Connemara Pony Research Articles

Obesity and obesity-associated metabolic disease conditions in Connemara ponies in Ireland.

Equine obesity combined with insulin dysregulation (ID) is a major risk factor associated with laminitis. Some pony breeds appear to be at increased risk. However, little is known regarding the prevalence of obesity or hyperinsulinaemia as evidence of ID in Irish ponies. To investigate the prevalence of obesity and associated endocrine/metabolic disease conditions in Connemara ponies and to determine if hyperinsulinaemia in these ponies could be predicted by morphometric or metabolic markers. Cross-sectional study. The study population included registered Connemara ponies recruited through public and veterinary social media posts. Ponies underwent a physical examination and information on their management and clinical history was obtained via owner questionnaire. The body condition score (BCS) was measured using the Henneke system; cresty neck score (CNS) and regionalised adiposity were also assessed. Hyperinsulinaemia was confirmed by measuring serum basal insulin concentration (BIC) or insulin concentration after an oral sugar test (OST). Blood glucose and triglyceride concentrations were measured. Characteristics of hyperinsulinaemic and insulin-sensitive ponies were compared by logistic regression. Two hundred ponies were included; 59 ponies (29.5%) had a BCS ≥7, 58 (29.0%) had a CNS ≥2.5 and 135 (67.5%) had regionalised adiposity; 137 (68.5%) ponies had at least one of these abnormalities. Owner-reported history or clinical evidence of chronic laminitis was found in 92 ponies (46.0%). Hyperinsulinaemia was confirmed in 32 ponies (16.0%), including 23 of 91 (25.3%) detected by OST and 9 of 109 (8.3%) by BIC. Hypertriglyceridaemia was observed in 12 of 198 ponies (6.1%) ponies and hyperglycaemia in 11 of 197 ponies (5.6%) ponies. The odds of hyperinsulinaemia increased by a factor of 6.53 (95% confidence interval: 2.95, 15.21) when BCS was ≥7. The OST was not performed in all ponies. Increased adiposity, laminitis and metabolic derangements are prevalent in this native Irish pony breed.

Genetic characterisation of the Connemara pony and the Warmblood horse using a within-breed clustering approach

BackgroundThe Connemara pony (CP) is an Irish breed that has experienced varied selection by breeders over the last fifty years, with objectives ranging from the traditional hardy pony to an agile athlete. We compared these ponies with well-studied Warmblood (WB) horses, which are also selectively bred for athletic performance but with a much larger census population. Using genome-wide single nucleotide polymorphism (SNP) and whole-genome sequencing data from 116 WB (94 UK WB and 22 European WB) and 36 CP (33 UK CP and 3 US CP), we studied the genomic diversity, inbreeding and population structure of these breeds.ResultsThe k-means clustering approach divided both the CP and WB populations into four genetic groups, among which the CP genetic group 1 (C1) associated with non-registered CP, C4 with US CP, WB genetic group 1 (W1) with Holsteiners, and W3 with Anglo European and British WB. Maximum and mean linkage disequilibrium (LD) varied significantly between the two breeds (mean from 0.077 to 0.130 for CP and from 0.016 to 0.370 for WB), but the rate of LD decay was generally slower in CP than WB. The LD block size distribution peaked at 225 kb for all genetic groups, with most of the LD blocks not exceeding 1 Mb. The top 0.5% harmonic mean pairwise fixation index (FST) values identified ontology terms related to cancer risk when the four CP genetic groups were compared. The four CP genetic groups were less inbred than the WB genetic groups, but C2, C3 and C4 had a lower proportion of shorter runs of homozygosity (ROH) (74 to 76% < 4 Mb) than the four WB genetic groups (80 to 85% < 4 Mb), indicating more recent inbreeding. The CP and WB genetic groups had a similar ratio of effective number of breeders (Neb) to effective population size (Ne).ConclusionsDistinct genetic groups of individuals were revealed within each breed, and in WB these genetic groups reflected population substructure better than studbook or country of origin. Ontology terms associated with immune and inflammatory responses were identified from the signatures of selection between CP genetic groups, and while CP were less inbred than WB, the evidence pointed to a greater degree of recent inbreeding. The ratio of Neb to Ne was similar in CP and WB, indicating the influence of popular sires is similar in CP and WB.

The effect of month and breed on plasma adrenocorticotropic hormone concentrations in equids

Use of plasma adrenocorticotropic hormone (ACTH) concentrations for the diagnosis of PPID in equids requires awareness of other factors that might influence ACTH concentrations, including breed and time of year. This study was designed to investigate effects of breed on plasma ACTH concentrations and potential interactions between breed and time of year. Ten breeds were selected from a laboratory database containing data on plasma ACTH concentrations. Breeds represented were Arabians, Cobs, Connemara ponies, donkeys, Irish Sports horses, New Forest ponies, Shetland ponies, Thoroughbreds, Warmbloods and Welsh breeds. Multivariable analysis was used to determine the effects of month and breed on plasma ACTH concentrations.A circannual pattern of ACTH concentration was documented, with a nadir in April and a peak in September. Arabian horses and donkeys had significantly higher ACTH concentrations than some other breeds, primarily from May to November, whereas in Shetland ponies and Welsh breeds, relatively higher ACTH concentrations only occurred from July to November. The annual increase in plasma ACTH appeared to commence in late April/early May in response to increasing daylight and decreased again promptly after the late September equinox as daylength fell below 12 h per day. Inter-breed differences in plasma ACTH were substantial and indicated that breed and time of year should be considered when interpreting plasma ACTH concentrations in equids suspected for PPID.

Warmblood fragile foal syndrome causative single nucleotide polymorphism frequency in horses in Ireland

BackgroundWarmblood Fragile Foal Syndrome (WFFS) is an autosomal recessive disorder caused by a mutation in the procollagen-lysine, 2-oxoglutarate 5-dioxygenase 1 (PLOD1) gene. Homozygosity for the mutation results in defective collagen synthesis which clinically manifests as the birth of non viable or still born foals with abnormally fragile skin. While the mutation has been identified in non Warmblood breeds including the Thoroughbred, to date all homozygous clinically affected cases reported in the scientific literature are Warmblood foals. The objective of this study was to investigate the carrier frequency of the mutation in the Thoroughbred and sport horse populations in Ireland.MethodsA test was developed at the UCD School of Veterinary Medicine using real-time PCR to amplify the PLOD1 gene c.2032G > A variant. A subset of the samples was also submitted to an external laboratory with a licensed commercial WFFS genetic test.ResultsWarmblood Fragile Foal Syndrome genotyping was performed on hair samples from 469 horses representing 6 different breeds. Six of 303 (1.98%) sport horses tested and three of 109 (2.75%) Thoroughbreds tested were heterozygous for the WFFS polymorphism (N/WFFS). The WFFS polymorphism was not identified in the Standardbred, Cob, Connemara, or other pony breeds.ConclusionsThe study identified a low frequency of the WFFS causative mutation in sport horses and Thoroughbreds in Ireland, highlighting the importance of WFFS genetic testing in order to identify phenotypically normal heterozygous carriers and to prevent the birth of nonviable foals.

Hoof wall separation disease: A Review.

Hoof wall separation disease (HWSD) is a genetic defect in Connemara ponies characterised by separation and cracking of the dorsal hoof wall. The disease can result in chronic inflammation, severe lameness and laminitis. Affected ponies typically show clinical signs within the first six months of life. The disease is inherited as an autosomal recessive trait. The genetic mutation is a frameshift mutation in the gene SERPINB11, (c.504_505insC). Carriers are completely normal, only ponies that are homozygous for the mutation will have clinical signs of the disease. Within the Connemara breed, carrier frequency has been estimated at 14.8% and the mutation has not been identified in other breeds at this time. While there is no definitive cure for HWSD, management through targeted hoof care and the use of special shoes may be beneficial. Additionally, environmental management may lessen the severity of clinical disease in affected ponies. Genetic testing of Connemara ponies is required for all new registrations. This review of Hoof wall separation disease (HWSD) in Connemara ponies describes the clinical presentation, histopathologic findings, genetic discovery and resulting DNA test and management considerations for affected ponies.

DDB2 Genetic Risk Factor for Ocular Squamous Cell Carcinoma Identified in Three Additional Horse Breeds.

Squamous cell carcinoma (SCC) is the most common cancer affecting the equine eye. A missense variant within the gene damage-specific DNA binding protein 2 (DDB2 c.1013C>T, p.Thr338Met) was previously identified as a causal recessive genetic risk factor for the development of ocular SCC within Haflingers, Belgian Draft horses, and Rocky Mountain Horses, but not in the Appaloosa or Arabian breeds. This study aimed to evaluate three cases of ocular SCC in additional breeds and determine if DNA testing for the DDB2 variant in warmblood horses and Connemara ponies is warranted. Histopathology confirmed ocular SCC in all three cases and DNA testing confirmed each horse was homozygous for the DDB2 risk factor. The DDB2 risk allele frequency was estimated to be 0.0043 for Holsteiners (N = 115), 0.014 for Belgian Warmbloods (N = 71), and 0.22 for Connemara Ponies (N = 86). Taken together these data support using DNA testing for DDB2 in Connemara Ponies to assist in mate selection and clinical management. Given the low observed allele frequencies in both the Holsteiner and Belgian Warmblood breeds and that the case under investigation was a warmblood cross-bred, evaluating additional SCC affected warmbloods is warranted to fully determine the importance of DDB2 genotyping as a risk factor in warmblood breeds.

Birth of first foals through embryo transfer after artificial insemination using frozen semen in Japan

Until now, there have been no reports of foals born through embryo transfer after artificial insemination using frozen semen in Japan. The aims of this study were to develop a riding crossbred horse and evaluate the prospects of embryo transfer technology in multiplying horse population. In both donor and recipient mares, luteolysis was induced by the administration of 0.1 mg Cloprostenol to synchronize the onset of estrus, and ovulation was induced by administering 2000 IU human chorionic gonadotropin (hCG) or 0.75 mg Deslorelin. Frozen semen from an Irish Connemara pony stallion was used to breed a Hokkaido native pony mare by deep-horn artificial insemination (dose, 400 × 106 sperm). A non-surgical technique was used to collect embryos from the donor mare at day 7 post-ovulation and transfer them transcervically into the uterus of recipient mares (n = 4) immediately after collection. Weekly blood samples were collected from the recipients throughout pregnancy. A total of four embryos were recovered from seven collection attempts (57% recovery) from a donor mare in a single breeding season. Three of the four transferred embryos maintained successful pregnancy and delivered a healthy live foal (75% birth). A normal progesterone profile was observed throughout gestation in recipient mares. In conclusion, for the first time, to the best of our knowledge, this study describes the birth of foals through non-surgical transcervical embryo transfer in Japan after artificial insemination using frozen semen. We expect that this new crossbreed (Connemara pony × Hokkaido native pony) will be a good riding breed.

Successful embryo transfer from Hokkaido native pony after artificial insemination with frozen semen.

There has been no report of equine embryo transfer in Japan for the last 24 years. Our objective was to establish an effective protocol for embryo transfer in domestic horse. A Hokkaido native pony was bred by deep-horn artificial insemination with frozen semen from a Connemara pony. Embryo collection was performed using a non-surgical method on day 7. Two embryos were obtained from three flushes (67% recovery) and were transferred fresh into crossbred recipient mares. Both recipient mares were diagnosed pregnant (100% pregnancy rate) 5 days after embryo transfer and had normal progesterone levels until the end of the observation on day 35 of gestation. This is the first successful embryo transfer in Japan by artificial insemination using frozen semen. Embryo transfer technology could be extremely useful in improving the productivity of Japanese domestic and special riding horses.

SERPINB11 frameshift variant associated with novel hoof specific phenotype in Connemara ponies.

Horses belong to the order Perissodactyla and bear the majority of their weight on their third toe; therefore, tremendous force is applied to each hoof. An inherited disease characterized by a phenotype restricted to the dorsal hoof wall was identified in the Connemara pony. Hoof wall separation disease (HWSD) manifests clinically as separation of the dorsal hoof wall along the weight-bearing surface of the hoof during the first year of life. Parents of affected ponies appeared clinically normal, suggesting an autosomal recessive mode of inheritance. A case-control allelic genome wide association analysis was performed (ncases = 15, ncontrols = 24). Population stratification (λ = 1.48) was successfully improved by removing outliers (ncontrols = 7) identified on a multidimensional scaling plot. A genome-wide significant association was detected on chromosome 8 (praw = 1.37x10-10, pgenome = 1.92x10-5). A homozygous region identified in affected ponies spanned from 79,936,024-81,676,900 bp and contained a family of 13 annotated SERPINB genes. Whole genome next-generation sequencing at 6x coverage of two cases and two controls revealed 9,758 SNVs and 1,230 indels within the ~1.7-Mb haplotype, of which 17 and 5, respectively, segregated with the disease and were located within or adjacent to genes. Additional genotyping of these 22 putative functional variants in 369 Connemara ponies (ncases = 23, ncontrols = 346) and 169 horses of other breeds revealed segregation of three putative variants adjacent or within four SERPIN genes. Two of the variants were non-coding and one was an insertion within SERPINB11 that introduced a frameshift resulting in a premature stop codon. Evaluation of mRNA levels at the proximal hoof capsule (ncases = 4, ncontrols = 4) revealed that SERPINB11 expression was significantly reduced in affected ponies (p<0.001). Carrier frequency was estimated at 14.8%. This study describes the first genetic variant associated with a hoof wall specific phenotype and suggests a role of SERPINB11 in maintaining hoof wall structure.

Donor-derived equine mesenchymal stem cells suppress proliferation of mismatched lymphocytes.

Recently, it has been shown that mesenchymal stem cells (MSCs) do not express the major histocompatibility complex (MHC) II antigen and are able to inhibit proliferation of MHC-mismatched stimulated lymphocytes, enabling their use as in vivo allogeneic transplants. However, prior to clinical application of allo-MSCs, in vitro tests are required to confirm the safety of treatment protocols. To evaluate the immunosuppressive capabilities of equine bone-marrow-derived MSCs (BM-MSCs) on MHC-mismatched lymphocytes. In vitro experiment. Phytohaemagglutinin-stimulated peripheral blood mononuclear cells (PBMCs) from 3 Thoroughbreds (recipients) were co-cultured with mismatched BM-MSCs from 3 Connemara ponies (donors). Proliferation of lymphocytes was monitored by carboxyfluorescein succinimidyl ester labelling and analysed by flow cytometry. In total, 6 horses were haplotyped using microsatellites to confirm mismatching. Optimisation of the conditions to stimulate Thoroughbred lymphocytes and titration of equine anti-CD4 and anti-CD8 antibodies were performed. Connemara pony and Thoroughbred BM-MSCs were isolated, expanded and characterised by tri-lineage differentiation. Finally, BM-MSCs from both breeds were set up in co-culture at different ratios with stimulated Thoroughbred lymphocytes. Proliferation of CD4(+) and CD8(+) cells was determined by flow cytometry. A high proportion of CD4/CD8 double-positive lymphocytes were found in freshly isolated PBMCs, although this percentage decreased after 4 days of culture. Mismatched BM-MSCs inhibited proliferation of stimulated lymphocytes in a dose-dependent manner, with the greatest suppression occurring at a 1:10 ratio of BM-MSCs to PBMCs. Proliferation of CD4(+) and CD8(+) subpopulations decreased in 1:10 co-culture, with statistical significance in the case of CD8(+) cells, while that of the CD4/CD8 double-positive population was similar to the phytohaemagglutinin control. The results demonstrate dose-dependent immunosuppression of stimulated lymphocytes by mismatched equine BM-MSCs, supporting their future application in allo-MSC clinical treatments.

Prevalence and risk factors for hyperinsulinaemia in ponies in Queensland, Australia

To determine the prevalence of hyperinsulinaemia in a population of ponies in Queensland, Australia, and identify associated factors. Breeders or traders of ponies within a 100 km radius of Gatton, Queensland, were recruited for study using an internet database. Clinical and management details were obtained, including body condition score, fat deposition and history or evidence of laminitis. Blood samples were analysed for serum insulin and triglyceride concentrations and plasma adrenocorticotrophic hormone (ACTH) and leptin concentrations following short-term removal from pasture and withholding of supplementary food for at least 12 h. Of 23 pony studs identified, 22 were available for visit. The study population consisted of 208 ponies: 70 Australian Ponies; 67 Welsh Mountain Ponies or Cobs; 51 Connemara Ponies; 20 Shetland ponies. We excluded 20 with suspected pituitary pars intermedia dysfunction (>15 years, ACTH >50 pg/mL). In total, 27% of the ponies (51/188) were hyperinsulinaemic (insulin >20 μIU/mL). The final multivariable model revealed increasing age, supplementary feeding and increased leptin and triglyceride concentrations to be associated with hyperinsulinaemia. Hyperinsulinaemia was prevalent and associated with age and evidence of metabolic disturbance, including elevated leptin and triglyceride concentrations, in this population. A significant number of ponies were at risk of hyperinsulinaemia, which has implications for strategies to reduce the risk of laminitis in this population.

Partial coronary epidermectomy (coronary peel), dorsodistal wall fenestration and deep digital flexor tenotomy to treat severe acute founder in a Connemara pony

SummaryA new surgical treatment is described that was used to treat acute founder of 16 days' duration in both front feet of an overweight pony. The decision to employ the new method was influenced by the founder having occurred relatively recently, the presence of a large founder distance and the low anticipated success rate based on data obtained from 166 previous cases of acute founder treated with a heart bar shoe, dorsal wall resection and deep digital flexor tenotomy method. The treatment provided rapid improvement in lameness and a successful outcome with a good cosmetic result.

Mitochondrial DNA sequence diversity in extant Irish horse populations and in ancient horses

Equine mitochondrial DNA sequence variation was investigated in three indigenous Irish horse populations (Irish Draught Horse, Kerry Bog Pony and Connemara Pony) and, for context, in 69 other horse populations. There was no evidence of Irish Draught Horse or Connemara Pony sequence clustering, although the majority of Irish Draught Horse sequences (47%) were assigned to haplogroup D. Conversely, 31% of the Kerry Bog Pony sequences were assigned to the rare haplogroup E. In addition to the extant population analyses, ancient DNA sequences were generated from three out of four Irish archaeological specimens, all of which were assigned to haplogroup A.