The use of foal and studbook traits in the breeding programmes of Finnhorse and Standardbred trotters

Genetic correlations for body measurements and subjectively scored traits between foals and studbook horses were estimated using bivariate linear mixed models. Observations for nine foal and eleven studbook traits in Finnhorses on 6529 foals and 6596 studbook horses and in Standardbred trotters on 3069 foals and 2112 studbook horses were available from the Finnish horse breeding shows. The number of sires with progeny in both foal and studbook data was 203 in Finnhorse and 145 in Standardbred trotters. Estimates of heritability for body measurements in foals and studbook horses using univariate models were high in both breeds (0.41-0.84). Heritability estimates for subjectively scored traits using univariate models were generally higher for foals (0.08-0.46) than for studbook horses (0.06-0.21) in both breeds. Genetic correlations between foals and studbook horses for body measurements were highly positive ranging from 0.74 to 0.96 in Finnhorses and from 0.79 to 0.99 in Standardbred trotters. Low to highly positive genetic correlations between foals and studbook horses for subjectively scored traits were obtained in Finnhorse trotters, whereas in Standardbred trotters genetic correlations for subjectively scored traits varied from moderately negative to highly positive. Higher estimates of heritability for foal traits and generally high genetic correlations between the foal and studbook traits indicate that an early selection for conformation traits would be efficient in the breeding programmes.     

Multiple rib fracture in a neonatal foal using a nylon strand suture repair technique

OBJECTIVES: To report rib fracture repair using the Securos Cranial Cruciate Ligament Repair System (SCCLRS; Securos Veterinary Orthopedics, Charlton, MA) in a neonatal foal. STUDY DESIGN: Case report. ANIMALS: A 1-day-old Standardbred foal with fracture of left ribs 2-9. METHODS: Four days after admission the foal was anesthetized and rib fractures were repaired using open reduction and the SCCLRS. RESULTS: Rib fractures were successfully stabilized and the foal was discharged 7 days postoperatively without further complications. CONCLUSIONS: The SCCLRS provided a straightforward, effective method of rib fracture repair in neonatal foals. CLINICAL RELEVANCE: Effective rib fracture repair in neonatal foals can be achieved with the SCCLRS.     

Prevalence (treatment days) and severity of illness in hypogammaglobulinemic and normogammaglobulinemic foals

Serum samples for determination of IgG concentration were obtained between postpartum hours 18 and 48 from 132 Standardbred foals. Results of the IgG assay were not known to farm personnel. None of the foals was given plasma IV for treatment of hypogammaglobulinemia. Foal health records were examined retrospectively to determine prevalence of infectious-type illness (foal treatment days [FTD]), prevalence of life-threatening infectious illness (foal treatment days-serious condition [FTD-SC]), and number of diseases (NOD) per foal. Values for FTD, FTD-SC, and NOD per foal were compiled for the first 21 days of life and for the first 90 days of life. The FTD, FTD-SC, and NOD per foal values were compared for foals with less than 400 mg of IgG/dl and for foals with greater than or equal to 400 mg of IgG/dl; the same variables were compared for foals with less than 800 mg of IgG/dl and for foals with greater than or equal to 800 mg of IgG/dl. Statistical analysis indicated that IgG concentration was not associated with FTD, FTD-SC, or NOD in foals of any of the groups. Also, despite a large subpopulation of hypogammaglobulinemic foals (13.6% with less than 400 mg of IgG/dl and 44.7% with less than 800 mg of IgG/dl), the 21-day and 90-day overall survival rates were 100 and 99.2%, respectively. The data strongly suggest that serum IgG concentration was not related to prevalence or severity of illness or to survival rate in this population of foals.     

Ocular abnormalities in healthy Standardbred foals

Objective To determine the prevalence and describe ocular abnormalities in healthy Standardbred foals within 48 h of birth. Animals One hundred and two neonatal foals. Procedures All foals had an unassisted delivery. On the basis of physical examination and the results of hematological and biochemical parameters, all foals were unaffected by systemic diseases. A complete ophthalmic examination was performed within 48 h of birth. Foals with ocular hemorrhages were re‐examined weekly until the abnormalities were resolved. Results 65/102 (63.7%) foals did not show ocular abnormalities, while in 37/102 (36.3%) cases, ocular abnormalities were present. Retinal and subconjunctival hemorrhages were recorded in 19/102 (18.6%), and in 13/102 (12.7%), respectively. In 4/102 (3.9%) animals, an entropion of the lower eyelid was present. Only one foal (1%) showed a congenital nuclear unilateral cataract. No other ocular abnormalities were detected. However, all foals showed various degrees of remnants of hyaloid system. One week after the first ocular examination, retinal hemorrhages had resolved in 100% of the eyes, whereas subconjunctival hemorrhages had disappeared in all eyes by the second week following the first examination. Conclusions The acquired ocular lesions observed with relatively high frequency in the examined healthy Standardbred foals were ocular hemorrhages, which always showed a good outcome. Although these abnormalities were present at birth, they were not considered strictly congenital but likely acquired during parturition. Instead, congenital ocular abnormalities were rarely diagnosed, and the entropion of the lower eyelid was the most common disease in the breed.     

Increase of serum gamma-glutamyltransferase in neonatal Standardbred foals

Serial blood samples were obtained from 16 Standardbred foals from time of birth to postpartum day 28. Sera were obtained and analyzed for gamma-glutamyltransferase (GGT), aspartate transaminase, and immunoglobulin (Ig) G. Presuckle colostrum from the respective mares of these foals was analyzed for GGT activity. Mean serum aspartate transaminase activities were significantly increased above presuckle values by postpartum hour 48 (P less than 0.01) and increased gradually over the first 14 days. Mean serum IgG concentrations were significantly greater than presuckle values by 5 hours after foals first suckled (P less than 0.01) and remained significantly increased during the 28-day sampling period. Serum GGT activity did not differ significantly over the period sampled. The SD were large, since there was a large degree of interindividual variation. Serum GGT activity in the foals was significantly increased over that in the mares throughout the period of the study. The profile of serum GGT activity over time in each foal did not show a pattern of change. There was no postsuckle increase in serum GGT activity nor a correlation between serum GGT activities and IgG concentrations at 24 hours after foals first suckled. Evidence was not obtained to support a colostric source of GGT involved in the increase of serum GGT activity in foals. Serum GGT activity seems to be increased in foals due to endogenous sources.     

Microcytosis, hypoferremia, hypoferritemia, and hypertransferrinemia in standardbred foals from birth to 4 months of age

At birth, 24 Standardbred foals were assigned at random to 1 of 2 groups and were given a placebo supplement (group 1) or an iron supplement (248 mg of iron/treatment; group 2). Foals were given iron supplement or placebo 4 times during the second and third weeks after birth. Hematologic variables and general health were monitored until foals were 4 months old. Mean PCV in foals of both groups decreased during the first 2 weeks after birth, but values remained within adult horse reference ranges. During the first 6 weeks after birth, foal erythrocytes were smaller than adult horse erythrocytes, but foal erythrocyte glucose-6-phosphate dehydrogenase activity was greater than that in adult horses. At every measurement, indices of anisocytosis were lower in foals, compared with adult horse reference values, suggesting that foals have a homogeneous population of microcytic erythrocytes during early foalhood. In 2-week-old foals of both groups and in 4-week-old placebo-treated foals, mean serum iron concentration was lower than that in adult horses. In foals at birth and during the first 4 months, total iron-binding capacity values were above the adult reference range. In newborn foals, transferrin saturation percentage values decreased to below the reference range in foals from 2 weeks to 4 months after birth. When foals were born, serum ferritin concentration values were above the adult horse reference range, but decreased to within the reference range by the time foals were 1 day old. From 2 through 6 weeks after birth, foal ferritin concentration values were below the adult reference range.(ABSTRACT TRUNCATED AT 250 WORDS)     

Observations on the long term effects of Brucella abortus infection in the horse, including effects during pregnancy and lactation

Five mares and a stallion were studied from three to 30 months after experimental infection with Brucella abortus strain 544. The mares bred normally. No organisms were recovered from horses or from pregnant Friesian heifer contacts. Titres of serum antibody in the antiglobulin (Coombs) and complement fixation tests fell more slowly than those assessed by other tests. The serum of one foal yielded maternal antibody. An intradermal test was positive in infected adults only, and negative in all foals.     

Estimates of genetic parameters for conformation measures and scores in Finnhorse and Standardbred foals

The aim of this study was to estimate genetic parameters for conformation measures and scores in the Finnhorse and the Standardbred foals presented in foal shows. Studied traits included height at withers and at croup, six subjectively evaluated conformation traits and overall grade. Data were from 10‐year period (1995–2004) and consisted of 5821 Finnhorse foals (1–3 years old) with 7644 records and 2570 Standardbred foals (1–2 years old) with 2864 records. Variance components were estimated with REML – animal model using VCE4 program. The model included age class, year of judging, sex and region as fixed effects, and additive genetic, permanent environmental and residual as random effects. Estimates of heritability for measured traits were very high in both breeds (0.88–0.90). Estimates of heritability for conformation traits varied from 0.13 to 0.32 in the Finnhorse and from 0.06 to 0.47 in the Standardbred. In both breeds, estimates of heritability were lowest for hooves and movements at walk, and highest for type and body conformation among scored traits. Estimate of heritability for overall grade was in the Finnhorse 0.32 and in the Standardbred 0.34. Genetic correlations between overall grade and different conformation traits were 0.35–0.84 in the Finnhorse and 0.31–0.88 in the Standardbred. Thus, selection based on the overall grade would improve all studied characteristics.     

Genetic correlations for foal and studbook traits with racing traits and implications for selection strategies in the Finnhorse and Standardbred trotter

Genetic correlations for body measurements and conformation and functional traits in foals and studbook horses with racing traits were estimated in the Finnhorse and Standardbred. Genetic response and accuracy were estimated using records of animal, half‐sibs and parents in selection scenarios for racing traits, for foal and racing traits, for studbook and racing traits, and using records of animal, half‐sibs and parents for foal traits and racing traits of parents. Racing time and earnings were the breeding objective. Low‐to‐moderate genetic correlations for body measurements and racing traits indicated that selection favours bigger horses at all ages. Being mainly favourable for the breeding objective, genetic correlations for conformation and functional traits with racing traits were highest for the foal traits of type, trot and overall grade and for the studbook traits of character and movements. Genetic correlations for foal and studbook conformation with racing traits were low in the Finnhorse and moderate to high in the Standardbred. In foals, the highest genetic correlations were for trot with racing time (?0.54) and with earnings (0.52) in the Finnhorse, and for overall grade with racing time (?0.54) and with earnings (0.54) in the Standardbred. In studbook horses, genetic correlations were high for character with racing time and earnings in the Finnhorse (?0.68, 0.61) and in the Standardbred (?0.63, 0.70), and for movements with racing time and earnings in the Finnhorse (?0.70, 0.69) and in the Standardbred (?0.90, 0.88). To increase accuracy of conformation and functional traits, foal traits would be more useful in the index with racing traits, as being less preselected than studbook traits. The foal traits (type, trot, overall grade) having moderate heritability and genetic correlations with racing traits would be useful in multi‐trait index before a racing career, where the greatest gain is because of a shorter generation interval. It would be feasible to implement for AI stallions.     

Blind-end atresia coli in two foals

Blind-end atresia coli was observed in two genetically unrelated foals at about the same time and location. The two foals, one an Appaloosa and the other a Quarterhorse, were born 4 days apart on nearby but separate farms. The Appaloosa foal died after surgical anastomosis of the affected segments of the colon. The Quarterhorse foal was euthanized after the defect was found at laparotomy. Both foals were necropsied and representative tissues were examined histopathologically. Histopathologic results were unremarkable. No cause of the defects could be determined and the timing and geographical location of the two events were considered coincidental.     

Factors Associated with Failure of Passive Transfer of Colostral Antibodies in Standardbred Foals

The records of 361 Standardbred mares and their 1986 or 1987 foals were evaluated to identify factors associated with failure of passive transfer (FPT) of colostral antibodies in equine neonates. Sixty-five foals (18%) were classified as FPT based on a serum immunoglobulin concentration of less than 400 mg/dl at 24 to 36 hours of age, determined by the glutaraldehyde coagulation test. The potential association of mare- and foal-related factors with FPT were assessed by reviewing a series of multiple logistic regression models. The season in which the mare foaled and foal exam score, a subjective assessment of foal vigor, maturity, and general health, were the primary factors associated with the development of FPT. Foals with FPT were more likely (odds ratio = 3.50; 95% confidence interval = 1.81-6.68) than normal foals to require medical therapy during the first 3 months after parturition.     

Epiphyseal cartilage canal blood supply to the distal femur of foals

REASONS FOR PERFORMING STUDY: The developmental pattern of the cartilage canal blood supply to epiphyseal growth cartilage has been linked to osteochondrosis (OC) in the tarsus of foals. This pattern has not yet been described in the distal femur, another site frequently affected by OC. OBJECTIVE: To describe the developmental pattern of the blood supply to the distal femoral epiphyseal growth cartilage in 8 Standardbred foals age 0-7 weeks. METHODS: One foal was sacrificed weekly from birth to age 7 weeks (n=8) to undergo a barium perfusion procedure to demonstrate vessels within cartilage canals of one hindlimb. The distal end of the femur was cleared in methyl salicylate and perfused vessels were studied in the intact bones. Each distal femur was then sawed into 5 mm thick slabs in the transverse plane, and the slabs decalcified and radiographed. Finally, the lateral trochlear ridge was separated from each slab and examined histologically. RESULTS: The cartilage canal blood supply regressed with increasing age, but several regions remained vascularised in the oldest foal at age 7 weeks. Vessels arose from perichondrial and subchondral arterial sources, and coursed perpendicular or parallel to the ossification front. The midsection of parallel vessels became incorporated into the ossification front during growth. Anastomoses formed and vessels within the distal portion of canals with an original perichondrial source shifted to use subchondral vessels as their arterial source. Both parallel and perpendicular vessels therefore traversed the ossification front to enter cartilage canals. No histological lesions were observed in sections from any of the foals. CONCLUSION: The same anatomical feature (traversing the ossification front to enter cartilage canals) reported to render vessels vulnerable to failure in the tarsus was also present in the distal femur of foals. POTENTIAL RELEVANCE: OC may occur by the same pathogenetic mechanism in the distal femur as in the tarsus of foals.     

Cryptosporidium parvum infection in a mare and her foal with foal heat diarrhoea

Cryptosporidium infection was molecularly investigated in mares and in their neonatal foals for which the occurrence of foal heat diarrhoea was also assessed. Thirty-seven mare/foal pairs were included in the study. All foals were born in the same stud farm during 2006-2008 breeding seasons. Two faecal samples, one prior to and one after delivery were collected from each mare, whereas three faecal samples were taken from each foal, i.e. at 8, 10 and 12 days of age. All samples (74 from mares and 111 from foals) were divided into two aliquots, one of which was examined for the presence of Cryptosporidium by a commercially available microplate ELISA kit, while the second aliquot of all ELISA-positive samples was molecularly examined. Nine out of 37 examined foals presented foal heat diarrhoea and one of them scored positive for Cryptosporidium, together with its mare. More specifically, four samples belonging to the same mare/foal pair resulted positive for Cryptosporidium upon both ELISA and PCR. The sequence analysis of the COWP gene showed the occurrence of the zoonotic species Cryptosporidium parvum. The possibility that foal heat diarrhoea-like episodes may be due to neonatal cryptosporidiosis and their relevance for the health of horses and of humans handling diarrhoeic neonatal foals and their mares are discussed.     

Macrocyclic lactone-resistant Parascaris equorum on stud farms in Canada and effectiveness of fenbendazole and pyrantel pamoate

The aims of studies in 2002 and 2003 on three farms with 76 foals naturally infected with Parascaris equorum were to (i) identify if the nematode was resistant to ivermectin and moxidectin, and (ii) confirm the effectiveness of fenbendazole and pyrantel pamoate for the parasite. Twelve clinical trials, each with a Fecal Egg Count Reduction Test, were conducted on two Thoroughbred and one Standardbred farms in southwestern Ontario, Canada. In each trial, Parascaris eggs/g feces were estimated for each foal pre- and post-treatment using the Cornell-Wisconsin double flotation and Cornell-McMaster dilution techniques. On each farm and for each trial, foals were randomized into treatment groups. Treatments were ivermectin, moxidectin, fenbendazole, pyrantel pamoate administered at the manufacturers' recommended dosages, and some foals were untreated. The overall efficacy for ivermectin was 33.5% (19 foals) and for moxidectin 47.2% (28 foals). Fenbendazole (16 foals) and pyrantel pamoate (21 foals) were highly effective for P. equorum each at 97.6%. For fenbendazole, 15 foals had 100% and for pyrantel pamoate 17 foals had >97% with 14 at 100%.     

Closure of the abdominal wall at the umbilicus and the development of umbilical hernias in a group of foals from birth to 11 months of age

The closure of the body wall defect at the umbilicus was studied in relation to the development of umbilical hernias in a group of 44 normal foals, 25 of which were followed from birth until five months of age, and 19 from birth until 11 months of age. At birth, 19 of the foals had a defect in the body wall at the umbilicus that was termed a 'palpable umbilical ring'. In 18 of them this defect disappeared within four days, but in the other the ring did not close and a hernial sac with abdominal contents was palpable. This foal was considered to be the only foal to have a truly congenital umbilical hernia. Twelve foals developed an umbilical hernia between five and eight weeks of age. The prevalence of umbilical hernias was much higher than in other studies, possibly owing to the prospective nature of the study.     

Coprophagy by foals: effect of age and possible functions

In colts and fillies observed from birth to 24 weeks old, coprophagy occurred from Weeks 1 to 19. Its frequency was greatest during the first two months. Coprophagy was rarely observed in mares and stallions. Foals usually ate the faeces of their mother but were observed to eat their own and those of a stallion and another unrelated mare. Urination by the foal occurred before, during or after 26 per cent of the coprophagy incidents. It is hypothesised that foals may consume faeces in response to a maternal pheromone which signals the presence of deoxycholic acid or other acids which the foal may be deficient in and which it may require for gut immuno-competence myelination of the nervous system. Such a pheromone may also serve to accelerate growth and sexual maturation. Coprophagy may also provide nutrients and introduce normal bacterial flora to the gut.     

Long-Term Follow-up of Partial Limb Amputation in 13 Horses

Thirteen cases of partial limb amputation in horses were reviewed. Nine horses (69%) survived 18 to 111 months (mean, 41 months). Four unsuccessfully treated horses were euthanatized within 21 days of surgery. The horses' ages at amputation were 4 to 13 years (mean, 7.3 years). There was no predilection for the left or right limb nor for fore or hind limb involvement. Osteomyelitis in six horses (46%) was the most common cause for amputation. Severe, open, comminuted fractures of the third metacarpal bone that were impossible to stabilize by any currently available technique in four horses (31%) were the second most common cause for amputation. One gelding was salvaged because of his sentimental value, two horses were used as breeding stallions, and six were broodmares. One stallion lived 30 months, completed two breeding seasons, and started a third. The other stallion began breeding, but became sterile. Three of the mares have produced five foals. One mare died while in foal. One mare aborted near-term twin fetuses and died of uterine hemorrhage. One mare aborted twice before the femoral head ligament on the contralateral limb ruptured, and she was euthanatized.     

Atresia coli in the foal: a review of six cases.

Physical examination and exploratory celiotomy were performed on five neonatal foals presented with signs of acute colic. Atresia coli was confirmed in each foal during surgery. The most consistent finding on physical examination was the absence of meconium staining following repeated enemas. The large, transverse and/or small colon were involved in all foals. One eight month aborted foetus was submitted for necropsy and diagnosed as having atresia coli and congenital hydrocephalus. Atresia coli should be considered for neonatal foals with signs of acute colic.     

Treatment of congenital hydrocephalus in a foal using a ventriculoperitoneal shunt

Objective: The objective of this report is to describe the presentation, diagnostic imaging findings, management, and complications of surgical shunt placement in a foal with congenital hydrocephalus. Case summary: A 3‐day‐old Quarter Horse colt was diagnosed with hydrocephalus on the basis of clinical signs and computed tomographic scan. A surgical shunt was placed from the right cerebral ventricle to the peritoneum. The foal demonstrated significant improvement in clinical signs until shunt complications occurred. New or unique information provided: To the authors' knowledge, the placement of a ventriculoperitoneal shunt to manage equine hydrocephalus has not been described. This case report provides a foundation for understanding the techniques and possible complications of surgical shunt placement in hydrocephalic foals.     

Impact of reproductive efficiency over time and mare financial value on economic returns among Thoroughbred mares in central Kentucky

Reason for performing study: There have been no studies reporting the impact of reproductive efficiency and mare financial value on economic returns. Objective: To explore the economic consequences of differences in reproductive efficiency over time in the Thoroughbred mare. Methods: Complete production records for 1176 mares were obtained. Production history and drift in foaling date were calculated. Multiple logistic regression was used to identify factors influencing the probability of producing a registered foal in 2005. The ‘net present value’ and ‘internal rate of return’ were calculated for economic scenarios involving different initial mare financial values, levels of reproductive efficiency, and durations of investment. Results: Among mares that did not produce a foal every year (63%), the mean time before failing to produce a registered foal was 3.4 years. The majority of mares drifted later in their foaling dates in subsequent foaling seasons. Increasing mare age, foaling after 1st April, needing to be mated multiple times during the season, and producing a lower number of foals in continuous sequence during previous years decreased the probability of producing a registered foal. Over a 7 year investment period, live foals must be produced in all but one year to yield a positive financial return. Profitability was highest among mares of greatest financial value. Conclusions: Mares are long‐term investments due to the extended period before there is a return on the investment. Improving our understanding of mare, stallion and management factors that affect the likelihood of producing a live foal are critical to ensuring a positive financial return. Additional work is needed to test the robustness of the study's conclusions when the cost and revenue assumptions are varied. Potential relevance: This information can assist in assessing mare profitability and developing management strategies to maximise profitability.