Equine pituitary pars intermedia dysfunction: current understanding and recommendations from the Australian and New Zealand Equine Endocrine Group

The purpose of this article is to provide a review of the current knowledge and opinions about the epidemiology, clinical findings (including sequelae), diagnosis, treatment and monitoring of equine pituitary pars intermedia dysfunction, particularly in the Australian context. This information and the recommendations provided will assist practitioners in making informed decisions regarding the diagnosis and management of this disorder.     

SCINTIGRAPHIC EVALUATION OF THE STIFLE IN NORMAL HORSES AND HORSES WITH FORELIMB LAMENESS

We tested the hypotheses that mature horses without lameness have a repeatable radiopharmaceutical uptake pattern in the stifle, which is bilaterally symmetric; immature horses have a different radiopharmaceutical uptake pattern; and forelimb lameness alters the radiopharmaceutical uptake pattern in the stifle. The objectives of the study were to describe the normal radiopharmaceutical uptake patterns using region of interest (ROI) analysis; to compare uptake patterns between left and right stifles of the same horse and between mature and immature horses; to compare radiopharmaceutical uptake in mature normal horses with those with forelimb lameness. Lateral scintigraphic images of the stifle from 51 horses aged 2-16 years were evaluated using seven ROIs and a reference site (midfemur). After subtraction of a background count, ratios between the mean counts per pixel for each ROI to the reference site were calculated. There was a repeatable radiopharmaceutical uptake pattern in mature normal horses that was bilaterally symmetrical. The caudoproximal aspect of the tibia and the patella had the highest ratios. Radiopharmaceutical uptake patterns in horses with forelimb lameness were not significantly different. Immature normal horses had a different symmetric pattern, with greatest radiopharmaceutical uptake ratios in the caudoproximal aspect of the tibia and the tibial crest. It was concluded that there are symmetric, repeatable radiopharmaceutical uptake patterns in both immature and mature horses, which are not altered by forelimb lameness.     

Biomechanical Comparison of the Herbert and AO Cortical Bone Screws for Compression of an Equine Third Carpal Bone Dorsal Plane Slab Osteotomy

Objective—To assess feasibility of insertion of 4.5-mm Herbert cannulated bone screws (HS) using fluoroscopic guidance and compare the mechanical shear strength of these HS and 4.5-mm AO cortical bone screws (AO) for fixation of dorsal plane slab osteotomies in equine cadaver third carpal bones (C3).
Animals or Sample Population—Eight equine cadavers.
Methods—Bone mineral composition and density of contralateral C3 were confirmed to be equivalent using dual-energy x-ray absorptiometry. A standard 10-mm C3 slab osteotomy was reduced using HS or AO instrumentation under fluoroscopic guidance. Specimens were loaded in shear until failure, using a materials testing apparatus.
Results—HS and AO instrumentation allowed accurate reconstruction of the osteotomy, but there was difficulty encountered seating the HS proximal self-tapping threads. There was no significant difference in maximal load to failure, stiffness, or mode of failure of constructs created with the HS and AO screws.
Conclusions —Use of 4.5-mm HS for repair of C3 radial facet, dorsal plane slab fractures may result in a mechanically comparable fixation to a repair using a 4.5-mm AO. Equine dorsal C3 may be too dense, however, to allow placement of the proximal self-tapping threads of the HS without potentially excessive application of torque to the screw itself.
Clinical Relevance —Dorsal plane, radial facet slab fractures of the equine C3 are a significant clinical problem. Accurate reconstruction and stabilization are necessary for return to athletic function.     

Frost Hardiness of Red Alder (Alnus rubra) Provenances in Britain

The phenology and frost hardiness of shoots of 15 provenancesof Alnus rubra growing in Scotland were measured over one autumn,winter and spring. Dates of budset (in September) and the onsetof rapid frost hardening (in October-November) occurred about2 days earlier for each degree latitude of origin northwards,except for an Idaho provenance. However, all provenances dehardenedat about the same time in March and burst their buds between8 and 14 April. Assuming that rapid frost hardening in the autumnwas triggered primarily by shortening daylengths, Alaskan provenancesof A. rubra seemed better adapted to British conditions thansouthern British Columbian provenances, which have been mostcommonly planted. However, even Alaskan provenances are proneto spring frost damage. Scottish A. glutinosa and Alaskan A.sinuata set buds and frost hardened 1–2 weeks before eventhe Alaskan A. rubra, and burst their buds 2–3 weeks laterin April-May. All three species were hardy to below –30°Cfrom December to mid-March.     

Autumn Frost Damage on Young Picea sitchensis 2. Shoot Frost Hardening, and the Probability of Frost Damage in Scotland

The natural increase in frost hardiness of detached shoots ofPicea sltchensis during August to November was measured usinga programmable freezing chamber. Oregon, Queen Charlotte Islandsand Alaskan provenances were compared, and the effects on hardeningof long days, warm temperatures and frosts were determined.A computer model was constructed to mimic the observed patternsof autumn frost hardening, as functions of air minimum temperatures,daylengths and the occurrence of frosts. The model was used(a) to describe the pattern of autumn frost hardening at differentsites in northern Britain, using past meteorological records,and hence (b) to determine when frosts occurred that might havedamaged young trees. The model accurately predicted known instancesof autumn frost damage at Kirroughtree and Carnwath. The predicted probability of autumn frost damage on young treesof P. sitchensis in upland areas of Scotland was much lowerthan that previously predicted for spring frost damage. Theestimated return time for autumn frost damage to an Oregon provenanceat Eskdalemuir was 8.3 years, and the return time for a Q.C.I.provenance was longer than 10 years. Most damaging frosts occurredin October, but frosts like those on 13–15 October 1971,which followed warm weather and caused wide spread damage inScotland, have been quite rare. Alaskan provenances would rarelybe damaged by autumn frosts, nor would trees of Q.C.I. provenancegrowing in lowland areas of Scotland, or at Masset on the QueenCharlotte Islands.     

Calving rates in a tropical beef herd after treatment with a synthetic progestagen, norgestomet, or a prostaglandin analogue, cloprostenol

Maiden heifers and lactating cows of known ovarian status and of several breeds were treated with a synthetic prostaglandin, cloprostenol, or a synthetic progestagen, norgestomet, at the start of an artificial insemination (AI) program. Animals in the cloprostenol treatment received 2 injections 10 days apart. Over the next 26 days those animals that showed oestrous behaviour were inseminated. Synchronisation rates and calving rates to insemination over the first 7 days were calculated. Those in the norgestomet treatment received an implant of norgestomet plus an injection of norgestomet and oestradiol valerate. The implant was removed 10 days later and the animals were given an injection of pregnant mare serum gonadotrophin (PMSG). They were inseminated at 48 h (maiden heifers) or 56 h (lactating cows) after implant removal. Calving rates to fixed-time insemination were recorded. After completion of the AI program the animals in both treatments were joined with bulls. Overall calving rates (AI plus bulls) were calculated. By day 7 of the program, 82% of the maiden heifers and 76% of the lactating cows in the cloprostenol treatment had been detected in oestrus. By day 21 the respective figures were 99% and 81% Norgestomet treatment had an immediate and a prolonged effect on ovarian activity in those females classified as having inactive ovaries at the start of the AI program. Calving rates of those females to fixed-time AI and overall were similar to those of the females with active ovaries in both treatments. Their calving rates to fixed-time insemination, and overall calving rates for the lactating females, were significantly higher than the corresponding values of their contemporaries treated with cloprostenol and inseminated on observed oestrus over 7 days. For those females classified as having active ovaries at the start of the AI program, calving rates to first insemination and overall were similar for both treatments. Overall calving rates of lactating cows of each breed were, with one exception, higher in the norgestomet treatment than in the cloprostenol treatment. Although norgestomet treatment was more expensive than cloprostenol treatment, the advantage in calf crop resulted in an overall monetary advantage to the norgestomet treatment.