Leader Browsing by Red and Roe Deer on Young Sitka Spruce Trees in Western Scotland. II. Effects on Growth and Tree Form

Some 2000 trees at 14 main sites in Glenbranter Forest, Argyll,were monitored during 1978–1990 for damage. Tree state(whether leaderless or with single or multiple leaders or trunks)and tree size were regularly recorded. Browsing of leaders depressed height increment by 5–10cm in the year of ocurrence compared with undamaged trees; therapid development of new leaders minimized the check in growth.Trees initially leaderless had equal height increment over ayear to trees initially with leaders if no damage occurred inthe year. At a subsidiary site where some trees were planted in smallexclosures, the trees protected from deer reached a safe heightafter five seasons of growth, unprotected trees reaching equalheight 1 year later. The girths attained when trees were 10–15 years old wereon average only slightly depressed by earlier browsing damageto leaders, reductions at most equalling one year's increment. Many trees became multi-trunked, there being a significant relationshipbetween the percentage incidence of multi-trunking and the numberof occurrences of leader damage. Unbrowsed trees mostly becamesingle-trunked. We judge that the present high incidence ofmulti-trunking (45 per cent in our 9–15 year-old stands)results largely from deer browsing.     

Biomechanical Analysis of Stacked Plating Techniques to Stabilize Distal Radial Fractures in Small Dogs

Objective— To evaluate the fatigue life of partially stacked and fully stacked (1.5/2.0 and 2.0/2.7 mm) veterinary cuttable plates (VCP) in a fracture gap model of the distal aspect of the radius. Study Design— In vitro biomechanical study. Methods— Constructs (n=4/group) were assembled for each of 8 groups using 8‐hole plates (1.5/2.0 and 2.0/2.7 mm VCP) in the following configurations: unstacked; 2‐hole stacked centered over the gap (COG); 4‐hole stacked COG; and fully stacked. Plate(s) were secured to 2 separate polyvinylchloride pipe lengths, mounted to a mechanical testing system with a custom jig, and were loaded in axial compression for 10⁶ cycles at 10 Hz or until failure at 6–60 N for the 1.5/2.0 mm VCP and 10–100 N for the 2.0/2.7 mm VCP. Differences in number of cycles, stiffness, and failure mode were recorded. Results— All construct failures occurred through a screw hole adjacent to the gap. Fully stacked and 4‐hole stacked 1.5/2.0 and 2.0/2.7 mm VCP withstood 10⁶ cycles. Fatigue life and stiffness of the 1.5/2.0 or 2.0/2.7 mm unstacked constructs were significantly less than the other constructs. Differences were identified in stiffness among the 1.5/2.0 mm stacked constructs and in fatigue life among the 2.0/2.7 mm VCP stacked constructs. Conclusion— Four‐hole partially stacked VCP (either 1.5/2.0 or 2.0/2.7 mm) have comparable mechanical properties to fully stacked VCP. Clinical Relevance— Partial stacking of 2 holes of VCP on both sides of the fracture gap may provide sufficient strength for healing, but this premise must be tested in vivo.     

Prevalence,number and morphological types of multinucleated histiocytic giant cells in equine inflammatory dermatoses: A retrospective light microscopic study of skin‐biopsy specimens from 362 horses

Reasons for performing study: Multinucleated histiocytic giant cells (MHGC) are seen frequently in skin‐biopsy specimens from horses with inflammatory dermatoses. However, the prevalence, number and morphological types of these cells have not been reported. Objective: To determine the prevalence, number and morphological types of MHGC in equine inflammatory dermatoses, and the association of these cells with specific conditions. Methods: Skin‐biopsy specimens from 335 horses with inflammatory dermatoses and from 27 horses with normal skin were evaluated for the prevalence, number and morphological types of MHGC. Results: The prevalence and number of MHGC were greater in granulomatous dermatoses than in nongranulomatous dermatoses. Infectious and noninfectious dermatoses were not different in terms of prevalence or morphological types of MHGC. Foreign‐body MHGC were the predominant type in almost all cases. MHGC were not seen in normal skin. Conclusions: MHGC are seen in a wide variety of equine inflammatory dermatoses, especially those that are granulomatous. Number and morphological types of MHGC are of no apparent diagnostic significance. Potential relevance: MHGC are frequently present in a wide variety of inflammatory dermatoses in the horse. Because the prevalence, number and morphological types of MHGC are of minimal diagnostic significance, special stains and tissue cultures are necessary to confirm specific diagnoses.     

Anastomosis group and pathogenicity of isolates of Rhizoctonia solani from potato crops in South Australia

Isolates of Rhizoctonia collected from the stems, roots, tuber sclerotia and soil of potato crops in Virginia and Lenswood, South Australia, were identified to anastomosis groups (AG). Of the 301 multinucleate isolates of Rhizoctonia solani tested, 90% were AG-3, 7% were AG-4 and 2% were AG-5; 12 isolates were binucleate Rhizoctonia spp. This is the first report of isolates of AG-4 and AG-5 causing disease in potato crops in South Australia. All AG-3, AG-4 and AG-5 isolates tested caused rhizoctonia disease symptoms on the potato cultivar Coliban in pathogenicity trials conducted under glasshotise conditions. Both AG-3 and AG-5 isolates caused black scurf and stem cankers, although symptoms of black scurf were less severe with AG-5. AG-4 isolates produced the most severe stem and stolon cankers of all isolates tested. The pathogenicity of tuber-borne inoculum was confirmed by growing plants from sclerotia-infested tubers. AG-8 isolates from diseased barley and wheat produced severe root cankers and caused loss of feeder roots on inoculated potato plants. Results suggest that rhizoctonia disease in potato fields in South Australia is caused by a combination of different anastomosis groups and this has important implications for crop rotations.     

Staining abnormalities of dermal collagen in cats with cutaneous asthenia or acquired skin fragility as demonstrated with Masson's trichrome stain

This retrospective study compared the Masson's trichrome staining properties of collagen in the skin of normal cats and cats with cutaneous asthenia or acquired skin fragility. A Masson's trichrome staining abnormality was seen in all ( n = 8) cats with cutaneous asthenia, three of four cats with acquired skin fragility, and none ( n = 10) of the normal cats. A grading system developed to classify the intensity and distribution of abnormally stained collagen fibres indicated that cats with cutaneous asthenia had higher scores ( P < 0.001) than normal cats. Cats with acquired skin fragility had intermediate scores that were not significantly different from either of the other two groups.     

Bacterial Isolates from Blood Cultures of Dogs Undergoing Dentistry

Bacteria in blood cultures in 30 dogs undergoing high-speed dental scaling and tooth extraction were examined. One or more positive blood cultures were identified in 9 of 30 (30%) dogs. Pasteurella spp. were most frequently (5 dogs) isolated and were sensitive to ampicillin, penicillin, cephalothin, chloramphenicol, tetracycline, amoxicillin with clavulanic acid, and sul-famethoxazole with trimethoprim. Twg groups of 15 dogs each, anesthetized or sedated but not undergoing dental procedures, served as non-dentistry controls. There were no significant (p < .05) differences between the number of positive cultures in dentistry and non-dentistry groups. In healthy dogs undergoing high-speed dental scaling and tooth extraction, the occurrence of bacteria in blood cultures was much lower than previously reported. The clinical significance of positive blood cultures was uncertain.     

Follicle Development during Luteal Phase and Altrenogest Treatment in Pigs

Synchronization of the oestrous cycle of gilts using altrenogest treatment has been found to increase ovulation rate. The current experiment investigated if the increase in ovulation rate after altrenogest treatment is related to increased follicle size at the end of altrenogest treatment compared with late luteal phase follicles. Crossbred gilts (n = 15) received altrenogest during 18 days [20 mg Regumate (Janssen Animal Health, Beerse, Belgium)], starting 5-7 days after onset of first oestrus. Control gilts (n = 15) did not receive altrenogest. At days 10-12 of the oestrous cycle [i.e. in the presence of corpora lutea (CL)], average follicle development was 2.51 +/- 0.20 mm (assessed with ultrasound) in altrenogest-treated gilts and 2.58 +/- 0.16 mm in control gilts (p > 0.10). During the last days of altrenogest treatment (i.e. when CL had gone into regression), average follicle size had increased to 3.01 +/- 0.31 mm (p < 0.05). Subsequent ovulation rate was 16.6 +/- 1.7 in altrenogest treated gilts and 15.1 +/- 1.2 in control gilts (p < 0.05). Altrenogest treatment resulted in increased follicle size after regression of the CL, showing that suppression of follicle growth by altrenogest alone is less severe than suppression by endogenous progesterone (either with or without altrenogest). Altrenogest treatment also resulted in a higher ovulation rate. However, it is unclear if the increased follicle size and higher ovulation rate after altrenogest treatment are causally related, as the relation between the two on an animal level was not significant.