Advance Publication

The Journal of Veterinary Medical Science

Accepted Date: 21 Jul 2011

J-STAGE Advance Published Date: 4 Aug 2011

1

1

FULL PAPER Internal Medicine 2

Therapeutic and adverse effects of flunixin-meglumine in adult and young 3

cats 4

5

Kenji TAKATA１）*, Yoshiaki HIKASA１）, Hiroshi SATO２） 6

１）Laboratory of Veterinary Internal Medicine, Department of Veterinary Medicine, 7

Faculty of Agriculture, Tottori University, Koyama-Minami 4-101, Tottori 680-8533, and 8

２）Laboratory of Pharmacology and Experimental Therapeutics, Division of 9

Pathological Sciences, Kyoto Pharmaceutical University, Misasagi-Nakauchicho 5, 10

Yamashinaku, Kyoto 607-8414, Japan 11

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13

14

CORRESPONDENCE TO: TAKATA, K., Laboratory of Veterinary Internal Medicine, 15

Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, 16

Koyama-Minami 4-101, Tottori 680-8533, Japan. 17

Tel:(81)857-31-5431, Fax:(81)857-31-5431 18

e-mail: k_takata32vet@yahoo.co.jp 19

20

Running head: 21

EFFECT OF FLUNIXIN IN ADULT AND YOUNG CATS 22

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1

ABSTRACT. In this study, we elucidated the difference in nonsteroidal 2

anti-inflammatory drug sensitivities between young and adult cats on therapeutic and 3

adverse effects. In the prevention of lipopolysaccharide (LPS)-induced hyperthermia 4

using flunixin-meglumine, young (<3 months old) and adult (>12 months old) cats of 5

both sexes were given LPS (0.3 µg/kg, i.v.), and body temperature was measured 24 hr 6

later. Flunixin (1 mg/kg, s.c.) was administered 30 min before the LPS injection. 7

LPS-induced hyperthermia was almost completely inhibited by pre-treatment with 8

flunixin in both adult and young cats. In addition, flunixin showed almost the same 9

antipyretic effects in both young and adult cats. The animals were administered flunixin 10

(1 mg/kg, s.c.) once a day for 3 days, and sacrificed 24 hr later to examine the 11

gastrointestinal mucosal lesions. In adult cats, flunixin caused many severe lesions in 12

the small intestine. In contrast, very few gastrointestinal lesions were produced by 13

flunixin in young cats. In the pharmacokinetics of flunixin, plasma concentrations of 14

flunixin were analysed using a high performance liquid chromatography. There were no 15

significant differences in plasma concentration of flunixin between young and adult cats 16

from 0.5 to 4 hr after the injection. These results demonstrated that NSAIDs could be 17

used more safely in young than in adult cats from the points of gastrointestinal adverse 18

effects. Furthermore, this difference in gastrointestinal lesions between adult and young 19

cats was not related with the plasma concentration of flunixin. 20

KEY WORDS: flunixin-megulumine, gastrointestinal effect, lipopolysaccharide, 21

nonsteroidal anti-inflammatory drug, pharmacokinetics 22

23

3

Nonsteroidal anti-inflammatory drugs (NSAIDs) are the most widely used analgesics 1

in veterinary and human medicine. In most species, they are very effective in acute and 2

chronic pains. For example, NSAIDs are often the first drugs used for treatment of pain 3

caused by osteoarthritis in veterinary medicine [22]. In the analgesic study of cats, the 4

effect of flunixin-meglumine (FNX) has been reported in 40 cats undergoing a variety of 5

surgical procedures [9]. It is also well known that NSAIDs cause some adverse effects 6

such as gastrointestinal side-effects in the veterinary medicine. In rats, many kind of 7

NSAIDs have been reported to cause gastrointestinal lesions because of the inhibition of 8

prostaglandins synthesis even new NSAIDs [1]. However, the data on the usage of 9

NSAIDs in cats are less complete than in dogs and, to date, there are no published data 10

about gastrointestinal side-effects in cats. 11

Most NSAIDs are cleared from the body through hepatic metabolism comprising 12

primarily glucuronidation followed by excretion of the resultant polar metabolites via bile 13

and/or urine. Flunixin is well absorbed from the gastrointestinal tract and undergoes 14

enterohepatic circulation, resulting in a bioavailability of >100% in dogs and cats [17]. At 15

least, two other active transport pathways are involved in the pharmacokinetics of 16

flunixin-meglumine in cats. In the primary pathway, flunixin is actively transported into 17

liver cells glucuroconjected, and then excreted into bile. The second pathway, renal 18

tubular secretion, is a minor pathway of excretion [10]. For many NSAIDs, 19

glucuronidation is an important pathway. For example, the metabolism of ketoprofen is 20

dominated by glucuronidation reactions in dogs [27]. However, many studies have 21

reported that glucuronidation in cats is limited [5, 7, 11, 19, 20, 25, 26, 31]. Therefore, 22

NSAIDs may induce more severely adverse-effects in cats compared with other species. 23

On the other hand, in human beings, NSAIDs are widely used in children. Adverse 24

4

gastrointestinal or renal events from short-term use of ether ibuprofen or acetaminophen 1

appear to be quite rare in children [15]. Furthermore, in vasopressin-dependent rats, it is 2

reported that lesion area of old rats caused by indomethacin is significantly severer than 3

lesion area of young rats [8]. However, there is little data comparing the use of NSAIDs 4

in young and adult cats. 5

There are many NSAIDs including the FNX in veterinary medicine market. In USA 6

and European countries, the FNX is commonly used in horses and dogs. Experimentally, 7

the FNX did not produce a remarkable adverse effect on the gastrointestinal tract in 8

calves [14]. In a comparative study of the postoperative analgesia of phenylbutazone, 9

FNX and carprofen, the FNX showed an analgesic effect of the longest duration (12.8 h), 10

compared to phenylbutazone (8.4 h) and carprofen (11.7 h) in horses [12]. However, 11

there are no available data about the therapeutic and adverse effects in cats. 12

The purpose of the present study was to elucidate the difference on therapeutic and 13

adverse effects of flunixin-meglumine between adult and young cats. As well as we know, 14

this is the first study about that. 15

16

MATERIALS AND METHODS 17

Animals: This study compared effects of flunixin administration (flunixin, 1 mg/kg, 18

s.c.) in young and adult cats in terms of antipyretic, pharmacokinetics and gastrointestinal 19

adverse effects. Young (<3 months, 0.4–0.9 kg body weight) and adult (>6 months, >3 kg 20

body weight) cats of both sexes were used (4 animals in each group). The cats were kept 21

in the experimental room more than 7 days before the start of the experiment. During 22

experiments, the animals were housed individually at an ambient temperature of 25 ± 1°C 23

5

with a 12 hr light/dark cycle, with the lights being switched on at 07:00. All of cats 1

received commercially available dry cat food containing >30% protein, >9% fat, <4% 2

fibre, <10% mineral and <10% water. Water was allowed ad libitum. Experiments were 3

conducted between 08:30 and 17:00. Study protocols were approved by the Animal 4

Research Committee of Tottori University, Tottori, Japan. 5

Drugs: Flunixin-meglumine (Banamin®; flunixin 50 mg/ml, Dainippon Sumitomo 6

Pharmaceutical Co. Ltd, Osaka, Japan), xylazine (Ceractal ®, 2% solution, Bayer, Japan), 7

sodium pentobarbital (NembutalⓇ, Dainippon Sumitomo Pharmaceutical Co. Ltd, Osaka, 8

Japan), and lipopolysaccharide (LPS, Lot no.116354OJC, W. E. Coli, Wako Pure 9

Chemical Industries Ltd, Osaka, Japan) were used in this study. 10

Design for prevention of LPS-induced hyperthermia using flunixin-meglumine: The 11

experiment consisted of five treatment groups in both young and adult cats. The four cats 12

were assigned to each of the five treatment groups. For the induction of pyrexia, LPS (0.313

μg/kg) was administered intravenously (i.v.). Flunixin-meglumine were administered 14

subcutaneously (s.c.) 0.5 hr before LPS injection. In both young and adult cats, the control 15

group was received 0.5 ml/kg physiological saline solution (PSS, s.c. and i.v.). The LPS 16

group was injected PSS before LPS injection. The cats in the other groups received 0.25, 17

0.5 or 1 mg/kg flunixin (s.c.), and LPS (0.3 µg/kg, i.v.). Those groups are hereafter referred 18

to as CONT, LPS, FNX0.25, FNX0.5 and FNX1.0. Body temperature was measured at 0.5 19

hr before and 0, 0.5, 1, 2, 4, 8 and 24 hr after the LPS injection. 20

Design for gastrointestinal lesions by flunixin: This experiment consisted of 21

non-injected groups (young and adult groups) and flunixin-injected groups (young and 22

adult groups). To determine gastrointestinal lesions, 1 mg/kg flunixin was administered 23

6

(s.c.) once a day after the morning meal for 3 days. In both groups, the animals were 1

sacrificed using xylazine (1.0-3.0 mg/kg, s.c.) and sodium pentobarbital（50-75 mg/kg, 2

i.v.）24 hr after the final injection of flunixin. Mucosal lesions in the stomach and 3

intestine were examined using a stereomicroscopy. The percentage of the lesion area was 4

calculated as 100% of total small intestine area. 5

Design for pharmacokinetics of flunixin: Flunixin-meglumine were administered 1.0 6

mg/kg subcutaneously (s.c.) in young and adult cats. The pharmacokinetics of flunixin 7

were analysed using a high-performance liquid chromatography (HPLC). The HPLC 8

analysis was performed by using a model L-62000 (Hitachi Co. Ltd, Tokyo, Japan). For 9

pharmacokinetic analysis, blood samples were collected from the jugular vein at 0, 0.5, 1, 10

2 and 4 hr after flunixin injection. The plasma was separated and stored at −30°C for 11

1 week, after which it was analysed by HPLC. Chromatographic separations were 12

performed on Asahipak ODS-3 (4.6 mm ID × 250 mm L; Asahi Kasei Co. Ltd, Japan). The 13

mobile phase was composed of acetonitrile–methanol–water (40:40:20, v/v/v), with 0.04% 14

glacial acetic acid. The solution was filtered through a 0.45 µm membrane prior to use. The 15

flow rate was 1.1 ml/min, and column temperature was maintained at 40°C. The channel 16

on the UV detector was configured at 330 nm. The volume injection was 20 µl. 17

Statistical analysis: All values are expressed as means and standard error. In the data 18

of body temperature, one-way analysis of variance for repeated measures was used to 19

examine the time effect within each group and the four groups’ effect at each time point. 20

When a significant difference was found, a least significant difference (LSD) test was 21

used to compare the means. The other data were subjected to an analysis of variance. 22

When F value was not significant, differences between two groups were analyzed by 23

Student’s t-test. When a significant F value was found, a Wilcoxon-Mann-Whitney test 24

7

was used for the statistical evaluation. The level of significance in all tests was set at P < 1

0.05. 2

3

RESULTS 4

Prevention of LPS-induced hyperthermia using flunixin-meglumine: As shown in Fig. 5

1, in young cats, the mean body temperature before LPS injection was 38.5 ± 0.1°C 6

(n = 4). In the LPS group, body temperature at 1, 2 and 4 hr was significantly higher 7

compared to at -0.5 hr (P<0.05). After LPS injection, body temperatures increased and 8

reached a maximum 2 hr after the injection (39.35 ± 0.15 °C). After the peak of 9

LPS-induced hyperthermia at 2 hr, body temperature decreased. Body temperature was 10

significantly higher in the LPS group compared to CONT at 0.5, 1, 2, 4 and 8 hr 11

(P<0.05). 12

As shown in Fig. 2, flunixin suppressed hyperthermia induced by LPS in a 13

dose-dependent manner. In the FNX0.25 group, body temperature at 0.5, 1, 2 and 6 hr 14

after LPS injection was significantly higher than at -0.5 hr (P<0.05). In the FNX0.5 and 15

FNX1.0 groups, body temperatures did not significantly change at each elapsed time 16

compared with -0.5 hr. Two hours after LPS injection, body temperature was significantly 17

lower in cats of FNX0.25 group than in the LPS group (P<0.01). In the FNX0.5 and 18

FNX1.0 groups, body temperatures at 1, 2 and 4 hr after LPS injection were significantly 19

lower than in the LPS group (P<0.05 to 0.01). 20

As shown in Fig. 3, in adult cats, mean body temperature in the LPS group was 21

significantly (P<0.05 to 0.01) higher at 1, 2, 4 and 8 hr compared with -0.5 hr. Body 22

temperature increased to a maximum (39.6± 0.27 °C) at 2 hr after the LPS injection, and 23

then decreased gradually. Body temperature was significantly (P<0.01) higher at 2, 4 and 24

8

6 hrs in the LPS group than the CONT group. 1

As shown in Fig. 4, flunixin suppressed hyperthermia caused by LPS injection in a 2

dose-dependent manner in adult cats. In the FNX0.25 group, body temperature at 4 and 8 3

hr after LPS injection was significantly (P<0.05 to 0.01) higher than at -0.5 hr value. In 4

the FNX0.5 and FNX1.0 groups, body temperatures did not significantly change at each 5

elapsed time compared with -0.5 hr. At 1 and 2 hr after LPS injection, body temperature 6

was significantly (P<0.01) lower in the FNX0.25 group than in the LPS group. Body 7

temperatures in FNX0.5 group were significantly (P<0.05 to 0.01) lower compared to the 8

LPS group at 1, 2 and 4 hr after LPS injection. Body temperature in the FNX1.0 group 9

was significantly (P<0.05 to 0.01) lower from 1 to 8 hr compared to the LPS group. 10

In both young and adult cats, body temperature increased significantly from 2 hr after 11

LPS injection. In both age groups, higher dosing levels of flunixin greatly suppressed the 12

hyperthermia induced by LPS. 13

Gastrointestinal side-effects: In both adult and young cats, lesions were observed in 14

the duodenum and lower small intestine following repeated doses of flunixin. In the 15

stomach, some lesions were observed in adult cats, but not in young cats. As shown in 16

Fig. 5, the lesion area (cm2) caused by flunixin in both duodenum and small intestine 17

were significantly less in young cats compared with adult cats. In addition, the lesion rate 18

(%) of small intestine was significantly less in young cats than adlut cats (Fig. 6). In both 19

adult and young cats of non-injected groups, gastrointestinal lesions were not observed. 20

Pharmacokinetics of flunixin: As shown in Fig. 7, in both adult and young cats, blood 21

levels of flunixin reached a maximum concentration at 0.5 hr after a subcutaneous 22

injection. One hr after injection, flunixin concentration decreased to approximately half 23

of the maximam level, and then decreased gradually. The area under time curve (AUC) of 24

9

the plasma flunixin concentration was not significantly different between adult and young 1

cats. 2

3

DISCUSSION 4

Flunixin is one of the traditional NSAIDs, and this drug has the strong anti- 5

cyclooxygenase(COX) activity [18]. COX has been recognised as the principal enzyme 6

catalyzing the synthesis of prostanoids from arachidonic acid. The COX has the two 7

isoforms, COX-1 and COX-2 [23, 24]. COX-1 is constitutively expressed in almost of 8

cells, while COX-2 is induced in inflammatory conditions. Much effort has gone into 9

developing NSAIDs that selectively inhibit COX-2 rather than COX-1, so as not to affect 10

the homeostasis functions of the prostanoids preferentially synthesised by COX-1, and in 11

particular to reduce the gastrointestinal bleeding caused by COX-1 inhibition [6, 14]. In 12

a vitro study, the FNX has a lower COX-2 selectivity in comparison with carprofen and 13

meloxicam [2]. LPS from Gram-negative bacteria, stimulates host defence cells to 14

release several endogenous pyrogens. Many evidences show that fever induced by LPS is 15

mediated by a number of endogenous pyrogenic cytokines produced [4, 23, 24, 28]. 16

These pyrogenic cytokines are transported to the thermoregulatory center in the preoptic 17

area, and they stimulate the production of COX-2-dependent prostaglandin (PG) E2, the 18

putative final mediator of the febrile response [16]. 19

The present study demonstrated that LPS caused hyperthermia in both young and 20

adult cats, and that flunixin suppressed dose-dependently hyperthermia induced by LPS. 21

This study also revealed that flunixin at the dose of more than 0.5 mg/kg (s.c.) can 22

significantly suppress hyperthermia. Then, veterinarians may be use flunixin in doses 23

10

higher than 0.5 mg/kg for treatment of bacterial febrile conditions. In a study, the FNX 1

has been administered at 1 mg/kg/day for 7 consecutive days in cats [29]. In this study, 2

the biochemical and haematological variables did not significantly alter in cats [29]. 3

Therefore, it is conceivable that the dosage of 0.5 to 1 mg/kg FNX may be safely used for 4

cats. 5

The present study further demonstrated that in both adult and young cats, lesions were 6

observed in the duodenum and lower small intestine following repeated doses of flunixin. 7

In the stomach, some lesions were observed in adult cats, but not in young cats. Since it 8

could be a result of the difference in small intestinal area between adult (387 ± 24.7 cm2) 9

and young cats (234 ± 15.7 cm2), we calculated the rate of erosions relative to the surface 10

area of the intestinal lumen. As shown in Fig. 6, in adult cats, the erosion area was 11

1.52 ± 0.89% of total surface area, while in the young cats it was 0.09 ± 0.04%, which 12

was significantly lower than adult cats. These results revealed that gastrointestinal lesions 13

were less in young than in adult cats. There are some possible explanations about those 14

results. Firstly, we examined about the plasma concentration of flunixin in this study. 15

Pharmacokinetic data of flunixin using HPLC in young cats were similar to those in adult 16

cats. In the pharmacokinetics of flunixin, Tmax after oral doses of flunixin is 17

approximately 1.3–2 hr in cats [30]. The elimination half-life has been found to be 1–1.5 18

hr, using an assay with a limit of 0.25 µg/mL [29, 30]. In our study, Tmax after 19

subcutaneous injection was 0.5–1 hr, and the elimination half-life was around 1 hr in both 20

young and adult cats. Therefore, our study demonstrated that plasma concentration of 21

flunixin was not different between young and adult cats. 22

An another possible explanation is that there may be significant age-based differences 23

in bile acids, enterobacteria, and mucosal defence. Alterations of intestinal glycocalyx 24

11

have been reported in rats after indomethacin administration, suggesting that changes in 1

epithelial mucin content may contribute to NSAID-induced deleterious effect on bowel. 2

Inflammation and ulceration are the ultimate result, once the mucosal barrier has been 3

disrupted by the local and systematic effects of damaging therapeutic agents [3]. 4

Intraluminal factors including bacteria may be key elements in the initiation of damage in 5

NSAID-induced mucosal erosions. On the other hand, the administration of indomethacin 6

has been reported to induce an increase in bacterial counts in the mucosa [1]. There is a 7

study suggesting that bacterial flora may play a role on the pathogenesis of NSAIDs 8

bowel injury. This study has demonstrated that antimicrobials attenuated NSAIDs 9

induced enteropathy in rats [13]. From these observations, it may be possible that 10

gastrointestinal bacteria counts may be lower in young cats than in adult cats. Therefore, 11

some factors described above may be involved in the reasons why NSAID-induced 12

erosion is milder in young than in adult cats. However, it is unknown why the 13

gastrointestinal effects in the young cat are milder than those in the adult cat. 14

In conclusion, this study demonstrated that flunixin suppressed dose-dependently 15

hyperthermia induced by LPS in both young and adult cats, and that flunixin-induced 16

gastrointestinal lesions were less in young than in adult cats. This difference between 17

young and adult cats on gastrointestinal adverse effects was not related with the plasma 18

concentration of flunixin. In the present study, as the FNX caused severe gastrointestinal 19

adverse effects in adult cats, it may not be suitable for the use to adult cats. Although the 20

essential causes of the difference are unknown, the present results suggest that NSAIDs 21

could be safer in young than in adult cats, with respect to gastrointestinal adverse effects. 22

23

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Legends for Figures 1

Fig. 1. Hyperthermia induced by LPS in young cats. LPS (0.3 µg/kg body weight) was 2

injected i.v. at 0 hr. The control group was received 0.5 ml/kg physiological saline 3

solution (PSS, s.c. and i.v.). The LPS group was injected PSS before LPS injection. Those 4

groups are hereafter referred to as CONT and LPS. Data show the mean value and S.E. of 5

4 cats. At 0.5, 1, 2, 4 and 8 hr after LPS injection, body temperature was significant 6

higher than control (CONT). * P<0.05, significantly different from body temperature at 7

-0.5 hr value. # P<0.05; ##P<0.01, significantly different from the CONT group. 8

9

Fig. 2. Effect of flunixin on hyperthermia induced by LPS in young cats. LPS (0.3 10

µg/kg body weight) was injected i.v. at 0 hr. Flunixin was administered s.c. at 0.5 hr 11

before LPS injection. The control group was received 0.5 ml/kg physiological saline 12

solution (PSS, s.c. and i.v.). The LPS group was injected PSS before LPS injection. The 13

cats in the other groups received 0.25, 0.5 or 1 mg/kg flunixin (s.c.), and LPS (0.3 µg/kg, 14

i.v.). Those groups are hereafter referred to as CONT, LPS, FNX0.25, FNX0.5 and 15

FNX1.0. Data show the mean value and S.E. of 4 cats. At 1, 2 and 4 hr after LPS 16

injection, both FNX0.5 and FNX1.0 significantly suppressed hyperthermia induced by 17

LPS. FNX 0.25 also significantly suppressed hyperthermia induced by LPS at 2 hr after 18

LPS injection. * P<0.05, significantly different from body temperature at -0.5 hr value. # 19

P<0.05; ##P<0.01, significantly different from the LPS group. The LPS group is same as 20

for Fig. 1. 21

22

Fig. 3. Effect of flunixin on hyperthermia induced by LPS in adult cats. LPS (0.3 µg/kg) 23

was injected i.v. at 0 hr. The control group was received 0.5 ml/kg physiological saline 24

17

solution (PSS, s.c. and i.v.). The LPS group was injected PSS before LPS injection. Those 1

groups are hereafter referred to as CONT and LPS. Data show the mean value and S.E. of 2

4 cats. Body temperature was significant higher at 2, 4 and 6 hr in the LPS group than the 3

control (CONT) group. * P<0.05; ** P<0.01, significantly different from -0.5 hr value. # 4

P<0.01, significantly different from the CONT group. 5

6

Fig. 4. Effect of flunixin on hyperthermia induced by LPS in adult cats. LPS (0.3 µg/kg) 7

was injected i.v. at 0 hr. The control group was received 0.5 ml/kg physiological saline 8

solution (PSS, s.c. and i.v.). The LPS group was injected PSS before LPS injection. The 9

cats in the other groups received 0.25, 0.5 or 1 mg/kg flunixin (s.c.), and LPS (0.3 µg/kg, 10

i.v.). Those groups are hereafter referred to as CONT, LPS, FNX0.25, FNX0.5 and 11

FNX1.0. Data show the mean value and S.E. of 4 cats. At 1 and 2 hr after LPS injection, 12

FNX0.25 significantly suppressed hyperthermia induced by LPS. FNX0.5 and FNX 1.0 13

groups were almost-completely suppressed hyperthermia induced by LPS. * P<0.05; ** 14

P<0.01, significantly different from body temperature at -0.5 hr value. # P<0.05; 15

##P<0.01, significantly different from the LPS group. The LPS group is same as for Fig. 16

3. 17

18

Fig. 5. Gastrointestinal lesions induced by flunixin in adult and young cats. 19

Flunixin (1 mg/kg body weight s.c.) was administered for 3 days; once a day after a 20

morning meal. The animals were sacrificed 24 hr after the final dose of flunixin, and 21

gastrointestinal mucosal lesions were examined. Data show the mean value and S.E. of 5 22

cats. In young cats, very few gastrointestinal lesions were produced by flunixin. * 23

P<0.05; ** P<0.01, significantly different from adult cats. 24

18

1

Fig. 6. Percentages of small intestinal lesion area induced by flunixin in adult and 2

young cats. The percentage of the lesion area was calculated as 100% of total small 3

intestine area. Flunixin (1 mg/kg body weight, s.c.) was administered for 3 days; once a 4

day after a morning meal. The animals were sacrificed 24 hr after the final dose of 5

flunixin, and gastrointestinal mucosal lesions were examined. Lesion rate (%) = 6

(lesion area in small intestine / total of small intestine area ) × 100. Data show the mean 7

value and S.E. of 5 cats. In young cats, very few small intestinal lesions were produced 8

by flunixin. * P<0.01, significant different from control group. 9

10

Fig. 7. Time-dependent changes of plasma concentration of flunixin in both adult and 11

young cats. Flunixin (1.0 mg/kg) was injected s.c. at 0 min. Data show the mean value 12

and S.E. of 5 cats. There is not significant difference on plasma concentration of flunixin 13

between adult and young cats. 14

Hyperthermia induced by LPS in young cats. LPS (0.3 µg/kg body weight) was injected i.v. at 0 hr. The control group was received 0.5 ml/kg physiological saline solution (PSS, s.c. and i.v.). The LPS group was injected PSS before LPS injection. Those groups are hereafter referred to as CONT and

LPS. Data show the mean value and S.E. of 4 cats. At 0.5, 1, 2, 4 and 8 hr after LPS injection, body temperature was significant higher than control (CONT). * P<0.05, significantly different from body temperature at -0.5 hr value. # P<0.05; ##P<0.01, significantly different from the CONT group.

Effect of flunixin on hyperthermia induced by LPS in young cats. LPS (0.3 µg/kg body weight) was injected i.v. at 0 hr. Flunixin was administered s.c. at 0.5 hr before LPS injection. The control group was received 0.5 ml/kg physiological saline solution (PSS, s.c. and i.v.). The LPS group was injected PSS before LPS injection. The cats in the other groups received 0.25, 0.5 or 1 mg/kg flunixin (s.c.), and LPS (0.3 µg/kg, i.v.). Those groups are hereafter referred to as CONT, LPS, FNX0.25, FNX0.5

and FNX1.0. Data show the mean value and S.E. of 4 cats. At 1, 2 and 4 hr after LPS injection, both FNX0.5 and FNX1.0 significantly suppressed hyperthermia induced by LPS. FNX 0.25 also significantly suppressed hyperthermia induced by LPS at 2 hr after LPS injection. * P<0.05,

significantly different from body temperature at -0.5 hr value. # P<0.05; ##P<0.01, significantly different from the LPS group. The LPS group is same as for Fig. 1.

Effect of flunixin on hyperthermia induced by LPS in adult cats. LPS (0.3 µg/kg) was injected i.v. at 0 hr. The control group was received 0.5 ml/kg physiological saline solution (PSS, s.c. and i.v.). The LPS group was injected PSS before LPS injection. Those groups are hereafter referred to as CONT and LPS. Data show the mean value and S.E. of 4 cats. Body temperature was significant higher at 2, 4 and 6 hr in the LPS group than the control (CONT) group. * P<0.05; ** P<0.01, significantly

different from -0.5 hr value. # P<0.01, significantly different from the CONT group.

Effect of flunixin on hyperthermia induced by LPS in adult cats. LPS (0.3 µg/kg) was injected i.v. at 0 hr. The control group was received 0.5 ml/kg physiological saline solution (PSS, s.c. and i.v.). The LPS group was injected PSS before LPS injection. The cats in the other groups received 0.25, 0.5 or 1 mg/kg flunixin (s.c.), and LPS (0.3 µg/kg, i.v.). Those groups are hereafter referred to as CONT, LPS, FNX0.25, FNX0.5 and FNX1.0. Data show the mean value and S.E. of 4 cats. At 1 and 2 hr

after LPS injection, FNX0.25 significantly suppressed hyperthermia induced by LPS. FNX0.5 and FNX 1.0 groups were almost-completely suppressed hyperthermia induced by LPS. * P<0.05; ** P<0.01, significantly different from body temperature at -0.5 hr value. # P<0.05; ##P<0.01,

significantly different from the LPS group. The LPS group is same as for Fig. 3.

Gastrointestinal lesions induced by flunixin in adult and young cats. Flunixin (1 mg/kg body weight s.c.) was administered for 3 days; once a day after a morning meal. The animals were

sacrificed 24 hr after the final dose of flunixin, and gastrointestinal mucosal lesions were examined. Data show the mean value and S.E. of 5 cats. In young cats, very few gastrointestinal lesions were

produced by flunixin. * P<0.05; ** P<0.01, significantly different from adult cats.

Percentages of small intestinal lesion area induced by flunixin in adult and young cats. The percentage of the lesion area was calculated as 100% of total small intestine area. Flunixin (1 mg/kg body weight, s.c.) was administered for 3 days; once a day after a morning meal. The

animals were sacrificed 24 hr after the final dose of flunixin, and gastrointestinal mucosal lesions were examined. Lesion rate (%) = (lesion area in small intestine / total of small intestine area )

× 100. Data show the mean value and S.E. of 5 cats. In young cats, very few small intestinal lesions were produced by flunixin. * P<0.01, significant different from control group.

Time-dependent changes of plasma concentration of flunixin in both adult and young cats. Flunixin (1.0 mg/kg) was injected s.c. at 0 min. Data show the mean value and S.E. of 5 cats. There is not

significant difference on plasma concentration of flunixin between adult and young cats.