In dogs, GDV is a life-threatening condition involving pathological gas distention and malposition of the stomach. The pathophysiology may involve gastroesophageal sphincter and pyloric dysfunction1; however, a definitive etiology has not been elucidated and is likely to be multifactorial. Several predisposing factors have been identified, including predispositions in specific breeds, such as Great Danes, German Shepherd Dogs, and Standard Poodles.2,3 Purebred dogs and large- and giant-breed dogs are also at higher risk; other factors associated with an increased risk of GDV include increasing age, increased thoracic depth-to-width ratio, a thin or lean body condition, and having a relative with a history of GDV.2,4–9 Male dogs have been found to have a higher incidence of GDV,5,8 but other studies2,4 have not confirmed this finding. One study2 demonstrated a marginally protective effect of neutering.
A possible association may also exist between GDV and previous splenectomy. To our knowledge, there are 19 cases of GDV following splenectomy in dogs reported in the literature. Three cases of GDV occurred from 2 to 17 months after splenectomy for splenic torsion,10,11 1 occurred 5 days after splenectomy for a ruptured splenic hemangiosarcoma,12 and 1 occurred 2 days following splenectomy because of an unreported disease process.13 In an article reporting 14 dogs that developed GDV after splenectomy, the interval between splenectomy and GDV and the underlying splenic diseases were not reported separately from the overall study population.14
Several theories have been proposed for why previous splenectomy may increase the risk for GDV. First, the anatomic void created after removal of the spleen, particularly if enlarged, may allow increased gastric mobility, ultimately resulting in GDV.10,12 Second, a splenic mass or torsion of the spleen may stretch the gastrosplenic, hepatoduodenal, or hepatogastric ligaments, resulting in increased gastric mobility.10,12 In cases of splenic torsion specifically, dogs may initially be predisposed to developing GDV for reasons unrelated to splenic disease and may develop intermittent gastric dilatation without volvulus first, thus stretching the gastrosplenic ligaments or displacing the spleen, ultimately resulting in splenic torsion. These patients may subsequently develop GDV due to their preexisting propensity.10
The occurrence of GDV following splenectomy may be coincidental, considering that both GDV and conditions necessitating splenectomy, such as hemangiosarcoma and splenic torsion, occur most commonly in large-breed dogs.11,12 In fact, a recent retrospective case-control study by Goldhammer et al13 did not find a significant association between GDV and history of previous splenectomy. In that study,13 the records of 33 GDV case animals and 39 weight-matched controls were searched for a history of previous splenectomy. A history of splenectomy was not identified in either group; thus, it was difficult to draw conclusions on a potential association between GDV and previous splenectomy.
Compelling evidence either supporting or refuting a relationship between splenectomy and GDV would prove helpful both for intraoperative decision making as well as preoperative client education regarding prophylactic gastropexy. The purpose of the study reported here was to determine whether there is a significant association between previous splenectomy and the development of GDV. Our hypothesis was that a history of previous splenectomy would be associated with a higher risk of GDV in dogs.
Materials and Methods
Case selection criteria—Medical records were searched for dogs that underwent exploratory laparotomy or abdominal ultrasonography at the Matthew J. Ryan Veterinary Hospital of the University of Pennsylvania and the Veterinary Medical and Surgical Group, Ventura, Calif, from August 1, 2004, to August 1, 2009, and from January 1, 2006, to August 1, 2009, respectively. The disparate study period start time reflects the availability of complete computerized records at the 2 hospitals.
Gastric dilatation-volvulus was diagnosed in patients on the basis of exploratory laparotomy. Incidence density sampling was used to identify 2 controls for each case within each hospital population where exploratory laparotomy or abdominal ultrasonography was performed and the surgical or ultrasonography report was available for review. The controls were matched within 3 years of age and 5 kg (11 lb) of the GDV case animals. The controls were also matched to the GDV case animals as closely as possible with respect to sex and neuter status, and with an exact breed or a related breed when possible.
For each case and control animal, the presence or absence of the spleen was recorded from the surgical or ultrasonography report. If the surgical or ultrasonography report did not note the absence of the spleen, the spleen was considered present. If the spleen was noted to be absent, the reason for previous splenectomy was recorded. The time elapsed between splenectomy and the development of GDV was recorded for the GDV cases, and the time elapsed between splenectomy and either laparotomy or abdominal ultrasonography was recorded for the control animals.
Statistical analysis—Descriptive statistics were calculated. After confirming the nonnormality of the data, continuous data were expressed as median and range and categorical data were expressed as frequencies. Age and body weight were compared between cases and controls via the Wilcoxon rank sum test. Sex, neuter status, and breed were compared between case and control animals via the Fisher exact test. The univariate OR with 95% CI for GDV associated with previous splenectomy was estimated via conditional logistic regression for matched sets. All analyses were performed with statistical software.a Values of P < 0.05 were considered significant.
Results
One hundred fifty-one dogs with GDV (diagnosed via laparotomy) and 302 controls (138 that underwent laparotomy and 164 that underwent abdominal ultrasonography) were included in the study. Signalment characteristics of case and control animals were summarized (Table 1). There were no significant differences between case and control animals with regard to these characteristics.
Characteristics of 151 dogs treated surgically for GDV and 302 control dogs with no history of GDV.
| Variable | Dogs with GDV (n = 151) | Control dogs (n = 302) |
|---|---|---|
| Age (y) | 9 (2–17) | 9 (1–17) |
| Body weight (kg) | 35 (16–79) | 35 (15–81) |
| Sex and neuter status | ||
| Sexually intact female | 6 (4) | 15 (5) |
| Spayed female | 50 (33) | 115 (38) |
| Sexually intact male | 28 (19) | 47 (16) |
| Castrated male | 67 (44) | 126 (42) |
| Breed | ||
| Akita | 7 (5) | 7 (2) |
| Doberman Pinscher | 7 (5) | 10 (3) |
| German Shepherd Dog | 17 (11) | 27 (9) |
| Golden Retriever | 4 (3) | 23 (8) |
| Great Dane | 16 (11) | 8 (3) |
| Labrador Retriever | 10 (7) | 39 (13) |
| Rottweiler | 6 (4) | 24 (8) |
| Saint Bernard | 8 (4) | 24 (8) |
| Standard Poodle | 22 (15) | 21 (7) |
| Mastiff | 0 (0) | 13 (4) |
| Other purebred | 37 (25) | 77 (26) |
| Mixed | 17 (11) | 45 (15) |
| Center | ||
| University of Pennsylvania | 130 (86) | 260 (86) |
| Veterinary Medical and Surgical Group | 21 (14) | 42 (14) |
Data are median (range) or No. (%).
Six (4%) dogs in the GDV group and 3 (1%) dogs in the control group had a history of previous splenectomy. On conditional logistic regression analysis, previous splenectomy was associated with development of GDV. In this population of dogs, the odds of GDV in dogs with a history of previous splenectomy were 5.3 times those of dogs without a history of previous splenectomy (P = 0.04; 95% CI, 1.1 to 26.8).
Conditions necessitating previous splenectomy in dogs with GDV were reported as lymphoid follicular hyperplasia with hemorrhage (n = 2), hematoma (2), or benign splenic mass (1) or were not recorded (1). Time elapsed between splenectomy and GDV ranged from 1.5 to 12 months, with a median time of 2.5 months. Cases of GDV with a history of splenectomy were represented by one each of the following breeds: Rottweiler, Shar-Pei cross, Standard Poodle, Greater Swiss Mountain Dog, Doberman Pinscher, and Samoyed.
Conditions necessitating previous splenectomy in control dogs were reported as hemangiosarcoma (n = 1) or benign splenic mass (1); in 1 case, the conditions necessitating previous splenectomy were not recorded (1). Time elapsed between previous splenectomy and either exploratory laparotomy or abdominal ultrasonography in these cases was 2 and 2.4 months; in 1 case, the time elapsed was not reported. Control animals with a history of splenectomy were represented by one each of the following breeds: Golden Retriever, Rottweiler, and German Shepherd Dog.
Discussion
The primary aim of this study was to evaluate a possible association between GDV in dogs and previous splenectomy. Although the incidence of previous splenectomy was low in both groups in this population of dogs, the odds of GDV in dogs with a history of previous splenectomy were 5.3 times those of dogs without a history of splenectomy. Although a direct cause and effect relationship between splenectomy and GDV could not be confirmed by this study, the results indicated that an association exists between previous splenectomy and GDV.
In a recent retrospective study, Goldhammer et al13 evaluated the potential association between splenectomy and GDV. In the first part of that study,13 the authors investigated the incidence of GDV following splenectomy. They identified 37 dogs that had a splenectomy performed and 43 weight-matched dogs that had a different abdominal surgery. One dog developed GDV 48 hours after splenectomy, and no control dogs developed GDV. As a result, there was no evidence that splenectomy was associated with an increased incidence of GDV in the 12 months following splenectomy. In the second part of the study by Goldhammer et al,13 which was similar in design to the study reported here, the authors investigated the incidence of previous splenectomy in dogs with GDV. They identified 33 dogs that had developed GDV and 39 weight-matched dogs evaluated for other reasons. No dog in either group had a history of previous splenectomy, and thus no significant association was identified. In contrast, 4% of the GDV group and 1% of the control group had a history of splenectomy in the present study, and a significant association was identified between GDV and a history of splenectomy. The disparate results between the study by Goldhammer et al13 and our study are likely due in part to differences in sample size, especially given the overall low incidence of splenectomy in both case and control animals.
In another recent study, Grange et al14 did not find splenectomy to be a risk factor for GDV. That study14 was similar in design to the first part of the study by Goldhammer et al,13 comparing the incidence of GDV in dogs after splenectomy with the incidence of GDV in dogs after other abdominal surgery. Compared with the study by Goldhammer et al,13 the study by Grange et al14 included a larger number of dogs with GDV that underwent splenectomy (n = 172) but a comparable number of control dogs that underwent splenectomy (47). The use of an owner questionnaire by Grange et al14 yielded a longer median follow-up time, compared with that in the study by Goldhammer et al.13 However, to follow the study design used by Grange et al14 and in the first part of the study by Goldhammer et al,13 dogs would have to be followed until death to know the true incidence of GDV after splenectomy or other abdominal surgery.
Results of the present study suggest that removal of the spleen may have greater relevance in increasing the risk of GDV than the nature of the splenic disease necessitating splenectomy. In 3 of the 19 previously reported cases of GDV following splenectomy, splenic torsion was the condition necessitating splenectomy.10–13 However, in our study population, benign splenic masses predominated among the cases of GDV following splenectomy, and splenic torsion was not identified as the cause for splenectomy in any GDV case. Cases of GDV following splenectomy for splenic torsion may not have been identified in our study population simply because of differences in the prevalence of various splenic diseases, compared with the prevalence in previous study populations. In addition, the previous reports of GDV following splenectomy for splenic torsion may have increased the frequency of prophylactic gastropexy in dogs undergoing splenectomy for splenic torsion at the hospitals in this study, which would decrease the risk of GDV in that group of dogs.
The results of this study suggest that prophylactic gastropexy may be a consideration in dogs undergoing splenectomy. In addition to the finding of increased odds of GDV in dogs with a history of previous splenectomy, GDV was documented following splenectomy in breeds that have not been previously identified as predisposed to the development of GDV, including a Samoyed and a Shar-Pei mix. Grange et al14 also documented GDV in atypical breeds following splenectomy, including a Bichon Frise and a Beagle. Although prophylactic gastropexy has historically been recommended after splenectomy for splenic torsion,10,11 the results of the present study support the more recent suggestion that prophylactic gastropexy may also be considered at the time of splenectomy for other splenic conditions, including large splenic tumors.12
Nevertheless, other factors should be considered in evaluating the potential role of prophylactic gastropexy at the time of splenectomy. These include the presence of other established risk factors for GDV, such as breed, age, and body condition score. The anesthetic condition of the patient and the nature of the splenic disease, such as whether a malignant diagnosis is known or evident before or during surgery, should also be considered in deciding whether to perform a gastropexy at the time of splenectomy. In addition, the cost, surgical time, and potential morbidity associated with gastropexy may be considered. The incidence of GDV in the population of splenectomized patients as a whole is unknown and would be difficult to establish without a prospective cohort study, reliably following a large group of splenectomized dogs to the end of life. As such, the potential risks versus benefits of prophylactic gastropexy in this population of patients are unknown.
Limitations of this study include those inherent in its retrospective nature. In some cases, the previous splenectomy had been performed by the referring veterinarian and the date of the splenectomy or histologic evaluation results were not available. In addition, we were unable to control for all factors that have previously been identified as potential risk factors for the development of GDV, such as detailed dietary and environmental data, which were not readily available in the medical records. There may also be other factors not yet identified that predispose to GDV and that were not controlled for in this study. As with any case-control study, there is a risk for selection bias of the controls, which were chosen from the hospital population and not from the general canine population. In the present study, GDV cases were defined on the basis of results of exploratory laparotomy, and control cases were included on the basis of either results of exploratory laparotomy or ultrasonography reports. Abdominal radiography may have been used as part of the initial diagnostic evaluation for both GDV cases and control cases prior to laparotomy but was not an inclusion criterion in this study. Additionally, some patients had preoperative diagnostic test results suggestive of GDV but this was not confirmed on exploratory laparotomy (eg, gastric dilatation without volvulus), and these patients were excluded from the analyses.
Although the present study had a relatively large sample size, the overall incidence of GDV in patients with previous splenectomy was low. This low incidence may be partly due to the high proportion of patients that undergo splenectomy for hemangiosarcoma or other malignant neoplasms. Dogs with malignant splenic neoplasms may die of their splenic disease soon after splenectomy, making it difficult to determine the risk of GDV or the importance of prophylactic gastropexy in these patients. In addition, owners may have chosen to euthanize their dogs rather than undergo surgery for GDV in light of a previous diagnosis of splenic malignancy. Because the population included in this study were dogs that underwent exploratory laparotomy for GDV, dogs with GDV for which the owner opted euthanasia as opposed to surgery were excluded. Therefore, cases in which owners declined surgery for GDV due to a previous diagnosis of splenic malignancy after splenectomy may have been excluded, resulting in underestimation of the incidence of previous splenectomy in the GDV group. However, owners may have also been reluctant to pursue abdominal ultrasonography or laparotomy for other problems (non-GDV) after a diagnosis of splenic malignancy was made via splenectomy, thus lowering the incidence of previous splenectomy identified in the control group as well.
In conclusion, in this population of dogs with a low overall incidence of previous splenectomy, there was an increased odds of GDV in dogs with a history of splenectomy. Prophylactic gastropexy may be considered in dogs undergoing a splenectomy, particularly if other risk factors for GDV are present.
ABBREVIATIONS
| CI | Confidence interval |
| GDV | Gastric dilatation-volvulus |
STATA statistical package, version 10, StataCorp LP, College Station, Tex.
References
1. Brockman DJ, Holt DE, Washabau RJ, Pathogenesis of acute canine gastric dilatation-volvulus syndrome: is there a unifying hypothesis?. Compend Contin Educ Pract Vet. 2000; 22:1108–1114.
2. Glickman LT, Glickman NW, Pérez CMet al., Analysis of risk factors for gastric dilatation and gastric dilatation-volvulus in dogs. J Am Vet Med Assoc. 1994; 204:1465–1471.
3. Brockman DJ, Washabau RJ, Drobatz KJ, Canine gastric dilatation/volvulus syndrome in a veterinary critical care unit: 295 cases (1986–1992). J Am Vet Med Assoc. 1995; 207:460–464.
4. Schellenberg DB, Yi Q, Glickman NWet al., Influence of thoracic conformation and genetics on the risk of gastric dilatation-volvulus in Irish Setters. J Am Anim Hosp Assoc. 1998; 34:64–73.
5. Glickman LT, Glickman NW, Schellenberg DBet al., Incidence of and breed-related risk factors for gastric dilatation-volvulus in dogs. J Am Vet Med Assoc. 2000; 216:40–45.
6. Glickman LT, Glickman NW, Schellenberg DBet al., Nondietary risk factors for gastric dilatation-volvulus in large and giant breed dogs. J Am Vet Med Assoc. 2000; 217:1492–1499.
7. Raghavan M, Glickman NW, McCabe Get al., Diet-related risk factors for gastric dilatation-volvulus in dogs of high-risk breeds. J Am Anim Hosp Assoc. 2004; 40:192–203.
8. Glickman LT, Glickman NW, Schellenberg DBet al., Multiple risk factors for the gastric dilatation-volvulus syndrome in dogs: a practitioner/owner case-control study. J Am Anim Hosp Assoc. 1997; 33:197–204.
9. Theyse LF, van de Brom WE, van Sluijs FJ, Small size of food particles and age as risk factors for gastric dilatation volvulus in Great Danes. Vet Rec. 1998; 143:48–50.
10. Millis DL, Nemzek J, Riggs C, Gastric dilatation-volvulus after splenic torsion in two dogs. J Am Vet Med Assoc. 1995; 207:314–315.
11. Neath PJ, Brockman DJ, Saunders HM, Retrospective analysis of 19 cases of isolated torsion of the splenic pedicle in dogs. J Small Anim Pract. 1997; 38:387–392.
12. Marconato L, Gastric dilatation-volvulus as complication after surgical removal of a splenic haemangiosarcoma in a dog. J Vet Med A Physiol Pathol Clin Med. 2006; 53:371–374.
13. Goldhammer MA, Haining H, Milne EMet al., Assessment of the incidence of GDV following splenectomy in dogs. J Small Anim Pract. 2010; 51:23–28.
14. Grange AM, Clough W, Casale SA, Evaluation of splenectomy as a risk factor for gastric dilatation-volvulus. J Am Vet Med Assoc. 2012; 241:461–466.
