Differential white blood cell counts in rabbits: a comparison of the Advia 2120 and a manual method

We evaluated the performance of the Advia 2120 (Siemens) differential leukocyte count (A-Diff) compared to the manual method (M-Diff) in rabbits. EDTA-anticoagulated blood samples collected for diagnostic purposes were analyzed within 6 h of collection. The M-Diff was performed blindly by 2 observers on blood smears by counting 200 cells. We initially included 117 samples; 25 samples were excluded because of suboptimal gating of leukocytes in the Advia peroxidase cytogram or poor blood smear quality. The correlation between the A-Diff and M-Diff was very high for heterophils (r = 0.924, p < 0.001) and lymphocytes (r = 0.903, p < 0.001), high for basophils (r = 0.823, p < 0.001), moderate for monocytes (r = 0.645, p < 0.001), and low for eosinophils (r = 0.336, p = 0.001). The Passing–Bablok regression analyses revealed a small-to-moderate constant error for lymphocytes and a slight constant error for basophils. Small proportional errors were detected for heterophils, lymphocytes, and eosinophils. The Bland–Altman analyses revealed that the Advia significantly underestimates heterophils and overestimates lymphocytes compared to M-Diff. The biases for the other leukocytes were minimal and likely clinical insignificant; however, our results, particularly for eosinophils, should be interpreted cautiously given the observed low percentages in our samples. Given the observed biases in heterophil and lymphocyte percentages in the Advia 2120 CBC results in rabbits, method-specific reference intervals should be used. The Advia can recognize leporine basophils. Evaluation of blood smears is still recommended to investigate abnormal results and erroneous cytograms reported by the Advia.     

Serum lipids and lipoproteins in equine colic and grass sickness

Serum total lipids, lipoprotein fractions, triglycerides, cholesterol, phospholipids and free fatty acids were measured in horses with acute, subacute and chronic grass sickness (equine dysautonomia) and in colic cases. The values were compared with those of normal grazing and stabled horses. A marked individual variation occurred, but total lipids, triglycerides and free fatty acids were significantly higher than normal in grass sickness and colic cases with cholesterol was significantly higher than normal in grass sickness cases only. Pre-beta lipoprotein was significantly increased in colic and subacute grass sickness although all abnormal groups showed this fraction which was absent from normal horses. The percentage of alpha 2b lipoprotein was significantly higher in colic and grass sickness. The changes described are typical of those occurring in fat mobilisation in the horse and are considered to be due to a number of factors including decreased food intake, cortisol and catecholamine release and insulin resistance.     

Central diabetes insipidus in a cat with central nervous system B cell lymphoma

A 6-year-old male neutered cat presented with blindness, lethargy, polydipsia, hyposthenuria and severe hypernatraemia. Central diabetes insipidus was demonstrated by means of a low measured anti-diuretic hormone (ADH) concentration in the face of hypernatraemia, and clinical response to supplementation with desmopressin. Magnetic resonance imaging of the brain showed a discrete mass in the region of the hypothalamus. The cat was euthanased and post-mortem histological examination demonstrated B cell lymphoma involving the brain, optic nerves, urinary bladder wall and diaphragm. To the authors' knowledge, this case report is the first to describe central diabetes insipidus caused by central nervous system lymphoma in the cat.     

Biomass production of upland vegetation types in England and Wales

Abstract The objective of the study was to describe the annual and seasonal production of live biomass of six plant species or communities of the uplands of the UK –Calluna vulgaris, Vaccinium myrtillus, Nardus stricta, Molinia caerulea, Eriophorum vaginatum and Agrostis–Festuca grassland. The species or communities are important for the management of the uplands to meet both biodiversity and agriculture objectives. The annual and seasonal production of live biomass was determined for sites within six regions of England and Wales in 1995, 1996 and 1997. The six regions were North‐east England, North‐west England, North Pennines, South Pennines, South‐west England and Wales. In each region, the Institute of Terrestrial Ecology's Land Classification Scheme was used to select three or four 2 km × 2 km squares that contained a mosaic of C. vulgaris and upland grassland plant species. Uniform plots of 1 ha were selected from each 2 km × 2 km square, within which three measurements were made on each sampling occasion. Biomass of each species or community was measured within 1·0 × 0·5‐m quadrats using the same standard procedures. Measurements of annual production of current season's shoots of the pioneer, building, mature and degenerate phases of C. vulgaris and of V. myrtillus were made in October, and of the annual production of live biomass of N. stricta, M. caerulea and E. vaginatum in August. A simulated grazing regime was imposed for the Agrostis–Festuca grassland with cuts being made to a height of 4 cm at 8‐week intervals. The annual production of live biomass produced was estimated as the sum of four harvests taken during the growing season. Seasonal measurements of the amount of live biomass of all the species were also made in April, June, August and October. For C. vulgaris, there were significant (P = 0·05) differences between the pioneer, building, mature and degenerate phases in the annual production of current season's shoots, with greater amounts being produced by the phases of greater age and with higher biomass. There were significant year (P < 0·05) and region (P < 0·05) effects, with the lowest production in 1995 and in the South‐west of England. The values were higher than those observed in previous studies in Scotland, and these were interpreted as being associated with a longer growing season rather than higher summer temperatures. There was no difference between years and regions in the annual production of V. myrtillus. For the grass species, there were small differences in annual production of live biomass between years and regions. However, the annual production of live biomass of N. stricta was significantly (P < 0·01) lower in 1995 than in 1996 and 1997 and significantly (P < 0·001) lower in the South Pennines region than elsewhere. The effect of a range of weather and other environmental variables on the annual production of live biomass of each species of grass was explored, but they provided only a limited insight into the reasons for the observed differences and were found to be of limited value as predictors.     

Suspected fatal venous air embolism during anaesthesia in a Pomeranian dog with pulmonary calcification

CASE HISTORY: Death occurred in a 1.25 kg, 9-month-old female Pomeranian dog undergoing anaesthesia for surgical repair of partially healed fractures of the radius and ulna.

CLINICAL FINDINGS: Following sedation, anaesthesia was induced using thiopentone and maintained with halothane in oxygen. An acute decrease in the dog's end-tidal carbon dioxide (EtCO₂) measurements was noted approximately 50 min after induction, immediately following delivery of a 5-ml bolus of lactated Ringer's solution (LRS) administered to flush a small (0.06 ml) volume of fentanyl via a pre-placed intravenous (I/V) catheter. Venous air embolism (VAE) was suspected and the dog died despite interventive therapy. On post-mortem examination, several air bubbles were noted when the right ventricle was opened under water. Histologically, the kidneys appeared abnormal with immature glomeruli, and the lungs appeared diffusely mineralised. The origin of the air was probably small bubbles and microbubbles that may have been present in the extension set and 20 ml syringe used for the administration of fentanyl and I/V fluids to the dog.

DIAGNOSIS: Renal dysplasia and diffuse pulmonary calcification, with VAE as the probable cause of death.

CLINICAL RELEVANCE: In this case of VAE-associated anaesthetic death, it is further speculated that underlying pulmonary disease, in the form of pulmonary calcification, may have contributed to an increased sensitivity to the adverse effects of VAE.     

Emerging technologies for identifying superior dairy cows in New Zealand

The performance of animals is determined by the interaction of their genes with environmental circumstances. Accordingly, animals exhibiting superior performance are not necessarily the animals with the best genes nor are they the best choice of parents. Statistical analyses of production records for repeated traits, e.g. lactation yields and reproductive performance, show that part of the variation in performance among animals in the same herd and year is due to genetic differences, and the remainder is due to so-called residual or environmental factors that are not passed on to offspring. These within-herd environmental factors can be partitioned into a component that affects performance throughout an animal's lifetime, and a part that is unique to each observation. The process of animal evaluation from pedigree and performance records partitions the superiority of each cow into these three components. Reliable assessment of the genetic merit of bulls has required progeny testing, and for cows has required observation of their own individual performance. Selection on the genetic or breeding value component has systematically improved animal performance over recent decades, but has been limited by the age at which assessments of genetic merit are available.

Emerging molecular technologies can read DNA sequences or measure RNA expression and have allowed the identification of a number of chromosome regions, and a few specific genes in those regions, that influence economic performance. This information allows better characterisation of the relationships between animals and more accurate predictions of genetic merit in bulls without progeny information and in cows that have yet to produce their own performance record. At some stage, enough genes responsible for variation in performance will be identified to allow faster genetic progress through selection of animals at young ages and therefore more rapid turnover of the generations. Mechanisms that modify gene expression have been identified and these may ultimately allow animals to be selected at an early age for lifetime productivity, accounting for processes that modify gene expression and lead to differences in performance that are not reflected by DNA sequence information. This review describes the status of these emerging technologies and their likely role in the improvement of dairy cattle.     

Abortions in sheep caused by Salmonella Brandenburg: Pathological findings

CASE HISTORY: A 7-year-old cat developed sporadic vomiting, reduced appetite, and weight loss over the previous 3 months.

CLINICAL FINDINGS: Palpation revealed a large mid-abdominal mass and the cat had marked eosinophilia. The cat progressively lost weight over the next 7 weeks when euthanasia was performed.

PATHOLOGICAL FINDINGS: Necropsy revealed a 3?cm diameter firm white intramural mass in the colon and another in the pylorus. Mesenteric and cranial mediastinal lymph nodes were firm, pale, and enlarged. Histopathological examination revealed foci of necrosis surrounded by thick dense collagen trabeculae and predominantly eosinophilic inflammation within the intestine and lymph nodes. Marked eosinophilic infiltration of the liver was also present.

DIAGNOSIS: The lesions were consistent with gastrointestinal eosinophilic sclerosing fibroplasia (FGESF).

CLINICAL RELEVANCE: This is the first report of FGESF in a New Zealand cat and the first time lesions of FGESF have been observed in extra-abdominal tissues. Intestinal neoplasia can be clinically identical to FGESF and histopathology is required for differentiation. Evidence suggests that FGESF has a more favourable prognosis than intestinal neoplasia.     

Salmonella Brandenburg — emergence of a variant strain on a sheep farm in the South Island of New Zealand

AIM: To compare the rectal and I/V administration of tramadol in dogs, to assess both its pharmacokinetic properties and absolute bioavailability.

METHODS: After rectal administration via suppositories and I/V injection of tramadol (4 mg/kg), the concentration of tramadol and its main metabolites, O-desmethyl-tramadol (M1), N-desmethyl-tramadol (M2) and N,O-didesmethyl-tramadol (M5), were determined in plasma, using high-performance liquid chromatography (HPLC). A balanced cross-over study was used, involving six male Beagle dogs.

RESULTS: Plasma concentrations after rectal and I/V administration were fitted on the basis of mono- and bi-compartmental models, respectively. Following rectal administration tramadol was detected from 5 minutes up to 10 hours, in lesser amounts than M5 and M2, while M1 was detected in negligible amounts. Following I/V administration tramadol was detected up to 10 hours, M2 and M5 were detected at similar concentrations, and M1 was present at low concentrations. The area under the curve (AUC) of the three metabolites did not differ significantly after either route of administration of tramadol. The absolute bioavailability of tramadol via rectal administration was 10 (SD 4)%.

CONCLUSIONS: After rectal administration of tramadol suppositories, absorption of the active ingredient was rapid, but its metabolism quickly transformed the parent drug to high levels of M2 and M5.

CLINICAL RELEVANCE: In the dog, rectal pharmaceutical formulation of tramadol would have a different pharmacokinetic behaviour than in humans.