Provisional clinical chemistry parameters in the African sharptooth catfish (Clarias gariepinus).

Pollution affects aquatic systems worldwide and there is an urgent need for efficient monitoring. Fish are generally sensitive to their environment and are thus considered to be valuable bioindicator species. The African Sharptooth catfish (Clarias gariepinus) is particularly important in this respect because of its very wide distribution. In order to use C. gariepinus as a bioindicator species its baseline clinical chemistry must be defined. Existing data are scarce, and the objective of this work was therefore to establish clinical chemistry parameters for C. gariepinus. Blood was collected from male and female catfish and a number of clinical chemistry parameters were determined. Plasma protein values, but particularly those of plasma albumin, were found to be very low, approximately half the value for dogs, but similar to the values in Channel catfish (Ictalurus punctatus). Plasma urea values in Sharptooth catfish were found to be much lower than in dogs, but only marginally lower than in Channel catfish. Plasma creatinine in Sharptooth catfish, however, was only a quarter of that of dogs and one third of that found in Channel catfish. These findings may have implications for using urea and/or creatinine as an index of renal glomerular filtration, as is done in mammals. Plasma enzyme activity ranges were much lower in Sharptooth catfish than in dogs, particularly for alkaline phosphatase (ALP) and alanine aminotransferase (ALT). By comparison, Channel catfish have an even lower ALT activity range but an ALP range that is very similar to dogs. The implications for using these enzymes as markers for liver disease are not clear from these data, as factors such as plasma half-life and tissue distribution remain to be determined. The very low plasma thyroxine (T4) levels have important implications for laboratory personnel, who will have to set up calibration and standardisation adaptations for the methods that are generally designed for human samples. Although the sample size was too small for reliable comparisons, it appeared that there was little difference in the parameters measured between male and female fish. The values obtained are a useful starting point for using C. gariepinus as a bioindicator species.

Erythrocyte morphology and haemoglobin types of neonatal roan antelopes (Hippotragus equinus) with hypochromic poikilocytic anaemia.

Neonatal, poikilocytic anaemia in some members of the Hippotragini has previously been documented but not fully investigated. This study was undertaken to describe the erythrocyte morphology of roan antelopes (Hippotragus equinus) during the first 4 weeks after birth and to identify aspects of haemoglobin (Hb) production that might be implicated in this syndrome. Twenty-nine roan antelope calves were sampled on, or close to, 1, 7, 14 and 28 days after birth. Erythrocyte morphology was characterized, and microhaematocrit values and Hb parameters determined, for each sampling occasion. Findings indicated a significant change in erythrocyte morphology during the neonatal period and two haemoglobin types, fetal and adult, were identified. The perinatal onset of adult Hb synthesis was delayed relative to the termination of fetal Hb production, resulting in the observed anaemia. Haemoglobin concentration and erythrocyte morphology were significantly correlated. These findings suggest an intimate relationship between Hb synthesis and the observed poikilocytosis. An imbalance in the synthesis of the alpha- and beta-globin chains of Hb (a thalassaemia) may prove to be the underlying pathophysiology of this syndrome.

A canine model of normovolaemic acute anaemia.

The objective was to develop a non-terminal, acute normovolaemic anaemia model in dogs that has minimal effects on patient well-being. Eleven normal Beagle dogs were used. About 20% of the circulating blood volume was removed from the jugular vein 1-3 times per day over a 3-4 day period until a haematocrit (Ht) of 13-17% was obtained. Normovolaemia was maintained by replacing the volume deficit of the red blood cells with Ringer's lactate and re-infusing the plasma. Full blood count and Ht were monitored twice daily. The 13-17% Ht was reached within 3-4 days with the number of phlebotomies ranging from four to seven. The model was primarily developed to determine echocardiographic values as well as Doppler abdominal splanchnic blood flow parameters in anaemic dogs as part of a study that will compare these results to similar studies in babesiosis-induced anaemia. The model may also be useful in the evaluation of the pathophysiology of anaemia in dogs or as a model for anaemia in humans.

Susceptibility of dogs to West Nile virus: a survey and pathogenicity trial.

A serological survey of dogs from the highveld region of South Africa showed that 37 per cent (138 of 377) had neutralizing antibodies to West Nile (WN) virus and only 2.7 per cent (10 of 377) had antibodies to Sindbis virus. WN virus was isolated from one of the WN-antibody negative sera. Because these results suggested that dogs may play an important part in the epidemiology of WN virus, a pathogenicity trial was carried out. Two of three dogs infected with WN virus had a mild recurrent myopathy, but no other abnormalities were detected in the biochemical or haematological tests performed on any of the dogs. All three dogs developed antibodies but a low titre-viraemia was detected in only one dog. It was concluded that dogs do not play an important part in the epidemiology of WN virus but they may play a small part in the maintenance of the virus.

The mixed acid-base disturbances of severe canine babesiosis.

Thirty-four dogs suffering from severe babesiosis caused by Babesia canis rossi were included in this study to evaluate acid-base imbalances with the quantitative clinical approach proposed by Stewart. All but 3 dogs were severely anemic (hematocrit <12%). Arterial pH varied from severe acidemia to alkalemia. Most animals (31 of 34; 91%) had inappropriate hypocapnia with the partial pressure of CO2 < 10 mm Hg in 12 of 34 dogs (35%). All dogs had a negative base excess (BE; mean of - 16.5 mEq/L) and it was below the lower normal limit in 25. Hypoxemia was present in 3 dogs. Most dogs (28 of 34; 82%) were hyperlactatemic. Seventy percent of dogs (23 of 33) were hypoalbuminemic. Anion gap (AG) was widely distributed, being high in 15, low in 12, and normal in 6 of the 33 dogs. The strong ion difference (SID; difference between the sodium and chloride concentrations) was low in 20 of 33 dogs, chiefly because of hyperchloremia. Dilutional acidosis was present in 23 of 34 dogs. Hypoalbuminemic alkalosis was present in all dogs. Increase in unmeasured strong anions resulted in a negative BE in all dogs. Concurrent metabolic acidosis and respiratory alkalosis was identified in 31 of 34 dogs. A high AG metabolic acidosis was present in 15 of 33 dogs. The lack of an AG increase in the remaining dogs was attributed to concurrent hypoalbuminemia, which is common in this disease. Significant contributors to BE were the SID, free water abnormalities, and AG (all with P < .01). Mixed metabolic and respiratory acid-base imbalances are common in severe canine babesiosis, and resemble imbalances described in canine endotoxemia and human malaria.

Changes in the blood-gas status of sheep with experimentally induced heartwater.

The blood-gas status of seven sheep with experimentally induced heartwater during the acute and terminal stages was investigated. Changes in blood gas included a decline in arterial oxygen tension (pO2) combined with a respiratory alkalosis. Although the sheep became hypoxaemic, blood-gas changes associated with respiratory failure were not observed.

Morphological evidence for infection of impala, Aepyceros melampus, platelets by a rickettsia-like organism.

Ultrastructural studies revealed the presence of a parasite, believed to be Ehrlichia platys, in the blood platelets of impala. At the time of blood sampling all the animals appeared healthy. This is the first report on the presence of this rickettsia in these animals, previously described in canine platelets.

Treatment and thrombocyte levels in experimentally induced canine ehrlichiosis and canine babesiosis.

Three dogs which were carriers of Babesia canis were infected with Ehrlichia canis. These animals developed clinical signs and haematological evidence of ehrlichiosis and made an uneventful recovery, despite the fact that they were subsequently treated with doxycycline only. Three control dogs which were also carriers of B. canis were clinically normal, despite the fact that they showed a distinct drop in the thrombocyte levels associated with increases in the numbers of parasitized red cells.

Serum- and bone-mineral status of ostriches with tibiotarsal rotation.

Tibiotarsal rotation in ostrich chicks is a serious problem that accounts for considerable financial loss to ostrich farmers. Serum- and bone-mineral analyses of 20 ostrich chicks with tibiotarsal rotation were compared with serum- and bone-mineral analyses of eight normal ostrich chicks of comparable age, sex and body mass, and raised under identical conditions. The serum-zinc values were significantly higher and the bone-calcium and phosphorus values significantly lower in the affected group than in the group of normal ostrich chicks. The results indicated poor mineralization of bone with subsequent reactive osteoid formation.

Further studies of the clinical pathology of sweating sickness in cattle.

Experimentally-induced cases of sweating sickness in calves were used in an effort to correlate the blood chemistry with some of the known pathological changes. Results showed that the "sweating" associated with necrotic dermatitis did not alter blood electrolyte levels. Laboratory evidence of a disseminated intravascular coagulopathy was found which correlated with the microthrombi described in cases of sweating sickness. A high blood cortisol level was found in one of the animals that died from the disease and could possibly be used as a prognostic indicator in clinical cases. Recommendations are made with regard to the supportive treatment based on the clinical pathological findings.

The clinical pathology of heartwater. I. Haematology and blood chemistry.

Clinical pathological studies were undertaken in 5 calves with experimentally-induced heartwater. The most important findings include a progressive anaemia which may be associated with bone marrow depression and fluctuations in the total and differential white cell count, of which an eosinopenia and a lymphocytosis were the most marked. A severe drop in serum protein, especially in the albumin levels, was observed in all 5 cases. This disease is probably associated with an increased capillary permeability, as the protein content of the pericardial fluid in 1 case that died, approximated that of the serum. The osmolality of the effused fluid was also higher than that of the blood. No significant changes in the serum electrolyte levels occurred, except for total calcium levels which tended to decrease to below normal during the acute stage of the disease. Marked increases in total bilirubin were recorded. This, however, was not associated with liver pathology or haemolysis and may possibly be ascribed to a fasting hyperbilirubinaemia. Darkening of plasma colour was associated with peak rises in total bilirubin. Increases in both blood urea and creatinine levels indicate interference with renal glomerular filtration during the acute stage of the disease.

The clinical pathology of heartwater. III. Changes in blood clotting, blood calcium, blood protein, haematocrit and white-cell counts in sheep with experimentally induced heartwater.

Studies to evaluate changes in blood clotting, blood calcium and protein, the haematocrit and white-cell counts were undertaken in seven sheep with experimentally induced heartwater. A marked decline in thrombocyte count was recorded during the acute stage of the disease. This was associated with increases in both prothrombin time (PT) and activated partial thromboplastin time (APTT); fibrinogen increased while there was no detectable increase in fibrinogen degradation products (FDP). At the same time total serum protein (TSP), albumin and globulin dropped very sharply; total calcium showed a progressive drop but ionized calcium rose initially and was followed by a terminal decline. The total leucocyte count showed a terminal increase while the haematocrit dropped progressively.

Some physiopathological features of experimental Homeria glauca (Wood & Evans) N. E. Br. poisoning in Merino sheep.

Five Merino sheep were dosed 3 g/kg of dry, finely-milled Homeria glauca (Natal yellow tulp) plant material. An electrocardiogram was recorded and the arterial and central venous blood pressure, blood gases, haematological variables, plasma electrolytes (Na+, K+, Ca2+, Mg2+, Cl- and PO4(2-) ) and a variety of serum enzymes and chemical constituents were measured hourly until death (3 sheep) or until sheep were in extremis (2 sheep). Heart rate rose progressively as a result of sinus and, later, ventricular tachycardia. Systolic blood pressure rose, but there was little change in the mean and diastolic arterial pressures and central venous pressure. There was progressive hypoxaemia, hypercarbia and acidaemia with depletion of plasma bicarbonate. Haemoconcentration, hyperkalaemia and hypochloraemia were found along with rising serum creatinine and plasma glucose. Rises in serum enzymes indicated widespread tissue damage. Electrocardiographic recordings were being made at the moment of death in 3 of the 5 sheep. In these 3 sheep the cause of death was ventricular fibrillation.

The clinical pathology and pathophysiology of heartwater: a review.

This paper reviews the available literature on the clinical pathology and pathophysiology of heartwater and makes comparisons with unpublished results obtained from a recent study in experimentally-induced heartwater in calves. The pathophysiological changes seem to center on an increased capillary permeability the result of which is reflected most noticeably in cardiac and lung function. There is a marked drop in cardiac output in severe cases and some workers have recorded a severe drop in diastolic blood pressure in the advanced stage of the disease. Changes in lung function are variable, depending on the stage of the disease, and may change from a respiratory alkalosis in the early febrile stage to a respiratory acidosis in more advanced cases. The basic cause for the increased capillary permeability is not known. The main clinical pathological changes measured include a progressive anaemia, fluctuations in total and differential white cell count, of which an eosinopenia and a lymphocytosis are the most marked, increases in total bilirubin which coincide with darkening of plasma colour, and a drop in total serum proteins mostly shown in the albumin levels.

Experimental studies with Stronglyloides papillosus in goats.

Unusual clinical and pathological observations in the field in goats and sheep suffering from Strongyloides papillosus infection prompted experimental work on this parasite. Goats were infected percutaneously with either single or multiple, low or high levels of S. papillosus. Young goats up to 12 months of age were found to be the most susceptible. Some animals, however, showed substantial resistance to infective doses. Clinical signs included transient diarrhoea, misshapen, elongated faecal pellets terminally, dehydration, anorexia, cachexia, gnashing of teeth, foaming at the mouth, anaemia and nervous signs such as ataxia, a wide-based stance, stupor and nystagmus. A 'pushing syndrome' was seen in 22% of the animals. The pathological changes are described and included enteritis, status spongiosus in the brain, hepatosis leading to rupture of the liver, nephrosis, pulmonary oedema, interstitial pneumonia and pneumonia. About 6% of the goats died acutely from fatal hepatic rupture. The development of an acquired immunity was determined. The immunity elicited an allergic skin reaction at the application site of larvae or injection sites of larval metabolites. This immunity, however, could be breached by large doses of larvae. The most profound clinicopathological changes induced by the parasites were an anaemia (most pronounced in the young goats) and hypophosphataemia. Trace element analyses provided evidence of Cu, Mn and possibly Se deficiencies in some goats.

The use of enzyme profiles in the training and racing of horses: a review.

The effects of age, training, racing and endurance riding on serum enzyme profiles in the horse are reviewed and discussed.

Thrombocytopaenia in canine babesiosis and its clinical usefulness.

Canine babesiosis is a common cause of thrombocytopaenia but there are few formal studies that have investigated this haematological finding in dogs. Thrombocyte counts from full blood counts were retrospectively analysed for the years 1996-2002. Thrombocyte counts and mean platelet volumes of dogs with babesiosis were compared with those of dogs, seen over the same period of time, that did not have babesiosis. There were 1162 cases in the Babesiosis group and 10 808 in the Non-babesiosis group. A frequency distribution of the thrombocyte counts showed a trimodal distribution in the Non-babesiosis group compared to a bimodal distribution in the Babesiosis group, with a strong positive skewness. The modes for the frequency distributions were 10, 40, 300 and 10, 35 x 10(9)/l thrombocytes, respectively. The median thrombocyte count in the Babesiosis group was 14 x 10(9)/l and 282 x 10(9)/l in the Non-babesiosis group. There was a statistically significant difference in the median thrombocyte count between the Babesiosis group and the Non-babesiosis group. In the Babesiosis group, 99% of the thrombocyte counts were below the lower reference range value (250 x 10(9)/l) and 62% of thrombocyte counts were below 25 x 10(9)/l. The mean platelet volume (11.1 fl) for the Babesiosis group was greater than the reference range (6-10 fl) and significantly larger than in the Non-babesiosis group (median 9.7 fl). Thrombocyte counts greater than 110 and 250 x 10(9)/l had a predictive value that the dog was not suffering from babesiosis of 99.3% and 99.8%, respectively. There was a statistically significant difference between the thrombocyte counts of dogs with babesiosis when grouped by parasitaemia scores. The mechanisms of the thrombocytopaenia are not fully understood, and multiple mechanisms, including concomitant thrombocytopaenia-inducing diseases such as ehrlichiosis, probably result in this haematological finding. Babesiosis in the South African canine population is associated with thrombocytopaenia in nearly all patients and is severe in the majority of them. In the absence of thrombocytopaenia, babesiosis is an unlikely diagnosis.

Met-haemoglobinuria in naturally occurring Babesia canis infection.

Higher levels of urinary met-haemoglobin were found in dogs with naturally occurring Babesia canis infection (n = 6) than in control subjects (n = 5). The urinary haemoglobin in the affected cases ranged from 1 to 4 g/l of which 28-95% was met-haemoglobin. This was a significant finding in that met-haemoglobin has been shown to be nephrotoxic in the dog, especially in the presence of aciduria. Acidic urine was also demonstrated in those dogs with B. canis infection, which may aggravate the nephrotoxic effect of the met-haemoglobinuria. Thus naturally infected B. canis cases showing haemoglobinuria may in fact have significant met-haemoglobinaemia, which may predispose them to renal disease.

Borrelia sp. infection in a horse.

The clinical signs, response to treatment and features of the spirochaete, Borrelia theileri as was found in a horse with suspected borreliasis are described.

The relationship in dogs between primary renal disease and antibodies to Encephalitozoon cuniculi.

Fifty-two serum samples from dogs with primary renal failure were tested for antibodies to Encephalitozoon cuniculi. Twelve were positive as compared to two positive samples from a control group of 42 dogs. There was a statistically significant difference between these two groups which suggests an association between infection with E. cuniculi and the development of chronic renal disease.