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  • Author or Editor: Astrid Bienert-Zeit x
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OBJECTIVE To monitor concentrations of sulfadimidine in the paranasal sinus mucosa (PSM) of unsedated horses following IV administration of trimethoprim-sulfadimidine via in vivo microdialysis.

ANIMALS 10 healthy adult horses.

PROCEDURES Concentric microdialysis probes were implanted into the subepithelial layers of the frontal sinus mucosa of standing sedated horses. Four hours after implantation, trimethoprim-sulfadimidine (30 mg/kg) was administered IV every 24 hours for 2 days; dialysate and plasma samples were collected at intervals during that 48-hour period and analyzed for concentrations of sulfadimidine. The dialysate concentration and relative loss of sulfadimidine from the perfusate were used to calculate the PSM concentration.

RESULTS Microdialysis probe implantation and subsequent in vivo microdialysis were successfully performed for all 10 horses. Following the first and second administration of trimethoprim-sulfadimidine, mean ± SD peak concentrations of sulfadimidine were 55.3 ± 10.3 μg/mL and 51.5 ± 8.7 μg/mL, respectively, in plasma and 9.6 ± 4.5 μg/mL and 7.0 ± 3.3 μg/mL, respectively, in the PSM. Peak sulfadimidine concentrations in the PSM were detected at 5.9 ± 2.7 hours and 5.4 ± 2.3 hours following the first and second drug administrations, respectively. For 12 hours, mean PSM sulfadimidine concentration remained greater than the minimum inhibitory concentration indicative of sulfonamide susceptibility of equine bacterial isolates (4.75 μg/mL).

CONCLUSIONS AND CLINICAL RELEVANCE In vivo microdialysis for continuous monitoring of PSM sulfadimidine concentrations in unsedated horses was feasible. Intravenous administration of trimethoprim (5 mg/kg) and sulfadimidine (25 mg/kg) proved likely to be efficient for treating sinusitis caused by highly susceptible pathogens, providing that the dosing interval is 12 hours.

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in American Journal of Veterinary Research



To compare anamnestic factors in Equine Odontoclastic Tooth Resorption and Hypercementosis (EOTRH) in affected and nonaffected horses to detect risk factors for horses developing EOTRH.


A total of 154 Icelandic horses, aged 15 years and older, examined at 22 locations in Lower Saxony, Germany. The investigations took place from October 2020 to December 2021.


Anamnestic data were collected using an owner-completed questionnaire. Horses underwent a thorough physical examination and CBC. The rostral oral cavity was clinically examined, and intraoral radiographs of the incisors were taken. Clinical and radiographic findings were scored. Based on the results, the study population was separated into “EOTRH-affected” and “EOTRH-healthy” horses. Both groups were compared to identify differences within the anamnestic factors. In case of inconclusive findings, some horses were classified as “suspicious”.


The diagnosis of EOTRH was made in 72.2% (109/151) of horses. The risk of contracting the disease increased with the age of the horse (P = .004). In addition, there was a predisposition for male animals (P = .032). Feeding, keeping, and dental treatments showed no significant influence, while place of birth seemed to influence horses developing EOTRH (P = .017).


The results highlight how widespread EOTRH is among the German Icelandic horse population and the need for raising awareness of EOTRH, as many horses were not suspected of having EOTRH beforehand. Moreover, numerous etiological propositions exist, but, to date, no studies have investigated their relevance.

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in Journal of the American Veterinary Medical Association