Evaluation of Factors Influencing the Generation of Ammonia in Different Bedding Materials Used for Horse Keeping

Bedding material is an important factor in determining stable air quality in terms of ammonia formation. The objective of this study was to analyze different bedding materials used for horse stables under standardized conditions, to determine which material is best suited for improving the climate of a stable. The particular concern was a reduction in gaseous ammonia concentrations. Therefore, the following materials were examined: wheat straw, wood shavings, hemp shives, linen shives, wheat straw pellets, and paper cuttings. Twelve containers were constructed in an environmentally controlled room, and the same material was placed into two containers, with the amount of material used being determined by its carbon content. A defined ratio of horse manure/urine mixture was added daily to each container over a period of 14 days. The concentrations of gaseous ammonia, carbon dioxide, nitrous oxide, and water vapor were measured continuously above the bedding within the containers. Means of gaseous ammonia were found to be 178.0 mg/m³ for wheat straw, 155.2 mg/m³ for wood shavings, 144.6 mg/m³ for hemp, 133.7 mg/m³ for linen, 60.3 mg/m³ for straw pellets, and 162.6 mg/m³ for paper cuttings. In conclusion, the results of this study have shown that straw pellets are suitable for horse stables, not only to improve air quality but also, first and foremost, in relation to ammonia binding and ammonia transformation within the bedding material, respectively. However, straw pellets may also have disadvantages. The high substrate temperatures that were measured in straw pellets could favor the growth of pathologic germs that can adversely affect animals' health.     

A study of cardiovascular function under controlled and spontaneous ventilation in isoflurane–medetomidine anaesthetized horses

Objective To determine, in mildly hypercapnic horses under isoflurane–medetomidine balanced anaesthesia, whether there is a difference in cardiovascular function between spontaneous ventilation (SV) and intermittent positive pressure ventilation (IPPV). Study design Prospective randomized clinical study. Animals Sixty horses, undergoing elective surgical procedures under general anaesthesia: ASA classification I or II. Methods Horses were sedated with medetomidine and anaesthesia was induced with ketamine and diazepam. Anaesthesia was maintained with isoflurane and a constant rate infusion of medetomidine. Horses were assigned to either SV or IPPV for the duration of anaesthesia. Horses in group IPPV were maintained mildly hypercapnic (arterial partial pressure of carbon dioxide (PaCO₂) 50–60 mmHg, 6.7–8 kPa). Mean arterial blood pressure (MAP) was maintained above 70 mmHg by an infusion of dobutamine administered to effect. Heart rate (HR), respiratory rate (f_R), arterial blood pressure and inspiratory and expiratory gases were monitored continuously. A bolus of ketamine was administered when horses showed nystagmus. Cardiac output was measured using lithium dilution. Arterial blood‐gas analysis was performed regularly. Recovery time was noted and recovery quality scored. Results There were no differences between groups concerning age, weight, body position during anaesthesia and anaesthetic duration. Respiratory rate was significantly higher in group IPPV. Significantly more horses in group IPPV received supplemental ketamine. There were no other significant differences between groups. All horses recovered from anaesthesia without complications. Conclusions There was no difference in cardiovascular function in horses undergoing elective surgery during isoflurane–medetomidine anaesthesia with SV in comparison with IPPV, provided the horses are maintained slightly hypercapnic. Clinical relevance In horses with health status ASA I and II, cardiovascular function under general anaesthesia is equal with or without IPPV if the PaCO₂ is maintained at 50–60 mmHg.     

Severity and persistence of footrot in Merino sheep experimentally infected with a protease thermostable strain of Dichelobacter nodosus at five sites

Objective To test the hypothesis that ovine footrot associated with a thermostable protease strain of Dichelobacter nodosus undergoes self cure or is sustained as an annually recurring disease, depending on the environment.
Design and procedure Forty Merino sheep from a single blood line were infected with a protease thermostable strain of D nodosus a t each of five sites in Western Australia. Footrot lesions and microscopic evidence of D nodosus were recorded every fortnight for 2.5 years, supplemented by laboratory culture. Rainfall, soil and air temperature, pasture quantity and composition and soil types were also recorded. Flocks that apparently self cured were relocated to a more favourable site for footrot in the final spring season.
Results The maximum prevalence of feet with clinical footrot lesions was 80.6, 1.3, 14.4, 3.8 and 88.1% at the five sites. Severe footrot occurred for three consecutive spring seasons at one site that had clay loam soil and at least 3500 kg/ha total pasture dry matter annually. However, the infection was asymptomatic for up to 10 weeks between outbreaks. D nodosus was isolated from flocks for 2.5 years at only two sites, although there was microscopic evidence of the organism at other sites in the final year. A thermolabile variant (strain U6) of D nodosus was isolated from the two sites where footrot persisted.
Conclusion Depending on time and location, ovine footrot induced by a protease thermostable strain of D nodosus either self cured or persisted as annual outbreaks interspersed with periods of asymptomatic infection.     

von Willebrand's disease in Scottish Terriers in Australia

SUMMARY Over a 5-year period (1988–92), von Willebrand factor antigen (vWf:Ag) assays were performed on plasma samples from 207 Scottish Terriers. Based on these tests, 47 dogs (23%) had vWf:Ag concentrations < 50 canine units (CU)/dL and were classified as heterozygous carriers of the von Willebrand's disease (vWD) gene, while 9 (4%) had concentrations below the sensitivity of the assays and were classified as homozygous. There was thus an overall prevalence of 27% for the vWD gene in the Scottish Terriers tested. The homozygous dogs (median age 0.6 years at diagnosis) consisted of 7 males and 2 females. Eight of these had haemorrhage attributable to the disease, mostly spontaneous and from the oral mucosa. Other signs included haemorrhage induced by trauma or surgery, easy bruising and epistaxis. Many haemorrhagic episodes were severe enough to warrant therapeutic intervention and there was a single fatality. Pedigree analysis, possible in 7 of the dogs, revealed that each was the progeny of a mating between dogs with vWf:Ag concentrations < 50 CU/dL, which supported an autosomal recessive mode of inheritance. A single heterozygous carrier suffered haemorrhage after surgery that, in contrast to the homozygotes, was mild and did not require therapy. The data indicate that vWD is a significant problem in Scottish Terriers in Australia. Accordingly, we recommend that steps be taken to reduce the prevalence of the disease and thereby the number of clinically affected dogs, such as the establishment of a national testing scheme to determine the vWD status of all breeding dogs.     

Transendoscopic injection of poly-L-lactic acid into the soft palate in horses: A new therapy for dorsal displacement of the soft palate?

The purpose of this study was to establish a minimal invasive, transendoscopic technique for injection of poly-L-lactic acid into the free edge of the soft palate that can be performed on the standing sedated horse. Furthermore, whether the implant material induces an increase in fibrous tissue at the injection site, resulting in a greater rigidity of the soft palate, was determined.In 4 horses, the injection was performed bilaterally along the caudal margin of the soft palate, and the influence of the treatment on the soft palate function was determined. Clinical, radiographic and endoscopic examinations at rest were performed before and up to 168 days after injection according to a standardized examination protocol.In 6 horses, the implant material was injected unilaterally into the right half of the caudal margin of the soft palate. After clinical and endoscopic follow-up examinations, 2 horses each were killed 28, 84, and 168 days after the implantation procedure. At necropsy, macroscopic comparison of the treated and the untreated halves of the soft palate showed the influence on the size of the ostium intrapharyngeum and on the soft palate thickness. The localization of the implant material in the soft palate and the tissue response to the poly-L-lactic acid were evaluated histologically.Transendoscopic injection into the soft palate requires neither general anesthesia nor wound management, and it is noted for minimal tissue trauma. After injection, no alteration of the soft palate function was observed in horses with normal upper airway mechanics. One horse with intermittent dorsal displacement of the soft palate showed an improvement of the soft palate function for 112 days after implantation. No significant alteration in the size of the ostium intrapharyngeum was evident in any horse. Histologic assessment indicated the presence of implant material during the entire observation period of 168 days. The implant was accompanied by a granulomatous inflammation, and it was encapsulated by fibrous tissue. This may result in an increase in stiffness, and subsequent a greater rigidity of the soft palate, preventing it from displacement. The injection may therefore be considered an alternative to established therapies in horses showing dorsal displacement of the soft palate because of its unstable free edge.     

Effect of acepromazine, xylazine and thiopentone on factor VIII activity and von Willebrand factor antigen concentration in dogs

The effect of acepromazine maleate, xylazine and thiopentone on the packed cell volume, plasma protein content, factor VIII activity and von Willebrand factor antigen concentration of blood was studied in normal dogs. The same variables were measured in dogs with haemophilia A given acepromazine maleate and thiopentone. Both the packed cell volume and plasma protein content decreased after the administration of either acepromazine maleate or xylazine. Values were not changed further after administration of thiopentone. Changes in the haemostatic variables measured were generally small. Consequently, blood samples collected from dogs under the influence of premedicant doses of acepromazine maleate or xylazine, and when subsequently anaesthetised with thiopentone, are adequate for the assay of factor VIII activity and von Willebrand factor antigen concentration for establishing an animal's haemophilia A and von Willebrand's disease status.     

Identification of toxigenic Pasteurella multocida in atrophic rhinitis of pigs by in vitro characterisation

Toxigenic strains of Pasteurella multocida were readily differentiated from non-toxigenic strains by an agarose overlay method using bovine turbinate cells or bovine lung cells. Cells which were young and densely confluent were best suited to this assay. The incubation period required to distinguish toxigenic strains was dependent on the confluence of the monolayers, which was affected by the seeding rate, cell passage level and growth time prior to overlay. The agarose overlay method correctly identified 11 of 11 reference strains of Pasteurella multocida, and visible cytotoxic changes were present in the monolayers after 48 to 65 h. Outbreaks of the enzootic form of atrophic rhinitis in 2 New South Wales piggeries were associated with the isolation of toxigenic type D strains of P. multocida.     

Use of a Medial Bone Plate for Repair of Radius and Ulna Fractures in Dogs and Cats: A Report of 22 Cases

Objective —This study evaluates the technique of medial bone plating in the repair of radius fractures in dogs and cats.
Study Design —A retrospective study was made of patients diagnosed with fractures of the radius that were stabilized by application of a bone plate to the medial side of the bone.
Animal Population —Sixteen client-owned dogs and 4 client-owned cats. The animals' ages varied from 5 months to 8 years, and their weight varied from 1.3 to 49 kgs.
Methods —Animals were evaluated using radiography or client assessment, or both.
Results —Medial plate application was technically easier to do than cranial plate application, the technique avoided the extensor tendons, and permitted greater versatility in the selection of smaller plates for the fixation of distal radius fractures. All fractures repaired by this method healed with no postoperative complications.
Conclusions —Medial plate application may be used for osteosynthesis of distal or middiaphy-seal radius fractures. Further studies are needed to evaluate the use of this technique in morphologically complex fractures. In patients with fractures of the proximal radius, cranial plate application is considered more appropriate.
Clinical Relevance —Medial plating of radial fractures has significant advantages compared with conventional plate application; it provides the surgeon with an alternative method of fixation for selected radius fractures in dogs and cats.