4-Methylpyrazole (4-MP), an alcohol dehydrogenase inhibitor, was administered to dogs to treat ethylene glycol (EG) intoxication. Eleven dogs were given 10.6 g of EG/kg of body weight; 5 dogs were treated with 4-MP 5 hours after EG ingestion and 6 dogs were treated with 4-MP 8 hours after EG ingestion. 4-Methylpyrazole was administered IV as a 50-mg/dl solution in 50% polyethylene glycol: initial dose, 20 mg/kg; at 12 hours after initial dose, 15 mg/ kg; at 24 hours after initial dose, 10 mg/kg, and at 30 hours after initial dose, 5 mg/kg. Physical, biochemical, hematologic, blood gas, serum and urine EG concentrations, and urinalysis findings were evaluated at 0, 1, 3, 6, 9, 12, 24, 48, 72 hours, and at 1 week and 2 weeks after EG ingestion. Dogs of both groups developed clinicopathologic signs associated with EG intoxication, including CNS depression, hyperosmolality, high anion gap metabolic acidosis, polydipsia, polyuria, calcium oxalate monohydrate and dihydrate crystalluria, and isosthenuria. Fractional excretion of sodium was increased in all dogs between 1 and 9 hours after EG ingestion, but remained increased beyond 24 hours only in the 2 dogs treated at 8 hours after EG ingestion that developed acute renal failure. All dogs treated 5 hours after EG ingestion recovered without morphologic, biochemical, or clinical evidence of renal impairment. Of the 6 dogs treated 8 hours after EG ingestion, 2 developed acute renal failure. One of the dogs treated 8 hours after EG ingestion remained isosthenuric for 2 months, but did not manifest any other signs of renal impairment. Of the dogs treated 8 hours after EG ingestion, 3 recovered without morphologic, biochemical, or clinical evidence of renal impairment. Serum half-life of EG was prolonged in the dogs treated 8 hours after EG ingestion. Percentage of EG excreted unchanged was 84 +/- 2% in the dogs treated 5 hours after EG ingestion, and was 40 +/- 10% in the dogs treated 8 hours after EG ingestion. 4-Methylpyrazole was effective in preventing renal failure in all dogs given 10.6 g of EG/kg when treatment was initiated by 5 hours after EG ingestion, and in 4 of 6 dogs when treatment was initiated by 8 hours after EG ingestion.

A sublethal dose of ethylene glycol was administered orally to 3 groups of dogs; dogs of a control group were given distilled water instead. Renal cortical biopsy samples were obtained from dogs of experimental and control groups at various times after treatment. Tissue was examined by use of light microscopy and transmission electron microscopy. In dogs of the control group, the light and electron microscopic appearances of tissue were within normal limits at all sample collection hours. In dogs of the experimental groups, renal corpuscular structure remained within normal limits by use of light and electron microscopy throughout the study, though morphologic change was seen in other structures of the cortex. Light microscopic lesions first appeared at 12 hours, and were similar to those reported in the literature. Ultrastructural lesions were first observed in the 5-hour samples, and similar to the light microscopic lesions, were most common in the proximal convoluted tubules (PCT). Initial PCT cellular changes included vacuolization of cells and distention of the parabasal extracellular spaces; PCT cellular lesions seen in later-hour samples included formation of apical buds and cellular rupture. Internalization or sloughing of the PCT brush border was not observed. Distal convoluted tubules (DCT) were frequently dilated and/or packed with cellular debris. A few DCT cells had degenerative or necrotic changes. In PCT and DCT, abnormal cells were frequently flanked by normal or nearly normal cells. During later hours, a few cells with types of changes first observed in early hours continued to be observed, implying ongoing response of cells to the toxin.

Renal ultrasonographic changes were evaluated in 5 dogs administered 10 ml of commercial antifreeze (95% ethylene glycol)/kg of body weight, PO, and in 2 dogs given placebos. Studies were made prior to and after ingestion on an hourly basis over a period of 8 to 10 hours. All dogs were anesthetized immediately after toxin or placebo ingestion for the duration of the study. Renal cortical echogenicity was evaluated in comparison with that of the adjacent liver and spleen. Echogenicity of the renal medulla and definition of the corticomedullary juction were assessed. Within 4 hours after ethylene glycol administration, renal cortical echogenicity of all intoxicated dogs increased from normal to surpass that of the liver and approach or equal that of the spleen. Medullary echogenicity in all intoxicated dogs progressively increased over the course of the study, with changes recognized within 5 hours after ethylene glycol administration. An ultrasonographic pattern consisting of nearly equal, marked increase in cortical and medullary echogenicity and relatively hypoechoic corticomedullary junction and central medullary regions was recognized concurrent with the development of anuria in 3 of the 5 intoxicated dogs. Mild, transient increases in cortical and medullary echogenicity were observed in anesthetized control dogs. However, no statistical difference (P less than 0.05) was detected between baseline, peak, and terminal echogenicity values in these dogs. Blood and urine samples were collected hourly from intoxicated dogs to coincide with ultrasonographic studies. Most clinicopathologic values derived from these samples were not statistically different (P less than 0.05) from those reported in a study that used a similar intoxication protocol in nonanesthetized dogs.

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 study was made to determine if mouse zygotes can be effectively vitrified in 7 M ethylene glycol in modified Dulbecco's phosphate buffered saline (PB1) and to find out if the development of vitrified-warmed zygotes in vitro can be improved by renewing the culture medium. The results showed that without medium change, vitrification reduced the development of zygotes to the expanded blastocyst stage (p0.01). With medium change, the development rate of vitrified-warmed zygotes exposed in 7 M ethylene glycol for 1 or 2 min was similar to that of unvitrified zygotes. However, prolonged exposure (5 min) markedly reduced the development rates of vitrified-warmed zygotes to the expanded blastocyst stage (p0.05). When the zygotes were vitrified in 7 M ethylene glycol and diluted at 18 degree C to 22 degree C, a slower efflux of ethylene glycol from the cell might have occurred, leading to a toxic effect of ethylene glycol in culture. The development rates of vitrified embryos cultured with medium change at 24 hr did not significantly differ from the untreated control (89.0% vs 96.5%). In conclusion, this study showed that mouse zygotes can be vitrified in 7 M ethylene glycol in PB1 and that changing the culture medium can improve the in vitro development rates of vitrified-warmed zygotes to the expanded blastocyst stage

The cryopreservation of mammalian embryos has become an integral part of method s to control animal reproduction. Numerous vitrification solutions have been formulated with ethylene glycol in combination with macromolecules, sugars and other cryoprotective agents. These indicate that a study of ethylene glycol as a cryoprotectant of choice in vitrification studies would be promising. To understand the cryobiology of ethylene glycol, several factors have to be studied. These are : cryoprotectant toxicity, osmotic stress and temperature at exposure. Understanding these factors could lead to the formulation of vitrification protocols that would lead to higher viability rates after cooling. First, ethylene glycol must be used as the sole cryoprotectant in a solution without macromolecules and sugars. Second, partial dehydration and permeation prior to cooling to subzero temperatures must be studied to achieve accurate exposure and a one-step dilution method. Third, the toxic effects of ethylene glycol must be overcome without sacrificing its vitrification properties by combining step-wise exposure at appropriate temperatures, low concentration and decreased volume. Fourth, the long-term effects of ethylene glycol on exposed or vitrified embryos must be determined. Lastly, the influence of culture on the viability of vitrified embryos must be studied to improve viability rates after warming

Ovulated mouse oocytes denuded of their cumulus cells, were vitrified in a solution containing 7 M ethylene glycol as the sole cryoprotectant using one or two steps of exposure before vitrification and were diluted in 1 M sucrose solution in 5 or 10 min after warming. The results proved that the viability of oocytes are detrimentally affected by exposure to the vitrification solution even without vitrification. At 5 min dilution time, the two-step exposure was superior to the one-step in terms of the post-warming recovery rate of vitrified oocytes with normal morphology and their subsequent development to the blastocyst stage (p0.001) after fertilization in vitro. At 10 min dilution time, no significant difference between one or two-step exposure was found. The effect of the addition of 0.5 M sucrose to the vitrification solution was also determined and did not result in a significant improvement in the viability of oocytes vitrified in one-step and diluted for 10 min. In conclusion, the results in this study indicate that oocytes can be vitrified with 7 M ethylene glycol as the sole cryoprotectant in the vitrification solution, and that the recovery of normal oocytes after one-step exposure in the vitrification solution can be improved by 10 min dilution time. However, the improvement in the recovery rate of oocytes with normal morphology and their subsequent developmental in vitro was not improved by the addition of 0.5 M sucrose to the vitrification solution

Investigation of the efficiency of ethylene glycol and sucrose application in the capacity of cryoprotectors for cryopreservation of cattle embryos and their thawing in the conditions of application of saline solutions (as their dissolution medium) and nutritive media with a various structure was realized in the conditions of the Republic of Belarus. Research results showed that application of ethylene glycol in concentration 1,5 M and sucrose in concentration 1,0M proved to be the most effective. Regardless of the applied media the average safety of embryos was 93,8-96%, and acceptability - 59,3-62,5%. Peculiar feature of ethylene glycol use as cryoprotector for preservation of cattle embryos was that it could be quickly absorbed by a cell and quickly deduced from it. It made it possible to realize embryo transfer immediately after thawing. Application of ethylene glycol and sucrose as cryoprotectors could considerably simplify the procedure of transplantation of the frozen-thawed embryos, practically reducing it to a procedure of artificial insemination