PEER REVIEWED

Magnitude and Duration of Effects of Two Corticosteroid Formulations (Dexamethasone Sodium Phosphate and Phenyl Propionate; Prednisolone Acetate) on Blood Glucose, Leukocyte Values, and Milk Yield in Dairy Cows

2 3 M.S. Lima1, DVM, PhD; G. Stilwell1, DVM, PhD; N. Carolino , MS, PhD; C.A. Hjerpe , DVM 1Faculdade de Medicina Veterinaria, CIISA, DC, Uniuersidade Tecnica de Lisboa, Portugal 2Unidade de Investiga<;iio de Recursos Geneticos, Reproduc;iio e Melhoramento Animal - INRB, Vale de Santarem, Santarem, Portugal 3School of Veterinary Medicine, University of California, Davis, Davis, CA 95616 Corresponding author: Dr. Miguel Lima, [email protected]

Abstract Key words: dairy cows, glucocorticoids, dexametha­ sone, prednisolone The magnitude and duration of the effects of two corticosteroid formulations were determined on blood Resume glucose and leukocyte values and milk yield in nor­ mal, lactating dairy cows. One formulation contained L'ampleur et la duree des effets de deux formula­ a combination of dexamethasone sodium phosphate tions de corticosteroi:des sur la concentration sanguine and dexamethasone phenyl propionate (DEX). The de glucose et de leucocytes et sur la production de lait other contained prednisolone acetate (PRED). Blood ont ete examinees chez des vaches laitieres normales samples were obtained prior to and at 6, 24, 48, 72, en lactation. Une des formulations contenait une com­ 96, and 144 hours following administration of a single binaison de phosphate de sodium de dexamethasone et dose of DEX or PRED. Milk yield was determined for de dexamethasone phenylpropionique (DEX) alors que two days prior to drug administration and for seven l'autre contenait de !'acetate de prednisolone (PRED). days afterwards. Des echantillons sanguins ont ete obtenus avant et 6, Both corticosteroids caused significant increases in 24, 48, 72, 96 et 144 heures suivant !'administration blood glucose values, although DEX caused significantly d'une dose unique de DEX ou de PRED. La production larger and longer lasting increases. DEX also caused de lait a ete determinee sur une periode de deux jours significant leukocytosis and neutrophilia. PRED caused avant !'administration des drogues et sur une periode significant, very short lasting neutrophilia, but had no de sept jours par la suite. significant effect on total blood leukocyte values. Both Les deux corticostero1des ont cause une augmen­ drugs caused significant reductions in blood eosino­ tation de la concentration du glucose sanguin bien que phil and lymphocyte values, and significant increases le traitement DEX ait entraine une augmentation plus in monocyte values. DEX also caused a significant, forte et plus longue. Le traitement DEX a aussi cause marked drop in milk production on days 1, 2, and 6, une leucocytose et une neutrophilie significatives. Le post-administration. PRED did not significantly affect traitement PRED a cause une neutrophilie significative milk production. mais de tres courte duree et n'avait pas d'effet significatif Because DEX produced more dramatic and persis­ sur le nombre total de leucocytes sanguins. Les deux tent changes in blood glucose values and milk production drogues ont entraine des reductions significatives du than did PRED, the authors believe that DEX is likely nombre d'eosinophiles et de lymphocytes sanguins et une to be more efficacious than PRED for treating ketosis augmentation significative du nombre de monocytes. Le in dairy cows. Because DEX produced more dramatic traitement DEX a aussi cause une reduction significa­ and persistent effects on blood neutrophil values than tive marquee de la production laitiere aux jours 1, 2 et PRED, it is also likely to be a better option for use as 6 suivant !'administration. Le traitement PRED n'a pas an anti-inflammatory drug. affecte la production de lait.

60 THE BOVINE PRACTITIONER-VOL. 44, NO. 1 En raison des changements plus dramatiques et • Effects on the immune system: 1) immunosup­ persistants du traitement DEX par rapport au traite­ pression, and 2) alleviation of the clinical mani­ ment PRED sur la concentration sanguine du glucose et festations of certain immune-mediated diseases. sur la production de lait, les auteurs croient que le traite­ In order to establish a rational therapeutic regimen ment DEX est probablement plus efficace que le traite­ for a particular corticosteroid, it is important to consider ment PRED pour le traitement de l'acetonemie chez the duration and magnitude of the effects. A major ob­ les vaches laitieres. En raison des changements plus jective of this study was to investigate the duration of dramatiques et persistants du traitement DEX par rap­ the effects of two previously untested corticosteroids, port au traitement PRED sur le nombre de neutrophiles DEX and PRED, on milk production and on several sanguins, ce traitement est done probablement aussi blood parameters, as an indication of their metabolic une meilleure option comme drogue anti-inflammatoire. action (glucose) and anti-inflammatory activity (total leukocytes, neutrophils, eosinophils, monocytes, and Introduction lymphocytes). This study is the first report in which a combina­ Corticosteroids are among the most used and most tion of short-lasting and long-lasting glucocorticoids was misused drugs in veterinary medicine. Even so, scien­ administered to dairy cattle. It is also the first report of tifically verified information concerning corticosteroid administration of dexamethasone sodium phosphate and therapy is scarce for most species of domestic animals, dexamethasone phenyl propionate (DEX) and predniso­ especially regarding optimal dosages, treatment inter­ lone acetate (PRED) to cattle, and the effects on blood vals, efficacy, and side effects. Frequently, therapeutic glucose and leukocyte values and milk yield. recommendations for veterinary use of corticosteroids are based on uncontrolled clinical experiences of indi­ Materials and Methods vidual veterinary clinicians, or on information obtained from clinical trials in man or other species.6 The well­ Twelve normal Holstein cows were randomly documented euphoric effect of corticosteroids can be a selected from a herd of approximately 200 lactating valid reason for their use. 15 dairy cattle. All were between two and eight years of The clinical problems for which bovine practitio­ age, weighed between 1,210 and 1,595 lb (550 and 725 ners most often use corticosteroids include: 1) ketosis in kg; average weight 1,450 lb or 659 kg), were producing dairy cows, 2) calving paralysis (i.e., paralysis involving between 51 and 117 lb (23 and 53 kg) (average of 84 lb the sciatic, obturator or peroneal nerves), 3) aseptic or 38 kg) of milk per day, and had calved at least 65 laminitis, 4) localized post-surgical or post-traumatic days previously. inflammatory reactions, and 5) severe inflammation A single intramuscular injection of DEXa was ad­ associated with infectious processes. In these instances ministered to four cows at a dose of0.027 mg/lb (0.06 mg/ corticosteroids are used in combination with appropriate kg). DEX was a suspension in which each mL of water bactericidal antimicrobial drugs. 24 contained 1 mg of dexamethasone sodium phosphate 15 The range of effects of corticosteroids reported2•9• ,18 and 2 mg of dexamethasone phenyl propionate. Other in various species of animals include: chemicals included in each mL of DEX formulation were • Effects on carbohydrate, protein, and lipid me­ trisodium citrate (11.4 mg), benzilic alcohol (10.4 mg), tabolism: 1) increased protein catabolism and glu­ sodium chloride (4 mg), tragacantha (1 mg), methylcel­ coneogenesis, 2) decreased peripheral utilization lulose MH50 (0.4 mg), and dimethicone (0.08 mg). The of glucose (insulin antagonism), and 3) decreases label specified a dose of 10 mL for an adult dairy cow. We in lipid reserves. assumed that the average weight of such a cow would be • Anti-inflammatory effects: 1) increases in number 1100 lb (500 kg), and calculated that such a cow should of circulating neutrophils, 2) decreases in number receive 30 mg of combined drug, which is a dose of0.027 of circulating lymphocytes and eosinophils, and mg/lb (0.06 mg/kg). The label indicated that DEX had 3) reductions in localized inflammatory effects. both short (sodium phosphate) and long-acting (phenyl • Mineralocorticoid effects: 1) increased sodium, propionate) effects. chloride, and water retention, and 2) increased A single intramuscular injection of PREDh was potassium, phosphorus, and calcium excretion. administered to four different cows at a dose of0.18 mg/ •Reproductive effects: 1) induction of normal par­ lb (0.40 mg/kg). PRED was a suspension of prednisolone turition in late-term bovine pregnancies, and 2) acetate crystals in which each mL of water contained 10 induction of abortions in cattle, after the 180th mg of prednisolone acetate. Other chemicals included day of gestation, when used in combination with in each mL of PRED formulation were benzilic alcohol a prostaglandin. (9.45 mg), sodium chloride (9 mg), polysorbate 80 (4

SPRING 2010 61 mg), carboxymethylcellulose (3 mg), and dimethylpo­ Statistical Analysis lysiloxane antifoam (1 mg). The label specified a dose of 10 to 20 mL for an adult cow. We assumed that the Parameters measured in this study (blood glucose, weight of such a cow would be 1100 lb (500 kg), chose total leukocytes, neutrophils, eosinophils, monocytes, to use the 20 mL (200 mg) dose, and calculated that the lymphocytes, and milk production) were submitted to cow would receive 200 mg, which is a dose of 0.18 mg/ several analyses of variance, with the objective of de­ lb or 0.4 mg/kg. The label indicated that PRED has a termining whether treatment with DEX or PRED was short-acting effect. associated with any statistically significant changes in Both drugs are registered in several European those parameters, and also to determine the times of countries for use in horses, cattle, sheep, goats, pigs, onset and persistence of any significant effects. dogs, and cats, and have label recommendations for The analysis of variance was done with the PROC use in allergic reactions, non-infectious inflammatory MIXED from SAS19 using the following mixed linear processes, osteoarthritis, shock, ketosis, and pregnancy model: y = x~ + Zy+ E. toxemia. Recommended milk and meat withdrawal pe­ In this model, Y is a vector of the parameter anal­ riods for DEX and PRED were zero and eight days, and ysed (glucose, total leukocytes, neutrophils, eosinophils, one and eight days, respectively. monocytes, lymphocytes, and milk production), b is a A single intramuscular injection of physiological vector of fixed effects, y is a vector of unknown random saline solution (20 mL) was administered to the remain­ effects, and e is a vector of residual effects. X and Z are ing four cows. Cows were randomly allocated to the three matrices of known incidence for fixed effects and random treatment groups. effects, respectively. The effect of the cow was consid­ The study (excepting blood leukocyte counts) was ered a random effect, while the effects of treatment, performed on the farm, and subject cows were allowed to time and their respective interaction, were considered roam freely with their herd mates during the study. All to be fixed effects. After that, the means and minimal cattle on this farm were tested annually for bovine leuke­ squares (least square means) of all the parameters for mia virus (BLV), and the herd was considered to be free each combination treatment*time were calculated, as of this disease. Cows were housed in confinement, had well as the differences between these means and the access to free stalls, and were fed a complete ration ad respective t-test. libitum. The total mixed ration (TMR) contained grass For each parameter studied, values from DEX and hay, alfalfa hay, grass silage, corn silage, corn grain, and PRED-treated cows were compared with those obtained various byproduct feeds, depending on availability and at the corresponding sampling time from the control cost, and proportioned using a least-cost computation for cows, except that comparisons with the controls were an average daily production level of99 lb (45 kg) of3.5% not performed on samples obtained at 144 hours post-ad­ fat corrected milk. Milking was performed three times ministration. Instead, the 144-hour values from the DEX per day, beginning at 6 am, 1 pm, and 8 pm. and PRED groups were compared with pre-treatment Blood samples were obtained from the coccygeal control group values, by pooling their combined -2 hour vein at 2 hours before, a few minutes before (zero), and and zero-hour values. In addition, values obtained from at 6, 24, 48, 72, 96, and 144 hours after administra­ DEX and PRED-treated groups during corresponding tion of the corticosteroids, except that 144-hour blood time periods were compared directly with each other. samples were not obtained from the controls. In order With two exceptions, no statistically significant to minimize the stress associated with handling and re­ differences were found in any of the comparisons made straint of the cows for venipuncture, blood samples were between the three treatment groups with respect to collected while the cows were resting in free stalls. The samples obtained and data collected during the pre­ first blood samples were obtained between 9:00 and 9:30 treatment period (-2 hours and zero hours). In the first am, and the corticosteroids were administered between exception, at -2 hours, eosinophil values from the DEX 11:00 and 11:30 am, immediately after the second blood group were significantly greater than those from both sample was obtained. PRED and control groups. Although eosinophil values Glucose was measured on the farm immediately from the DEX group were significantly elevated, they after blood collection using a portable analyzer. c Blood were within the reference range (Figure 4), and two was also collected in EDTA tubes, and the leukogram hours later, were no longer significantly elevated. One was determined by an impedance and optical counter1 could speculate than one or more DEX cows might have in the laboratory. Blood smears were used for obtaining been briefly exposed to an allergen to which they were differential leukocyte counts. Individual cow milk pro­ mildly sensitized. In the second exception, at -1 day, duction data was obtained from the farm's automated milk yield was significantly lower in the PRED group electronic database. than in the control group.

62 THE BOVINE PRACTITIONER-VOL. 44, NO. 1 Results DEX induced significant reductions in blood lym­ phocyte counts at 48 and 96 hours post-administration, Both DEX and PRED caused significant increases while PRED induced significant lymphopenia at 6, 24, in blood glucose values (Figure 1). The highest values 48, 96, and 144 hours (Figure 6). occurred at 24 hours post-administration in the cows DEX caused a significant, marked drop in milk pro­ treated with DEX. DEX caused blood glucose values duction on days 1, 2, and 6 post-administration (Figure to be significantly elevated from six hours through 96 7). The magnitude of this reduction was approximately hours. Blood glucose values in DEX-treated cows were 29% on day 1, 18% on day 2, and 21% on day 6. PRED significantly higher than in PRED-treated cows at 24, did not have any significant effect on milk production 48, and 144 hours. PRED caused a significant elevation (Figure 7). in blood glucose values only at 24 hours. Results obtained from administration of DEX and DEX caused significant increases in total blood leu­ PRED to lactating Holstein cows are summarized in kocyte values at six and 24 hours post-administration, Table 1. with peak total leukocyte values occurring at 24 hours (Figure 2). PRED did not have any significant effect on total leukocyte counts. DEX-treated cows had signifi­ LEUKOCYTES cantly higher leukocyte values than PRED-treated cows at 24 hours post-treatment. 16000 DEX caused significant, marked neutrophilia from 14000 six hours through 72 hours post-administration, with 12000 blood neutrophil values peaking at 24 hours (Figure 3). 10000 ~DEX PRED caused significant neutrophilia only at six hours ~ 8000 ■ PRED 6000 D CONTROLS post-administration. DEX-treated cows had significantly 4000 higher neutrophil values than PRED-treated cows at 24 2000 and 48 hours. O ...... LAitl~ ...... &-.~-...~~---.,:&.a lliilio\ Both DEX and PRED caused significant reductions -2 0 6 24 48 72 96 144 in blood eosinophil values at 48 hours post-administra­ TIME tion (Figure 4). DEX caused significant elevations in blood mono­ Figure 2. Effects of administration of DEX and PRED cyte values at six and 48 hours post-administration. on total blood leukocyte values in Holstein cows. Results PRED caused a significant elevation in blood monocyte are expressed as the mean ± standard error. (Reference values only at 24 hours, at which time monocyte values values: 4,000-12,000/µl, Smith21 .) ap < 0.05 and bp< 0.01 were significantly higher in PRED cows than in DEX when compared with control values; wp < 0.05 when cows (Figure 5). DEX is compared with PRED.

GLUCOSE NEUTROPHILS

9,0 8,0 7,0 ..J 6,0 ~ 5,0

~ 4,0 □ CONTROLS 3,0 2000

2,0 0 ~IL.lljl..___...... ---~L.&p,1--~-.....ij~ ...... ;.-.:..i, 1,0 -2 0 6 24 48 72 96 144 0,0 TIME -2 0 6 24 48 72 96 144 TIME Figure 3. Effects of administration of DEX and PRED Figure 1. Effects of administration of DEX and PRED on blood neutrophil values in Holstein cows. Results on blood glucose values in Holstein cows. Results are are expressed as the mean ± standard error. (Reference expressed as the mean ± standard error. (Reference values: 600 - 4000/µl, Smith21 .) ap < 0.05, cp < 0.005, dp values: 1.9-3.9 mmol/L, Smith21 .) bp < 0.01, ep < 0.0005, < 0.001, ep < 0.0005, and rp < 0.0001 when compared rp < 0.0001, when compared with control values; wp < with control values. wp < 0.05 and xp < 0.01 when DEX 0.05, zp < 0.0001, when DEX is compared with PRED. is compared with PRED.

SPRING 2010 63 EOSINOPHILS LYMPHOCYTES

450 7000 -,------,,...... -.,...---,------.,,,...------400 6000 350 ..pµ.~~~:;;:...:..;..~ ~ ~ ~ ~ ~~~ 300 ~DEX -' 250 sooo ~~~ ~ ~~~~-;-rr...;.:.;..7;:t:;:-....:..:..~..... ---- ~ 200 ■ PRED ..J 4000 l".J DEX 150 □ CONTROLS ~ 3000 ■ PRED 100 □ CONTROLS 50 2000 0 -2 0 6 24 48 72 96 144 1000 TIME 0 ..µ,,a.._,_,..c...L..L,...W::.L...L.,:J~...... ~.L.:,.L.-...J~----.,.LA---- -2 0 6 24 48 72 96 144 Figure 4. Effects of administration of DEX and PRED TIME on blood eosinophil values in Holstein cows. Results are expressed as the mean ± standard error. (Reference Figure 6. Effects of administration of DEX and PRED values: 0-2,400/µl, Smith21.) ap < 0.05, dp < 0. 001, and on blood lymphocyte values in Holstein cows. Results ep < 0.0005 when compared with control values. wp < are expressed as the mean ± standard error. (Refer­ 21 0.05 when DEX is compared with PRED. ence values: 2,500 - 7,500/µl, Smith .) ap < 0.05, bp < 0.01, cp < 0.005, and rp < 0.0001 when compared with control values.

MONOCYTES

1200 MILK YIELD

1000 60 ,0 -~ ~ ,~ ...... ,... ;._··_---..-.... 't . - - -).r ~~ ,-·-·+>·· 800 -~ lil!DEX 50 ,0 -~ _, I ""i .;!, 600 ■ PRED , J I I ... 'I' T _L C/)40 ,0 I- ; - - ~- - 400 D CONTROLS a: a - I li!IDE X ~30,0 ...... W PRED 200 ~ ~ ■ :::i ~ ; ' Ii o CONTR OLS 20 ,0 .. ~ .. 0 ; II -2 0 6 24 48 72 96 144 ~ 10 ,0 .. .. ~ ; - TM: ; 0,0 ~ -2 -1 0 1 2 3 4 5 6 7 Figure 5. Effects of administration of DEX and PRED on blood monocyte values in Holstein cows. Results are TIME expressed as the mean ± standard error. (Reference Figure 7. Effects of administration of DEX and PRED values: 25 - 840 /µl, Smith21 . ) ap < 0.05 when compared on daily milk production in Holstein cows. Results are with control values; Yp < 0.005, when DEX is compared expressed as the mean± standard error. ap < 0.05 when withPRED. compared with control values.

Discussion The pharmacological mechanism of action of cor­ ticosteroids in the treatment of ketosis in dairy cattle Problems of cattle for which systemic corticosteroid is not yet fully understood. According to McDonald, 15 therapy is most frequently recommended are ketosis corticosteroids cause both an increase in gluconeogen­ and inflammatory processes. Unfortunately, there is esis and a decrease in peripheral utilization of glucose. not yet a corticosteroid having activity against only According to Herdt and Emery, 11 glucocorticoids induce one of these two kinds of problems. Apparently, the hyperglycemia in both healthy and ketotic ruminants. anti-inflammatory effects and metabolic effects are dif­ The mechanism by which this hyperglycemia is induced ferent aspects of the same process.15 This has practical may be different in ruminants than in monogastric ramifications, because the ketotic state in dairy cattle is animals. So far, available evidence suggests that sometimes secondary to a subacute infectious process, corticosteroids induce a hyperglycemia in ruminants such as metritis or peritonitis. Should a corticosteroid by changing glucose distribution, rather than by in­ be administered to such cases, the infectious process creasing the rate of gluconeogenesis. This conclusion may be exacerbated4 or the effectiveness of antimicrobial is supported by research showing that glucocorticoid therapy may be severely compromised. 5 therapy in cattle and sheep does not result in a negative

64 THE BOVINE PRACTITIONER-VOL. 44, NO. 1 Table 1. Summary of the effects of administration of DEXa and PREDh on glucose, leukocyte values, and milk yield in lactating Holstein dairy cows. Parameter measured DEX PRED Hyperglycemia At 6 through 96 hours At 24 hours Leukocytosis At 6 and 24 hours None Neutrophilia At 6 through 72 hours At 6 hours Eosinopenia At 48 hours At 48 hours Monocytosis At 6 and 48 hours At 24 hours Lymphopenia At 48 and 96 hours At 6, 24, 48, 96, and 144 hours Milk production decrease During days 1, 2, and 6 None aDEX is dexamethasone sodium phosphate and dexamethasone phenyl propionate. hPRED is prednisolone acetate.

nitrogen balance, or cause an increase in the enzymes erate blood glucose increases. Prednisone, prednisolone of gluconeogenesis. 11 pivalate, and triamcinolone acetonide, produced modest Several studies have shown that glucocorticoids increases. 1 4 10 26 decrease milk production in healthy dairy cows. • • • Peak blood glucose values were achieved within In addition, a correlation was found between the mag­ 24 hours following administration of six of these com­ nitude of the drop in milk production and the induced pounds. With the seventh compound (prednisone), peak hyperglycemia. A tentative conclusion was reached that glucose levels were achieved at 36 hours following ad­ a reduction in the utilization of glucose for synthesis of ministration. Blood glucose values returned to baseline lactose may be, at least in part, responsible for the in­ levels by 72 hours following administration of six of these crease in the blood levels of glucose. 11 Recently however, seven compounds. With the seventh compound (predni­ two different groups of researchers have reported that sone), blood glucose values had not returned to baseline administration of a single dose of dexamethasone-21- values by the end of the 96-hour observation period. isonicotinate to healthy dairy cattle during the second Flumethasone and dexamethasone produced the week oflactation did not significantly affect milk produc­ most dramatic reductions in milk production in normal tion, even though blood glucose values were significantly cows. Flumethasone pivalate produced moderate reduc­ increased. Jorritsma et al1 2 studied calving heifers, and tions, while 9-fluoroprednisolone acetate, prednisone, Furll and J ackeF studied very high producing cows. prednisolone pivalate, and triamcinolone acetonide It has been shown in ketotic dairy cattle that an produced modest reductions. Milk production was most increase in blood glucose levels is associated with a severely depressed on day 1 post-administration with 4 26 decrease in blood ketone bodies. • This suggests that five of these compounds. With the other two compounds in bovine ketosis the beneficial effect of corticosteroid (prednisone and triamcinolone acetonide), milk produc­ treatment might be a result of increased blood glucose tion was most depressed on day 2 post-administration. concentration, which is then responsible for normalizing Following administration of six of these seven com­ the metabolic machinery. 15 pounds, milk production returned to baseline levels All of the many synthetic corticosteroid compounds on day 3. Milk production had still not returned to currently available for use by clinicians are not univer­ baseline levels by the end of the observation period (day sally interchangeable. Different compounds can have 4) following administration of the seventh compound different kinds and degrees of activity on target cells, (prednisone). The authors reported that flumethasone different rates of absorption from injection sites, and and dexamethasone produced the greatest increases in different rates of clearance from blood and tissues. As blood glucose values and the greatest decreases in milk a case in point, Braun et al4 evaluated seven different production; they were also most efficacious for treat­ corticosteroid compounds for their effects on blood glu­ ment of ketosis. cose levels and milk production in normal and ketotic Weirda et al26 later conducted a similar study in dairy cows, and for efficacy in treatment of ketosis. which dexamethasone di-methyl butyrate and dexa­ Three compounds, flumethasone, dexamethasone, and methasone 21-isonicotinate were administered to nor­ flumethasone pivalate, produced dramatic increases mal lactating dairy cows. Dexamethasone di-methyl in blood glucose values in normal lactating cows. One butyrate produced the greatest increases in blood compound (9-fluoroprednisolone acetate) produced mod- glucose values, with peak values occurring at 72 hours

SPRING 2010 65 post-administration, and returning to baseline levels persistent, the magnitude of this milk suppression was at 96 hours post-administration. With dexametha­ classified by the authors as "modest".4 sone 21-isonicotinate, blood glucose values peaked at The product label states that administration of 24 hours and returned to baseline levels at 96 hours DEX to ketotic cows will increase blood glucose concen­ post-administration. Dexamethasone 21-isonicotinate trations for seven to eight days (168 to 192 hours). In produced the largest decreases in milk production, and the present study performed in normal lactating dairy the magnitude of those reductions was similar in both cows, DEX produced a rapid, marked increase in blood high-producing (>55 lb [25 kg]/day) and low-producing glucose values, and hyperglycemia persisted from six (<55 lb/day) cows. Dexamethasone di-methyl butyr­ hours through 96 hours post-administration. Blood ate reduced milk production in high-producing cows, glucose values were not determined between 96 and 144 but not in low-producing cows. With both compounds, hours. However, at 144 hours, blood glucose values in the greatest decreases in milk production occurred on DEX cows were significantly higher than in PRED cows, day 2 post-administration. Milk production returned but the controls were not available for comparison. As to baseline levels on day 3 (dexamethasone di-methyl a substitute for controls, 144-hour blood glucose values butyrate) or day 4 (dexamethasone 21-isonicotinate) from DEX cows were statistically compared with pooled post-administration. pre-treatment values from control cows, but the differ­ Both compounds were equally effective for treating ence was not significant. ketosis in dairy cows, which was somewhat in conflict Possibly, the effects of DEX on blood glucose values with Braun et al4 who reported corticosteroid efficacy to actually are more persistent in ketotic cows than in be highly correlated with the degree of hyperglycemia normal cows. Nevertheless, because of the marked and produced and the magnitude of milk yield reduction. One persistent effects of DEX on both blood glucose values could speculate that the capability of dexamethasone and milk production, the authors anticipate that it will 21-isonicotinate to produce longer acting hyperglycemia, prove to be a highly efficacious drug for treatment of and greater and more persistent reductions in milk pro­ ketosis in dairy cows. Parenthetically, it is unlikely that duction, might have compensated for its more modest PRED would be a satisfactory treatment for ketosis, hyperglycemic effect. However, this explanation finds because its rather "modest" effect on blood glucose levels only modest support from two studies. occurred only at 24 hours. Jorritsma et al12 administered dexamethasone-21- Among existing anti-inflammatory drugs, the isonicotinate to normal dairy heifers in the second week corticosteroids are some of the most efficient. In this of lactation. Blood glucose values were significantly study, changes in the concentrations of some of the elevated only on day 2 post-administration, and milk formed elements of the blood were used as an indicator production was not significantly affected. Furll and of these anti-inflammatory effects. 15 Several different Jackel7 administered dexamethasone-21-isonicotinate mechanisms of action have been proposed to explain to normal, very high producing dairy cows in the second these effects. 13 According to Ferguson and Hoenig,6 these week oflactation. Blood glucose values were significantly anti-inflammatory effects result in changes in the con­ elevated from day 1 through day 3 post-administration centration, distribution and function ofleukocytes, and without any significant effect on milk production. in inhibition of phospholipase A activity in the plasma Wagner and Apley23 also observed no effect on milk membrane of these leukocytes. production following administration of isoflupredone Following administration of various corticosteroids to dairy cows that were recovering from experimental to various species of domestic animals, the following endotoxin-induced mastitis, but did not study the effect changes in the leukogram have been observed: neutro­ on blood glucose. It should be obvious, at this point, philia, without a left shift (no increase in numbers of that the mechanisms by which glucocorticoid therapy immature neutrophils); eosinopenia; monocytosis in the 14 15 promotes recovery from ketosis in lactating dairy cows dog and occasionally in the cat, • and lymphopenia. are far from adequately understood. The mechanisms involved in the mediation of these Of the nine corticosteroid compounds that had changes in the leukogram are as follows: 14 neutrophilia previously been evaluated in lactating dairy cows results from a combination of a) decreased migration of (excluding isoflupredone), only prednisone produced circulating neutrophils into peripheral tissues, and b) as persistent a hyperglycemic effect as DEX did in the increased release of neutrophils into the blood stream present study. However, the degree of hyperglycemia from the bone marrow. Lymphopenia results from a) produced by prednisone in that study was characterized increased migration of circulating lymphocytes into as only "modest".4 Of these same nine compounds, only lymphoid tissues and/or bone marrow, and b) temporary prednisone caused more persistent suppression of milk sequestration in these locations. Eosinopenia results production than DEX in this study. However, although from a combination of a) sequestration of eosinophils in the effect of prednisone on milk production was quite tissues, and b) inhibition of their release from the bone

66 THE BOVINE PRACTITIONER-VOL. 44, NO. 1 marrow. Monocytosis may be caused by mobilization of as hamsters, mice, rats, and rabbits, glucocorticoid­ marginated cells within the blood vasculature. induced lymphopenia in cattle is not as easily induced Veterinary textbooks usually summarize the effects or as profound. of corticosteroid therapy on the leukogram of animals Although glucocorticoid-induced monocytosis as follows: The peak response occurs from four to eight has been described in the dog and cat, 14•15 the effect of hours following administration. Values then return to glucocorticoids on bovine monocyte kinetics is not so reference ranges within 24 hours following a single injec­ well understood.17 In our study, significant increases in tion of a short acting corticosteroid. Following long-term blood monocyte values occurred at 24 hours following therapy, where the corticosteroid is injected daily for 10 administration of PRED and at six and 48 hours after or more days, values return to reference ranges with the administration of DEX. Schalm et al20 first reported 14 25 two to three days. • These summary statements do not glucorticoid-induced monocytosis in dairy cows following specify the corticosteroid compounds used or the animal treatment with 9-floroprednisolone. Administration of species in which the studies were conducted. Our study adrenocorticotropic hormone to normal cattle did not 7 8 22 and others · · demonstrate that this definition does not result in any changes in the numbers of circulating adequately describe the effects of modern corticosteroid monocytes. 16 compounds on the leukogram of cattle. In our study, the effects of both corticosteroids on Conclusions lymphocyte counts were somewhat surprising in that PRED caused lymphopenia at 6, 24, 48, and 96 hours, Because DEX produced more dramatic and persis­ while DEX caused lymphopenia only at 48 and 96 hours. tent changes in blood glucose values and milk production This was the only parameter studied in which the effects than did PRED, the authors believe that DEX is likely of PRED were more marked than those of DEX. to be more efficacious than PRED for treating ketosis Another unexpected observation was made during in dairy cows. Because DEX produced more dramatic this study. Prior to administration of either cortico­ and persistent effects on blood neutrophil values than steroid, blood neutrophil concentrations were always PRED, it is also likely to be a better option for use as higher than blood lymphocyte concentrations, both in an anti-inflammatory drug. the principals and in the controls. This finding is the reverse of what is stated in most hematology textbooks. Acknowledgments The authors do not believe that this could have been a result of any stress associated with sample collection The authors wish to acknowledge the contributions since a great deal of effort was made to minimize this to this manuscript of the following individuals and or­ stress. In addition, there is always a significant time ganizations: Casal de Quintanelas, Prof. Yolanda Vaz, lag (at least four hours) between application of a stress Dr. Kenneth Latimer, Dr. Salome Gon~alves, Dr. Bruno to an animal and the appearance of neutrophilia and Baptista, CIISA and Intervet who financed this study. lymphopenia in the animal's hemogram. 14 Most textbooks state that administration of cortico­ Endnotes steroids to animals will produce lymphopenia. However, three groups of workers recently reported that blood aDexafort - Intervet Portugal-Sau.de Animal, 2725-397 lymphocyte values were not significantly affected by ad­ Mem Martins/Portugal ministration of a single dose of a corticosteroid to cattle. bHostacortina - Intervet Portugal-Sau.de Animal, 2725- Furll and J ackeF and Thanasak et al2 2 administered 397Mem Martins/Portugal dexamethasone-21-isonicotinate to normal high produc­ ci-Stat, Sensor Devices Incorporated, Waukesha, WI, ing dairy cattle in the second week oflactation. Bednarek USA et al3 administered flumethasone to calves with an dCell Dyn 3700, Abbott Diagnostic Division, Abbott experimentally induced, noninfectious, lung inflamma­ Park, IL, USA tion model. Either not all corticosteroid compounds are capable of eliciting lymphopenia, or not all corticosteroids References are capable of eliciting lymphopenia in all species. It is 1. Baird GD, Heitzman RJ: Glucocorticoid administration in the dairy also possible that changes in lymphocyte values might cow. Br Vet J 125:xiii-xv, 1969. have been observed in these three studies if higher dos­ 2. Barth AD: Induced abortion in cattle, in Morrow DA (ed): Current ages and/or repeated injections had been utilized. Therapy in Theriogenology 2. Philadelphia, WB Saunders Co, 1986, According to Roth and Kaeberle 17 there are marked pp 205-209. 3. Bednarek D, Szuster-Ciesielska A, Zdzisinska B, Kondracki M, species differences in the response of circulating lym­ Paduch R, Kandefer-Szerszen M: The effect of steroidal and non­ phocytes to glucocorticoid hormone administration. steroidal anti-inflammatory drugs on the cellular immunity of calves Compared with the corticosteroid-sensitive species, such with experimentally-induced local lung inflammation. Vet Immun and Immunopath 71:1-15, 1999.

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