades, the disease has become rare due to the increase of artificial insemination. CASE PRESENTATION: On an organic breeding farm in Switzerland with a high percentage of natural pen matings, piglets of three litters showed haemorrhages on the skin, prolonged bleeding time and were generally in a reduced general state. A pathological examination revealed multifocal haemorrhages in the stomach, kidneys, dermis, mesenterium and spinal cord. Haematology showed a massive thrombocytopenia and regenerative anaemia. Due to these findings the diagnosis of thrombocytopenic purpura was established.To avoid further matings of the same boar and sow and thus more affected piglets, out of three possible boars the responsible sire had to be determined. This was achieved through array genotyping and subsequent computation of identity by descent and calculation of Mendelian errors for parentage verification. Thereby the responsible boar was identified and as a consequence removed from the farm. Further preventive measures, that had been established, included the recording of all matings and regular exchange of boars. CONCLUSION: The decreased number of natural matings with the surge of artificial insemination has probably reduced the number of cases of thrombocytopenic purpura and thus the disease awareness of farmers and veterinarians. However, as consumers wish for better animal welfare and higher ecological standards we may see a rise in natural matings and thus a return of the disease. In case of affected litters, genetic testing was proven a valid method for investigation and prevention of more cases and may be used more in the future.

Crossed beaks in a local Swiss chicken breed.

BACKGROUND: Crossed beaks have been reported to occur in Appenzeller Barthuhn, a local Swiss chicken breed. The assumed causes for this beak deformity which are also seen in other bird species including domestic chickens, range from environmental influences to genetic factors. The aim of this project was to characterize the prevalence, the phenotype, and the underlying genetics of crossed beaks in Appenzeller Barthuhn chickens. RESULTS: The estimated prevalence of 7% crossed beaks in Appenzeller Barthuhn was significantly higher compared to two other local Swiss chicken breeds. A breeding trial showed significantly higher prevalence of offspring with deformed beaks from mating of affected parents compared to mating of non-affected parents. Examination of 77 Appenzeller Barthuhn chickens with crossed beaks showed a variable phenotype presentation. The deviation of the beak from the median plane through the head ranged from 1° to 61°. In more than 60% of the cases, the upper and lower beak were bent in the same direction, whereas the remaining cases showed different forms of crossed beaks. Computed tomographic scans and bone maceration of the head of two chickens with crossed beaks revealed that the maxilla and the mandibula were affected, while other parts of the skull appeared to be normal. The gene LOC426217, a member of the keratin family, was postulated as a candidate gene for beak deformity in domestic chickens. Sequencing of the coding region revealed two significantly associated synonymous variants for crossed beaks in Appenzeller Barthuhn chickens. A genome-wide association study and a comparative analysis of runs of homozygosity based on high-density SNP array genotyping data of 53 cases and 102 controls showed no evidence of association. CONCLUSIONS: The findings suggest a hereditary cause of crossed beaks in Appenzeller Barthuhn chickens. However, the observed variation in the phenotype, together with the inconclusive molecular genetic results indicates the need for additional research to unravel the genetic architecture of this beak deformity.