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Reasons for performing study The pathogenesis of bilateral dynamic laryngeal collapse associated with poll flexion ( DLC) of horses is unknown but might be associated with intrinsic laryngeal muscle weakness. Objectives To investigate histopathological characteristics of the cricoarytenoideus dorsalis, the cricothyroid ( CT) and the cricoarytenoideus lateralis muscles in DLC-affected horses and compare these with unaffected controls. Our hypotheses were that evidence of neurogenic atrophy of the CT or cricoarytenoideus dorsalis muscles would be found in DLC-affected horses and that observed changes would be symmetrically (left/right) distributed, or that muscle fibre diameter would be significantly reduced in DLC-affected horses compared to unaffected controls, reflecting an underlying paresis. Study design Case-control study. Methods Five DLC horses and 8 controls were included. Muscle samples were harvested immediately following euthanasia. Fibre type proportions and size were evaluated by multiple immunofluorescence labelling of cryosections, and compared between sides (left/right) and groups ( DLC-affected cases/ unaffected controls). Subjective and objective assessments of fibre type grouping were compared between sides and groups. Results Fibre type proportions, fibre size and the subjective assessment of fibre type grouping did not reveal any statistically significant differences between the groups. Objective assessment of fibre type grouping revealed significantly more large clusters of T1 fibres within the left cricoarytenoideus lateralis muscle of DLC-affected cases versus controls, and within the right CT muscle of control horses compared to the DLC-cases. Conclusions The absence of bilateral symmetric fibre type grouping, fibre type loss and fibre atrophy in the DLC-affected cases do not support a neuromuscular component within the pathogenesis of DLC. The objective assessment of fibre type grouping revealed some statistical differences between the DLC-affected cases and the unaffected controls; however, these findings were inconsistent with regard to DLC. An alternative aetiology of DLC seems likely. [ABSTRACT FROM AUTHOR]

Abstract Background Less than a third of Norwegian-Swedish Coldblooded Trotters (NSCTs) have started racing as three year olds since the year 2000 despite the fact that large sums are paid out as price-money in the three year season. Recruitment races are arranged by the Norwegian Trotting Association (NTA) to stimulate early training. The management of young horses varies considerably and a large majority is reared by amateurs. The aim of the present study was to identify predictors of early race starts in young NSCT horses under field conditions. Methods Of the 801 registered NSCT horses born in 2005, 144 were randomly selected by stratified sampling with gender and paternal progeny as stratification factors. All horses were examined clinically. Further data were collected from NTA and by interviews of breeders, owners and trainers. The set of dependent variables consisted of "passed recruitment race", "start in regular race by the end of the three year season" and "start in regular race by the end of October in the four year season". Univariate and logistic regression analyses were performed. Results Genetic performance potential, as indicated by best linear unbiased prediction (BLUP) indices, was the major predictor of the three dependent variables despite large variation in management. Dam's index was a better predictor than sire's index. However, the probability of early race starts in a horse with a low genetic performance potential can be increased by a favourable management. Examples of advantageous management factors in the present study were a flat pasture the first summer and early training. Nearly all horses racing in the three or four year seasons had passed a recruitment race in the two year season. Conclusions The results confirm the value of the published BLUP index as an important tool for the NSCT breeding program. Recruitment races stimulate early training.

STIM1 and ORAI1 regulate store-operated Ca 2+ entry (SOCE) in most cell types, and mutations in these proteins have deleterious and diverse effects. We established a mouse line expressing the STIM1 R304 W gain-of-function mutation causing Stormorken syndrome to explore effects on organ and cell physiology. While STIM1 R304 W was lethal in the homozygous state, surviving mice presented with reduced growth, skeletal muscle degeneration, and reduced exercise endurance. Variable STIM1 expression levels between tissues directly impacted cellular SOCE capacity. In contrast to patients with Stormorken syndrome, STIM1 was downregulated in fibroblasts from Stim1 R304W/R304W mice, which maintained SOCE despite constitutive protein activity. In studies using foetal liver chimeras, STIM1 protein was undetectable in homozygous megakaryocytes and platelets, resulting in impaired platelet activation and absent SOCE. These data indicate that downregulation of STIM1 R304 W effectively opposes the gain-of-function phenotype associated with this mutation, and highlight the importance of STIM1 in skeletal muscle development and integrity., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

A uveal leiomyosarcoma of a horse is reported. There are few published reports of intraocular tumors in horses. Intraocular tumors challenge animal welfare by causing uveitis, glaucoma, and loss of vision. Knowledge regarding treatment of intraocular tumors with globe preservation is sparse, and further investigations on this topic are required.

Objective: To evaluate prevalence and characteristics of cataracts in the Norwegian Buhund breed 20 years after high reported prevalence of especially pulverulent nuclear cataracts (PNCs)., Animals Studied: Two hundred and fifty Norwegian Buhund dogs in Norway, Sweden, and Denmark (117 males and 133 females) with previously unknown eye health status were included. Forty-five dogs had multiple examinations (two to six times over a 6-year period). Median age was 4.4 years [0.2-15.2] at first examination and 5.3 years [0.2-15.2] at last examination., Procedures: All dogs underwent regular screening for inherited eye diseases., Results: At the last observation of each dog, 52.4% were affected by PNC, categorized as minimal (33 of 250 dogs; 13.2%), mild (31 dogs; 12.4%), moderate (38 dogs; 15.2%), or pronounced (29 dogs; 11.6%). Moderate or pronounced changes were only seen in older dogs, and progressive changes were identified in some of the re-examined dogs. Some dogs, free of lenticular changes at early examinations, were affected by PNC at re-examinations. The odds for finding PNC increased with dog's age up to approximately 8 years. Presumably inherited cataracts other than PNC were found in 53 dogs (21.2%) with cortical (17.6%) and posterior polar (6.4%) locations as the most common ones., Conclusions: The high prevalence of PNC in the breed reported 20 years ago persists. PNCs are not always visible in young dogs, and the rate of progression varies. The prevalence of other types of cataract is also high, but cataracts rarely cause loss of vision in this breed., (© 2017 American College of Veterinary Ophthalmologists.)

Listeria monocytogenes has been reported to cause various infectious diseases in both humans and animals. More rarely, ocular infections have been reported. To our knowledge, only two cases of Listeria keratitis have been described in horses. We report kerato-conjunctivitis in four Norwegian horses associated with L. monocytogenes. Clinically, all cases were presented with recurrent unilateral kerato-conjunctivitis. L. monocytogenes bacteria were isolated from swab samples from all cases, and cytology carried out in 3 cases was indicative of L. monocytogenes infection. The present report describes the first known cases in which L. monocytogenes has been isolated from keratitic lesions in horses in Norway. A potential risk factor may be feeding of silage or haylage, but other sources of infection cannot be ruled out. The phenotypic features including antimicrobial susceptibility and serotype of the isolates are described. Laboratory detection of L. monocytogenes demands extra caution since only low numbers of bacteria were detected in the eye-swabs, probably due to the low volume of sample material and the intracellular niche of the bacterium. A general poor response to treatment in all these cases indicates that clinicians should pay extra attention to intensity and duration of treatment if L. monocytogenes is identified in connection with equine kerato-conjunctivitis.

Objective: To evaluate the effect of intratesticular administration of lidocaine on cardiovascular responses and cremaster muscle tension during castration of isoflurane-anesthetized stallions., Animals: 28 healthy stallions (mean +/- SD age, 4.2 +/- 2.8 years) with no testicular abnormalities that were scheduled for castration., Procedure: Each horse was given acepromazine (20 microg/kg, IM), romifidine (50 microg/kg, IV), and butorphanol (20 microg/kg, IV). Anesthesia was induced with ketamine (2.5 mg/kg, IV) and midazolam (50 microg/kg, IV) and maintained with isoflurane (1.7% end-tidal concentration). After 10 minutes at a stable anesthetic plane, a needle was placed in each testicle and either no fluid or 15 mL of 2% lidocaine was injected; 10 minutes after needle placement, surgery was commenced. Pulse rate and arterial blood pressures were measured invasively at intervals from 5 minutes prior to castration (baseline) until 5 minutes after the left spermatic cord was clamped. The surgeon subjectively scored the degree of cremaster muscle tension. In 2 horses, lidocaine labeled with radioactive carbon (C(14)) was used and testicular autoradiograms were obtained., Results: Compared with baseline values, castration significantly increased blood pressure measurements; intratesticular injection of lidocaine decreased this blood pressure response and cremaster muscle tension. In 2 horses, autoradiography revealed diffuse distribution of lidocaine into the spermatic cord but poor distribution into the cremaster muscle., Conclusions and Clinical Relevance: In isoflurane-anesthetized stallions, intratesticular injection of lidocaine prior to castration appeared to decrease intraoperative blood pressure responses and cremaster muscle tension and may be a beneficial supplement to isoflurane anesthesia.