The effects of hypohydration on central venous pressure and splenic volume in adult horses

Background: Central venous pressure (CVP) is used in many species to monitor right‐sided intravascular volume status, especially in critical care medicine. Hypothesis: That hypohydration in adult horses is associated with a proportional reduction in CVP. Animals: Ten healthy adult horses from the university teaching herd. Methods: In this experimental study, horses underwent central venous catheter placement and CVP readings were obtained by water manometry. The horses were then deprived of water and administered furosemide (1 mg/kg IV q6h) for up to 36 hours. Weight, CVP, vital signs, PCV, total protein (TP), and serum lactate were monitored at baseline and every 6 hours until a target of 5% decrease in body weight loss was achieved. The spleen volume was estimated sonographically at baseline and peak volume depletion. Linear regression analysis was used to assess the association of CVP and other clinical parameters with degree of body weight loss over time. Results: There was a significant association between CVP and decline in body weight (P < .001), with a decrease in CVP of 2.2 cmH₂O for every percentage point decrease in body weight. Other significant associations between volume depletion and parameters measured included increased TP (P= .007), increased serum lactate concentration (P= .048), and decreased splenic volume (P= .046). There was no significant association between CVP and vital signs or PCV. Conclusions and Clinical Importance: These findings suggest that CVP monitoring might be a useful addition to the clinical evaluation of hydration status in adult horses.     

Repeatability, reproducibility, and effect of head position on central venous pressure measurement in standing adult horses

Background: Central venous pressure (CVP) is a used as an estimation of intravascular volume status in various species. Techniques for measuring CVP in horses have been described, but the repeatability of these readings at a single time point or over time has not been established. Hypothesis: That CVP measurements in healthy adult horses would be repeatable at each time point, that these readings would be reproducible over time, and that alteration in head position relative to the heart would alter CVP. Animals: Ten healthy adult research horses. Methods: In an experimental study, horses were instrumented with a central venous catheter. Readings were taken in triplicate q6h for 2 days by water manometry, and twice daily with the head in neutral, elevated, and lowered positions by electronic manometry. Results: Variation in the “neutral” measurements obtained at each time point was <0.1 ± 1.0 cmH₂O (P= .718). There was a significant decrease in CVP over time (P= .015), which was eliminated when results were controlled for acute decrease in body weight of ?1.35% (presumed hypohydration because of lack of acclimatization and decreased water intake). Head height had a significant and directional effect on CVP in that the elevated head position decreased CVP ?2.0 ± 6.5 cmH₂O (P < .001) while the lowered head position increased CVP by 3.7 ± 5.5 cmH₂O (P < .001). Conclusions and Clinical Importance: CVP values obtained by water manometry were repeatable in adult horses, but were reproducible only when controlled for changes in hydration. Care should be taken to maintain consistency in head position to prevent erroneous readings.     

Effect of Blood Transfusion in Combination with Dextran-40 and Hypertonic Saline Solution on Cardiopulmonary Haemodynamics of Endotoxin (Lipopolysaccharide) Shock in Buffalo Calves

The intravenous (i.v.) infusion of lipopolysaccharide (LPS) of E. coli endotoxin in buffalo calves (n = 15) at 5 μg/kg bw per h for 3 h caused a significant (p<0.05) fall in plasma volume, blood volume, haematocrit haemoglobin, and systolic, diastolic and pulse pressure, mean arterial pressure and central venous pressure (CVP), with a marked rise in respiration. Treatment with a combination of i.v. infusion of 7.2% hypertonic saline solution, Plasmex-D-40 (Dextran-40) and blood successfully alleviated hypovolaemia, and raised systolic, diastolic and pulse pressure, mean arterial pressure and central venous pressure. The whole blood was collected from apparently healthy male buffalo calves 24 h prior to infusion and was transfused without cross-matching. No significant fall in haemoglobin, haematocrit and body temperature was observed after transfusion. All these values tended to remain near normal levels. However, this combination of treatment had no effect on high respiratory rate. A one-time blood transfusion did not evoke any cross-reaction and was helpful in raising haematocrit and haemoglobin close to pre-infusion values. The general symptoms of restlessness, respiratory distress, profuse salivation, violent movement of the ears, snoring, intermittent struggle, etc. were markedly reduced. All the treated animals became quiet and lay with eyes open and survived the 7 h of observation.     

Evaluation of the dorsal aorta cannulation technique for pharmacokinetic studies in Atlantic salmon (Salmo salar) in sea water

The antimicrobial drug flumequine was given intravascularly and orally to cannulated and non-cannulated Atlantic salmon (Salmo salar) in sea water at 11°. The cannulated fish were divided into two groups, which were given flumequine (25 mg/kg) intravenously into the caudal vein (n = 8) and orally via a stomach tube down the oesophagus (n= 8). After a washout period of 2 days, the intravenously administered fish were given the drug orally, and the orally administered fish were given the drug intravenously. Blood samples were taken at different time points after drug administration through a cannula inserted into the dorsal aorta. The fish in the non-cannulated group were either given flumequine intravenously or orally, and blood samples were collected by killing five fish at predetermined time points after administration. The haematocrit values were measured in all the fish daily for 4 days after drug administration and thereafter, in all the collected blood samples throughout the whole experiment. The haematocrit values differed significantly between the cannulated and the non-cannulated fish. We found low haematocrit values and slow drug elimination in the cannulated groups, compared with higher haematocrit values and faster drug elimination in the non-cannulated groups, but further investigations are needed to prove any causal relations of this observation. The volume of distribution (V_d(ss)) was twice as large in the cannulated groups compared with the non-cannulated group, in the fish administered the drug intravenously. In the last part of the elimination phase, the half-lives differed considerably between the cannulated and the noncannulated groups both after oral and intravenous administration. The slower depletion of the drug concentration in the plasma of the cannulated fish is due to the large V_d(ss) as there are only small differences in clearance (Cl_T) between the groups. In this study the elimination of flumequine in cannulated Atlantic salmon differed from the elimination of flumequine in non-cannulated Atlantic salmon.     

Peritonitis in horses: 55 cases (2004-2007)

Factors associated with the outcome of peritonitis in horses are seldom described. The objectives of this study were to determine the common clinical signs and clinicopathologic findings and to reveal prognostic factors associated with the outcome of peritonitis in equine patients. Data were examined in a retrospective manner in 55 horses diagnosed with and treated for peritonitis. The most common clinical and clinicopathologic findings were tachycardia (94%), increased amount of peritoneal fluid on ultrasound (84%), altered mucous membranes (82%), bacteria noted on the direct smear (67%), hyperfibrinogenaemia (58%) and left shift (40%). The most commonly isolated organism was E. coli (37%). Survival rates were as follow: 78% in the whole study, 81% in the abdominal lavage group, 93% in the medically and 46% in the surgically managed groups. Complications were more common in the non-survivor group (P < 0.001). Initial haematocrit and surgical interventions were strongly associated with non-survival in the multivariate logistic regression model (P = 0.049, OR: 1.07 and P = 0.01, OR: 9.87, respectively). Prognosis of peritonitis without gastrointestinal rupture depends on the initial hydration status, surgical interventions and development of secondary complications, while other clinical and clinicopathologic findings do not appear to correlate with survival. Prospective evaluation of hydration and perfusion parameters and abdominal lavage warrants further investigation.     

Comparison of blood counts in splenic, renal and mesenteric arterial and venous blood in post-pubertal rabbits

OBJECTIVES: To compare blood counts between arterial and venous blood to and from visceral organs and indirectly look into the function of the organs. METHODS: Splenic, renal and superior mesenteric arterial and venous blood samples were obtained from the arteries and veins in 38 post-pubertal rabbits and blood profile, including complete and differential blood counts, haemoglobin concentration and haematocrit, were measured with an automatic haematology analyser. RESULTS AND CONCLUSIONS: The rabbit spleen released a large amount of leucocytes (both lymphocytes and granulocytes) into the splenic venous blood (a venous increase of 33% in total leucocyte count), and also received more leucocytes (36-58% more in terms of concentration) from the artery than the kidney or intestine. Significantly fewer red blood cells were present in the renal venous blood than in the arterial blood (a venous reduction of 5% in erythrocyte count), but it remains to be clarified why and how the reduction was induced. More than 3-4% of water might be taken into the mesenteric venous blood during microcirculation (a venous reduction of 3-4% in erythrocyte-related parameters) and a significant number of leucocytes (mainly large leucocytes) in the mesenteric blood capillaries might migrate into the surrounding intestinal tissue (a venous reduction of 13% in leucocyte count).     

Haematology and some blood chemical parameters of young carp till the age of three years

Haematological and biochemical analyses of blood were performed in carp (Cyprinus carpio L.) kept in small ponds. Caught and anaesthetised carp were clinically examined and blood samples were taken at regular intervals during the three years. In the first year of examinations, the haemoglobin and haematocrit values of carp fry significantly increased (P < 0.01) from June to September. The intensive growth of carp in the summer period in the second year was accompanied by adequate erythropoiesis. During hibernation haematocrit and haemoglobin significantly decreased (P < 0.05) and mean corpuscular haemoglobin concentration (MCHC) increased (P < 0.01) in both scaly and mirror carp. MCHC increased also with the age and increasing body weight of the fish. Mirror carp had lower haematocrit and haemoglobin values than scaly carp (P < 0.01). Comparative haematological analyses between carp of normal and poor body condition showed that moderate anaemia appeared in those with poor body condition. The results indicate that there is marked seasonal and age-dependent variation in the values of haematocrit and haemoglobin. Pond water quality investigations indicated good environmental conditions. A 50% increase (P < 0.05) of glucose concentration was found from June to September in the blood plasma of carp in the third year, accompanied by an even more increased (80%; P < 0.01) concentration of total lipids. At the same time, considerable changes of cholesterol and total protein concentrations were not observed. The results suggest that the investigated haematological and biochemical variables could be successfully utilised in monitoring the metabolic balance and health status of fish in intensive culture.     

Bioelectrical impedance analysis determination of water content and distribution in the horse

A horse’s hydration status is critical to its health. The accurate and quantitative determination of it has been problematic because of size, length and density of hair, and uneven topography. The objective of this study was to validate a bioelectrical impedance analysis (BIA) method for objectively quantifying hydration status. Monofrequency BIA values and simple biometric measurements were used to construct predictive equations for total body water, plasma, extracellular, and intra-cellular fluid volumes. These predictive equations were correlated with standard body fluid dilution reference methods. The result was an accuracy of ±0.64% for total body water, ±0.17% for plasma volume, ±1.91% for extra-cellular fluid, and ±0.57% for intra-cellular fluid compartments. Less than 5 min was required for all of the measurements and determinations. Therefore, it appears that an accurate measurement of body fluid distribution can be performed on horses using a fast, easy, non-invasive, inexpensive BIA method.     

Oxygen consumption and responses of the freshwater snail Bulinus (Physopsis) globosus to gradients of different oxygen tensions

A gradient or choice apparatus, based on the ‘fluvarium’ principle and suitable for testing the responses of the freshwater snail Bulinus (Physopsis) globosus to different partial oxygen tensions was used. In a gradual oxygen gradient established with this apparatus, B. (P.) globosus shows a significant preference for oxygenated water. In experiments with a choice between low and high partial oxygen tensions, B. (P.) globosus shows a greater preference for oxygenated water. Oxygen consumption rates vary considerably among individuals and decreases when lowering the Pq in the water.     

Cattle lice in New Zealand: effects on host liveweight gain and haematocrit levels

The effects of Damalinia bovis and Linognathus vituli infestations on the liveweight gains and haematocrit levels of cattle were evaluated in eight controlled trials involving a variety of cattle breeds and age-groups ranging from 2 to 20 months. There were no statistically significant differences in weight gain or haematocrit levels between louse-infected and louse-free groups in any trial.

The difference between these results and those obtained by North American workers could be due to the fact that Haematopinus eurysternus, one of the predominant louse species in North America, was not present in any of the trials.

It is concluded that under most conditions New Zealand farmers are unlikely to benefit financially from increased weight gains following treatment of cattle for lice.     

Storage‐associated artefact in equine muscle biopsy samples

Reasons for performing study: Muscle biopsy is increasingly used in equine veterinary practice for investigating exertional, inflammatory or immune mediated myopathies and unexplained muscle atrophy. Although formalin‐fixed samples are often used, for complete evaluation, fresh‐frozen tissue is required. Freezing muscle in veterinary practice is impractical: samples sent to specialist laboratories for processing are therefore susceptible to delays, potentially leading to artefact and compromising histological interpretation. Hypothesis: Altered temperature, duration and hydration status influence the severity of storage‐induced artefact in equine muscle. Methods: Skeletal muscle obtained immediately post euthanasia was divided into 6 independent samples from each of 8 horses. One sample per horse was frozen immediately in isopentane precooled in liquid nitrogen. Additional samples were stored in conditions designed to mimic possible situations encountered in practice, including increased storage times, temperature and hydration status. Following storage, stored samples were frozen as before. Cryosections were stained using haematoxylin and eosin and ranked for artefact on 2 occasions by 2 blinded observers. The best samples were processed subsequently with a panel of routine stains and immunolabelled for collagen V to enable the measurement of minimum fibre diameters. Results: Both prolonged storage and increased hydration resulted in more storage‐associated artefact. Samples stored for 24 h chilled on dry gauze were ranked higher than those stored on damp gauze; however, a panel of routinely‐used histochemical staining techniques was unaffected by chilled 24 h storage. There was no significant effect of storage on mean fibre diameter; however, both chilled dry and damp storage for 24 h caused a significant increase in fibre‐size variability. Conclusion and potential relevance: Caution should be exercised when interpreting fibre size profiles in shipped samples. Equine muscle biopsy samples are optimally shipped in dry gauze, sealed in plastic containers and shipped on ice packs to be processed within 24 h and can thus be interpreted by the receiving laboratory with minimal artefact.     

Some Blood Parameters of the Yellowfish (Barbus Holubi) and the Barbel (Clarias Gariepinus)

Haemoglobin concentrations, haematocrit values, red blood cell counts, red blood cell diameter, white blood cell counts and plasma haemoglobin concentrations were performed on the yellowfish (Barbus holubi) and the barbel (Clarias gariepinus). Wide variations were observed in haematocrit values and haemoglobin concentrations and statistically significant correlations existed between mean corpuscular volume and average corpuscular haemoglobin and between the red blood cell count and mean corpuscular volume in the case of the yellowfish and between the red blood cell count and haemoglobin concentration in the case of the barbel. It was found that the determination of one variable is not sufficient for the routine assessment of other haematological parameters in these fish due to poor correlations observed. This can only be done in the case of the variables mentioned.     

Influence of acepromazine maleate on the equine haematocrit

The effect of acepromazine maleate (ACP) on the equine venous haematocrit and total plasma protein concentration was studied in six clinically normal horses. Total plasma protein concentration was not appreciably influenced by ACP. However, the haematocrit decreased with the duration, but not the degree, of the decrease being dose-related. Mean haematocrit values returned to control levels by 12 h after 0.05 mg ACP/kg body weight and 21 h after 0.15 mg ACP/kg body weight.     

Collagenous and elastic system fibres in the aorta of cattle poisoned by Solanum glaucophyllum

The proportions of fibres of the collagenous and elastic systems were measured in the aortas of three normal heifers and in nine heifers given the calcinogenic plant Solanum glaucophyllum for 15, 30 or 60 days. There were decreases in the amount of collagen relative to reticulin, and in the proportion of elastic fibres which were related to the period of dosing. These changes may have an adverse influence on the animals' cardiovascular function.     

Mapping of the dog skin based on biophysical measurements

Trans epidermal water loss (TEWL), skin hydration status and pH were determined in 14 skin regions of five healthy male Beagle dogs (2–4 years) both before and after anaesthesia. Trans epidermal water loss was highest for the footpad and head and lowest for the inguinal region. Skin hydration status was higher in the ear but did not vary significantly in other regions. Skin pH was usually alkaline with the highest values on the lower back and tail. Following anaesthesia, TEWL and skin hydration were significantly lower on the head, upper back and footpad, and upper back and elbow respectively, while skin pH was unaffected by this procedure. While measurement of pH would seem to be valid anywhere on the body in anaesthetized dogs, regional factors should be considered when interpreting TEWL and skin hydration values and when treating regional skin diseases in veterinary practice.     

Ultrasonographic measurement of caudal vena cava to aorta ratios for determination of volume depletion in normal beagle dogs

A noninvasive method for quantifying hydration status would be helpful for clinical management and for research applications in dogs. This prospective, experimental, pilot study aimed to assess the feasibility of ultrasonographic measurement of the caudal vena cava to aorta ratio as a method for quantifying volume depletion in dogs. In 12 normal beagle dogs, furosemide was administered intravenously at a dose of 1 mg/kg, every 2 h, for 8 h, to induce consecutive volume depletion. Every 30 min after administration, ultrasonographic images of the caudal vena cava and aorta, and physical and biological parameters related to dehydration were acquired. On transverse and longitudinal planes of caudal vena cava and aorta images, the height and area of the caudal vena cava and aorta were measured to calculate the caudal vena cava/aorta ratios. All images were acquired by approaching from the right intercostal space with the dogs in left lateral recumbency. A negative correlation was present between the percentage of weight loss in dogs and all four investigated caudal vena cava/aorta ratios (transverse plane width of the caudal vena cava [TW]/aorta; transverse plane height of caudal vena cava [TH]/aorta; longitudinal plane area of the caudal vena cava [TA]/aorta; and longitudinal plane maximal height of the caudal vena cava [L]/aorta). Significant differences (P < 0.001) were seen between dogs with and without clinical signs of dehydration for all caudal vena cava/aorta ratios. Findings indicated that ultrasonographic caudal vena cava/aorta ratios are feasible methods for quantifying volume depletion and for use as an adjunct to standard subjective methods for estimating hydration status in dogs.     

Aspects of the pathology of Lamproglena clariae (Copepoda: Lernaeidae) on gills of Clarias gariepinus from the Vaal River system,South Africa

Lamproglena clariae attaches to gill filaments of Clarias gariepinus, penetrates the gill tissue and consumes blood. Hence, the purpose of this study was to investigate the mechanical damage caused by this parasite on gill filaments of the host. Infestation intensity and haematocrit values of fish blood were determined and correlated. Fish were killed, gills dissected out and observed with a dissection microscope. Gill filaments with adult females in situ were fixed in a solution of alcohol, formaldehyde and acetic acid and preserved in 70% ethanol. Fixed specimens were studied by histological examination following staining with Heidenhein’s azan solution. Gross morphology revealed varying degrees of swelling of gill filaments near the attached specimens of L. clariae. Epithelial hyperplasia, resulting in fusion of gill lamellae and necrosis of the host tissue in the vicinity of the parasite were revealed through histological examination. No correlation was evident between the infestation intensity and fish haematocrit values. Although results showed that L. clariae causes localized infestation, high intensity of infestation may be detrimental to the fish. Hyperplasia of epithelial tissue resulting in fusion of lamellae would result in restriction of air passages and thus hinder the process of respiration of the host.     

Usefulness of Venous Blood in Estimating Acid-Base Status of the Seriously III Dog

The usefulness of venous blood in determining the acid-base status of seriously ill animals has not been investigated. The purpose of this study was to determine whether a useful relationship exists between the acid-base parameters of central venous and arterial blood in ill dogs.
Paired arterial and venous blood samples were obtained from 46 dogs seen in the Critical Care Unit of the Veterinary Teaching Hospital of Colorado State University irregardless of their hemodynamic status. Cardiopulmonary arrest patients were not included in the study.
Results of this study indicate venous blood samples can be used in the assessment of acid-base status. Statistical significance was seen in comparing arterial versus venous pH (P < 0.001), PCO2 (P < 0.001), and bicarbonate (P < 0.001). Linear regression equations will allow one to predict arterial values from venous samples.     

The Mammary Blood Flow in the Cow as Measured by the Antipyrine Absorption Method

After intramammary application of 3 g antipyrine dissolved in 30 ml distilled water into each quarter the absorption of antipyrine from the udder proceeds as a first order reaction. As the injected amount is known as well as the amount of antipyrine milked out about 1 hour later can be determined, it is possible to calculate the amount absorbed at any time between injection and emptying.It is shown, that the concentrations of antipyrine in the blood from the jugular vein and external pudic artery are identical after intramammary application of antipyrine. In experiments on lateral recumbent cows it is shown that the venous blood returns from the udder via both the subcutaneous abdominal and the external pudic veins. In the standing cows blood samples were drawn from the jugular and the subcutaneous abdominal veins. The blood samples from the subcutaneous abdominal veins were drawn during manual compression of the external pudic veins to get representative concentrations of antipyrine in the total venous blood from the udder. On account of the amount of antipyrine absorbed and the difference in antipyrine concentrations between the subcutaneous abdominal veins and the jugular vein the mammary blood flow in lactating cows was found to vary between 22–101 ml/min. per 100 g gland tissue.The possibility of calculating the mammary blood flow after injection in two glands only — while the two remaining glands might be used for other studies — is shown and discussed. The influence of the individual differences in the venous anastomoses on the results is discussed, and a procedure is described to select cows suitable for experiments on mammary blood flow.     

Phase II open‐label study of single‐agent hydroxyurea for treatment of mast cell tumours in dogs*

This prospective study evaluated the efficacy and safety of hydroxyurea (HU) in dogs with measurable mast cell tumours (MCTs). Dogs were treated with HU at 60 mg kg^?1per os q24h for 14 days then 30 mg kg^?1 q24h thereafter or until MCT recurrence. Forty‐six dogs were enrolled. The overall response rate was 28%. Two dogs had a complete response (CR) for 256 and 448 days, respectively. Eleven dogs had a partial response for a median duration of 46 days (range, 28–189 days). Grade 2 to 4 neutropenia occurred in eight dogs and grade 4 thrombocytopenia in two. Grade 3–4 anaemia occurred in seven dogs; overall, there was a significant decrease in haematocrit after treatment with HU. The median drop in haematocrit was 10%. This study demonstrated that HU has activity in the treatment of MCTs with mild anaemia being the primary adverse event.