Cephalometric Study of the Overjet Development in Warmblood Foals

Class II malocclusion is the most frequently occurring congenital malocclusion in horses. Radiographic cephalometric procedures adopted from human dentistry were used to study the development of overjet in a population of 650 Warmblood foals. Thirteen foals were diagnosed with measurable overjet at the beginning of the study. The malocclusion in nine foals resolved spontaneously and four foals without overjet at 2 weeks of age developed the condition during the first year of life. A cephalostat used in human orthodontics to immobilize the patient's head while being radiographed was replaced by a researcher-made head-holding device, whose size was based on the results of a pilot study. Laterolateral digital radiographs of each foal's head (cephalograms) were taken at five time points until the age of 12 months. Thirteen cephalometric points were identified and nine distances were measured on each radiograph. Additionally, the angle between the long axis of the upper and lower incisors was evaluated. Cephalometric measurements proved to be useful to identify foals that showed spontaneous regression of the malocclusion over the study time between 9 and 16 weeks of age.

Chronic severe pyloric lesions in horses: 47 cases

BACKGROUND

The clinical findings and outcome associated with chronic severe equine pyloric lesions have not been well described previously.

OBJECTIVES

To describe the history, clinical signs, endoscopic and ultrasound results, laboratory data, treatment, pathological findings and survival of horses with chronic severe pyloric lesions.

STUDY DESIGN

Retrospective case series.

METHODS

Medical records from horses treated at clinics in Czech Republic and Germany in which chronic severe pyloric lesions were confirmed endoscopically and/or on post-mortem examination were reviewed.

RESULTS

Forty-seven horses were identified, median age 3 years (range 0.8-16 years). There were 3 geldings, 23 mares and 19 stallions and the majority were Warmbloods (60%). The most common presenting signs were poor body condition (40; 87%), slow eating (39; 83%), recurrent colic (35; 74%) and selective appetite (30; 64%). The most consistent laboratory abnormality was hypoalbuminaemia (10; 36%). Slow gastric emptying was confirmed in 29 individuals during gastroscopy and/or ultrasonography. Endoscopy revealed distal oesophagitis in 9 of 47 horses, and severe equine squamous gastric disease in all cases. Pyloric lesions were depressed, flat or raised fibrinosuppurative pyloric ulcers and were seen in 45 (2 pylori were not seen endoscopically). Thirty-two cases were treated, with 28 responding well initially. All treated cases received anti-ulcer medication and four underwent gastrojejunostomy. Clinical signs recurred after medical treatment in at least 11 cases. Only 18 of 44 cases (41%) survived long term (3 were lost to follow-up). Horses diagnosed at 3 years of age or younger were significantly less likely to survive more than 6 months than older horses (27.8% vs. 72.2%, P<0.001).

MAIN LIMITATIONS

The study is retrospective, some records were incomplete and case identification was subjective.

CONCLUSIONS

Chronic severe pyloric lesions can be associated with delayed gastric emptying identified with ultrasonography and/or endoscopy. The prognosis is poor in young horses.

Long term silent carriers of Streptococcus equi ssp. equi following strangles; carrier detection related to sampling site of collection and culture versus qPCR

After strangles outbreaks, Streptococcus equi ssp. equi (S. equi) can persist in clinically normal silent carriers for months to years. Two naturally occurring outbreaks of strangles with 53 and 100% morbidity, respectively, were followed longitudinally to assess occurrence of carrier state and optimal detection methods Outbreak A involved 98 yearling warmbloods, and outbreak B 38 mature Icelandic horses. Fully recovered horses were sampled at least 6 months after index cases using nasal swabs (one sampling occasion only) nasopharyngeal lavage and guttural pouch visualisation and lavages for culture and qPCR to S. equi. Any horse with at least a single sample positive was deemed a carrier. Descriptive statistics and sensitivity and negative predictive values were calculated. Comparisons were made with McNemars and Fishers exact tests. Carrier rates in outbreak A were 3% based on culture and 15% based on qPCR and for outbreak B 13% based on culture and 37% based on qPCR. All culture positives were also qPCR positive. One carrier culture negative sampled after an additional 8 months was culture positive to S. equi, indicating that qPCR positives should be suspected to carry live bacteria. Findings indicate that reliance on guttural pouch sampling and appearance does not capture all silent carriers. All culture positives were identified by qPCR and even horses positive by qPCR but culture negative should be suspected carriers of live bacteria.

Decreased Clinical Severity of Strangles in Weanlings Associated with Restricted Seroconversion to Optimized Streptococcus equi ssp equi Assays

Background

Streptococcus equi ssp. equi causes characteristic clinical signs that are most severe in young horses, including fever, purulent nasal discharge, and lymph node abscessation in the head region.

Hypothesis/Objectives

Clinical, serologic, and microbiologic factors related to unexpectedly mild disease severity in a natural outbreak of strangles in immunologically naïve weanlings were investigated.

Animals

One‐hundred and twelve warmblood weanlings.

Methods

Prospective longitudinal observational study of a natural outbreak of strangles. The entire cohort was examined at the peak of the outbreak by deep nasal swabs for culture and quantitative PCR (qPCR) for the presence of S. equi and clinically and serologically in a sequential manner by an optimized ELISA from the index case throughout the outbreak until resolution. Descriptive statistics were calculated and comparisons made using a nondirectional Wilcoxon signed‐rank test.

Results

Outbreak morbidity was 53%, with 9 of 14 horses culture positive and 26 of 53 horses qPCR positive for S. equi lacking clinical signs characteristic of strangles. By resolution, 91 of 112 had seroconverted to Antigen A by ELISA but seroconversion to antigen C (part of the SeM protein) was minimal. Sequencing of the isolates detected no alterations in the SeM protein, but identified a 61 bp deletion in the gene SEQ_0402.

Conclusions and Clinical Importance

Absence of clinical signs alone in naïve horses may be an insufficient criterion to release horses from strangles quarantine measures. Restricted seroconversion to antigen C may have been associated with decreased clinical severity. The role of a minor gene deletion in SEQ_0402 in the virulence of S. equi warrants further investigation.

Study of the relationship between overjet development and some skull bone measurements in Warmblood foals

Overjet is defined as the projection of the maxillary incisors labial to their antagonists in a horizontal direction. This malocclusion in horses can lead to incorrect dental wear and is aesthetically undesirable. Whether lengthening of the maxilla or shortening of the mandible causes the condition has not yet been determined. Therefore, a measurement technique was developed to investigate the correlations between skull bone measurements in overjet-affected individuals. The position of the incisors in 650 Warmblood foals born in a private German stud was examined at two weeks of age, revealing the prevalence of overjet to be 2 per cent. Five measurements were made on each foal's head and comparisons with a second set of measurements that were made later in the foals first year showed a change in the presence or degree of overjet over time. Nine of 13 foals diagnosed with measurable overjet at the beginning of the study resolved spontaneously. Thirteen foals had no evidence of overjet at birth, of which four developed the condition during the first year of life. The methods used for measuring longitudinal changes in different skull bones and for the assessment of malocclusion in foals affected with overjet were considered effective.

Sarkoidose bei einer Warmblutstute

Gegenstand und Ziel: Darstellung klinischer und pathomorphologischer Untersuchungsbefunde bei einem adulten Warmblutpferd mit einer progredienten, generalisierten Hauterkrankung. Falldarstellung: Fallbericht einer sechs Jahre alten Hannoveraner Warmblutstute. Ergebnisse: Klinisch zeigte die Stute am ganzen Körper eine schmerzhafte Dermatitis mit Krusten und Pusteln ohne Pruritus. Weiterführende Untersuchungen ergaben keine Hinweise auf belebte Krankheitserreger. Pathomorphologisch bestand eine generalisierte, exfoliative und krustöse Dermatitis, die sich histologisch als überwiegend granulomatöse, teils lymphohistiozytäre und pustulöse Dermatitis superficialis et profunda darstellte. Granulomatöse Entzündungsprozesse wurden auch in Thymus, Herz, Lunge, Milz, Leber und in einzelnen Lymphknoten nachgewiesen. Mittels histologischer Spezialuntersuchungen ergaben sich keine Hinweise auf die Krankheitsursache. Schlussfolgerung: Aufgrund der vorliegenden Befunde wurde die Diagnose einer equinen Sarkoidose gestellt. Klinische Relevanz: Bei einer generalisierten exfoliativen Dermatitis mit dem Bild einer granulomatösen Entzündung ist die equine Sarkoidose differenzialdiagnostisch in Betracht zu ziehen.

Intestinal and hepatic contributions to the pharmacokinetic interaction between gamithromycin and rifampicin after single-dose and multiple-dose administration in healthy foals

BACKGROUND

Standard treatment of foals with severe abscessing lung infection caused by Rhodococcus equi using rifampicin and a macrolide antibiotic can be compromised by extensive inhibition and/or induction of drug metabolising enzymes (e.g. CYP3A4) and transport proteins (e.g. P-glycoprotein), as has been shown for rifampicin and clarithromycin. The combination of rifampicin with the new, poorly metabolised gamithromycin, a long-acting analogue of azithromycin and tulathromycin with lower pharmacokinetic interaction potential, might be a suitable alternative.

OBJECTIVES

To evaluate the pharmacokinetic interactions and pulmonary distribution of rifampicin and gamithromycin in healthy foals, and to investigate the cellular uptake of gamithromycin in vitro.

STUDY DESIGN

Controlled, four-period, consecutive, single-dose and multiple-dose study.

METHODS

Pharmacokinetics and lung distribution of rifampicin (10 mg/kg) and gamithromycin (6 mg/kg) were measured in nine healthy foals using LC-MS/MS. Enzyme induction was confirmed using the 4β-OH-cholesterol/cholesterol ratio. Affinity of gamithromycin to drug transport proteins was evaluated in vitro using equine hepatocytes and MDCKII-cells stably transfected with human OATP1B1, OATP1B3 and OATP2B1.

RESULTS

Rifampicin significantly (P<0.05) increased the plasma exposure of gamithromycin (16.2 ± 4.77 vs. 8.57 ± 3.10 μg × h/mL) by decreasing the total body clearance. Otherwise, gamithromycin significantly lowered plasma exposure of single- and multiple-dose rifampicin (83.8 ± 35.3 and 112 ± 43.1 vs. 164 ± 96.7 μg × h/mL) without a change in metabolic ratio and half-life. Gamithromycin was identified as an inhibitor of human OATP1B1, OATP1B3 and OATP2B1 and as a substrate of OATP2B1. In addition, it was extracted by equine hepatocytes via a mechanism which could be inhibited by rifampicin.

MAIN LIMITATIONS

Influence of gamithromycin on pulmonary distribution of rifampicin was not evaluated.

CONCLUSION

The plasma exposure of gamithromycin is significantly increased by co-administration of rifampicin which is most likely caused by inhibition of hepatic elimination.

Efficacy of Tulathromycin for the Treatment of Foals with Mild to Moderate Bronchopneumonia

BACKGROUND

There is conflicting data regarding the efficacy of tulathromycin for the treatment of foals with bronchopneumonia.

HYPOTHESES

Tulathromycin is effective for the treatment of bronchopneumonia in foals and noninferior to the combination of azithromycin and rifampin.

ANIMALS

A total of 240 foals on a farm endemic for infections caused by Rhodococcus equi.

METHODS

In a controlled, randomized, and double-blinded clinical trial, foals with ultrasonographic pulmonary lesions (abscess score 10-15 cm) were allocated to 3 groups: 1-tulathromycin IM q 7 days (n = 80); 2-azithromycin-rifampin, orally q24h (n = 80); or 3-untreated controls (n = 80). Physical examination and thoracic ultrasonography were performed by individuals unaware of treatment group assignment. Foals that worsened were considered treatment failures and removed from the study.

RESULTS

The proportion of foals that recovered was significantly higher for foals treated with tulathromycin (70 of 79) or azithromycin-rifampin (76 of 80) compared to that of control foals (22 of 80). The difference in the percentage of efficacy of azithromycin-rifampin versus tulathromycin was 6.4% (90% CI = -0.72-13.5%). Given that the confidence interval crossed the predetermined noninferiority limit of 10%, the null hypothesis that the response rate in the azithromycin-rifampin group is superior to that of the tulathromycin group could not be rejected. Resolution of ultrasonographic lesions occurred faster in foals treated with azithromycin-rifampin than in foals treated with tulathromycin.

CONCLUSION AND CLINICAL IMPORTANCE

Tulathromycin was effective for the treatment of bronchopneumonia in foals at this farm but not as effective as the combination of azithromycin-rifampin.

Effects of two alfalfa preparations with different particle sizes on the gastric mucosa in weanlings: alfalfa chaff versus alfalfa pellets

Background

Feeding alfalfa hay is often recommended for its buffering components, like protein and calcium, to prevent lesions of the gastric mucosa in horses. Until now, there has been no information regarding the influence of alfalfa particle size on the gastric mucosa. The aim of this study was to investigate the effects of feeding two alfalfa preparations with different particle sizes (alfalfa chaff vs alfalfa pellets) in comparison with grass hay on the gastric mucosa in weanling horses. We hypothesized that feeding a high proportion of fine alfalfa particles would negatively impact gastric mucosa and that feeding long alfalfa chaff would improve gastric mucosal health in weanlings.

Results

Before weaning, the prevalence of gastric mucosa lesions (one or more lesions considering all locations in the stomach) was 84.3 %; at 14 days after weaning, it was almost 100 %. Before and after weaning, most of the lesions were found at the greater curvature of the squamous mucosa and at the lesser curvature. After weaning, gastric mucosal lesions at the pylorus were significantly more severe in the group fed alfalfa chaff (p = 0.002). In the other regions, no differences related to the feeding regimes were observed.

Conclusions

Feeding alfalfa failed to improve gastric mucosal lesion scores in weanlings. Furthermore, foals fed alfalfa chaff had higher lesion scores at the pylorus. Alfalfa leaves contain a superior protein source and high amounts of calcium and magnesium, providing extra nutritional advantages in growing horses. At this time, either traditional grass hay rations or grass hay with alfalfa pellets can be recommended.

Efficacy of gamithromycin for the treatment of foals with mild to moderate bronchopneumonia

Background

Gamithromycin is active in vitro against the bacterial agents most commonly associated with bronchopneumonia in older foals. However, the clinical efficacy and safety of this drug have not been investigated.

Hypothesis

Gamithromycin is effective for the treatment of bronchopneumonia in foals.

Animals

One hundred and twenty‐one foals on a farm endemic for infections caused by Rhodococcus equi.

Methods

In a controlled, randomized, and double blinded clinical trial, foals with ultrasonographic evidence of pulmonary abscesses (abscess score 8.0–20 cm) were randomly allocated in 3 treatment groups: (1) gamithromycin IM q7 days (n = 40); (2) azithromycin with rifampin, PO q24h (n = 40); or (3) no antimicrobial treatment (controls; n = 41). Physical examination and thoracic ultrasonography were performed by individuals unaware of treatment group assignment. Foals that worsened were removed from the study.

Results

The proportion of foals that recovered without the need to be removed from the study was significantly higher for foals treated with gamithromycin (38 of 40) or azithromycin with rifampin (39 of 40) than for controls (32 of 41). Treatment with gamithromycin or with azithromycin‐rifampin resulted in a significantly faster decrease in the clinical score and abscess score compared to the controls. Adverse reactions characterized by colic (n = 18) and hind limb lameness (n = 14) were observed only in foals treated with gamithromycin.

Conclusion and Clinical Importance

Gamithromycin was noninferior to azithromycin with rifampin for the treatment of bronchopneumonia in the study population but had a higher frequency of adverse reactions.

An outbreak of Arthroderma vanbreuseghemii dermatophytosis at a veterinary school associated with an infected horse

We report a case of an outbreak of inflammatory dermatophytoses caused by Arthroderma vanbreuseghemii (formally Trichophyton mentagrophytes pro parte) that involved an infected horse, the owner and at least 20 students, staff and stablemen at a veterinary school in Bern (Switzerland) that presented highly inflammatory dermatitis of the body and the face. Transmission from human to human was also recorded as one patient was the partner of an infected person. Both the phenotypic characteristics and ITS sequence of the dermatophytes isolated from the horse and patients were identical, consistent with the conclusion that the fungus originated from the horse. Three infected persons had not been in direct contact with the horse. Although direct transmission from human to human cannot be ruled out, fomites were most likely the source of infection for these three patients. Inspection of the literature at the end of the nineteenth and beginning of the twentieth century revealed that this dermatophyte was frequently transmitted from horses to humans in contact with horses (stablemen, coachmen, carters and artillery soldiers). The rarity of the present case report at the present time is likely related to the transformation of civilisation from the nineteenth century to nowadays in Europe with the change of horse husbandry. In addition, the inadequate immune response of the horse and the high number of people in contact with it at the equine clinic may explain the exceptional aspect of this case report.