SEARCH

SEARCH BY CITATION

Keywords:

  • Gastricalm;
  • Mucosa;
  • NSAID;
  • Polaprezinc

Abstract

  1. Top of page
  2. Abstract
  3. Materials and Methods
  4. Results
  5. Discussion
  6. Footnotes
  7. Acknowledgments
  8. References

Background: Nonsteroidal anti-inflammatory drugs frequently cause gastrointestinal (GI) injury. Zinc-l-carnosine has antioxidant, anti-inflammatory, mucosal protective, and healing properties in rodent models and in some human studies of GI injury.

Hypothesis: The combination of zinc-l-carnosine and vitamin E attenuates aspirin-induced gastroduodenal mucosal injury.

Animals: Eighteen healthy random-source Foxhound dogs.

Methods: In this randomized, double-blinded, placebo-controlled study dogs were treated with placebo (n = 6; 0X group), 30 mg/30 IU (n = 6; 1X group), or 60 mg/60 IU (n = 6; 2X group) zinc-l-carnosine/vitamin E orally every 12 hours for 35 days. Between Day 7 and 35, GI mucosal lesions were induced with aspirin (25 mg/kg PO q8h). Mucosal injury lesions (hemorrhage, erosion, and ulcer) were assessed by gastroduodenoscopy on Days 14, 21, and 35 with a 12-point scoring scale.

Results: At baseline (Day −1) gastroscopy scores were not significantly different between groups (mean ± SD: 0X, 4.4 ± 0.8; group 1X, 4.4 ± 0.6; group 2X, 4.2 ± 0.3; P= .55). Gastroscopy scores increased significantly in all groups between Day −1 and Days 14, 21, and 35 (P < .0001). On Day 35, gastroscopy scores were 29.2 ± 5.2 (0X), 27.3 ± 3.7 (1X), and 28.6 ± 3.3 (2X). Mean gastroscopy scores were not significantly different among treatment groups on any of the days (P= .61).

Conclusions and Clinical Importance: Administration of the combination of zinc-l-carnosine and vitamin E at 1X or 2X dosing did not attenuate aspirin-induced gastroduodenal mucosal injury.

Abbreviations:
ANOVA

analysis of variance

GI

gastrointestinal

NSAID

nonsteroidal anti-inflammatory drug

Nonsteroidal anti-inflammatory drugs (NSAIDs) are prescribed commonly in dogs for treatment of pain and inflammation. NSAIDs inhibit cyclooxygenases 1 and 2, which play a role in maintaining the integrity of normal gastrointestinal (GI) mucosa.1–3 NSAIDs are a frequent cause of GI injury, resulting in adverse effects such as inappetence, nausea, vomiting, diarrhea, and GI hemorrhage associated with irritation and erosion of the GI epithelium.4 In humans, 25% of chronic NSAID users develop ulceration, and 2–4% suffer GI bleeding or perforation.5 Similar epidemiological data are not available for dogs, but GI lesions secondary to NSAID administration occur frequently in dogs.6

Data on the efficacy of gastroprotectants for preventing GI lesions secondary to NSAID use in dogs are limited. There is a consistently lower, but not statistically significant, mucosal lesion score in dogs treated with either the histamine type-2 receptor blocker cimetidine or the proton-pump inhibitor omeprazole compared with untreated controls, in an aspirin-induced gastritis model.7 Other studies have shown a protective effect of misoprostol in experimental models of aspirin-induced gastritis in dogs.8–10

Several studies have shown the potential beneficial effects of zinc-l-carnosine, or polaprezinc, on the prevention, attenuation, and healing of GI mucosal lesions in rats, Mongolian gerbils, and healthy human volunteers.11–18 Zinc is an essential trace mineral that plays a critical role in many biochemical functions, including DNA, RNA, and protein synthesis. Carnosine is a naturally occurring bioactive dipeptide that has antioxidant properties and forms a stable complex with zinc. In cell-culture studies, zinc-l-carnosine stimulates epithelial cell migration,11 increases cell proliferation,11 attenuates the production of pro-inflammatory cytokines,19 and increases the expression of 72 kDa heat-shock protein, an endogenous cytoprotectant.14,16,20 The gastroprotective effects of zinc-l-carnosine have not yet been evaluated in dogs.

Zinc-l-carnosine formulated in combination with the antioxidant vitamin E as α-tocopheryl acetate (GastriCalm) has been commercially available for several years. This randomized, double-blind, placebo-controlled study aimed to test the hypothesis that this preparation of zinc-l-carnosine/vitamin E attenuates aspirin-induced GI mucosal injury in dogs.

Materials and Methods

  1. Top of page
  2. Abstract
  3. Materials and Methods
  4. Results
  5. Discussion
  6. Footnotes
  7. Acknowledgments
  8. References

Eighteen random source intact Foxhound dogs (10 females, 8 males), ranging in age from 1 to 2 years and in body weight from 16.8 to 23.4 kg, were studied. All dogs had an acclimation period of at least 3 weeks before the start of the study (Day 0). Dogs were included in the study based on a normal physical examination, unremarkable CBC, and serum biochemistry panel; and negative evaluations for GI parasites by fecal flotation and fecal Giardia antigen immunoassay testing.a The study protocol was approved by the Institutional Animal Care and Use Committee of The Ohio State University.

Before the start of the study, all dogs were treated with two 3-day courses of fenbendazole (50 mg/kg PO q24h).b Fecal flotations (sugar and zinc sulfate centrifugation technique) and Giardia antigen immunoassay testinga were performed before and after fenbendazole.b All dogs had negative fecal parasite examinations between 7 and 11 days before Day 0. Fecal flotation (zinc centrifugation technique), and Giardia antigen immunoassay testing were repeated on Day 35 at the conclusion of the study. Seven dogs from the same source, noted to have fleas on acquisition, were treated before the study with praziquantel for tapeworms and nitenpyram for fleas.c,d

Dogs were housed in individual indoor runs with a 12-hour on/off lighting schedule. Dogs were given water ad libitum and were fed 5 cups of a dry commercial dog food once daily.e In preparation for each gastroduodenoscopic procedure, dogs were fasted for approximately 22 hours. Blood samples were collected by jugular venipuncture before Day −1 (baseline) and on Days 14 and 35 of the study. Samples were chilled immediately after collection, the serum was separated, and samples were analyzed the same day. CBC and serum biochemistry profiles were performed on automated analyzers, which were calibrated daily.f,g

Treatments (aspirin, test drug, and placebo) were performed by members of the research team who did not participate in observations (clinical observations, fecal scores, endoscopy) and vice versa. Those conducting observations were blinded to the treatment groups throughout the study. From Day 0 until Day 35, dogs were treated with 1 tablet (1X group, n = 6) or 2 tablets (2X group, n = 6) of 30 mg zinc-l-carnosine/ 30 IU vitamin E every 12 hours PO, or a placebo tablet (0X group, n = 6) every 12 hours PO.h,i In the 1X group, the mean dose of zinc-l-carnosine/vitamin E was 1.49 mg/1.49 IU per kilogram of bodyweight twice daily, respectively (range 1.30–1.57 mg or IU/kg/dose). In the 2X group, it was 2.83 mg/2.83 IU per kilogram of body weight twice daily (range 2.63–3.55 mg or IU/kg/dose). On Days 7–35, all dogs were given approximately 25 mg/kg buffered aspirin every 8 hours PO (rounded to the nearest 0.25 of a 325-mg tablet), for the induction of GI lesions. Dogs were monitored once daily for food intake and 3 times daily for vomiting and diarrhea. Body weight was measured once weekly. Food intake was estimated as a percentage of the total daily food allotment rounded to the nearest 5%. Fecal consistency was graded with a 5-point grading scale (Table 1). A fecal consistency score of ≤3 was considered diarrhea. A qualitative test for the presence of fecal occult blood was performed weekly.j

Table 1.   Fecal consistency grading scale.
Fecal Consistency GradeDescription
  • *

    A fecal consistency score ≤3 is considered diarrhea.

1Greater than two thirds of the feces in a defecation are liquid
The feces have lost all form, appearing as a puddle or squirt
2Approximately equal amounts of feces in a defecation are soft and liquid
3Greater than two thirds of the feces in a defecation are soft
The feces retain enough form to pile but have lost their firm cylindrical appearance*
4Approximately equal amounts of feces in a defecation are firm and soft
5Greater than two thirds of the feces in a defecation are firm
They have a cylindrical shape with little flattening

Gastroduodenoscopy was performed under general anesthesia on Days −1, 14, 21, and 35. Dogs were premedicated with acepromazine (0.1 mg/kg IM); general anesthesia was induced with thiopental (10 mg/kg IV) and maintained with isoflurane in oxygen.k,l,m Gastroduodenoscopy was performed (by M.B.) with dogs in left lateral recumbency. During the procedure 5 mL/kg/h of NaCl 0.9% was administered IV and blood pressure was monitored every 10 minutes. At no time was clinically relevant hypotension detected. All videoendoscopic procedures were recorded digitally, and mucosal lesions were independently scored at a later time by 2 experienced endoscopists (S.J., R.S.) who were blinded to the treatment groups.n

Gastroduodenal mucosal lesions were scored on the basis of a 12-point scale described previously (Table 2).21 The stomach and duodenum were divided endoscopically into 5 anatomical regions: A, pylorus and pyloric antrum; B, angularis incisura, extending along the lesser curvature; C, greater curvature from the cardia to the pyloric antrum; D, cardia, extending from the greater curvature region to the lesser curvature that was not included with the angularis incisura; and E, proximal duodenum to the major duodenal papilla. Lesions that bordered 2 regions were assigned to the most appropriate region and were not counted twice when assessing the adjacent region. Each score was assigned based on the most severe lesions present in each region. Scores for all 5 regions were summed for a total endoscopy score, and scores for the 4 stomach regions were summed to form a total gastroscopy score.

Table 2.   Endoscopy scoring scale.
ScoreDescription*ScoreDescription*
  • *

    Erosion: superficial discontinuation of the mucosal epithelium. Ulcer: lesion producing wide discontinuation of the mucosa with a central defect and a raised margin.

1Normal73–5 erosions
21 mucosal hemorrhage8>5 erosions
32–5 mucosal hemorrhages91 ulcer
4>5 mucosal hemorrhages102 ulcers
5Diffuse mucosal hemorrhages113 or more ulcers
61–2 erosions12Perforating ulcer

Statistical Analysis

Eighteen dogs were randomly assigned to 3 treatment groups (0X, 1X, 2X) within 3 phases (n = 6 per phase), or 2 dogs per treatment group per phase, resulting in a randomized complete block design.

With only 6 dogs in each group, this study was considered to be a pilot study exploring a possible protective effect of zinc-l-carnosine/vitamin E on aspirin-induced gastroduodenal mucosal lesions. Therefore, for the purpose of the analysis, endoscopy variables and food consumption were treated as continuous data and normality was assumed. There were minimal differences between mean and median, supporting the assumption of normality. After investigation of the variance-covariance structure of the data, a repeated measures analysis of variance (ANOVA) was used for analysis of the total endoscopy scores, total gastroscopy scores, regional endoscopy scores, food consumption, and body weights. The analyses were performed by PROC MIXED of the SAS system, version 9.1. The statistical models included treatment, day, and the treatment by day interaction as fixed effects and phase and phase by treatment as random effects. For each dog, days with food withheld or where consumption was not reported were not included in the analysis.

Number of days with vomiting, number of days with diarrhea, and number of days positive for fecal occult blood were analyzed by the Cochran-Mantel-Haenszel test, testing the equality of mean scores between treatments. Phase was used as a stratification variable. The analyses were performed by PROC FREQ of the SAS system, version 9.1. Presence of vomiting on at least 1 day, presence of diarrhea on at least 1 day, and presence of fecal occult blood on at least 1 occasion were analyzed by exact logistic regression, with phase as a stratification variable. The binary regression option to LogXact from Cytel Studio 7 was used to perform the analyses.

Correlation of total gastroscopy score and regional duodenal score between scorers 1 and 2 was analyzed with a Pearson's correlation test. Hematology and biochemistry variables were analyzed by ANOVA. Significance level was set at P < .05.

Results

  1. Top of page
  2. Abstract
  3. Materials and Methods
  4. Results
  5. Discussion
  6. Footnotes
  7. Acknowledgments
  8. References

Clinical Variables

All dogs completed the study. Throughout the study, body weight was maintained within 1 kg of Day 0 in all but 3 dogs. One dog (1X group) gained 13.6%, and 2 dogs (0X and 2X group) lost 6.5% and 10.8% of their body weight, respectively. There was no significant difference in mean body weight between the groups on any of the days. No significant differences among slopes were detected for the treatment day interaction, treatment, and time.

Daily estimated food intake varied markedly throughout the study for most dogs, regardless of treatment or day of the study (range 0–100%), and decreased significantly over time in all groups (P= .0001). On Day 0 it was 87.5 ± 10.84 (mean ± SD), 89.2 ± 18.55, and 96.7 ± 8.16% for groups 0X, 1X, and 2X, respectively. On Day 34, food intake had decreased to 60.9 ± 8.99, 60.4 ± 9.28, and 53.6 ± 9.28%, in groups 0X, 1X, and 2X, respectively.

Vomiting occurred on at least 1 day during the study in 3 of 6 dogs (on 1, 2, and 5 days) from the 0X group, in 3 of 6 dogs (on 1, 1, and 2 days) from the 1X group, and in 4 of 6 dogs (on 1, 3, 7, and 8 days) from the 2X group. These differences were not significant. No significant difference in mean number of days with vomiting was observed among any of the groups.

Diarrhea was observed on one or more days in 2 of 6 dogs (on 1 and 2 days) in the 0X group, and in 3 of 6 dogs in both the 1X (on 1, 5, and 6 days) and 2X (on 4, 8, and 10 days) groups. There was no significant difference among groups in the proportion of dogs with diarrhea present on at least 1 day or in the number of days with diarrhea among any of the groups (0X versus 1X, P= .23; 0X versus 2X, P= .083; 1X versus 2X, P= .37).

Endoscopy Scores

On Day −1 none of the dogs had erosions or ulcerations. Mean total endoscopy scores, total gastroscopy scores, and regional gastric scores for regions A–E were not significantly different on Day −1 among groups. All dogs subsequently developed lesions during the study.

Total gastroscopy score in each group was not significantly different on Day −1 (mean ± SD: 0X group, 4.4 ± 0.8; 1X group, 4.4 ± 0.6; 2X group, 4.2 ± 0.3; P= .55). Gastroscopy scores in all 3 groups increased significantly between Day −1 and Days 14, 21, and 35 (P < .0001; Fig 1). On Day 35, total gastroscopy scores had increased to 29.2 ± 5.2, 27.3 ± 3.7, and 28.6 ± 3.3 in the 0X, 1X, and 2X treatment groups, respectively. The gastroscopy scores were not significantly different among groups on any of the days (P= .61).

image

Figure 1.  Total gastroscopy score (and mean) of mucosal lesions in dogs of the 0X, 1X, and 2X treatment groups (n = 6 in each) before (Day −1), and during (Days 14, 21, and 35) the induction of gastroduodenal lesions with aspirin. There is a significant difference between Day −1 and Days 14, 21, and 35 in all groups, but no significant difference among groups at any time point.

Download figure to PowerPoint

Total duodenal scores (region E) were not significantly different on Day −1 among groups (mean ± SD: 1 ± 0.0, 1 ± 0.2, 1 ± 0.0 for the 0X, 1X and 2X treatment groups, respectively; P= .44). There was no significant effect of treatment on the duodenal lesion score (P= .23), but there was a significant interaction between treatment and time (P=.020). The duodenal score increased significantly at Days 21 and 35 compared with Days −1 and 14 in the 0X group (P≤ .0073, Fig 2). In both treatment groups (1X and 2X), there was no significant difference between the treatment days. On Day 35, the duodenal score in the 0X group was significantly higher than in either treatment group (P= .0009 with 1X and P= .0414 with 2X).

image

Figure 2.  Endoscopy score (and mean) of duodenal mucosal lesions in dogs of the 0X, 1X, and 2X treatment groups (n = 6 in each) before (Day −1), and during (Days 14, 21, and 35) the induction of gastroduodenal lesions with aspirin. The duodenal score increased significantly at Days 21 and 35 compared with Days −1 and 14 in the 0X group, but not in the 1X and 2X groups. There was a significant interaction between treatment and time. Treatment had no significant effect on lesion scores.

Download figure to PowerPoint

Compared with Day −1, scores were significantly increased on all other days for total endoscopy score, and regional endoscopy scores of regions A, B, C, and D in all groups (P < .0002 for each comparison, data not shown). Treatment had no significant effect on gastric regional scores (P≥ .13). There were no other significant differences among any of the treatments or any of the days for any of the regions scored.

Total gastroscopy scores and regional endoscopy scores for the duodenum were significantly correlated between scorer 1 and scorer 2 (r= 0.95; 95% CI: 0.92–0.97, and r= 0.63; 95% CI: 0.47–0.76, respectively; Fig 3A and B).

image

Figure 3.  Correlation between scorers for total gastroscopy score (A) and regional duodenal score (B) in dogs of the 0X, 1X, and 2X treatment groups (n = 6 in each) before (Day −1), and during (Days 14, 21, and 35) the induction of gastroduodenal lesions with aspirin.

Download figure to PowerPoint

CBC and Biochemical Evaluation

CBCs and serum biochemistry profile results at baseline were within the reference range or deviated minimally from this range in all dogs. None of the variables that deviated from the reference range were considered clinically relevant. None of the dogs was anemic. Two dogs (2X group) had mild eosinophilia (1.8 and 1.6 × 109/L; reference range, 0.1–1.2 × 109/L), which was attributed to parasitism identified and treated before the start of the study. At baseline, there was no statistical difference in hematological results or in serum biochemistry results between the groups. During the course of the study, serum biochemistry results varied minimally from baseline and generally remained within or near the normal reference ranges for each variable, with no significant differences between groups.

Between Day <−1 and Day 14 of the study, hematocrit decreased significantly in all groups, but remained within the reference range in all dogs except 1 dog in the 1X group (34% on Day 14; reference range, 36–54; Fig 4). On Day 35, hematocrit had partially recovered and was not significantly different from results on Day <−1 in any of the 3 treatment groups. There was no significant effect of treatment on hematocrit (P= .47).

image

Figure 4.  Hematocrit (and mean) in dogs of the 0X, 1X, and 2X treatment groups (n = 6 in each) before (Day −1), and during (Days 14, 21, and 35) the induction of gastroduodenal lesions with aspirin. Between Day <−1 and Day 14 of the study, mean hematocrit decreased significantly in all groups. On Day 35, hematocrit had partially recovered and was not significantly different from results on Day <−1 in any of the groups. There was no significant effect of treatment on hematocrit (P= .47). Horizontal dashed lines indicate the reference range for hematocrit.

Download figure to PowerPoint

Fecal Evaluation

All dogs were negative for fecal occult blood on Day 0, and after 7 days of treatment with 0X or test product only (Day 7). After the start of aspirin treatment, testing was positive in 2 dogs in the 0X group, 3 dogs in the 1X group (1 positive fecal in 2 dogs, and 3 positive fecals in 1 dog) and 4 dogs in the 2X group (1 dog was positive twice). None of the dogs developed melena. There was no significant difference between the groups in the proportion of dogs with a positive fecal occult blood test or in the number of days with a positive fecal occult blood test (0X versus 1X, P= .38; 0X versus 2X, P= .23; 1X versus 2X, P= 1.00).

Fecal flotations and Giardia immunoassays on Day 35 were negative for GI parasites in all dogs, but Capillaria ova were identified in 2 dogs (1 in the 1X and 1 in the 2X treatment group).

Discussion

  1. Top of page
  2. Abstract
  3. Materials and Methods
  4. Results
  5. Discussion
  6. Footnotes
  7. Acknowledgments
  8. References

This randomized, double-blinded, placebo-controlled study did not show a significant protective effect of zinc-l-carnosine/vitamin E on the development of aspirin-induced gastroduodenal mucosal lesions in healthy dogs. All dogs developed marked mucosal lesions, and the mean gastroscopy scores were not significantly different among groups on any of the days. These results are in contrast with previous studies that showed that misoprostol and omeprazole protect dogs against aspirin-induced GI mucosal injury.9,10 Based on the results of this study, zinc-l-carnosine/vitamin E cannot be recommended for prevention of GI mucosal injury induced by aspirin and possibly other NSAIDs.

The zinc-l-carnosine/vitamin E product was well tolerated. Throughout the study, body weight either increased or remained within 1 kg of Day 0 in almost all dogs, despite a significant decrease in food intake during the course of the study. In accordance with management practices in the housing facility, all dogs were given the same amount of food each day (5 cups), regardless of their weight. Food intake was estimated as a percentage of the total daily allotment. As a result, the variable food intake during the study period was not reflected in a decrease in body weight, as most dogs ingested enough to maintain their weight.

Vomiting and diarrhea occurred infrequently in all groups, but a slightly higher frequency of vomiting was observed in the 2X group. Fecal consistency was normal (score 4 or 5) for most days in all dogs, and there was no significant difference among the groups. Safety studies with zinc-l-carnosine have shown vomiting and diarrhea as possible adverse effects of treatment given to dogs at 50, 120, or 300 mg/kg/d for 13 weeks.22 The doses of zinc-l-carnosine used in our study were much lower than those reported in this toxicity study; thus a significant effect of zinc-l-carnosine on the frequency of vomiting or diarrhea would not be expected.

Various NSAIDs have been associated with GI injury in dogs.23–27 Aspirin was chosen in this study because at high doses it predictably induces GI mucosal lesions, and it has often been used as an experimental model for GI injury in other studies. The dosage of aspirin used in prior studies has varied, and the protocol for the evaluation of mucosal lesions has not been standardized.7,9,10,21,28–31 In our study, all dogs developed multiple mucosal erosions or ulcers. No significant differences in total or in regional gastric scores were noted between the 0X group and either of the treatment groups throughout the study. This is in contrast with studies that have shown the prostaglandin analogue misoprostol to exert a significant gastroprotective effect with similar and even higher dosages of aspirin.9,10 Zinc-l-carnosine/vitamin E administration at 1X or 2X dosing was not effective for prevention of gastric lesions in this model of GI injury. The dose of zinc-l-carnosine, 30 or 60 mg/dog twice daily (∼2.6–7.1 mg/kg/d), was chosen based on the manufacturer's recommended dosage in the product package insert. However, this is markedly lower than the range of 10–100 mg/kg reported to have a beneficial protective effect on the GI mucosa of rats.12 The dose of vitamin E (∼2.6–7.1 IU/kg/d), administered concurrently as part of the GastriCalm formulation, was considered too low to have any beneficial antioxidant effect.

In general, there was a good correlation between the scorers, which was in support of the grading system as an objective measure of mucosal damage. The correlation between the scorers for the total gastroscopy scores was strengthened by the data points collected at baseline (Day −1), which markedly contributed to the linear shape of the entire cloud of data points, and thus to an excellent correlation. Duodenal lesions scores in general were much lower, increasing the effect of a single-point scoring difference on the overall correlation. In addition, duodenal lesions in some of the dogs were considered to be iatrogenic by one scorer, but interpreted as aspirin induced by the other, which lessened the correlation of duodenal scores.

In humans, there is evidence that eradication of Helicobacter pylori infections before the start of NSAID therapy significantly reduces the risk of subsequent GI ulceration.32–35 The prevalence of helicobacter-like organisms (HLO) in the GI tract of healthy dogs and dogs with GI signs approaches 100%.36,37 Currently, the role of HLO as a cause of GI signs and gastritis in dogs has not been clearly established.38–40 The presence of HLO was not evaluated in our study because the prevalence in random source research dogs reportedly approaches 100%, the available diagnostic tests are imprecise, and the pathogenic relevance of HLO in dogs is inconclusive.21,28,41,42

GI lesions were evaluated by gastroduodenoscopy and fecal occult blood testing. Despite the presence of multiple gastric erosions or ulcerations in all dogs, only 12 of 90 hemoccult tests (13%) during the study were positive. Fecal occult blood was identified in only 9 of 18 dogs (50% of the dogs in each treatment group) at any time. This inconsistency might be explained by intermittent rather than continuous bleeding from the ulcerated sites, as was observed endoscopically. In addition, a guaiac-based fecal occult blood test was used in this study, in which a color change of guaiac after oxidation by fecal hemoglobin indicates a positive result. Guaiac-based fecal occult blood tests have been used for the detection of upper GI bleeding in people, but are considered rather insensitive as hemoglobin is degraded within the upper GI tract before reaching the stool.43,44 Thus, the fecal occult blood test used in this study was an unreliable indicator of GI mucosal injury. This result is in accordance with previous studies that reported poor sensitivity of fecal occult blood testing for the detection of GI lesions in dogs.45,46

Overall, hematologic and serum chemistry results varied minimally from baseline during the study and generally remained within or near the normal reference ranges for each parameter. The hematocrit and hemoglobin concentration decreased from baseline at Day 14 or 35 in almost all dogs, but remained within the reference range in all dogs except one. The most likely explanation for the decrease in erythrocyte parameters was subclinical blood loss associated with bleeding from the GI mucosal erosions and ulcers seen in all dogs. The eosinophilia observed was attributable to endoparasites or fleas that were identified and treated during the acclimation period. All dogs were free of detectable parasites before the treatment phase began.

At the end of the study (Day 35), 2 dogs with eosinophilia were unexpectedly found to be positive for Capillaria. Infection was not detected in previous fecal examinations, and the short courses of fenbendazole before the start of the study would likely not have adequately eliminated this parasite. This was considered to be an incidental infection in both dogs. At no time during the study did the dogs become clinical for this respiratory nematode and it would not be expected to have affected the results, but it could explain the eosinophilia in these 2 dogs.

This study did not include a group of dogs without any treatment or a group treated with zinc-l-carnosine/vitamin E only. Including these groups would have allowed for evaluation of the development of GI lesions during the course of the study, and the effect of zinc-l-carnosine/vitamin E alone on the GI mucosa. Based on previous toxicity studies, it is unlikely that zinc-l-carnosine/vitamin E at the dose used in our study would have contributed to the development of GI lesions. A toxicity study in dogs treated with 50, 120, or 300 mg/kg/d of zinc-l-carnosine for 13 weeks, or with 8 or 20 mg/kg/d for 52 weeks revealed no GI mucosal lesions on necropsy in any of the dogs (n = 4–6 dogs per group).22 Mucosal lesions were only detected in a single dog after a single dose of 200 mg/kg.22 Hemorrhage, erosion, ulceration, and an inflammatory cell infiltration were noted in this dog.

The study also did not include a group of dogs treated with a medication such as misoprostol, which is known to reduce the development of aspirin-induced GI ulceration in dogs.8–10 Inclusion of a group treated with misoprostol would have allowed for comparison of zinc-l-carnosine/vitamin E with a drug that has proven efficacy in an aspirin model.

The number of dogs in this study was small, affecting the statistical power of the analysis and limiting the ability to detect smaller effects of the treatment.

This study aimed to investigate the gastroprotective effects of zinc-l-carnosine/vitamin E on the development of GI mucosal lesions in an aspirin-induced gastritis model in dogs. Zinc-l-carnosine/vitamin E at 30 or 60 mg was well tolerated but did not prevent aspirin-induced erosions and ulceration of the stomach. The gastroprotective effect of zinc-l-carnosine/vitamin E in other models of gastric injury or in the clinical setting (eg, naturally occurring gastritis) cannot be extrapolated from these results. Therefore, the role for zinc-l-carnosine as a gastroprotectant in the clinical setting needs further investigation.

Footnotes

  1. Top of page
  2. Abstract
  3. Materials and Methods
  4. Results
  5. Discussion
  6. Footnotes
  7. Acknowledgments
  8. References

a SNAP Giardia; IDEXX Laboratories, Westbrook, ME

b Panacur granules, 222 mg/g; Patheon Inc, Toronto, ON, Canada

c Droncit, 34 mg tablets; Bayer HealthCare LLC, Animal Health Division, Shawnee Mission, KS

d Capstar; Novartis Animal Health US Inc, Greensboro, NC

e Iams Chunks; The Iams Company, Cincinnati, OH

f CellDyn 3500; Abbott Laboratories, Abbott Park, IL

g Hitachi 911; Linco Research, St Charles, MO

h GastriCalm; IVX Animal Health Inc, St Joseph, MO

i Placebo; IVX Animal Health Inc

j Hemoccult SENSA; Beckman Coulter Inc, Brea, CA

k Acepromazine maleate; Vedco Inc, St. Joseph, MO

l Sodium thiopental; Abbott Animal Health, Abbott Park, IL

m IsoFlo; Abbott Animal Health

n Sony RDR GX355 DVD recorder; Sony Corp, Tokyo, Japan

Acknowledgments

  1. Top of page
  2. Abstract
  3. Materials and Methods
  4. Results
  5. Discussion
  6. Footnotes
  7. Acknowledgments
  8. References

The authors acknowledge Dr Kenneth Kwochka and Dr Lyn Huffaker for their contributions in making this study possible, and Ms Yukie Ueyama and Ms Pam Pugh for their technical assistance.

Funding was provided by IVX Animal Health Inc, St Joseph, MO.

References

  1. Top of page
  2. Abstract
  3. Materials and Methods
  4. Results
  5. Discussion
  6. Footnotes
  7. Acknowledgments
  8. References