Pharmacokinetics of intravenously and orally administered pyrimethamine in horses.

Single-dose pharmacokinetic variables of pyrimethamine were studied in horses. Pyrimethamine (1 mg/kg of body weight) was administered IV and orally to 6 adult horses, and plasma samples were obtained at frequent intervals thereafter. Plasma pyrimethamine concentration was assayed by gas chromatography, and concentration-time data were analyzed, using a pharmacokinetic computer program. The IV and oral administration data were best described by 3-compartment and 1-compartment models, respectively. The median volume of distribution at steady state after IV administration was 1,521 ml/kg and the median elimination half-time was 12.06 hours. Mean plasma concentration after oral administration fluctuated between a maximal concentration of 0.18 microgram/ml and 0.09 microgram/ml (24 hours after dosing). Bioavailability after oral administration was 56%.     

Influence of dietary composition on gastric emptying and motility in dogs: potential involvement in acute gastric dilatation

Gastric dilatation-volvulus is a dramatic and life-threatening disease of large-breed dogs. The cause is unknown, but ingestion of dry cereal-based food is frequently incriminated as a predisposing factor. The purpose of this study was to examine the effect of commercial diets on gastric motility and emptying in the dog. Four large-breed dogs were fed 3 different diets (diet A = canned meat-based; B = cereal-based with 77% added water; and C = dry cereal-based) in a randomized block design. Each experiment was done in triplicate. Motility was assessed, using 5 AgAgCl electrodes and 2 strain gauges sutured along the serosa of the stomach and proximal duodenum. Dogs were fed at the same time each day and the time to change from the fed to the fasted pattern of gastrointestinal motility (changeover) was measured. Gastric emptying was assessed by recording gastric radioactivity. After feeding a meal mixed with 99mTc-labeled resin, the log of activity was plotted against time, and the half-time of gastric emptying (t1/2 GE) was calculated. Mean (+/- SEM) times from feeding to changeover for the 3 diets were: diet A, 9.7 +/- 0.9; B, 10.5 +/- 0.4; and C, 11.0 +/- 0.8 hours. Diet had minimal influence on the half time of gastric emptying (diet A, 2.2 +/- 0.3; B, 2.6 +/- 0.4; and C, 2.9 +/- 0.3 hours; P greater than 0.05). The data indicate that gastric motility and emptying in healthy large-breed dogs were not affected by dietary composition. Because most large dogs are fed cereal-based food for reasons of cost and ease of use, these diets may have been wrongly incriminated as a predisposing factor in gastric dilatation-volvulus.     

Familial po1ycystic kidnev disease in bull terriers

Polycystic kidney disease was observed in eight related bull terriers. Two dogs died suddenly, two were presented for haematuria, while the remainder were outwardly normal but detected during ultrasonographic screening programmes. A definitive diagnosis was made at either necropsy or using renal ultrasonography, although affected dogs also had abnormal urinalyses with haematuria, proteinuria, cast formation and sometimes bacterial infection. Valvular heart disease was detected clinically or at necropsy in all the affected dogs. The presence of polycystic kidney disease in several related dogs suggests that this condition is familial. The disease has clinical and pathological similarities with autosomal dominant polycystic kidney disease of humans.     

Memory retrieval from long and short lists

Reaction time in Sternberg's memory retrieval task with both short and long lists is a bilinear function of list length, changing slope at the limits of memory span. Separate long-term and short-term retrieval processes are implied. An alternative one-process model expressed by a logarithmic function is also considered.     

Laboratory procedures for the diagnosis of gastrointestinal tract diseases of dogs and cats

An increasing number of laboratory tests are available for diagnosis of gastrointestinal tract diseases in dogs and cats. Use of these tests can lead to more accurate and rapid diagnoses. This review discusses laboratory tests, both new and old, and the role they currently play in the evaluation of animals presented with gastrointestinal problems. A minimum database helps assess the severity of the disorder, detect extra-gastrointestinal causes of problems and assists in formulating diagnostic and therapeutic plans.

Faecal examination remains one of the most important diagnostic procedures in the investigation of gastrointestinal problems. Zinc sulphate faecal flotation is an excellent routine screening technique for helminth and protozoal infections, including giardiasis. Rectal cytology can assist in the diagnosis of large bowel disorders. Interpretation of faecal immunodiagnostic tests is hampered by insufficient knowledge of test sensitivities and specificities. Routine faecal cultures are not warranted and faecal occult blood tests are rarely indicated.

Serum tests for gastric inflammation are now under development. The serum trypsin-like immunoreactivity test remains the gold standard technique for the diagnosis of exocrine pancreatic insufficiency. Breath hydrogen tests can be helpful in assessing the functional relevance of mild abnormalities in small-bowel biopsy specimens. Subnormal concentrations of serum cobalamin appear to be more specific indicators of gastrointestinal disease in cats than in dogs. Tests for small intestinal bacterial overgrowth remain controversial and assessment of gastrointestinal permeability has yet to prove its value in the diagnostic assessment of companion animals with gastrointestinal problems. Faecal alpha₁-protease inhibitor (α₁-PI) shows promise for the diagnosis of protein-losing enteropathy.     

Undernutrition During Foetal and Post‐Natal Life Affects Testicular Structure and Reduces the Number of Sertoli Cells in the Adult Rat

To test whether undernutrition during foetal to pre‐pubertal life would have long lasting effects on testicular histology in adult male offspring, eleven adult Sprague–Dawley pregnant rats were divided into two groups: Control group, n = 4, fed ad libitum, during gestation and lactation (until 25 day post‐partum). Underfed group pregnant females (n = 7) were kept in cages where only dams had access to food (standard rat chow, 33.5% of ad libitum intake of Control group pregnant dams). After parturition, litters were adjusted to either 14 (Underfed group) or eight (Control group) pups. Mothers were weighed weekly. At 25 day of age pups were weaned, housed at four animals per cage, fed ad libitum and weighed weekly until euthanized at 100 day of age. Testes were processed for standard histology and morphometrical evaluation. At weaning, mother weight was lower in Underfedthan in Control group (mean ± SD): 214.1 ± 26.2 g vs 361.9 ± 33.1 g. Body weight at 100 days of age (254 ± 26.9 g vs 342.4 ± 10.2 g, p ≤ 0.001), testicular weight (1.29 ± 0.16 g vs 1.45 ± 0.13 g, p = 0.03), number of Sertoli cells per seminiferous tubule cross section (18.2 ± 1.2 vs 20.2 ± 1.3, p ≤ 0.01) and per testis (30.5 ± 4.2×10⁶ vs 36.0 ± 5.4×10⁶) were lower (p < 0.05) in Underfed than in Control group. This is the first report stating that foetal to pubertal subnutrition is accompanied by changes in testicular structure and lower Sertoli cell numbers in adult life, strongly suggesting lower daily sperm production.     

CLINICAL APPLICATION OF PATLAK PLOT CT‐GFR IN ANIMALS WITH UPPER URINARY TRACT DISEASE

Glomerular filtration rate (GFR), an important parameter of renal function, is difficult to assess clinically. Serum creatinine and blood urea nitrogen measurements lack sensitivity, whereas radionuclide determination of GFR is not always available and requires postinjection patient isolation. GFR can be determined using computed tomography (CT), most commonly via Patlak plot analysis. Four adult cats, two adult dogs, and a foal underwent abdominal CT under general anesthesia for various diseases of the upper urinary tract. CT‐GFR was measured with a single‐slice dynamic acquisition and Patlak plot analysis. In five animals, the total CT‐GFR appeared to be below normal, corresponding with mild (two animals) and moderate (two animals) increases of serum creatinine in four. In the two animals with normal or increased CT‐GFR, serum creatinine was within the reference values. A significant negative logarithmic relationship was found between CT‐GFR and serum creatinine values (P=0.008; r²=0.75). No complications occurred during or following CT‐GFR. CT examination provided clinically relevant information in 3/5 patients with possible ureteral obstruction and in 3/3 patients with suspected ureteral calculi. Single‐slice dynamic CT‐GFR was practical and provided clinically useful information in this small series of patients undergoing CT of the upper urinary tract. There was a significant relationship between CT‐GFR and serum creatinine values, which supports the clinical potential of CT‐GFR and justifies further investigation of this technique.