Application of PCR to a clinical and environmental investigation of a case of equine botulism.

PCR for the detection of botulinum neurotoxin gene types A to E was used in the investigation of a case of equine botulism. Samples from a foal diagnosed with toxicoinfectious botulism in 1985 were reanalyzed by PCR and the mouse bioassay in conjunction with an environmental survey. Neurotoxin B was detected by mouse bioassay in culture enrichments of serum, spleen, feces, and intestinal contents. PCR results compared well with mouse bioassay results, detecting type B neurotoxin genes in these samples and also in a liver sample. Other neurotoxin types were not detected by either test. Clostridium botulinum type B was shown to be prevalent in soils collected from the area in which the foal was raised. Four methods were used to test for the presence of botulinum neurotoxin-producing organisms in 66 soil samples taken within a 5-km radius: PCR and agarose gel electrophoresis (types A to E), PCR and an enzyme-linked assay (type B), hybridization of crude alkaline cell lysates with a type B-specific probe, and the mouse bioassay (all types). Fewer soil samples were positive for C. botulinum type B by the mouse bioassay (15%) than by any of the DNA-based detection systems. Hybridization of a type B-specific probe to DNA dot blots (26% of the samples were positive) and PCR-enzyme-linked assay (77% of the samples were positive) were used for the rapid analysis of large numbers of samples, with sensitivity limits of 3 x 10(6) and 3,000 cells, respectively. Conventional detection of PCR products by gel electrophoresis was the most sensitive method (300-cell limit), and in the present environmental survey, neurotoxin B genes only were detected in 94% of the samples.

Displacements, malpositions, and miscellaneous injuries of the mare's urogenital tract.

Although they are pivotal events in the continued production of new generations of horses, breeding and foaling are not without risk to the mare. This article reviews the accidents that can occur and result in injury, displacement, and malpositions of the urogenital tract of the mare.

The pathogenesis and treatment of osteomyelitis and laminitis in a stallion after the prolonged topical application of formalin to the distal phalanx.

A 12-year-old Quarterhorse stallion was presented with a severe lameness in the left forefoot. There was a 3 cm diameter cavity in the sole that extended to the solar surface of the distal phalanx. Radiographs revealed an osteomyelitis and a sequestrum which probably developed following the prolonged topical application of 10 percent formalin. The sequestrum was removed and the infected bone curetted under general anaesthesia. The horse was shod with heart bar shoes on both front feet 7 days after the surgery. Eight months later, radiographs showed marked rotation of the distal phalanx despite continual shoeing with heart bar shoes. Surgical resection of the dorsal wall of the hoof at the toe removed the pressure applied by the laminar wedge, and combined with the stabilising and supporting action of the heart bar shoe, permitted realignment of the distal phalanx approximately 30 degrees closer to the normal skeletal axis by 26 days post-operatively. This case highlights some of the recent developments in the treatment of laminitis and suggests that effective treatment is possible if the value of the animal warrants the time and investment.

Management of twin conceptuses by manual embryonic reduction: comparison of two techniques and three hormone treatments.

One hundred mares carrying twin conceptuses between gestation days (GD) 12 and 30 were assigned to 4 groups. Group-1 mares (n = 20) were given a placebo (sterile saline solution, IV, and sesame oil, IM). Group-2 mares (n = 32) were given a single dose of progesterone (625 mg, IM) in sesame oil. Group-3 mares (n = 28) were given multiple progesterone treatments (625 mg, IM) at 6-day intervals until GD 42. Group-4 mares (n = 20) were given a single treatment of flunixin meglumine (500 mg, IV) and progesterone (625 mg, IM). Each group was further assigned to equal subgroups A and B according to the age of the embryos. In subgroup A, with embryos at GD 12 to 16, embryonic vesicle rupture was performed after the selected conceptus was moved to the tip of a uterine horn. In subgroup B, with embryos at GD 17 to 30, embryonic vesicle rupture was performed on the selected conceptus in situ. An additional 6 mares carrying single conceptuses (GD 12, 14, 16, 20, 25, and 30) were used as subjects for sham embryonic vesicle rupture. Both rupture techniques usually caused the release of prostaglandin (PG) F2 alpha for up to 90 minutes. Amounts of PGF2 alpha were directly correlated with the pressure required to effect embryonic vesicle rupture. Sham embryonic vesicle rupture attempts caused small PGF2 alpha releases after each manipulation, which rapidly returned to basal values. All 6 mares were still pregnant at GD 42. Flunixin meglumine inhibited PGF2 alpha release after embryonic vesicle rupture, regardless of the technique.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of follicular status on twinning rate in mares.

Between 1982 and 1985, 1015 mares were evaluated using the following parameters: age, mare status (maiden, barren, lactating), Caslick index, Caslick operation, ovarian cycle, ovarian and follicular size, treatments (hCG and intrauterine infusions), number of ovulations after mating (184 mares), number of conceptuses present, dimensions of embryonic vesicles, and pregnancy status 45 days after mating. Mares were examined ultrasonographically between Days 12 and 25 to detect the presence of embryonic vesicles and measure the dimensions of each vesicle. The data were analysed by a stepwise logistic regression method. Mare and follicular status were significant (P less than 0.005) predictors of pregnancy outcome. Results from 2949 mare cycles (268 maiden; 1047 lactating; 618 barren) for twin conceptus rates were 15.3%, 8.8% and 14.0% respectively. Based on follicle status, twin-conceptus rates with a single palpable follicle greater than 25 mm in diameter were 11% in maiden, 11% in barren and 5.3% in lactating mares. In 23.7% of cycles (22.4%, 28.8% and 20.7%) 2 palpable follicles greater than 25 mm were recorded, resulting in twin conception rates of 30%, 23.3% and 22% in maiden, barren and lactating mares, respectively. Twin conceptus rate for all mares with a single follicle greater than 25 mm was 7.6% and with 2 follicles greater than 25 mm 23.6%. Mares with 2 large follicles (greater than 40 mm) at mating had a 38.2% (29/76) twin conception rate. Mares with known synchronous double ovulations had a 40% (22/55) twin conception rate. An analysis of co-variance was used to calculate the daily embryonic growth rate between Days 10 and 16 of gestation for 11 Standardbred mares.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimental medication of equine ringworm due to Trichophyton equinum var. autotrophicum.

Twelve medicaments were tested for their efficacy in the treatment of Trichophyton equinum var. autotrophicum; povidone iodine, thiabendazole ointment, captan ointment and Burroughs Wellcome Ringworm Ointment gave satisfactory results but their usefulness may be limited for treatment of large numbers of horses. Aqueous washes containing 0.5% hexetidine or 0.3% chloramine-T did not prevent fungi being isolated from lesions for up to 7 days after treatment. Similarly neither etisazole nor thiabendazole suspension prevented fungi from being isolated from lesions for up to 15 days after treatment. Commonly used aqueous solution of 2.5% lime sulphur and 2% captan were least successful, as fungi could still be isolated from lesions for up to 30 days after treatment. The need to treat large numbers of horses may dictate the use of such solutions rather than ointments because of ease of application and cost factors. Treatments consisting of 10% nystatin ointment, 10% iodine fortis, 10% Medol and a proprietary ointment, Queensland Itch Dressing, were not satisfactory. Clinical appraisal and a scratch test must be used together to evaluate progress of treatment. Mass medication of large numbers of horses should be primarily aimed at reduction of spread of infection; normal hair growth should not be used as an indication of the removal of infective agents in the hair as regrowth was altered very little by medication. Hence assessments of cure on the basis of regrowth of hair alone are of dubious value.

Methods for the treatment of twin pregnancy in the mare.

Within a group of 130 mares which, in the event, carried twin pregnancies, 29 (22.3 per cent) produced their twins following diagnosis of a single palpable follicle at service and a single pregnancy 42 days later. The whole group of 130 twin-pregnant mares gave birth to only 17 live foals (13 per cent). Breeding results for the following season were available for 102 of these mares, when 38 (37 per cent) produced live foals. Thus over the two seasons an average 23 per cent of this group produced live foals. In a second group, comprising 70 mares, twin pregnancy had been diagnosed in all of them by rectal palpation. Five methods of treatment were then applied to five subgroups of mares and 20 (28 per cent) of the 70 mares produced live foals that season. Breeding results for the following season were available for 53 of these mares; 33 (61 per cent) then produced live foals. Thus over the two seasons an average 46 per cent of the treated group produced live foals. The administration of a prostaglandin analogue at less than 35 days of gestation was outstandingly successful as a method of treatment.

Transuterine migration of the fetus in the mare between day 42 and parturition.

A total of 2187 Thoroughbred and Standardbred mares was examined over a 4-year period to determine the location of the fetus at 42 days, the location of the previous fetus as determined by examination 5-15 days after foaling, and pregnancy location the next season. Maiden mares showed 44 and 56% of pregnancies in the left and right horns respectively. No transuterine migration was observed in 139 maiden mares examined after their first foal. Lactating mares showed 62% implantations and full-term pregnancies on one side of the uterus with the next season's pregnancy being in the opposite uterine horn. No ready explanation could be found for 19% of the group which showed unilateral location of pregnancy at all 3 examinations. Evidence of transuterine migration after pregnancy examination at Day 42 was found in 18%. Further, in 50% of these mares, the placental cord was attached to the entrance of the non-pregnant horn. Mares that had a fetus in the same horn in two consecutive seasons had a significantly higher rate of abortion (P less than 0.01) when compared to mares with a fetus in the opposite horn the next season.

Clinical survey of tumours and tumour-like lesions in horses in south east Queensland.

The results of a retrospective survey of tumours and tumour-like lesions encountered in horses in a veterinary practice in south east Queensland between 1956 and 1978 are presented. Forty-two per cent of the lesions were examined histologically. The most commonly occurring neoplasms were the equine sarcoid, papilloma and squamous cell carcinoma of the eye and external genitalia. Neurofibroma was an important problem in the eyelid region. Intra-abdominal tumours were rarely encountered in this series.

The effect of equine coital exanthema on the fertility of mares covered by stallions exhibiting the clinical disease.

The effect on the fertility of mares during two outbreaks of equine coital exanthema have been described. Conception was not prevented, nor was pregnancy terminated in mares showing active lesions of coital exanthema. Normal pregnancy rates occurred in mares served during active infection of the stallions. Origin of the disease was not determined.

The epidemiology of ringworm in racehorses caused by Trichophyton equinum var autotrophicum.

The epidemiology of dermatomycocis due to Trichophyton equinum var autotrophicum was studied in a number of thoroughbred stables in south-east Queensland. The significant factors in the epidemiology were defined. The infection was readily transmitted, particularly by infected saddle-girths, on which the fungus could survive for 12 months. Mild abrasion from the saddle during work favoured the development of lesions and prolonged the recovery period. A pronounced age and seasonal incidence of the disease was demonstrated as young horses under the age of 3 years were most susceptible, and the majority of cases occurred in periods of high humidity.