The efficacy of 4-methylpyrazole (4-MP) and ethanol as treatment for ethylene glycol (EG) intoxication in cats was compared. Twenty-two cats were assigned at random to 6 experimental groups. Cats of 1 experimental group were given only 4-MP; those of another experimental group were given only EG. Cats of 3 experimental groups were intoxicated with EG and given 4-MP at 0 hour or 2 or 3 hours after EG ingestion, and those of 1 experimental group were given EG and treated with ethanol 3 hours after EG ingestion. Physical, biochemical, hematologic, blood gas, serum and urine EG concentrations, and urinalysis findings were evaluated at 0, 1, 3, 6, 9, 12, 24, 48, and 72 hours, 1 week, and 2 weeks after EG ingestion, or 4-MP treatment in cats of the 4-MP only group. The half-life of EG and percentage of ingested EG excreted unchanged were determined for each group. 4-Methylpyrazole treatment at 0 hour was most effective at preventing metabolism of EG. 4-Methylpyrazole was not effective in preventing development of renal failure when given 2 or 3 hours after EG ingestion. Ethanol given 3 hours after EG ingestion was successful in preventing development of renal dysfunction in 2 of the 6 cats treated 3 hours after EG ingestion. Of the remaining 4 cats treated with ethanol, 2 developed transient renal dysfunction and 2 developed acute oliguric renal failure and were euthanatized. 4-Methylpyrazol given 2 or 3 hours after EG ingestion was less effective in preventing EG metabolism than was ethanol given 3 hours after EG ingestion. Therefore 4-MP, at the dose found to be effective in dogs, cannot be recommended as an alternative to ethanol for treatment of EG intoxication in cats.

A relation exists between colloid osmotic pressure and serum total protein concentration; equations describing this relation have been used to determine a calculated value for colloid osmotic pressure. However, the relation between total protein concentration and colloid osmotic pressure is altered by the method used to measure protein and by changes in the ratio of concentrations of albumin (A) to globulin (G). We developed nomograms for estimating colloid osmotic pressure from A and G concentrations, using samples obtained from clinically normal animals and compared the accuracy of these nomograms with that of previously described equations relating colloid osmotic pressure to total protein concentration. For comparison, serum samples from canine (n = 106), equine (n = 79), feline (n = 24), and bovine (n = 27) patients admitted to the University of Georgia Veterinary Medical Teaching Hospital were used. Results indicated that nomograms based on protein concentration estimated by a refractometer generally were the least reliable. Although predictive nomograms, using total protein concentration determined by the biuret method, provided better results for serum samples, there was considerable variation between measured and calculated values for colloid osmotic pressure in all species studied. Calculated values for colloid osmotic pressure derived from A and G concentrations were most closely related to measured values for colloid osmotic pressure in dogs, horses, and cats. However, calculated values for colloid osmotic pressure differed from measured values by as much as 5 mm of Hg for some samples by each of the methods of estimation. These results indicate that, although calculated values for colloid osmotic pressure may be most accurate when variations in the A-to-G ratio are accounted for in the nomogram, none of the calculation methods provided a consistently accurate estimate of colloid osmotic pressure.

The hypothalamic-pituitary-adrenocortical (HPA) axis was studied in 8 healthy cats after administration of supraphysiologic doses of methylprednisolone (MP). Ovine corticotropin-releasing hormone (oCRH) administration increased cortisol and adrenocorticotropic hormone (ACTH) concentrations. Significant (P < 0.05) suppression of cortisol and a trend toward suppression of ACTH was observed after 1 week of MP administration. The HPA axis quickly recovered from suppressive effects of MP 1 week after administration of the steroid was discontinued. Side effects of oCRH administration were minimal in 7 cats; however, 1 cat had a severe hypotensive reaction. Clinical abnormalities were not associated with MP administration. The HPA axis was suppressed by supraphysiologic doses of MP in all treated cats that lacked clinical signs consistent with iatrogenic HPA axis suppression. Despite the relatively active pars intermedia in cats, compared with human beings and dogs, feedback of MP on the HPA axis resulted in similar trends in oCRH-stimulated ACTH and cortisol concentrations as observed in human beings and dogs. Lack of consistent correlation between ACTH and cortisol concentrations was observed in 3 cats and possibly was related to the active pars intermedia in the cat.

We measured immunoreactive (IR) plasma concentrations of the proopiomelanocortin (POMC)-derived. peptides (adrenocorticotropic hormone [ACTH]; beta-endorphin/beta-lipotropin [beta END/beta LPH]; and alpha-melanocyte stimulating hormone [alpha MSH]) and of cortisol in 100 clinically normal cats. Median plasma concentration of IR-ACTH was 2.7 pmol/L (range, less than or equal to 1.1 to 22 pmol/L), of beta END/beta LPH was 28 pmol/L (range, 3.8 to 130 pmol/L), of alpha MSH was 36 pmol/L (range, less than or equal to 3.6 to 200 pmol/L), and of cortisol was 35 nmol/L (range, 5 to 140 nmol/L). Plasma concentrations of IR-ACTH, alpha MSH, and beta END/beta LPH were at or below the assay sensitivity in 34, 3, and 0% of the cats, respectively. We did not detect a correlation between plasma concentrations of IR-ACTH and beta END/beta LPH (r = 0.23) or between plasma concentrations of IR-ACTH and alpha MSH (r = 0.19). However, there was a significant (P < 0.001) correlation between plasma concentrations of IR-beta END/beta LPH and alpha MSH (r = 0.81). There was not a significant correlation between plasma concentration of cortisol and plasma concentration of any of the IR-POMC peptides. High plasma concentrations of IR-alpha MSH and beta END, POMC peptides secreted predominantly by melanotrophs in other species, indicate that clinically normal cats have an actively secreting pars intermedia. Although the beta END/beta LPH assay used in this study measures the pars distalis-derived peptide beta-LPH, as well as beta END itself, over 95% of the IR-beta END/beta LPH activity in feline plasma containing high concentrations of alpha MSH, but low concentrations of IR-ACTH, was found to coelute with human beta END on gel filtration chromatography. In contrast to the high plasma concentrations of IR-alpha MSH and beta END/ beta LPH, many cats had low to undetectable concentrations of IR-ACTH, a peptide secreted predominantly by pars distalis corticotrophs. The pattern of plasma POMC peptide concentrations found in cats is similar to that reported in rats, but is markedly different from that reported in dogs, in which the secretion of pars intermedia POMC peptides is normally low.

The effect of a dietary supplement, choreito, on in vitro struvite crystal growth in feline urine was evaluated. Adult specific-pathogen-free cats (4 females, 4 males) considered to be clinically normal on the basis of physical examination findings and normal results of CBC, serum biochemical analyses, and urinalyses obtained before the beginning of the study were used. Before 24-hour urine sample collections were made, cats were fed a commercial canned diet with 0 or 500 mg of choreito supplement/kg of body weight for at least 2 weeks in a cross-over design with 4 cats/treatment. Filtered urine samples were analyzed for urine pH, specific gravity, osmolality, and urine electrolytes. The struvite activity product was calculated, using a statistical software program that calculates urine saturation. Urine samples were placed in wells of cell culture plates, increasing concentrations of ammonium hydroxide were added to adjacent wells to stimulate struvite crystal growth, and the plates were incubated at 37 C. Crystal growth was assessed by determination of number of crystals and supersaturation index by direct visualization, using an inverted microscope. Supplementation of the diet with choreito (at this concentration) did not change urine pH, specific gravity, osmolality, urine electrolyte composition, or calculated struvite activity product. However, supplementation significantly (P < 0.05) reduced crystal number and supersaturation index. These results indicate that direct observation of struvite crystal formation in whole urine may more accurately predict the effects of treatments to prevent or treat struvite urolithiasis than do calculations based on electrolyte concentration that do not account for the effect of urine macromolecules. It also may mean that choreito consumption affects the concentration of inhibitors or promoters in urine. It was concluded that choreito significantly (P < 0.05) reduced growth of struvite crystals in feline urine, and thus may have a role in prevention of feline struvite urolithiasis. In vivo studies will be necessary to test this hypothesis.

Bronchoalveolar lavage was performed through an endotracheal tube in 34 specific-pathogen-free cats to determine expected values for bronchoalveolar lavage fluid cytologic analysis, using this method of collection. Saline solution for lavage was instilled in 3 separate aliquots at a volume of 5 ml/kg of body weight each. Analysis of sequential aliquots was performed to investigate the differences in cell counts among the 3 fractions. The effect of combining aliquots, including or omitting the first fraction, was evaluated to determine whether all aliquots could be combined for analysis without substantially affecting results. The total number of nucleated cells retrieved from each cat ranged from 0.9 to 31.1 X 10(6). Most of these cells were macrophages (78 +/- 15%, mean +/- SD) and eosinophils (16 +/- 14%). The first aliquot had the greatest number of epithelial cells, and the lowest total nucleated cell count and relative and absolute eosinophil counts. Differences among aliquots also were identified for relative and absolute macrophage counts, relative and absolute neutrophil counts, and absolute lymphocyte count. Statistically significant differences were found for many of the cell counts when values from the combination of the second and third aliquots were compared with values from the combination of all 3 aliquots. Magnitude of the differences was small, and these differences were not believed to be of practical consequence.

A relation exists between colloid osmotic pressure and serum total protein concentration; equations describing this relation have been used to determine a calculated value for colloid osmotic pressure. However, the relation between total protein concentration and colloid osmotic pressure is altered by the method used to measure protein and by changes in the ratio of concentrations of albumin (A) to globulin (G). We developed nomograms for estimating colloid osmotic pressure from A and G concentrations, using samples obtained from clinically normal animals and compared the accuracy of these nomograms with that of previously described equations relating colloid osmotic pressure to total protein concentration. For comparison, serum samples from canine (n = 106), equine (n = 79), feline (n = 24), and bovine (n = 27) patients admitted to the University of Georgia Veterinary Medical Teaching Hospital were used. Results indicated that nomograms based on protein concentration estimated by a refractometer generally were the least reliable. Although predictive nomograms, using total protein concentration determined by the biuret method, provided better results for serum samples, there was considerable variation between measured and calculated values for colloid osmotic pressure in all species studied. Calculated values for colloid osmotic pressure derived from A and G concentrations were most closely related to measured values for colloid osmotic pressure in dogs, horses, and cats. However, calculated values for colloid osmotic pressure differed from measured values by as much as 5 mm of Hg for some samples by each of the methods of estimation. These results indicate that, although calculated values for colloid osmotic pressure may be most accurate when variations in the A-to-G ratio are accounted for in the nomogram, none of the calculation methods provided a consistently accurate estimate of colloid osmotic pressure. For clinical patients, colloid osmotic pressure based on these nomograms cannot replace direct measurement.

We measured glomerular filtration rate (GFR) estimated by plasma disappearance of 99mTc-labeled diethylenetriaminepentaacetic acid, serum concentrations of thyroxine (T4), creatinine, and urea nitrogen, and urine specific gravity in 13 cats with naturally acquired hyperthyroidism before and 30 days after treatment by bilateral thyroidectomy, and in a group of 11 control cats. Mean (+/- SD) serum T4 concentration decreased from a pretreatment value of 120.46 (+/- 39.21) nmol/L to a posttreatment value of 12.15 (+/- 6.26) nmol/L (P < 0.0001; reference range, 10 to 48 nmol/L). Treatment of hyperthyroidism resulted in a decrease in mean (+/- SD) glomerular filtration rate, from 2.51 (+/- 0.69) ml/kg of body weight/min to a posttreatment value of 1.40 (+/- 0.41) ml/kg/min (P < 0.0001). Mean serum creatinine concentration increased from 1.26 (+/- 0.34) mg/dl to 2.05 (+/- 0.60) mg/dl (P < 0.01). Mean serum urea nitrogen concentration increased from 26.62 (+/- 6.83) mg/dl to a mean postthyroidectomy concentration of 34.92 (+/- 8.95) mg/dl (P < 0.01). All changes were significant. Two cats developed overt renal azotemia after treatment of hyperthyroidism. Our results provide further evidence that treatment of hyperthyroidism can result in impaired renal function. In addition, our results suggest that, in some instances, thyrotoxicosis might mask underlying chronic renal insufficiency.

Ursodeoxycholic acid (UDCA; 10 mg/kg of body weight) was administered orally to 5 healthy cats for 3 months. Signs of illness were not apparent in any cat during treatment with UDCA. Results of monthly CBC, serum biochemical analysis, and urinalysis were unchanged during drug administration. There was a decrease in serum cholesterol concentration in 4 cats. Total postprandial serum bile acids (PPSBA) concentration was significantly (P = 0.0003) increased over total preprandial serum bile acids (PRSBA) concentration at all sample collection periods. The PRSBA and PPSBA concentrations were significantly (P < 0.05) increased at all sample collection periods after administration of UDCA, compared with baseline values. Ursodeoxycholic and tauroursodeoxycholic acids were not detected in serum prior to initiating administration of UDCA. Both bile acids were detected in the serum of all cats 1 and 2 months after UDCA administration and were detected in the serum of 2 cats 3 months after initiating UCDA administration. Hepatic ultrasonographic findings were normal before and after completion of UDCA administration. A mild, focal lymphocytic infiltrate was observed in 3 cats 3 months after initiating UDCA administration. Results of the study indicate that UDCA is absorbed into the systemic circulation of cats after oral administration, undergoes hepatic conjugation, and appears to be safe.

A former secondary lead smelter was in operation in Granite City, Ill, until the early 1980s. As a result, the surrounding area is heavily contaminated with lead. Soil concentrations as high as 5,000 ppm have been measured in prior studies. Because of growing concerns about health defects associated with low levels of lead exposure in human beings, a major study has been conducted on people living in the area. The study reported here was a corollary to the human exposure study. Lead concentration was determined in 84 dogs and 26 cats in the town and ranged between < 5 and 28 microgram/dl. None of the dogs had clinical signs of lead poisoning. The CBC and serum biochemical values did not indicate many significant differences between dogs with a high (larger than or equal to 10 microgram/dl) or low blood lead concentration (BLC). Hemoglobin concentrations were lower, and WBC counts were higher in dogs and cats with higher BLC, but they were still within reference ranges. Free erythrocyte protoporphyrin concentration was determined. Normal values appeared to be similar for dogs and cats. Only animals with BLC larger than or equal to 20 microgram/dl were found to have somewhat increased concentration of free erythrocyte protoporphyrin. Delta-aminolevulinic acid dehydratase activity was measured and found to be negatively correlated with BLC. The relation was strong, even at low BLC (5 to 10 microgram/dl) in both species. Age or sex difference was not observed. Therefore, biological changes associated with low BLC were limited to BLC in the 10- to 30-microgram/dl range.