Correction: The genetic consequences of dog breed formation-Accumulation of deleterious genetic variation and fixation of mutations associated with myxomatous mitral valve disease in cavalier King Charles spaniels.

[This corrects the article DOI: 10.1371/journal.pgen.1009726.].

The genetic consequences of dog breed formation-Accumulation of deleterious genetic variation and fixation of mutations associated with myxomatous mitral valve disease in cavalier King Charles spaniels.

Selective breeding for desirable traits in strictly controlled populations has generated an extraordinary diversity in canine morphology and behaviour, but has also led to loss of genetic variation and random entrapment of disease alleles. As a consequence, specific diseases are now prevalent in certain breeds, but whether the recent breeding practice led to an overall increase in genetic load remains unclear. Here we generate whole genome sequencing (WGS) data from 20 dogs per breed from eight breeds and document a ~10% rise in the number of derived alleles per genome at evolutionarily conserved sites in the heavily bottlenecked cavalier King Charles spaniel breed (cKCs) relative to in most breeds studied here. Our finding represents the first clear indication of a relative increase in levels of deleterious genetic variation in a specific breed, arguing that recent breeding practices probably were associated with an accumulation of genetic load in dogs. We then use the WGS data to identify candidate risk alleles for the most common cause for veterinary care in cKCs-the heart disease myxomatous mitral valve disease (MMVD). We verify a potential link to MMVD for candidate variants near the heart specific NEBL gene in a dachshund population and show that two of the NEBL candidate variants have regulatory potential in heart-derived cell lines and are associated with reduced NEBL isoform nebulette expression in papillary muscle (but not in mitral valve, nor in left ventricular wall). Alleles linked to reduced nebulette expression may hence predispose cKCs and other breeds to MMVD via loss of papillary muscle integrity.

10-year parasitological examination results (2003 to 2012) of faecal samples from horses, ruminants, pigs, dogs, cats, rabbits and hedgehogs.

The results of coproscopical examinations in domestic animals and hedgehogs carried out as routine diagnostics in the years 2003 to 2012 at the Institute for Parasitology, University of Veterinary Medicine Hannover, Germany, are presented. Of 3475 horse faecal samples, 30.1% contained stages of strongyles and 1.3% eggs of Strongyloides westeri and Parascaris equorum, respectively. The most frequently observed parasite stages in 1416 cattle faecal samples were Eimeria oocysts (21.3%) and strongyle eggs or larvae (15.9%). Dictyocaulus viviparus larvae and Fasciola hepatica eggs were identified in 0.9 and 1.3% of samples. Of 574 bovine faecal samples analysed by carbol-fuchsin staining, 39.9% were positive for Cryptosporidium oocysts. Stages of strongyles were found in 52.4% of sheep (n = 374) and 44.9% of goat faeces (n = 98) and Eimeria oocysts in 41.4 and 32.7% of their faeces, respectively. Of 1848 pig faecal samples, 3.0% contained stages of strongyles, 1.6% eggs of Ascaris suum and 3.3% coccidian (Eimeria or Cystoisospora spp.) oocysts. The most frequently detected helminth eggs in faecal samples of dogs (n = 2731) and cats (n = 903) were Toxocara spp. (2.8 and 3.9%, respectively). Cystoisospora oocysts were identified in 5.6% of dog and 2.4% of cat faeces. Furthermore, 0.7% of the cat samples were positive for small Toxoplasma gondii-like oocysts. The faecal samples of rabbits (n = 434) contained eggs of Passalurus ambiguus (3.0%), strongyles (1.8%) and Trichuris leporis (0.2%) as well as Eimeria oocysts (21.2%). The most abundant nematodes in the samples of hedgehogs (n = 205) were Capillaria spp. (39.5%) and Crenosoma striatum (26.8%); coccidian oocysts were found in 14.2% of the samples.

Macrocyclic lactone resistance in Dirofilaria immitis: Failure of heartworm preventives and investigation of genetic markers for resistance.

Macrocyclic lactone (ML) endectocides are used as chemoprophylaxis for heartworm infection (Dirofilaria immitis) in dogs and cats. Claims of loss of efficacy (LOE) of ML heartworm preventives have become common in some locations in the USA. We directly tested whether resistance to MLs exists in LOE isolates of D. immitis and identified genetic markers that are correlated with, and therefore can predict ML resistance. ML controlled studies showed that LOE strains of D. immitis established infections in dogs despite chemoprophylaxis with oral ivermectin or injectable moxidectin. A whole genome approach was used to search for loci associated with the resistance phenotype. Many loci showed highly significant differences between pools of susceptible and LOE D. immitis. Based on 186 potential marker loci, Sequenom(®) SNP frequency analyses were conducted on 663 individual parasites (adult worms and microfilariae) which were phenotypically characterized as susceptible (SUS), confirmed ML treatment survivors/resistant (RES), or suspected resistant/loss of efficacy (LOE) parasites. There was a subset of SNP loci which appears to be promising markers for predicting ML resistance, including SNPs in some genes that have been associated with ML resistance in other parasites. These data provide unequivocal proof of ML resistance in D. immitis and identify genetic markers that could be used to monitor for ML resistance in heartworms.

Comparison of Ancylostoma caninum worm counts acquired by endoscopy and necropsy.

Many regulatory agencies require that the efficacy of veterinary anthelmintic medications be evaluated by enumerating parasites in treated and untreated animals after necropsy. Current ethical considerations, i.e., the 3 Rs of research, call for the replacement of this method with less invasive techniques that would not require animal sacrifice. This study tested standard gastrointestinal endoscopy as an in vivo method of quantifying the intestinal hookworm, Ancylostoma caninum. Worm counts were compared with those from gold standard necropsy. Thirteen dogs inoculated with third-stage A. caninum larvae underwent endoscopy 4-6 weeks post-infection, just prior to necropsy. Two-thirds of the adult hookworms were located in the middle section of the small intestine that could not be reached for endoscopic examination. Not surprisingly, the total worm counts obtained by endoscopy did not correlate with those from necropsy (R(2)=0.05, p=0.464). One method to increase small intestinal access would be to use specialized balloon or spiral endoscopes developed for this purpose in human gastroenterology. Based on the results of this study, standard endoscopy alone is unsuitable for quantification of A. caninum in the small intestine. Parasites in more accessible sites, such as whipworms in the cecum and colon, might be more appropriate targets for endoscopic counting.

Seroprevalence of Taenia saginata cysticercosis in the federal state of Lower Saxony in Germany.

Based on ELISA results from randomly selected serum samples taken from 128 cattle from different administrative and urban districts in the federal state of Lower Saxony in Germany a seroprevalence estimate of Taenia saginata cysticercosis in this area was derived. This estimate was subsequently used to calculate the sample size required in an epidemiological study to determine the actual prevalence of this infection in the cattle population (n = 2 604 767) in this federal state. The sample size was calculated as 1518 and the samples were collected according to the distribution of cattle among the 48 administrative and urban districts in Lower Saxony. The samples were tested with an evaluated antibody ELISA. The results showed a positive antibody titre rate of 8.83% from the total tested samples.