Endoscope-Guided Balloon Sinuplasty of the Equine Nasomaxillary Opening

Objective— To describe and evaluate an endoscope-guided balloon sinuplasty technique for dilation of the equine nasomaxillary opening (NMO).
Study Design— Experimental study.
Animals— Equine cadaver heads (n=5); Quarter Horses (n=4).
Methods— A custom rigid balloon introducer was passed into position within the NMO at the caudal recess of the middle meatus. Under endoscopic guidance, a balloon catheter was passed via the introducer into the NMO and inflated to 6 atmospheres, for 30 seconds 3 times, to dilate the NMO. Drainage rates after sinuplasty were evaluated for the caudal maxillary sinus in 5 cadaver heads and balloon sinuplasty was performed in 4 live horses. All skulls were examined to assess the efficacy of NMO dilation.
Results— Positioning of the balloon catheter was readily achieved in all heads. Dilation was observed endoscopically and confirmed on necropsy in all heads. Drainage rates from the caudal maxillary sinus increased significantly (∼1.5 ×) in all 5 cadaver heads after sinuplasty ( P =.001).
Conclusions— Dilation of the NMO improved sinus drainage in all 5 cadaver heads. Endoscopic evaluation of the ostium revealed marked dilation of the NMO in live horses and indicates potential clinical use in standing horses.
Clinical Relevance— Balloon sinuplasty of the NMO opening is an easily performed, clinically applicable technique for use in standing horses. Clinical studies will be necessary to evaluate the efficacy of this technique in diseased sinuses.     

Induration of the Cricoid Cartilage Complicates Prosthetic Laryngoplasty in a Horse

Objective— To report intraoperative complications during needle penetration and suture placement through the cricoid cartilage during a prosthetic laryngoplasty procedure.
Study Design— Case report.
Methods— An 11-year-old American Paint gelding with grade IV left laryngeal hemiplegia underwent a terminal prosthetic laryngoplasty for teaching purposes. Passage of the needle through the cricoid cartilage was difficult and resulted in needle breakage before eventual success using a new needle. The larynx was examined postmortem.
Results— Palpation of the larynx revealed hardening of the cricoid cartilage. Radiographic examination indicated the presence of diffuse radiopaque speckling. Histologic examination did not find accumulations of calcium salts, rather it revealed a loss of proteoglycans within the cricoid cartilage.
Conclusions— Laryngeal mineralization occurs in the horse and human with advancing age. The loss of proteoglycan and subsequent stiffening of the cricoid cartilage likely resulted in the intraoperative complications noted in this report.
Clinical Relevance— Radiographic examination of the larynx before performing a prosthetic laryngoplasty may reveal the presence of areas of increased radiodensity. The interpretation of this is to be made with caution as it may represent mineralization, or hardening due to the changes in proteoglycan concentration, monomer size or charge.     

Germinable soil seedbanks of central Queensland rangelands invaded by the exotic weed Parthenium hysterophorus L.

The germinable soil seedbank was determined at two sites in central Queensland on four separate occasions between February 1995 and October 1996. These sites were infested with parthenium weed ( Parthenium hysterophorus L.), a serious invasive exotic weed. During this period, the seedbank varied between 3282 and 5094 seeds m⁻² at the Clermont site, and between 20 599 and 44 639 seeds m⁻² at the Moolayember Creek site. Parthenium hysterophorus exhibited a very abundant and persistent seedbank, accounting for 47–73% of the seedbank at Clermont and 65–87% of the seedbank at Moolayember Creek. The species richness and species diversity of the seedbank, and the seed abundance of many species, was lower at Moolayember Creek during spring (the time of year when the most dense infestations of the weed originate). Parthenium hysterophorus seedlings also emerged more rapidly from the soil samples than did those of all other species. Hence, it seems that various aspects of the weed's seed ecology, including abundance and the persistence of its seedbank and the rapid emergence of its seedlings, are major factors contributing to its aggressiveness in semiarid rangeland communities in central Queensland. The domination by P . hysterophorus of the seedbanks of these sites suggests that the weed is having a substantial negative impact on the ecology of these plant communities. The diversity of these seedbanks was found to be lower in comparison with that observed in other grassland communities that were not dominated by an invasive weed species. Hence, the prolonged presence of P . hysterophorus may have substantially reduced the diversity of these seedbanks, thereby reducing the ability of some of the native species to regenerate in the future.