Free, autogenous, full-thickness skin grafts were applied to 10 dogs; 5 dogs were given an iron chelator, deferoxamine-10% hydroxyethyl pentafraction starch (DEF-HES; 50 mg/kg of body weight, IV), and 5 dogs were given an equal volume of 10% hydroxyethyl pentafraction starch (HES) in 0.9% saline solution (5 ml/kg, IV). All dogs (DEF-HES/HBO- and HES/HBO-treated) were exposed to 60 minutes of hyperbaric oxygen (HBO) at 2 atmospheres absolute pressure twice daily for 10 days, beginning the day of surgery. The percentage of viable graft on day 10 was lower in HES/HBO-treated-dogs (mean +/- SD, 13.3 +/- 21.3%; median, 3.0%) than in DEF-HES/HBO-treated dogs (64.7 +/- 39.2%; 88.3%; P = 0.095, Mann-Whitney two-tailed test). There was a positive correlation between percentage of viable graft (on day 10) and percentage of haired skin on the graft site (on day 28) for all dogs (r = 0.91) and for HES/HBO-treated dogs (r = 0.97). The DEF-HES/HBO-treated dogs had less consistent correlation (r = 0.67). Perivascular aggregates of foamy cells were observed in the superficial and reticular portions of the dermis and in the subcutaneous tissue on both surfaces of the panniculus muscle in the graft sites of DEF-HES/HBO-treated dogs. These cells were also observed in the dermis, but not subcutaneous tissue of the control skin sections, and in some viscera of DEF-HES/HBO-treated dogs. Deferoxamine appears to attenuate the detrimental effect of HBO and HES on survival of free skin grafts. However, clinical use of HBO is not recommended as adjunct treatment for free skin grafts in dogs in the first 10 days after grafting. Administration of DEF-HES is not recommended because it has failed to improve the survival of free skin grafts, and the consequence of the cellular response seen in this study is undetermined.

Free, autogenous, full-thickness skin grafts were applied to 10 dogs; 5 dogs were given an iron chelator, deferoxamine-10% hydroxyethyl pentafraction starch (DEF-HES; 50 mg/kg of body weight, IV), and 5 dogs were given an equal volume of 10% hydroxyethyl pentafraction starch (HES) in 0.9% saline solution (5 ml/kg, IV). All dogs (DEF-HES/HBO- and HES/HBO-treated) were exposed to 60 minutes of hyperbaric oxygen (HBO) at 2 atmospheres absolute pressure twice daily for 10 days, beginning the day of surgery. The percentage of viable graft on day 10 was lower in HES/HBO-treated-dogs (mean +/- SD, 13.3 +/- 21.3%; median, 3.0%) than in DEF-HES/HBO-treated dogs (64.7 +/- 39.2%; 88.3%; P = 0.095, Mann-Whitney two-tailed test). There was a positive correlation between percentage of viable graft (on day 10) and percentage of haired skin on the graft site (on day 28) for all dogs (r = 0.91) and for HES/HBO-treated dogs (r = 0.97). The DEF-HES/HBO-treated dogs had less consistent correlation (r = 0.67). Perivascular aggregates of foamy cells were observed in the superficial and reticular portions of the dermis and in the subcutaneous tissue on both surfaces of the panniculus muscle in the graft sites of DEF-HES/HBO-treated dogs. These cells were also observed in the dermis, but not subcutaneous tissue of the control skin sections, and in some viscera of DEF-HES/HBO-treated dogs. Deferoxamine appears to attenuate the detrimental effect of HBO and HES on survival of free skin grafts. However, clinical use of HBO is not recommended as adjunct treatment for free skin grafts in dogs in the first 10 days after grafting. Administration of DEF-HES is not recommended because it has failed to improve the survival of free skin grafts, and the consequence of the cellular response seen in this study is undetermined.

Immunoglobulin E is produced in response to parasitic nematodes that undergo blood and tissue migrations. Results of our previous studies indicated that IgE and IgG respond to Dirofilaria immitis in experimentally infected dogs. To determine the association between treatment with the larvicide, diethylcarbamazine (DEC), and antibody responses and to examine the potential influence of infection with a nonfilarid intestinal nematode on isotype-specific immune responses, we monitored, by use of isotype-specific ELISA, separate IgE and IgG responses against D immitis in 4 groups (A-D) of 8 dogs experimentally coinfected with D immitis and Ancylostoma caninum. All dogs were monitored from 2 weeks before inoculation with D immitis, through postinoculation (PI) week 20. Group-B dogs received a daily regimen of 6.6 mg of DEC/kg of body weight. Group-C dogs received 4.95 mg of oxibendazole/kg daily. Group-D dogs received DEC and oxibendazole, equivalent to the daily doses given to dogs of groups B and C. All dogs given oxibendazole had no A caninum at necropsy. Of the groups receiving DEC, 3 group-B dogs each had 1 to 2 D immitis at necropsy. When results of chronologic IgE determination for all groups were statistically compared, only groups B and C had significant (P = 0.0148 and P << 0.00005, respectively) increases in IgE values. Group-C dogs had the highest IgE values from PI week 10 until the end of the study, whereas IgG values were statistically identical to those of group-A dogs. Group-B dogs given only DEC and having the least number of D immitis of all groups, had IgE values that peaked at PI week 6; values were significantly (P = 0.0002) higher than those for all other groups. In Group-B dogs, IgG values increased significantly (P << 0.00005) only at PI week 20 and were significantly (P << 0.00005) decreased after PI week 6, compared with values for all other groups. Group D containing 6 dogs infected with 1 to 18 D immitis found at necropsy had IgE values betwee.

Immunoglobulin E is produced in response to parasitic nematodes that undergo blood and tissue migrations. Results of our previous studies indicated that IgE and IgG respond to Dirofilaria immitis in experimentally infected dogs. To determine the association between treatment with the larvicide, diethylcarbamazine (DEC), and antibody responses and to examine the potential influence of infection with a nonfilarid intestinal nematode on isotype-specific immune responses, we monitored, by use of isotype-specific ELISA, separate IgE and IgG responses against D immitis in 4 groups (A-D) of 8 dogs experimentally coinfected with D immitis and Ancylostoma caninum. All dogs were monitored from 2 weeks before inoculation with D immitis, through postinoculation (PI) week 20. Group-B dogs received a daily regimen of 6.6 mg of DEC/kg of body weight. Group-C dogs received 4.95 mg of oxibendazole/kg daily. Group-D dogs received DEC and oxibendazole, equivalent to the daily doses given to dogs of groups B and C. All dogs given oxibendazole had no A caninum at necropsy. Of the groups receiving DEC, 3 group-B dogs each had 1 to 2 D immitis at necropsy. When results of chronologic IgE determination for all groups were statistically compared, only groups B and C had significant (P = 0.0148 and P << 0.00005, respectively) increases in IgE values. Group-C dogs had the highest IgE values from PI week 10 until the end of the study, whereas IgG values were statistically identical to those of group-A dogs. Group-B dogs given only DEC and having the least number of D immitis of all groups, had IgE values that peaked at PI week 6; values were significantly (P = 0.0002) higher than those for all other groups. In Group-B dogs, IgG values increased significantly (P << 0.00005) only at PI week 20 and were significantly (P << 0.00005) decreased after PI week 6, compared with values for all other groups. Group D containing 6 dogs infected with 1 to 18 D immitis found at necropsy had IgE values between those of group-B dogs and those of non-DEC-treated groups at PI week 6. There was no difference in IgG values between 3 groups at PI week 6, and IgE values were found to be a better correlator than were IgG values to the number of D immitis larvae killed in the tissues during this period. All differences in IgG and IgE values not only correlated with treatment status and number of D immitis adults found at necropsy, but also with the developmental stage of D immitis commonly present in the groups at each time point and the number of adult D immitis found at necropsy.

Adrenocortical function was assessed in 27 Beagle pups at 2, 4, 6, 8, 10, and 12 weeks of age by determination of plasma sodium, potassium, and chloride concentrations; serum aldosterone and cortisol concentrations; and plasma ACTH concentrations. Serum cortisol concentration was measured before and 1 and 2 hours after IM administration of 2.2 IU of ACTH/kg of body weight. Serum progesterone concentration also was determined for all pups at 2, 4, and 6 weeks of age. Mean baseline cortisol concentration was lower for pups 8 weeks old or younger than for mature dogs. Nevertheless, mean serum ACTH-stimulated cortisol concentration in dogs of all age groups increased into the adult reference range after administration of ACTH. For pups 4 weeks old or younger, increase in cortisol concentration was maximal at 2 hours after ACTH administration. However, in pups between 6 and 12 weeks of age, the increase in cortisol concentration was maximal 1 hour after ACTH administration in about a third of the pups, whereas the remaining pups had peak values at 2 hours. Mean plasma sodium, potassium, and chloride concentrations for each age group were within the reference ranges established for mature dogs, with the exception of lower mean plasma sodium and chloride concentrations in pups 4 weeks old or younger. Mean serum aldosterone concentration in pups of each age group was substantially higher than the range of aldosterone concentrations for clinically normal mature dogs. Median progesterone concentration was uniformly less than 0.2 ng/ml for all pups 6 weeks old or younger. The normal endogenous ACTH concentration and adequate cortisol responses to exogenous ACTH seen in our pups would support functional pituitary gland and adrenal cortex for cortisol production. The low baseline cortisol concentration observed in the pups of this study may be related to reduced binding of cortisol to plasma proteins, as exists in human infants.

Adrenocortical function was assessed in 27 Beagle pups at 2, 4, 6, 8, 10, and 12 weeks of age by determination of plasma sodium, potassium, and chloride concentrations; serum aldosterone and cortisol concentrations; and plasma ACTH concentrations. Serum cortisol concentration was measured before and 1 and 2 hours after IM administration of 2.2 IU of ACTH/kg of body weight. Serum progesterone concentration also was determined for all pups at 2, 4, and 6 weeks of age. Mean baseline cortisol concentration was lower for pups 8 weeks old or younger than for mature dogs. Nevertheless, mean serum ACTH-stimulated cortisol concentration in dogs of all age groups increased into the adult reference range after administration of ACTH. For pups 4 weeks old or younger, increase in cortisol concentration was maximal at 2 hours after ACTH administration. However, in pups between 6 and 12 weeks of age, the increase in cortisol concentration was maximal 1 hour after ACTH administration in about a third of the pups, whereas the remaining pups had peak values at 2 hours. Mean plasma sodium, potassium, and chloride concentrations for each age group were within the reference ranges established for mature dogs, with the exception of lower mean plasma sodium and chloride concentrations in pups 4 weeks old or younger. Mean serum aldosterone concentration in pups of each age group was substantially higher than the range of aldosterone concentrations for clinically normal mature dogs. Median progesterone concentration was uniformly less than 0.2 ng/ml for all pups 6 weeks old or younger. The normal endogenous ACTH concentration and adequate cortisol responses to exogenous ACTH seen in our pups would support functional pituitary gland and adrenal cortex for cortisol production. The low baseline cortisol concentration observed in the pups of this study may be related to reduced binding of cortisol to plasma proteins, as exists in human infants. The hyponatremia and increased aldosterone concentration may be explained by reduced renal tubular response to aldosterone, as also evidenced in the human infant kidney.

Because caffeine is metabolized by the hepatic P-450 cytochrome oxidase system, clearance of caffeine is an excellent quantitative test of hepatic function in human beings. It is currently used in much the same way that creatinine clearance is used to assess renal function. Caffeine clearance was measured in lactating dairy cows initially to determine the suitability of caffeine clearance as an indicator of hepatic function in cattle. Pharmacokinetic variables of caffeine were studied in 6 adult lactating dairy cows after IV administration of a single dose of caffeine sodium benzoate (2 mg of caffeine/kg of body weight). Caffeine concentration was analyzed by use of an automated enzyme immunoassay. The lower limit of detection of the assay for caffeine in serum was 0.079 micrograms/ml. Serum caffeine concentration-time curves best fit an open two-compartment pharmacokinetic model. Harmonic mean elimination half-life was 3.8 (range, 2.6 to 6.9) hours, and total clearance was 0.118 (range, 0.090 to 0.197) L/kg/h. Milk caffeine concentration was similar to serum concentration 1.5 to 24 hours after caffeine administration. Adverse effects were not observed in cows given caffeine.

Because caffeine is metabolized by the hepatic P-450 cytochrome oxidase system, clearance of caffeine is an excellent quantitative test of hepatic function in human beings. It is currently used in much the same way that creatinine clearance is used to assess renal function. Caffeine clearance was measured in lactating dairy cows initially to determine the suitability of caffeine clearance as an indicator of hepatic function in cattle. Pharmacokinetic variables of caffeine were studied in 6 adult lactating dairy cows after IV administration of a single dose of caffeine sodium benzoate (2 mg of caffeine/kg of body weight). Caffeine concentration was analyzed by use of an automated enzyme immunoassay. The lower limit of detection of the assay for caffeine in serum was 0.079 micrograms/ml. Serum caffeine concentration-time curves best fit an open two-compartment pharmacokinetic model. Harmonic mean elimination half-life was 3.8 (range, 2.6 to 6.9) hours, and total clearance was 0.118 (range, 0.090 to 0.197) L/kg/h. Milk caffeine concentration was similar to serum concentration 1.5 to 24 hours after caffeine administration. Adverse effects were not observed in cows given caffeine.

The effect of premedication with phenylbutazone on systemic hemodynamic and diuretic effects of furosemide was examined in 6 healthy, conscious, mares. Mares were instrumented for measurement of systemic hemodynamics, including cardiac output and pulmonary arterial, systemic arterial, and intracardiac pressures, and urine flow. Each of 3 treatments was administered in a randomized, blinded study; furosemide (1 mg/kg of body weight, IV) only, phenylbutazone (8.8 mg/kg PO, at 24 hours and 4.4 mg/kg IV, 30 minutes before furosemide) and furosemide, or 0.9% NaCl. Phenylbutazone administration significantly attenuated, but did not abolish, the diuretic effect of furosemide. Phenylbutazone completely inhibited the immediate effect of furosemide on cardiac output, stroke volume, total peripheral resistance, and right ventricular peak pressure. Premedication with phenylbutazone did not inhibit equally the diuretic and hemodynamic effects of furosemide, indicating that some of furosemide's hemodynamic effects are mediated by an extrarenal activity of furosemide.

The effect of premedication with phenylbutazone on systemic hemodynamic and diuretic effects of furosemide was examined in 6 healthy, conscious, mares. Mares were instrumented for measurement of systemic hemodynamics, including cardiac output and pulmonary arterial, systemic arterial, and intracardiac pressures, and urine flow. Each of 3 treatments was administered in a randomized, blinded study; furosemide (1 mg/kg of body weight, IV) only, phenylbutazone (8.8 mg/kg PO, at 24 hours and 4.4 mg/kg IV, 30 minutes before furosemide) and furosemide, or 0.9% NaCl. Phenylbutazone administration significantly attenuated, but did not abolish, the diuretic effect of furosemide. Phenylbutazone completely inhibited the immediate effect of furosemide on cardiac output, stroke volume, total peripheral resistance, and right ventricular peak pressure. Premedication with phenylbutazone did not inhibit equally the diuretic and hemodynamic effects of furosemide, indicating that some of furosemide's hemodynamic effects are mediated by an extrarenal activity of furosemide.

Serial sections of bone and soft tissue from the metacarpophalangeal joints of 2 mature and 2 immature horses were evaluated for substance P immunoreactive sensory nerve fibers. Formalin-fixed specimens were sectioned, either nondemineralized or demineralized with formic acid or EDTA. Rabbit antiserum to substance P (SP) was used in the strep. tavidin-biotin-peraxidase complex method for immunolocalization of SP antigen, and staining with 3,3'- diaminobenzidine was used for permanent identification of SP fibers. Abundant sensory nerve fibers were identified in the joint capsule, synovial membrane subintimal layers, collateral ligaments, suspensory ligament and distal sesamoidean ligament attachments to the sesamoid bones, and the periarticular periosteal layers. Sparse SP-immunoreactive nerve fibers were found in subchondral bone plates of the metacarpus, proximal first phalanx, and dorsal articular surface of the sesamoid bones. Most SP fibers were associated with blood vessels in the small cancellous spaces and haversian canals of the subchondral bone. The deeper marrow spaces contained increased numbers of SP sensory fibers; a few appeared in small groups and as several SP-immunoreactive fibers in a larger nerve. Cortical bone contained only a few SP fibers in the haversian canals. Substance P fibers were not identified in the osteocytic lacunae, canaliculi, or the bony lamellae of the haversian systems of the subchondral bone plate, and its extension to the metaphyseal and diaphyseal cortical bone. Equine metacarpophalangeal joint soft tissues have an abundant sensory nerve supply, similar to that of other species. However, the subchondral bone plate also has sparse sensory nerve fibers, which is a unique finding, and may help explain signs of bone pain associated with disease states of the fetlock.

Serial sections of bone and soft tissue from the metacarpophalangeal joints of 2 mature and 2 immature horses were evaluated for substance P immunoreactive sensory nerve fibers. Formalin-fixed specimens were sectioned, either nondemineralized or demineralized with formic acid or EDTA. Rabbit antiserum to substance P (SP) was used in the strep. tavidin-biotin-peraxidase complex method for immunolocalization of SP antigen, and staining with 3,3'- diaminobenzidine was used for permanent identification of SP fibers. Abundant sensory nerve fibers were identified in the joint capsule, synovial membrane subintimal layers, collateral ligaments, suspensory ligament and distal sesamoidean ligament attachments to the sesamoid bones, and the periarticular periosteal layers. Sparse SP-immunoreactive nerve fibers were found in subchondral bone plates of the metacarpus, proximal first phalanx, and dorsal articular surface of the sesamoid bones. Most SP fibers were associated with blood vessels in the small cancellous spaces and haversian canals of the subchondral bone. The deeper marrow spaces contained increased numbers of SP sensory fibers; a few appeared in small groups and as several SP-immunoreactive fibers in a larger nerve. Cortical bone contained only a few SP fibers in the haversian canals. Substance P fibers were not identified in the osteocytic lacunae, canaliculi, or the bony lamellae of the haversian systems of the subchondral bone plate, and its extension to the metaphyseal and diaphyseal cortical bone. Equine metacarpophalangeal joint soft tissues have an abundant sensory nerve supply, similar to that of other species. However, the subchondral bone plate also has sparse sensory nerve fibers, which is a unique finding, and may help explain signs of bone pain associated with disease states of the fetlock.