Dez Hughes

Acid-base and electrolyte abnormalities in dogs with gastrointestinal foreign bodies

Gastrointestinal foreign bodies occur commonly in dogs. The objective of the study was to describe the acid-base and electrolyte abnormalities identified in dogs with gastrointestinal foreign bodies and determine if these abnormalities are related to the site or type of foreign body present. Medical records of 138 dogs were reviewed, and information on signalment, initial venous electrolyte and acid-base values, surgical findings, relevant historical information, imaging modalities used, cost of hospital visit, intra- or postoperative complications, and survival was obtained. The site of the foreign body was recorded in 94.9% of cases and the most common site was the stomach (50%), followed by the jejunum (27.5%). The foreign bodies were linear in 36.2% of cases. The most common electrolyte and acid-base abnormalities regardless of the site or type of foreign body were hypochloremia (51.2%), metabolic alkalosis (45.2%), hypokalemia (25%), and hyponatremia (20.5%). No significant association was found between electrolyte or acid-base abnormalities and the site of foreign body. Linear, as opposed to discrete, foreign bodies were more likely to be associated with a low serum sodium concentration (odds ratio, 0.85; 95% confidence interval, 0.75-0.95). Hyperlactatemia (> 2.4 mmol/L) was seen in 40.5% of dogs. A wide variety of electrolyte and acid-base derangements are found in dogs with gastrointestinal foreign bodies. Hypochloremia and metabolic alkalosis are common in these dogs. Hypochloremic, hypokalemic metabolic alkalosis is seen with both proximal and distal gastrointestinal foreign bodies.

Diagnosis and Management of Peritonitis

Peritonitis is a clinical syndrome rather than a definitive diagnosis and, as such, the underlying cause must be identified. Many potential causes exist, and peritonitis may be classified as primary or secondary, local or diffuse, acute or chronic, or according to the causative agent. Peritonitis is one of the most common initiators of the systemic inflammatory response syndrome faced by the small animal practitioner. Because systemic inflammatory response syndrome is such a devastating disease process, aggressive stabilization, rapid definitive diagnosis, and prompt surgical and medical treatment are vital for optimizing outcome.

Characterization and measurement of immunoglobulins in the grey seal (Halichoerus grypus)

Immunoglobulin concentrations were measured in the serum and colostrum of adult and pup Grey seals from North Rona in the outer Hebrides and the Isle of May in the Firth of Forth. IgG was shown to be the main immunoglobulin and two subclasses were identified. Serum immunoglobulin content was low in the week-old pups and increased up to 5 weeks, although it remained substantially lower than in the adults. Colostral immunoglobulins were high and cannot explain the low values in the pup serum. It is considered that the increased opportunistic infections seen in Grey seal pups may be related to this low immunoglobulin status.

Effect of body position on the arterial partial pressures of oxygen and carbon dioxide in spontaneously breathing, conscious dogs in an intensive care unit.

OBJECTIVE To evaluate the effect of body position on the arterial partial pressures of oxygen and carbon dioxide (PaO(2), PaCO(2)), and the efficiency of pulmonary oxygen uptake as estimated by alveolar-arterial oxygen difference (A-a difference). DESIGN Prospective, randomized, crossover study. SETTING University teaching hospital, intensive care unit. ANIMALS Twenty-one spontaneously breathing, conscious, canine patients with arterial catheters placed as part of their management strategy. INTERVENTIONS Patients were placed randomly into lateral or sternal recumbency. PaO(2) and PaCO(2) were measured after 15 minutes in this position. Patients were then repositioned into the opposite position and after 15 minutes the parameters were remeasured. MEASUREMENTS AND MAIN RESULTS Results presented as median (interquartile range). PaO(2) was significantly higher (P=0.001) when patients were positioned in sternal, 91.2 mm Hg (86.0-96.1 mm Hg), compared with lateral recumbency, 86.4 mm Hg (73.9-90.9 mm Hg). The median change was 5.4 mm Hg (1.1-17.9 mm Hg). All 7 dogs with a PaO(2)<80 mm Hg in lateral recumbency had improved arterial oxygenation in sternal recumbency, median increase 17.4 mm Hg with a range of 3.8-29.7 mm Hg. PaCO(2) levels when patients were in sternal recumbency, 30.5 mm Hg (27.3-32.7 mm Hg) were not significantly different from those in lateral recumbency, 32.2 mm Hg (28.3-36.0 mm Hg) (P=0.07). The median change was -1.9 mm Hg (-3.6-0.77 mm Hg). A-a differences were significantly lower (P=0.005) when patients were positioned in sternal recumbency, 21.7 mm Hg (17.3-27.7 mm Hg), compared with lateral recumbency, 24.6 mm Hg (20.4-36.3 mm Hg). The median change was -3.1 mm Hg (-14.6-0.9 mm Hg). CONCLUSIONS PaO(2) was significantly higher when animals were positioned in sternal recumbency compared with lateral recumbency, predominantly due to improved pulmonary oxygen uptake (decreased A-a difference) rather than increased alveolar ventilation (decreased PaCO(2)). Patients with hypoxemia (defined as PaO(2)<80 mm Hg) in lateral recumbency may benefit from being placed in sternal recumbency. Sternal recumbency is recommended to improve oxygenation in hypoxemic patients.

Lymphocyte populations in the synovial membranes of dogs with rheumatoid arthritis

Lymphocyte populations in the synovial membranes of dogs with canine rheumatoid arthritis (CRA) were investigated by immunohistochemical staining techniques. T-lymphocytes were the predominant cell type distributed throughout the supporting layer of the synovial membranes. B-lymphocytes expressing IgG were seen far more commonly than those expressing either IgA or IgM. Synovial membrane biopsies from normal and osteoarthritic joints did not have the marked cellular infiltrates seen in joints with CRA. The synovial immunohistopathological features in dogs with CRA are similar to those seen in human rheumatoid arthritis.

Clinical investigation of a point-of-care blood ammonia analyzer

BACKGROUND Hyperammonemia has frequently been implicated in the pathogenesis of hepatic encephalopathy. Blood ammonia determination requires minimal delay between sampling and analysis for accurate results. OBJECTIVES The aim of this study was to investigate the PocketChem BA, a new point-of-care (POC) blood ammonia analyzer for clinical use by determining machine precision, linearity, repeatability, and accuracy. METHODS Coefficients of variation were determined by repeated measurement of 2 control solutions. Linearity was investigated by testing serial dilutions of a stock solution. For accuracy, samples from clinical cases were used to compare the results on the PocketChem BA with those obtained using an enzymatic reference method for canine plasma. Canine and feline patients were consecutively enrolled if blood ammonia was assayed and samples could be analyzed shortly after collection. Classification of results (as normal or high, using 100 micromol/L as a cutoff value), Bland-Altman and Deming regression plots, and intraclass correlation coefficients were used to compare the methods. Stability of samples and test strips also was assessed over time. RESULTS Coefficients of variation were 10.6% and 4.8% for low and high controls, respectively. Concentrations of ammonia in diluted stock solutions correlated positively with mean measured concentrations (Pearson coefficient 0.988, P<.001). Of the 54 samples obtained from 38 dogs and 4 cats, 41 had ammonia concentrations within the readable range. Results from the POC analyzer and the reference method were correlated positively (intraclass coefficient 0.800, 95% confidence interval 0.655-0.888), with the POC analyzer having negative constant and proportional biases. The methods agreed in the classification of 45/54 (83.3%) samples, with 7 false negative results on the POC analyzer. Results of repeated sample and strip analyses at 1 and 24 hours were significantly different (P<.05) from those at 0 hour. CONCLUSIONS The PocketChem BA has acceptable precision, adequate linearity, and satisfactory agreement with a reference method, but negative constant and proportional biases. The POC analyzer may be suitable for clinical use in patients suspected of having hepatic encephalopathy, using a lower reference limit of 60 mumol/L to decrease false negative results.

Immune responses in common and grey seals during the seal epizootic

Serological surveys of common and grey seals were performed to monitor the spread of the phocid distemper outbreak in 1988 and its effects on the host immune response. The disease affected mainly common seals; grey seals were largely unaffected but did have anti-CDV antibodies which developed during 1988. Canadian seals, both common and grey, showed evidence of a morbillivirus infection but without the apparent mortality observed in British common seals. Common seal circulating immunoglobulin levels were not greatly affected during the outbreak, although there was some reduction in the most severely affected pups. Vaccination of common seals with CDV antigens elicited high titres of antibodies and produced clinical protection. Vertical transmission of host immunity was shown in grey seals although the longevity of protection has not been determined. The large population of common seals which are not immune emphasises that such an epizootic could have serious consequences again in the future.

Fluid therapy with artificial colloids: complications and controversies

Objectives To discuss the advantages and disadvantages of colloidal therapy in veterinary medicine. Databases used MEDLINE (1966-present), Commonwealth Agricultural Bureau Abstracts (1973-present), personal files.

Plasma Lactate Concentration as a Prognostic Biomarker in Dogs With Gastric Dilation and Volvulus

Initial and serial plasma lactate concentrations can be used to guide decision making in individual dogs with GDV but care is necessary in phrasing conversations with owners. Published data suggests that survival is more likely and the chance of complications less in dogs with an initial plasma lactate of <4 mmol/L. An initial lactate >6 mmol/L makes gastric necrosis and greater expense more likely. However, because of the overlap between groups and the good overall survival rates, exploratory laparotomy should always be recommended irrespective of the plasma lactate concentration. Falls in plasma lactate of greater than ~40% after fluid resuscitation are likely to indicate better survival. If the initial plasma lactate concentration is moderately to severely increased (5->10 mmol/L) and a sustained increase in plasma lactate occurs after fluid resuscitation, the cause should be aggressively pursued. Many dogs with persistent hyperlactatemia over 24-48 hours do not survive.

Analysis and significance of anti-nuclear antibodies in dogs

Assays for detecting and measuring antinuclear antibodies (ANA) in dogs were compared. They included the indirect immunofluorescence test, using rat liver as substrate, and ELISAs for three nuclear antigens: double-stranded DNA, single-stranded DNA, and histone. There was no correlation between the ANA titre and antibodies to the three nuclear antigens. Analysis of ANA in different arthropathies showed no specific disease association. HEP-2 cells showed no fluorescence reaction with either ANA-positive or ANA-negative dog sera. Western blotting produced too complex a pattern to identify specific antigens. The antigens that reacted with ANA in dogs were not identified; there is either a broad range of reactivities or non-specific binding of immunoglobulins.