Cholinesterase activity:muscarinic receptor ratios in canine and feline brains.

In response to findings that brain cholinesterase (ChE): muscarinic cholinergic receptor density (mChR) ratio is highly conserved between bird species (I), this study investigated the conservation of brain ChE:mChR between 2 mammalian species. Whole brains of 7 normal greyhounds, 14 normal non-greyhound dogs, and 8 normal cats, were assayed for ChE, mChR and protein. The same assays were made on cerebrum, cerebellum and brainstem from the greyhounds and 6 of the non-greyhound dogs. The Ellman assay was used to measure serum ChE activity, mChR were labelled with tritiated quinuclidinyl benzilate, and protein was measured by Lowry assay. Brain ChE:mChR was not highly conserved between the species. There was a statistically significant difference in brain mChR between greyhounds and non-greyhounds but this did not translate to a statistically significant difference in mean ChE:mChR. Measurement of ChE:mChR is unlikely to be useful in endangered carnivores for which normal ChE levels are unknown, because it cannot be assumed that endangered species would have the same ChE:mChR as their domestic relatives.

Rapid method for the detection of cyanide gas release from plant material using CYANTESMO paper.

A method for detection of cyanide gas release from solutions and from suspensions of plant material is described which offers advantages in speed, safety and simplicity over the picric acid method.

The presence of a muscarinic receptor on canine erythrocyte membranes.

Muscarinic receptors were present on erythrocyte ghosts of the domestic dog (Canis familiaris) at a concentration of 0.61 nmol/mg protein, and had a KD of 62.5 nmol. Properties including a mean nonspecific binding of 80%, the high risk that adherence of additional molecules of radioligand would occur, and the necessity for extensive dilution of erythrocyte ghosts to obtain a practical quantity of muscarinic receptors, lead us to conclude that the canine erythrocyte ghost is not an efficient or practical model to study muscarinic receptors and their interactions with cholinergic agonists or antagonists.

Deer velvet antler: some unanswered questions on toxicology.

Deer velvet antler is marketed as a remedy for a wide range of disorders. However, there is a lack of information in the scientific literature to support these claims, and there is also a lack of information on potential toxicity. Areas of potential concern include drug residues, possible deleterious androgenic effects on fetuses and neonates and allergic reactions.

Detection of metabolites of a veterinary counter-irritant in canine urine.

Routine paper chromatographic screening of the urine of racing greyhounds exposed to BIGELOIL, a veterinary counter-irritant, revealed metabolites suggestive of menthol, an ingredient of BIGELOIL. To determine whether BIGELOIL use caused these metabolites, 2 Dalmatian dogs were exposed to BIGELOIL. Thin-layer chromatographic screening of their urine confirmed that exposure to BIGELOIL by either dermal or oral routes causes the same metabolites as those observed in the racing greyhounds. Metabolites suggestive of thymol were also present in some samples. We conclude that, if metabolites suggestive of menthol are detected in urine of animal athletes, further analysis for the other performance-affecting ingredients of BIGELOIL should be undertaken.

Stability of water nitrate levels during prolonged boiling.

The stability of nitrate in boiling water was examined. No changes in nitrate concentrations occurred when 100 and 500 ppm potassium nitrate solutions were boiled for up to 24 h.

Lipofuscin and abnormalities in colloid in the equine thyroid gland in relation to age.

Lipofuscin accumulation and other histological changes in thyroid tissue, previously reported to be age-related, were studied in 31 horses aged up to 35 years. The number of lipofuscin granules relative to thyrocytes increased from birth to 5 years of age. There was a wide individual variation in the number of lipofuscin granules in thyrocytes in mature horses, but this was not directly related to age. Several abnormalities were identified in thyroid colloid. The prevalence of spherites, lipofuscin granules, nucleated cells and shreds of colloid increased with age, but the prevalence of calcium oxalate crystals, erythrocytes, basophilic zones and solid fragments of colloid did not. In horses younger than 7 years, particularly large lipofuscin granules were found in thyrocytes of a small proportion of follicles which also contained abnormal colloid. Such follicles became more common in older horses without being accompanied by large lipofuscin granules. No correlation was found between granule numbers and frequency of colloid abnormalities. These results cast doubt on the traditional assumption that lipofuscin is indigestible cellular residue, since there was little evidence for excretion of granules. It is postulated that lipofuscin in this tissue may be a normal stage in lysosomal catabolism.

The frequent occurrence of thyroid tumours in aged horses.

Thyroid tumours have been described as "moderately common" in horses, but diseases associated with them are rare and the actual incidence has not been reported. A survey of thyroids from 29 horses aged 12 to 32 years revealed gross lesions in 11 animals, all older than 17. Most lesions were microfollicular adenomas. There was no evidence that the horses suffered from long-standing iodine deficiency or diffuse hyperplasia. Adenomas were more common than hyperplastic nodules and it is unlikely that the former arose from the latter. One thyroid adenocarcinoma was discovered. Progression from thyroid hyperplasia to adenomas and thence to adenocarcinomas has been reported in rodent species, but this study suggests that such progression does not occur in horses. As evidence of its occurrence in man is also lacking, the horse may be a more appropriate model than the rodent for human thyroid neoplasia.

A method of cerebro-cortical biopsy in lambs.

A suction needle brain biopsy technique is a safe and effective method of obtaining cerebral cortex for experimental purposes in lambs. The biopsies are performed under general anaesthesia using halothane and oxygen following barbiturate induction. The method may have a number of related used in this of other species.

Lipopigments in veterinary pathology: pathogenesis and terminology.

The lipopigments are a heterogenous group of pigments whose pathogenesis and terminology is confused. Whereas there is epidemiological and observational evidence that ceroid is derived from degeneration and peroxidation of unsaturated lipid, the assumption that all so-called lipopigments are similarly formed, is questioned. In particular, recent studies have distanced the pathogenesis of the pigment found in the ceroid-lipofuscinoses from that perceived for ceroid. The importance of protein rather than lipid in the pathogenesis of the pigment of ceroid-lipofuscinosis and of age pigment from the equine thyroid is noted. In the former the essential feature is storage of the DCCD binding protein subunit c of mitochondrial ATP synthase. There is a need for more analytical studies on isolated pigments which are generally more soluble than anticipated by the literature. It is proposed that the term ceroid be limited to a family of pathological pigments where lipid degeneration and peroxidation is implied from observational and/or epidemiological factors. The term age pigment is unequivocal and preferred for age related pigment not obviously complicated by other factors. The terms lipofuscin and lipopigment retain a usefulness as generic terms, particularly where the nature of the pigment is uncertain. The term ceroid-lipofuscinosis for the inherited storage diseases of children and animals is misleading. The term "proteolipid proteinosis" has been suggested to define this group of diseases but this is perhaps premature until their full pathogenesis is known.

An ovine pulmonary tumour of alveolar epithelial Type II cells.

A small tumour was found at the periphery of the lung during routine necropsy of a 13-year-old Romney ewe. The tumour consisted of vacuolated, cuboidal cells which lined alveolar spaces without destroying them. Electron microscopy revealed numerous microvilli on the free surface of the cells and irregularly shaped osmiophilic inclusions within the vacuoles. No viral particles were found and the tumour was diagnosed as a well differentiated Type II pneumocyte adenocarcinoma of unknown aetiology.

Mannosidosis: ocular lesions in the bovine model.

The ocular pathology of mannosidosis was studied in the bovine model. There was wide-spread vacuolation of many cell types including corneal epithelium, Descemet's endothelium, corneal fibroblasts, pigmented cells, lens epithelium, lens fibres, pigment epithelium and all cell types of the neuroretina. On electron-microscopy most vacuoles were seen to be membrane bound vesicles compatible with being secondary lysosomes and similar to those previously described elsewhere in the body. Additional vacuoles were seen due to dilatations between lens epithelial cells and between lens fibres. The cause of lens and corneal opacities seen in human patients is unclear from the present study but are presumably a consequence of the lesions noted.