Retrospective analysis of the clinical utility of ambulatory electrocardiographic (Holter) recordings in syncopal dogs: 44 cases (1991-1995)

The objective of this study was to evaluate retrospectively the clinical utility of ambulatory (Holter) electrocardiographic monitoring in syncopal dogs and to compare the Holter recording with the clinic electrocardiogram (ECG) in these animals. Fifty Holter reports and 44 medical records from 44 dogs were evaluated. A syncopcal episode occurred during monitoring in 24% of the recordings. No obvious relationship was found between the frequency of syncope occurring before Holter recording and the likelihood of a dog having an episode during recording. Holter recordings were helpful in establishing a diagnosis 42% of the time, but no relationship was detected between the frequency of episodes occurring before Holter recording and the likelihood of a diagnostically useful Holter. An arrhythmia was ruled out as the cause of syncope in 12% of the recordings and was implicated as the cause of syncope in 30% of recordings. Of these, 20% were ventricular tachyarrhythmias and 10% were bradyarrhythmias including pacemaker failure. Ambulatory electrocardiographic recordings led to a therapeutic change in 38% of cases. A comparison of the Holter recordings and clinic ECGs documented the expected increased sensitivity for Holter detection of arrhythmias. The average clinic ECG heart rate consistently exceeded the average Holter heart rate with a mean difference between the average heart rates recorded by the two techniques of 31 bpm (range -8-87 bpm).     

Economic costs associated with two testing strategies for screening feeder calves for persistent infection with bovine viral diarrhea virus

OBJECTIVE: To develop partial budgets of the economic costs of 2 test strategies for screening cattle for persistent infection with bovine viral diarrhea virus (BVDV). DESIGN: Partial budget analysis. ANIMALS: 938 calves arriving at 2 stocker operations. PROCEDURE: Calves were tested to determine prevalence of persistent BVDV infection. Test strategies that were evaluated included a single-test strategy consisting of immunohistochemical staining of skin biopsy specimens from all animals and a 2-test strategy consisting of polymerase chain reaction (PCR) assaying of pooled blood samples followed by immunohistochemical staining of skin biopsy specimens from animals in pools for which assay results were positive. Break-even costs (i.e., cost of persistent BVDV infection per animal necessary to justify whole-herd diagnostic testing) associated with each test strategy were calculated as a function of disease prevalence and test cost. RESULTS: Apparent prevalence of persistent BVDV infection was 0.32%. Sensitivity and specificity of the PCR assay for pooled samples were 100% and 89.7%, respectively. Regardless of the prevalence of persistent BVDV infection, the break-even cost for the 2-test strategy was lower than the break-even cost for the single-test strategy. However, the economic advantage was greatest when prevalence was low. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that using a 2-test strategy to screen cattle for persistent BVDV infection, whereby the first test involves PCR assaying of pooled samples and the second involves immunohistochemical testing only of those animals represented in pooled samples with positive assay results, will reduce the cost of screening incoming feedlot cattle, compared with immunohistochemical testing of all animals.     

Plasma and skin concentrations of polyunsaturated fatty acids before and after supplementation with n-3 fatty acids in dogs with atopic dermatitis

OBJECTIVE: To determine essential fatty acid concentrations in plasma and tissue before and after supplementation with n-3 fatty acids in dogs with atopic dermatitis. ANIMALS: 30 dogs with atopic dermatitis. PROCEDURE: Dogs received supplemental flaxseed oil (200 mg/kg/d), eicosapentaenoic acid (EPA; 50 mg/kg/d)-docosahexaenoic acid (DHA; 35 mg/kg/d), or mineral oil as a placebo in a double-blind, placebo-controlled, randomized trial. Clinical scores and plasma and cutaneous concentrations of linoleic acid, arachidonic acid, alpha-linolenic acid (alpha-LLA), EPA, DHA, prostaglandin E2, and leukotriene B4 were determined. RESULTS: Total plasma concentrations of alpha-LLA and EPA increased and those of arachidonic acid decreased significantly with administration of EPA-DHA, and concentrations of alpha-LLA increased with flaxseed oil supplementation; nevertheless, there was no significant change in the concentrations of these fatty acids or eicosanoids in the skin. There was no correlation between clinical scores and plasma or cutaneous concentrations for any of the measured fatty acids or eicosanoids. CONCLUSION AND CLINICAL RELEVANCE: Results indicated that at the dose used, neither the concentrations of fatty acids in skin or plasma nor a decrease in the production of inflammatory eicosanoids was a major factor involved in the mechanism of action in dogs with atopy that responded to fatty acid supplementation.     

Evaluation of a rebound tonometer for measuring intraocular pressure in dogs and horses

OBJECTIVE: To compare intraocular pressure (IOP) measurements obtained with a rebound tonometer in dogs and horses with values obtained by means of applanation tonometry and direct manometry. DESIGN: Prospective study. ANIMALS: 100 dogs and 35 horses with clinically normal eyes, 10 enucleated eyes from 5 dogs, and 6 enucleated eyes from 3 horses. PROCEDURES: In the enucleated eyes, IOP measured by means of direct manometry was sequentially increased from 5 to 80 mm Hg, and IOP was measured with the rebound tonometer. In the dogs and horses, results of rebound tonometry were compared with results of applanation tonometry. RESULTS: For the enucleated dog and horse eyes, there was a strong (r2 = 0.99) linear relationship between pressures obtained by means of direct manometry and those obtained by means of rebound tonometry. Mean +/- SD IOPs obtained with the rebound tonometer were 10.8 +/- 3.1 mm Hg (range, 5 to 17 mm Hg) and 22.1 +/- 5.9 mm Hg (range, 10 to 34 mm Hg) for the dogs and horses, respectively. Mean IOPs obtained with the applanation tonometer were 12.9 +/- 2.7 mm Hg (range, 8 to 18 mm Hg) and 21.0 +/- 5.9 mm Hg (range, 9 to 33 mm Hg), respectively. Values obtained with the rebound tonometer were, on average, 2 mm Hg lower in the dogs and 1 mm Hg higher in the horses, compared with values obtained with the applanation tonometer. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the rebound tonometer provides accurate estimates of IOP in clinically normal eyes in dogs and horses.     

The effect of treatment duration on weaning weights in a cow-calf herd with a protracted severe outbreak of diarrhea in calves

The objective of this study was to describe a multiyear outbreak of calf diarrhea in an Alberta cow-calf herd and the impact of severe diarrhea on calf productivity. A retrospective analysis was performed through the use of detailed individual animal records and laboratory reports. The most significant laboratory finding was Salmonella Typhimurium isolated from the fecal samples of 2 ill members of the treatment crew and from 3 calves on postmortem examination. In 2002, at the peak of the outbreak, 90.3% (325/360) of the calves required treatment and 8.9% (32/360) of the calves died. In 2003, the severity of the problem had declined with only 20.9% (47/225) of the calves requiring treatment and 3.1% (7/225) of the calves dying. In both years, the weaning weights of treated calves were significantly reduced compared with those of nontreated calves. For calves weaned in 2002, after adjusting for the effect of calf sex, calves treated more than 6 times had 200-day adjusted weaning weights that were 15.2 kg (95% CI; 5.8 to 24.4 kg) lighter than of those calves treated only once or not at all (P = 0.0015, n = 321). For calves weaned in 2003, calves were 5.5 kg (95% CI; 0.23 to 10.8, P = 0.04, n = 207) lighter per treatment day with electrolytes, when calf sex and dam age were controlled for. Assuming that increased days of treatment or number of treatments is representative of disease severity, long-term calf performance is negatively affected by severe calfhood disease. The estimated lost revenue and treatment expenses, excluding the cost of labor, cow feed, and maintenance, was $22 800 in 2002 and $1589 in 2003.     

The influence of environment on development of the mucosal immune system

The mucosal immune system expresses active responses against pathogens and also tolerance against harmless food and commensal bacterial antigens. The mechanisms that determine which of these outcomes occur after recognition of antigens by T-cells are not clear. One possibility is that it is determined by the initial interaction between a dendritic and a na?ve T-cell in organised lymphoid tissue. However, such organised structures are, evolutionarily, quite recent and the original immune system must have made appropriate responses in more diffuse immunological architecture; a second possibility is that the critical interaction is between primed T-cells and their environment, in the lamina propria of the intestine. The mucosal immune system of neonates is poorly developed and inefficient at expressing appropriate immune responses. Development is influenced by a range of environmental factors including maternally derived antigen or antibody and commensal flora and pathogens. The intestine is a complex immunological structure in which the immune system and the macro- and microenvironment interact.     

The effect of grazing forage containing condensed tannins on gastro-intestinal parasite infection and milk composition in Angora does

The objective of this study was to evaluate effects of the condensed tannin (CT)-containing forage sericea lespedeza (sericea lespedeza (SL); Lespedeza cuneata; 15.2% CT), on fecal egg count (FEC), larval development (larvae/10 g of feces), worm burden and immune response compared with a crabgrass (Digitaria ischaemum)/Kentucky 31 tall fescue (Festuca arundinacea; control forage (CTF)) forage low in CT (0.32% CT) in grazing Angora does and their kids. Fifty worm-free mixed-age does were randomly allocated to three treatments. One treatment (10 does; initial liveweight (LW) = 45+/-1.5 kg) entailed grazing of SL forage from April 25 to July 15, 2002 with a second treatment of CTF (20 does; initial LW = 43+/-1.4 kg) grazing during the same period. Does of the third treatment (20 does; initial LW = 44+/-1.4 kg) grazed a sward of SL for 2 weeks and then one of CTF for 2 weeks followed by alternating between the two pastures every 2-week rotational grazing (ROT). To gauge levels of infective larvae on pasture, three worm-free Angora kids (initial LW = 3.6+/-0.2 kg) were randomly selected as tracers. Tracers grazed for final 60 days and were euthanized for determination of worm burden. The immune response of does was measured by skin thickness reaction after the intradermal injection of 250 microg phytohemagglutinin (PHA). Mean FEC for SL and ROT were substantially lower (P < 0.01) than for CTF does (145, 329 and 894 eggs/g, respectively). The FEC for kids was lower (P < 0.05) for SL than for ROT and CTF (550, 2757 and 3600 eggs/g, respectively). Total fecal egg output (3.3, 6.0 and 26.9 x 10(5) eggs/day, respectively) and larval development (242, 263 and 792 larvae/10 g, respectively) were lower (P < 0.05) for SL and ROT than for CTF. Tracers grazing on SL had lower total worm burdens than ROT and CTF (P < 0.01). The immune response was higher (P < 0.01) for SL (4.9 mm) and ROT (6.0 mm) than for CTF (3.0 mm) at 12 h after injection of PHA. The packed cell volume (PCV) in does was higher (P < 0.01) for SL and ROT than for CTF (27, 26 and 23%, respectively). Does that grazed CT-containing forage had considerably lower milk somatic cell counts (SCC) than does grazing non-CT-containing forage. In summary, grazing CT forages reduced FEC, larval development and worm burden, and also appeared to enhance immune response. The CT-containing forage SL reduced gastro-intestinal parasite infections of Angora does and kids.     

The use of multilocus enzyme electrophoresis to characterise intestinal spirochaetes (Brachyspira spp.) colonising hens in commercial flocks

Multilocus enzyme electrophoresis (MLEE) was used to identify, examine genetic relationships and look at disease associations of a collection of 53 intestinal spirochaete isolates previously recovered from the faeces of adult hens on 14 farms in Qld, Australia. The MLEE results were compared with those previously obtained using species-specific PCR amplifications. The isolates were divided into five Brachyspira species groups by MLEE: Brachyspira murdochii (n=17), B. intermedia (n=15), B. pilosicoli (n=14), B. innocens (n=2) and "B. pulli" (n=1). Three new MLEE groups each containing single isolates also were identified. The results of the PCR assay for B. pilosicoli were concordant with the MLEE results, but the 23S rDNA-based PCR for B. intermedia had failed to detect 8 of the 15 isolates. The B. innocens/B. murdochii nox-based PCR had correctly identified all the isolates of B. murdochii, but did not identify either of the two B. innocens isolates. Using MLEE, isolates from two farms (14%) were identified as B. murdochii, whilst the pathogenic species B. intermedia and B. pilosicoli were present in hens from eight (57%) and five (36%) farms, respectively, and were identified together in four (29%) farms. All seven of the farms with production problems or wet litter were colonised with B. intermedia and/or B. pilosicoli. Six farms had multiple spirochaete isolates available for examination. Two broiler breeder farms both had five isolates of B. pilosicoli that shared the same MLEE electrophoretic type (ET), whilst one laying hen farm had three isolates of B. intermedia that all belonged to the same ET. Hence on each of these farms a predominant strain of a pathogenic species was present. On the other farms isolates of the same species were more diverse and belonged to different ETs. These results show that the epidemiology of intestinal spirochaetal infections in broiler breeder and laying hen flocks can vary considerably between farms, although the reasons for these differences were not established.     

Varanid herpesvirus 1: a novel herpesvirus associated with proliferative stomatitis in green tree monitors (Varanus prasinus)

Stomatitis is a common problem in lizards, and the etiologies of stomatitis in lizards are not well understood. Four green tree monitor lizards (Varanus prasinus) from two different collections were evaluated because of proliferative stomatitis. Degenerate PCR primers targeting a conserved region of herpesvirus DNA-dependent DNA polymerase were used to amplify and sequence a product from gingival tissue of three of four lizards (cases 1, 3, and 4). DNA in situ hybridization of tissues from three lizards was positive for herpesvirus in the oral mucosa of all three lizards tested (cases 1-3) and the brain of two lizards (cases 1 and 3). Comparative sequence analysis suggests that this virus is a novel member of the subfamily alpha-herpesvirinae, and is here termed varanid herpesvirus 1.