Clinical presentation, management, and survival in dogs with persistent atrial standstill in the United Kingdom.

OBJECTIVES: To investigate the clinical and echocardiographic presentation of dogs with persistent atrial standstill (PAS), identify variables measured at first presentation that could predict their survival, and document the progression of the disease after pacing. MATERIALS AND METHODS: Retrospective study of medical records of dogs diagnosed with PAS at three referral hospitals of the United Kingdom over seven years. RESULTS: Twenty-six dogs were diagnosed with PAS during the study period. Median age of the population was three years (range: seven months-12.5 years). The most common clinical sign was syncope (14/26). Twenty-four dogs received artificial pacemakers (PM). Major complications after PM implantation were observed in four dogs (four/24). Serial echocardiographic examinations showed that cardiac dimensions of PAS dogs with left atrial or left ventricular dilation at first presentation did not return to reference range after pacing. Further dilation of the cardiac chambers, recurrence of congestive heart failure (CHF), or development of new episodes of CHF were documented in seven, four, and 10 PAS dogs, respectively, despite pacing. Median survival time for cardiac-related deaths after PM implantation was 1512 days (18-3207). Neither CHF nor echocardiographic variables at presentation predicted survival after PM implantation in PAS dogs. CONCLUSIONS: Persistent atrial standstill (PAS) is an uncommon bradyarrhythmia, occurring in young adult dogs. Affected dogs were often presented with syncope. Whilst syncope resolved, cardiac remodeling persisted after PM implantation. Long-term survival was favorable after PM implantation and was not predicted by congestive status or cardiac chamber size at first presentation.

Differences in Left Ventricular Enlargement Secondary to Chronic Volume Loading Between English Springer Spaniels and Two Similar Sporting Breeds.

INTRODUCTION: English springer spaniels have larger, rounder ventricles than most other breeds. How this geometry impacts responses to volume overload remains unknown. We compared left ventricular size between English springer spaniels and two similarly sized sporting breeds (Border collies and Labrador retrievers) in naturally occurring chronic left ventricular volume loading conditions (mitral regurgitation and patent ductus arteriosus [PDA]) to examine whether differences in remodelling responses exist between these breeds. ANIMALS, MATERIALS AND METHODS: We searched records for cases of mitral regurgitation and PDA in three breeds. We recorded age, sex, presence of congestive heart failure (CHF), body weight and specific echocardiographic variables. We compared normalised measures of left ventricular size between breeds. Cases with CHF were further examined as a separate group. RESULTS: One-hundred-and-ninety-one dogs were included: 110 with degenerative mitral valve disease, 42 with mitral dysplasia and 39 with PDA. One third of all cases had CHF. All measures of left ventricular size were larger in English springer spaniels in mitral regurgitation cases (P<0.001), whereas PDA cases did not differ. English springer spaniels with PDA resulting in CHF had larger systolic dimensions and volumes than similarly affected non-English Springer Spaniel dogs (P=0.003). CONCLUSIONS: English springer spaniels have greater left ventricular dimensions when exposed to chronic mitral regurgitation, compared with Border collies and Labrador retrievers, but not when exposed to volume overload from a PDA. English springer spaniels differ in their left ventricular morphology from two other sporting breeds, supporting previous studies that they have a unique cardiac morphotype.

Pacemaker-lead-associated thrombosis in dogs: a multicenter retrospective study.

INTRODUCTION: Pacemaker implantation is the treatment of choice for clinically relevant bradyarrhythmias. Pacemaker-lead-associated thrombosis (PLAT) occurs in 23.0-45.0% of people with permanent transvenous pacemakers. Serious thromboembolic complications are reported in 0.6-3.5%. The incidence of PLAT in dogs is unknown. ANIMALS, MATERIALS AND METHODS: multicenter retrospective study of seven centers with 606 client-owned dogs undergoing permanent pacemaker implantation between 2012 and 2019. 260 dogs with a transvenous pacemaker with echocardiographic follow-up, 268 dogs with a transvenous pacemaker without echocardiographic follow-up and 78 dogs with an epicardial pacemaker. RESULTS: 10.4% (27/260) of dogs with transvenous pacemakers and echocardiographic follow-up had PLAT identified. The median time to diagnosis was 175 days (6-1853 days). Pacemaker-lead-associated thrombosis was an incidental finding in 15/27 (55.6%) dogs. Of dogs with a urine protein:creatinine ratio measured at pacemaker implantation, dogs with PLAT were more likely to have proteinuria at pacemaker implantation vs. dogs without PLAT (6/6 (100.0%) vs. 21/52 (40.4%), P=0.007). Urine protein:creatinine ratio was measured in 12/27 (44.4%) dogs at PLAT diagnosis, with proteinuria identified in 10/12 (83.3%) dogs. Anti-thrombotic drugs were used following the identification of PLAT in 22/27 (81.5%) dogs. The thrombus resolved in 9/15 (60.0%) dogs in which follow-up echocardiography was performed. Dogs with PLAT had shorter survival times from implantation compared to those without PLAT (677 days [9-1988 days] vs. 1105 days [1-2661 days], P=0.003). CONCLUSIONS: Pacemaker-lead-associated thrombosis is identified in 10.4% (27/260) of dogs following transvenous pacing, is associated with proteinuria, can cause significant morbidity, and is associated with reduced survival times.

Analysis of canine cardiovascular therapeutic agent prescriptions using electronic health records in primary care veterinary practices in the United Kingdom.

INTRODUCTION/OBJECTIVES: Canine cardiovascular (CV) diseases are often managed in primary care settings. The objectives were to describe CV therapeutic agent (CVTA) prescribing patterns in primary care practices in the United Kingdom (UK) and to evaluate recorded clinical signs, diagnostic tests and justifications for use of torasemide, a recently marketed and authorised loop-diuretic in the UK. ANIMALS, MATERIALS AND METHODS: Electronic health records (EHRs) describing 3,579,420 consultations (1,043,042 unique dogs) were collated (1 April 2014 and 31 December 2018) by the Small Animal Veterinary Surveillance Network from 270 veterinary practices. Consultations prescribing at least one CVTA were identified. Annual variation in individual CVTA prescriptions was analysed using mixed-effects binomial regression models. Free-text clinical narratives were manually read to determine the first-prescribing event for torasemide. RESULTS: Twenty-nine thousand and seven consultations (0.81% of all consultations, 95% confidence interval [CI], 0.76-0.86) prescribed CVTA in 14,148 (1.36%) dogs. Furosemide (52.8% of CV-prescribing consultations, 95% CI 50.7-54.9) and pimobendan (51.9%, 95% CI 50.1-53.7) were most prescribed. Longitudinal analysis (2014-2018) showed a significant negative temporal trend for angiotensin-converting enzyme inhibitors (p < 0.001), and furosemide (p = 0.003) and a positive temporal trend for pimobendan (p = 0.020) and torasemide (p < 0.001). First prescriptions of torasemide were identified in 16.5% of torasemide-prescribing consultations. Where justification for prescription of torasemide was identified (32.5%), furosemide resistance was the most common (92.0%). CONCLUSIONS: EHRs can be used to temporally monitor prescribing habits, including responses to market authorisations. Despite authorisation in the UK for torasemide use as a first-line diuretic, it was most commonly prescribed after furosemide resistance.

Changes of SERCA activity have only modest effects on sarcoplasmic reticulum Ca2+ content in rat ventricular myocytes.

Changes of the activity of the sarco-endoplasmic reticulum Ca(2+)-ATPase (SERCA) affect the amplitude of the systolic Ca(2+) transient and thence cardiac contractility. This is thought to be due to alterations of SR Ca(2+) content. Recent work on mice in which the expression of SERCA is decreased found that a large reduction of SERCA expression resulted in a proportionately much smaller decrease of SR Ca(2+) content. The aim of the current work was to investigate the quantitative nature of the dependence of both the amplitude of the systolic Ca(2+) transient and SR Ca(2+) content on SERCA activity during acute partial inhibition of SERCA. Experiments were performed on rat ventricular myocytes. Brief application of thapsigargin (1 µm) resulted in a decrease of SERCA activity as measured from the rate of decay of the systolic Ca(2+) transient. This was accompanied by a decrease in the amplitude of the systolic Ca(2+) transient which was linearly related to that of SERCA activity. However, the fractional decrease in the SR Ca(2+) content was much less than that of SERCA activity. On average SR Ca(2+) content was proportional to SERCA activity raised to the 0.38 ± 0.07 power. This shallow dependence of SR content on SERCA activity arises because Ca(2+) release is a steep function of SR Ca(2+) content. In contrast SR Ca(2+) content was increased 4.59 ± 0.40 (n = 8)-fold by decreasing ryanodine receptor opening with tetracaine (1 mm). Therefore a modest decrease of SR Ca(2+) content results in a proportionately larger fall of Ca(2+) release from the SR which can balance a larger initiating decrease of SERCA. In conclusion, the shallow dependence of SR Ca(2+) content on SERCA activity is expected for a system in which small changes of SR Ca(2+) content produce larger effects on the amplitude of the systolic Ca(2+) transient.

Clinical and diagnostic imaging findings in dogs with atrial appendage aneurysm: 7 cases (2014-2020).

INTRODUCTION/OBJECTIVE: Atrial appendage aneurysm in dogs is a rare condition and has not been well described. The aim of this study is to describe clinical and diagnostic imaging findings, especially computed tomography (CT), of atrial appendage aneurysms in dogs. ANIMALS: Seven client-owned dogs with a presumptive diagnosis of left or right atrial appendage aneurysm. MATERIALS AND METHODS: Retrospective study. Medical records were searched to identify dogs with a presumptive diagnosis of left (LAAA) or right atrial appendage aneurysm (RAAA). Signalment, history, examination findings, diagnostic test results, and imaging procedures were reviewed. Archived diagnostic images were retrieved and evaluated by two board-certified radiologists and a board-certified cardiologist. Data analysis was descriptive. RESULTS: Six cases were diagnosed with RAAA and one with LAAA with a median age of 8 years. Five affected dogs were small to medium-breed male dogs. All dogs underwent a thoracic CT examination for various reasons and all cases of RAAA were incidental findings. CT was useful to identify and assess the atrial appendage aneurysm, as well as neighboring structures, although possible pericardial defects could not be visualized. Five dogs had a concurrent echocardiographic examination, which successfully identified the LAAA and two RAAA. CONCLUSIONS: This case series described the clinical and CT findings in seven dogs with atrial appendage aneurysm, as well as echocardiographic findings in five of these cases. Right atrial appendage aneurysms appear to be mainly incidental findings. CT seems to be more sensitive than echocardiography in the detection of atrial appendage aneurysm.

Glucocorticoid metabolism and the action of 11 beta-hydroxysteroid dehydrogenase 2 in canine congestive heart failure.

The enzyme 11-beta-hydroxysteroid dehydrogenase isoenzyme 2 (11BHSD2) is responsible for converting the active glucocorticoid cortisol to inactive cortisone and in the renal medulla protects the mineralocorticoid receptor (MR) from activation by cortisol. Derangements in 11BHSD2 activity can result in reduced conversion of cortisol to cortisone, activation of the MR by cortisol and, consequently, sodium and water retention. The objective of this study was to examine glucocorticoid metabolism in canine congestive heart failure (CHF), specifically to evaluate whether renal 11BHSD2 activity and expression were altered. Dogs were prospectively recruited into one of two phases; the first phase (n=56) utilized gas chromatography-tandem mass spectrometry to examine steroid hormone metabolites normalised to creatinine in home-caught urine samples. Total serum cortisol was also evaluated. The second phase consisted of dogs (n=18) euthanased for refractory CHF or for behavioural reasons. Tissue was collected from the renal medulla for examination by quantitative reverse transcription polymerase chain reaction, immunohistochemistry and protein immune-blotting. Heart failure did not change urinary cortisol:cortisone ratio (P=0.388), or modify renal expression (P=0.303), translation (P=0.427) or distribution of 11BHSD2 (P=0.325). However, CHF did increase excretion of 5α-tetrahydrocortisone (P=0.004), α-cortol (P=0.002) and α-cortolone (P=0.009). Congestive heart failure modifies glucocorticoid metabolism in dogs by increasing 5α-reductase and 20α-hydroxysteroid dehydrogenase activity. Differences between groups in age, sex and underlying disease processes may have influenced these results. However, 11BHSD2 does not appear to be a potential therapeutic target in canine CHF.

Total anomalous pulmonary venous connection in a mature dog.

A 2-year 10-month, male neutered, crossbreed dog presented for evaluation of cyanosis and exercise intolerance. Doppler echocardiography revealed severe dilation of the right atrium and right ventricle with moderate pulmonary hypertension. Right-to-left shunting across a large ostium secundum atrial septal defect was confirmed by contrast echocardiography. Thoracic radiography revealed a vascular pattern together with cardiomegaly. Computed tomography angiography identified an anomalous pulmonary venous connection in which all pulmonary veins, apart from the right middle vein, coalesced into a single, large aneurysmal vein that then drained into the right atrium via the cranial vena cava. The distal opening of the right middle pulmonary vein could not be determined. A presumptive diagnosis of partial anomalous pulmonary venous connection was made. The dog was medically managed with sildenafil (1.5 mg/kg by mouth [PO] every 8 h) and remained clinically stable for 2 months before euthanasia due to worsening exercise intolerance. On postmortem examination, all pulmonary veins, including the right middle vein, were shown to communicate with a single, large central vein. This large vein then connected with the right atrium via the cranial vena cava, consistent with a total anomalous pulmonary venous connection. This case report describes a rare congenital abnormality which has not been previously reported in a mature dog.

Missouri statewide alcoholism treatment survey.

Respondents to a statewide survey of alcoholism treatment services throught that prevention should be given prime priority consideration.

Variation of serum inorganic phosphorus and association with haemoglobinuria and osteomalacia in female water buffaloes in Pakistan.

Data from an animal health service in the Punjab of Pakistan showed that 39 adult female buffaloes with haemoglobinuria were 21 times more likely to have serum inorganic phosphorus (serum P) levels < 0.97 mmol/l than 24 controls sampled during the period of case occurrence (December 1984-March 1985). Age > 7 years or early lactation (1-60 days post partum) were unrelated to the disease. Similarly, symptoms of osteomalacia in 19 multiparous buffaloes were associated with low P (OR = 14.3) but not with age. Subsequently, a serum survey was carried out from February 1985 to July 1987 to investigate serum P variations with season and host factors. Data from 139 farms (426 adult female buffaloes, 468 lactations) indicated strong farm and seasonal effects on serum P. Serum P declined during the study period and was lowest during December-March 1985/1986 and again 1986/1987. Calving season, parity > 1, high pregnancy > 6 months, or daily milk production were not related to serum P in the final model. Seasonal effects were interpreted as soil borne and related to feed changes from maize to berseem in December.

Financial analysis of dipping strategies for indigenous cattle under ranch conditions in Uganda.

A financial analysis was performed to assess the performance of three acaricide-treatment groups of indigenous breeds (Zebu and Nganda) of cattle on a ranch in Luwero District, Uganda. The treatments were based on different frequencies: twice-a-week dipping, once-a-month dipping and no tick control. The objective was to evaluate the economic justification for intensive acaricide application for tick and tick-borne disease control in Uganda. Data were collected by monitoring cattle performance over a period of 34 months. Biological data collected included the number of cows at the beginning and end of the study, net starting liveweight, number of calves born, number of animals dying due to tick-borne diseases and other causes, number of animals sold or slaughtered and milk yield. Records of variable costs (acaricides, drugs, labour, etc.) and output prices were assembled and calculated by treatment group. Gross margin and marginal analysis were used in the financial analysis. The exchange rate in 1990-1993 was one US$ to 1200 Uganda shillings. The gross benefits obtained from animal sales, herd value and milk yield were Uganda shillings 1175, 1389 and 1311 per kg of net starting liveweight for animals dipped twice-a-week, once-a-month and not dipped, respectively. The variable costs were Ug. shs. 424, 390 and 360 per kg of net starting liveweight, respectively. Consequently, the gross margins were Ug. shs. 751, 999 and 951 per kg of net starting liveweight. Furthermore, the marginal rate of return (MRR) in changing from no tick control to once-a-month dipping was 160%, while changing from no tick control to twice-a-week dipping was negative (-313%). The above results showed that the value of increased gains in production obtained from twice-a-week dipping strategy does not offset the costs of inputs for intensive dipping. Once-a-month dipping (strategic) therefore appears to be the most-profitable tick-control strategy for the farmer. The need to conduct further studies in different livestock- production systems and to rationalise future tick control policies is discussed.

Bronchopulmonary lavage for pulmonary alveolar proteinosis.

In summary, total-lung bronchopulmonary lavage was performed five times on two patients under general anesthesia with controlled ventilation using a Robert-Shaw double lumen ETT. One lavage was complicated by a hydrothorax that was treated without untoward sequelae. No significant hypoxemia, circulatory impairment or leakage of lavaged fluid into the opposite lung was noted on any occasion. The average time of all procedures was 108 minutes (range 80-150 minutes), and patients were extubated on all occasions 2 to 5 hours after the treatment. Patients were discharged 24 to 36 hours after the last lavage with improvement, though not resolution, of the alveolar infiltrates radiographically. The ABG analysis revealed minimal improvement in oxygenation in Case No.1 from a preoperative paO2 of 60 mmHg on room air to a paO2 of 74 mmHg on the day of discharge. However, the patient was able to resume his normal activity level. In Case No.2, the patient's resting paO2 did not improve significantly from the preoperative value of 82 mmHg. Subjectively, however, the patient noted marked improvement. Prior to bronchopulmonary lavage, this patient's SaO2 decreased from 97% to 81% after walking 800 feet. Approximately a week and a half after discharge, the patient reported being able to run without symptoms and generally was feeling well. With careful attention to detail and the coordination of resources from the departments of anesthesia, pulmonary medicine, respiratory therapy and nursing services, bronchopulmonary lavage can be performed safely and efficiently in order to curtail the progressive hypoxemia which often develops in patients with PAP.

[Comparative electron microscopic studies on the localization of silicon in leaves of two different grass species]. / Vergleichende elektronenmikroskopische Untersuchungen zur Lokalisation von Silizium in Blättern zweier verschiedener Gräserarten.

The quality of green fodder can be diminished by lignifying and mineralizing the plant cell walls. In many grasses epidermal cell walls are penetrated with silica; those plants are extremely rough and sharp-edged and are not ingested by animals. The process of silicification of cell walls was studied comparatively in two grasses, the soft Perennial Ryegrass (Lolium perenne) and the rough Tufted Hair-grass (Deschampsia caespitosa). In Lolium only the epidermal cell walls of the leaf edges and the trichomes are penetrated with silica, whereas in Deschampsia silica could be demonstrated in the walls of all epidermal cells and of the trichomes. In addition, silica containing cells, the so called silica bodies, were found in Deschampsia leaves. Silica was detected using two analytical electron-microscopical techniques, the Electron-Energy-Loss-Spectroscopy (EELS) and the Electron-Spectroscopic-Imaging (ESI).

Horner's syndrome after epidural block in early pregnancy.

Horner's syndrome after epidural block in a first-trimester parturient has not previously been reported. The authors describe a case of unilateral Horner's syndrome after single-dose epidural block in a 12-week pregnant female.

[The fertility of the water buffalo (Bubalus bubalus)]. / Zur Fruchtbarkeit des Wasserbüffels (Bubalus bubalus).

In the present study the conception- and calving-frequencies of Nili-Ravi milk buffaloes were calculated over a year's period in the Punjab region of Pakistan. The results show prominent fluctuations throughout the year with a minimum calving-frequency of 1.6% in March and a minimum conception-frequency of 1.8% in May and maximum calving frequencies of 15.2% in November. This distribution occurs in association with unsuitable and suitable climatic conditions respectively, and also in association with the feeding situation which is better in autumn than in spring (Nothelle, 1992). Thibault and Levasseur (1974) believe that there is an inborn seasonal nature of sexual activity for nearly all mammals. This principle surely applies to the milk buffaloes, although it is confirmed that the buffalo cow is a poly-oestrous animal with a regular sexual cycle all over the year. Through breeding-, feeding-, animal husbandry- and management practice it is possible to compensate the fluctuations of conception- and calving frequencies over the whole year.

Long-term pharmaceutical cost reduction using a data management system.

UNLABELLED: Cost containment is an important issue in medicine today, and the ability to control costs and maintain quality patient care presents a challenge to practitioners. Educating practitioners about drug costs has been identified as an effective method, but the benefits of education are usually short-lived. To evaluate the role of education in cost control, pharmaceutical use and performance improvement data were analyzed at a tertiary care institution during two time periods. A total of 4,530 anesthesia records and associated performance improvement data from March to June 1993 were analyzed as a baseline. These data were shared with the clinicians of an anesthesia department and used to educate practitioners regarding the costs and use of injectable pharmaceuticals and to identify areas in which cost savings could be achieved. The same information from 10,600 cases during January to October 1996 were compared with the early group. The expenditures for injectable pharmaceuticals to provide anesthesia were decreased by more than $30,000 per month, or $32 per case, without changing the performance indicators that were monitored, and has been maintained for >3 yr. IMPLICATIONS: By using a data management system, the cost for medications to provide anesthesia has been reduced without changing the quality of patient care.

Allergic and nonallergic asthmatics have distinct patterns of T-cell activation and cytokine production in peripheral blood and bronchoalveolar lavage.

Activation of lymphocyte subpopulations was determined in conjunction with levels of cytokines in peripheral blood and bronchoalveolar lavage (BAL) of asthmatics. Allergic asthmatics had increased numbers of CD4+ IL-2R+ T cells in peripheral blood and BAL, and T-cell activation closely correlated with numbers of low-affinity IgE receptor (CD23) bearing B cells. In contrast, in nonallergic asthmatics both CD4+ and CD8+ T cells from blood and BAL had increased expression of IL-2R, HLA-DR, and VLA-1. Furthermore, in the nonallergic asthmatics CD8+ T cells were decreased in blood but increased in BAL. Cytokine levels were determined in BAL fluid and supernatants from purified peripheral blood T cells and enriched BAL lymphocyte preparations. Allergic asthmatics were characterized by increased levels of IL-4 and IL-5, and this elevated IL-4 contributed to the elevated IgE levels found in these allergic subjects. In contrast, nonallergic asthmatics had elevated levels of IL-2 and IL-5, with IL-2 contributing to T-cell activation. In both types of asthma, the close correlation of IL-5 levels with eosinophilia suggests that IL-5 is responsible for the characteristic eosinophilia of asthma. Thus, we provide evidence of distinct T-cell activation resulting in different spectra of cytokines in allergic and nonallergic asthma.

The impact of tick control on the productivity of indigenous cattle under ranch conditions in Uganda.

The impact of tick control on the productivity of indigenous cattle was investigated in three herds of East African shorthorn Zebu and Zebu x Ankole (Nganda) breeds, maintained under three tick management systems practised under ranch conditions: twice-a-week dipping, once-a-month dipping, and no tick control. The milk production and the growth rates of pre-weaned and post-weaned calves were monitored once a month over a period of 34 months. Milk offtake was 23% higher during the heavy rainy seasons than in the long dry seasons. Twice-a-week dipping increased the milk offtake by 21% in the second year of study and prolonged the duration of lactation in cows. Similarly, twice-a-week dipping increased the pre-weaning growth rate by 39% in the second year of study, but had no significant effect on the post-weaning growth rate. Generally, the growth rate of calves were greatest during the heavy rainy seasons and least during the long dry seasons. These results provide a basis for assessing the losses under different tick management systems in the various production systems.

Population dynamics of ticks on indigenous cattle in a pastoral dry to semi-arid rangeland zone of Uganda.

Studies on seasonality and population dynamics of ticks on indigenous cattle and their crosses (calves) were carried out in Buruli Ranching Scheme, Nabiswera, Luwero district of Uganda on three treatment groups of animals: group 1 (twice a week dipping), group 2 (once a month dipping) and group 3 (no tick control). During this study, four major species of ticks of economic importance were recorded in decreasing order of abundance: Rhipicephalus appendiculatus, Rhipicephalus evertsi evertsi, Amblyomma variegatum and Boophilus decoloratus. Of these ticks, a seasonal pattern of activity was only observed in R. appendiculatus ticks, with peak activities occurring during rainy seasons. Greater numbers of ticks were recorded on cows than calves in the three treatment groups, with the exception of A. variegatum where the reverse occurred. The mean numbers of ticks per animal were highly significantly different (p < 0.01) when group 1 animals were compared with group 2 and 3 animals. However, no significant differences (p > 0.05) were observed in mean tick numbers between group 2 and 3 animals. Highly significant differences (p < 0.01) were observed in mean tick numbers on cows and calves (more than 12 months old) in different calving seasons. The state of lactation only affected tick counts on cows in group 1; significantly more ticks (p < 0.01) were observed in lactating than non-lactating cows. Furthermore, significantly greater (p < 0.05) numbers of ticks (with the exception of B. decoloratus) were recorded during the second year of study (March 1992-May 1993) than the first year (January 1991-February 1992), despite lower rainfall during the former period.