SEARCH

SEARCH BY CITATION

Keywords:

  • horse;
  • heart rate;
  • packed cell volume;
  • lactate;
  • pain;
  • borborygmi;
  • gastrointestinal

Summary

  1. Top of page
  2. Summary
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Manufacturers' addresses
  8. References

Reason for performing study: It is the impression of some surgeons that geriatric horses have a lower survival rate compared to mature nongeriatric horses following colic surgery. One possible reason for this is that geriatric horses may be more critically ill at admission and have more severe disease than mature nongeriatric horses.

Objective: To compare admission historical, physical examination and laboratory data for geriatric and mature nongeriatric horses referred for signs of colic.

Methods: Medical records of horses admitted with a presenting complaint of colic between 2000 and 2006 were reviewed. Geriatric horses ≥16 years (n = 300) and mature nongeriatric horses 4–15 years (n = 300). Information obtained included duration of colic prior to admission, admission level of pain, heart rate, intestinal borborygmi, packed cell volume (PCV), plasma creatinine and blood lactate concentrations and peritoneal fluid total protein. Data were analysed using a Chi-squared test or an analysis of variance. Level of significance was P<0.05.

Results: There was no difference between geriatric and mature horses in the duration of colic prior to admission or in admission heart rate, PCV, or plasma creatinine or blood lactate concentrations. However, geriatric horses were more likely to be moderately painful and less likely to be bright and alert than mature horses; and less likely to have normal intestinal borborygmi than mature horses. Peritoneal fluid total protein concentration was higher in geriatric than mature horses.

Conclusions and potential relevance: Geriatric horses presenting with signs of colic had a similar admission cardiovascular status based on heart rate, PCV, and plasma creatinine and blood lactate concentration to mature horses. Geriatric horses, however, may have different causes of colic, which may be more serious than mature horses based on pain, lack of intestinal borborygmi and peritoneal fluid total protein concentration.


Introduction

  1. Top of page
  2. Summary
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Manufacturers' addresses
  8. References

With improvements in husbandry and medical care, horses now have longer active and useful lives. Gastrointestinal tract problems and signs of colic were the most common reasons for admission of geriatric horses to a large animal referral hospital (Brosnahan and Paradis 2003). It is the impression of some surgeons that geriatric horses have a lower short-term survival compared to mature nongeriatric horses following abdominal surgery. Geriatric horses (age ≥16 years) overall and with gastrointestinal disease that were admitted on an emergency basis had a lower survival rate compared to mature horses of other age categories (Southwood et al. 2008); the reasons for lower survival of geriatric horses was not addressed in that study.

One possible reason for the lower survival rate of geriatric compared to mature nongeriatric horses with colic is that geriatric horses may be more critically ill at admission and have more severe disease than mature nongeriatric horses. It is also the impression of some clinicians that geriatric horses are less likely to demonstrate substantial signs of colic (i.e. rolling and thrashing) compared to younger horses. Stoic behaviour could result in a delay of treatment with the horse being more cardiovascularly compromised at admission to a tertiary care facility. Duration of colic and admission level of pain, intestinal borborygmi, heart rate, packed cell volume (PCV), total plasma protein (TPP), plasma creatinine and blood lactate concentration, and gross appearance of the peritoneal fluid have all been associated with survival vs. nonsurvival of horses with colic (Proudman et al. 2002, 2005a,b; Linden et al. 2003; Southwood 2004; Garcia-Seco et al. 2005; Johnston et al. 2007) and could be used to compare cardiovascular status (critical illness) and severity of disease in geriatric compared to mature nongeriatric horses with colic. In a previous study (Grulke et al. 2001), horses with colic were placed into: 1) a shock category based on heart and respiratory rate, arterial blood pressure, PCV, lactate and blood urea nitrogen; and 2) a disease gravity category based on palpation per rectum, intestinal borborygmi, abdominal distention and severity of pain. Shock and disease gravity were both associated with outcome. Evaluation of shock and disease gravity using these clinical findings can be used to assess differences in geriatric compared to mature geriatric horses with colic.

Geriatric horses were recently reported to have a lower survival rate following colic surgery compared to nongeriatric horses (Krista and Kuebelbeck 2009). The proposed reason for the lower survival rate was that a higher number of geriatric horses were subjected to euthanasia during surgery; however, the number of geriatric horses recovering from surgery was insufficient to evaluate the survival rate of recovered geriatric compared to mature nongeriatric horses andadmission data were not reported. To the authors' knowledge there have been no large studies comparing admission historical, physical examination, or laboratory data in geriatric compared to mature nongeriatric horses with colic. This study was the first in a 2 part series evaluating colic in geriatric compared to mature nongeriatric horses. Our null hypothesis was that admission historical, physical examination and laboratory data for geriatric horses showing signs of colic would not be different to that for mature nongeriatric horses. Therefore, the objective of the study was to compare admission historical, physical examination and laboratory data in geriatric and mature nongeriatric horses with signs of colic.

Materials and methods

  1. Top of page
  2. Summary
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Manufacturers' addresses
  8. References

Horses

Medical records were reviewed for all horses presenting to the veterinary teaching hospital for signs of colic between January 2000 and September 2006. The hospital was closed for several months in 2004 because of a Salmonella outbreak; therefore, cases from 2004 were excluded. Age classification was geriatric or mature nongeriatric. Geriatric horses were aged ≥16 years. Mature nongeriatric horses were aged 4–15 years. Because of the large number of mature nongeriatric horses, random numbers were generated (Office Excel 2003)1 and mature nongeriatric horses were selected with the number of mature nongeriatric horses equalling the number of geriatric horses for each given year.

Subject details, history and physical examination findings

Information obtained from the medical record included: age, breed, gender, history of previous colic episodes (yes, no), duration of abdominal pain prior to admission (hours), level of abdominal pain at admission (alert, dull, mild, moderate, severe), abdominal distention (normal, mild, moderate, severe), heart rate (HR, beats/min), respiratory rate (RR, breaths/min), rectal temperature (RT, °C); capillary refill time (CRT, s), and intestinal borborygmi (normal, hypermotile, hypomotile, absent). The presence of reflux following passage of a nasogastric tube (NRG, litres) was recorded.

Laboratory data

Laboratory data included packed cell volume (PCV, %), total plasma protein (TPP, g/l), leucocyte count (×109/l), neutrophil count (×109/l), fibrinogen concentration (mg/l), plasma creatinine concentration (mg/l), and blood lactate concentration (mmol/l). Whether or not abdominocentesis was performed (yes, no), peritoneal fluid colour (green or brown, red, orange, yellow), as well as peritoneal fluid total protein (g/l), nucleated (×109/l) and red (×109/l) cell count was recorded.

Treatment and outcome

Horses were managed medically or surgically. Medically managed cases included horses in which a surgical recommendation for a presumed surgical lesion was declined by the owner. Outcome was defined by short-term survival, which was survival to hospital discharge (nonsurvivors or survivors).

Statistical analyses

Continuous data were analysed using a mixed model analysis of variance (PROC MIXED)2. The class variables were age classification (geriatric, mature), treatment (medical, surgical), outcome (survivors, nonsurvivors), and their interactions. Interactions that were not statistically significant were removed from the final model. The F-protected least significant difference (LSD) method was used to compare means when the interaction was significant. The dependent variables were duration of colic, HR, RR, RT, capillary refill time, nasogastric reflux, PCV, TPP, total leucocyte count, neutrophil count, fibrinogen concentration, plasma creatinine concentration, blood lactate concentration, peritoneal total protein, peritoneal nucleated cells and peritoneal red cells. The level of significance was P<0.05. Data are presented as mean ± s.d.

Categorical data were analysed using a Chi-squared test or a Fisher's exact test if the count was <5 in at least one cell (PROC FREQ)2. Categorical data included age classification (geriatric, mature), outcome (nonsurvivor, survivor), treatment (medical, surgical), breed, previous episode of colic (yes, no), level of pain at admission (alert, dull, mild, moderate, severe), intestinal borborygmi (normal, hypermotile, hypomotile, absent) and peritoneal fluid colour (green or brown, red, orange, yellow). The level of significance was P<0.05. Data are presented as numbers of horses (n) and percentages (%).

Results

  1. Top of page
  2. Summary
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Manufacturers' addresses
  8. References

Horses

There were 2573 colic admissions between January 2000 and August 2006; 271 for 2004 were excluded. The birth date was not specified for 12 horses and there were 573 foals and juvenile horses (i.e. age <4 years). There were a total of 412 geriatric horses and 112 were excluded because the medical record was missing. Therefore, there were 300 geriatric horses included. There were 1305 mature nongeriatric horse admissions; 300 (23%) mature nongeriatric horses were randomly selected.

Subject details and history

The mean ± s.d. age of geriatric-horse admissions was 20 ± 3.9 years (range 16–37 years) and the mean age of mature nongeriatric horses was 8.5 ± 3.3 years (range 4–15 years). There were 124 female, 12 intact male and 157 castrated male geriatric horses and 140 female, 27 intact male and 133 castrated male mature nongeriatric horses. Arabian, Pony and Quarter Horse breeds were significantly more common in the geriatric age classification whereas Standardbreds, Thoroughbreds and Warmbloods were more common in the mature nongeriatric age classification. Duration of colic is shown in Table 1.

Table 1. Admission history and physical examination findings in geriatric (age ≥16 years) compared to mature (age 4–15 years) horses, medically compared to surgically treated horses, and nonsurvivors compared to survivors
 Age classificationTreatmentOutcome
Geriatric fMatureMedicalSurgicalNonsurvivorSurvivor
  • *

    Significant difference between categories indicated;

  • significant interaction between age classification and outcome;

  • #

    # significant interaction between treatment and outcome. Level of significance was P<0.05.

Duration of colic (hours)21.6 ± 34.918.2 ± 28.721.4 ± 32.918.3 ± 30.817.8 ± 30.821.0 ± 32.5
Heart rate (beats/min)#63 ± 2257 ± 2257 ± 2363 ± 2173 ± 26*53 ± 17*
Respiratory rate (breaths/min)†#25 ± 1423 ± 1423 ± 1225 ± 1629 ± 17*21 ± 11*
Rectal temperature (°C)37.7 ± 0.5*37.8 ± 0.5*37.8 ± 0.5*37.3 ± 0.5*37.7 ± 0.5*37.9 ± 0.6*
Capillary refill time (s)#2.4 ± 0.6*2.5 ± 0.7*2.4 ± 0.72.5 ± 0.62.7 ± 0.7*2.3 ± 0.5*
Nasogastric reflux (l)#3.1 ± 5.32.2 ± 4.12.3 ± 4.72.9 ± 4.83.5 ± 5.4*2.2 ± 4.3*

Physical examination findings

Admission physical examination findings are shown in Table 1. There was a significant association between signs of pain at admission and age classification (P = 0.03), treatment (P<0.001), and outcome (P<0.001) (Fig 1). Geriatric horses were more likely than mature horses to be moderately painful and mature horses were more likely than geriatric horses to be bright and alert and not showing signs of pain. Medically treated horses were more likely than surgically treated horses to be bright and alert and not showing signs of pain and surgically treated horses were more likely than medically treated horses to be moderately or severely painful. Survivors were more likely than nonsurvivors to be bright and alert and not showing signs of pain or showing mild pain. Nonsurvivors were more likely than survivors to be dull or show severe pain.

image

Figure 1. The percentage of horses (y-axis) with different levels of pain at admission (alert, dull, mild, moderate, or severe) based on age classification (geriatric, mature), treatment (medical, surgical), and outcome (nonsurvivor, survivor). The asterisk represents a significant difference between the categories indicated by the bar. Level of significance was P<0.05.

Download figure to PowerPoint

There was a significant association between admission intestinal borborygmi and age classification (P = 0.005), treatment (P<0.001), and outcome (P<0.001) (Fig 2). Intestinal borborygmi were more likely to be normal in mature than geriatric horses. Medically treated horses were more likely than surgically treated horses to have normal or hypermotile borborygmi and surgically treated horses were more likely than medically treated horses to have absent borborygmi. Survivors were more likely than nonsurvivors to have normal, hypermotile or hypomotile intestinal borborygmi and nonsurvivors were more likely than survivors to have absent intestinal borborygmi.

image

Figure 2. The percentage of horses (y-axis) with different intestinal borborygmi at admission (normal, hypermotile, hypomotile or absent) based on age classification (geriatric, mature), treatment (medical, surgical) and outcome (nonsurvivor, survivor). The asterisk represents a significant difference between the categories indicated by the bar. Level of significance was P<0.05.

Download figure to PowerPoint

There were significant associations between admission abdominal distention and age classification (P<0.001), treatment (P<0.001), and outcome (P<0.001) (Fig 3). There were more geriatric horses than mature horses with no abdominal distention and more mature horses than geriatric horses with severe abdominal distention. There were more medically than surgically treated horses with no abdominal distention and more surgically than medically treated horses with moderate and severe abdominal distention. Survivors were more likely than nonsurvivors to have no abdominal distention and nonsurvivors were more likely than survivors to have moderate abdominal distention.

image

Figure 3. The percentage of horses (y-axis) with different degrees of abdominal distention at admission (normal, mild, moderate, or severe) based on age classification (geriatric, mature), treatment (medical, surgical), and outcome (nonsurvivor, survivor). The asterisk represents a significant difference between the categories indicated by the bar. Level of significance was P<0.05.

Download figure to PowerPoint

Age classification and outcome: There was a significant interaction between age classification and outcome for admission respiratory rate and rectal temperature. The difference in respiratory rate for nonsurvivors vs. survivors was greater for mature horses (32 ± 19 and 20 ± 10 breaths/min, respectively) than for geriatric horses (28 ± 16 and 22 ± 11 breaths/min, respectively); however, the difference between nonsurvivors and survivors was significant for both age classifications. The difference in RT between nonsurvivors and survivors was significant for mature horses (38.1 ± 0.6 and 37.7 ± 0.4°C, respectively) and was not significant for geriatric horses (37.7 ± 0.5 and 37.7 ± 0.4°C, respectively).

Treatment and outcome: There was a significant interaction between treatment and outcome for heart rate, respiratory rate, CRT and NGR. The heart rate for nonsurvivors was higher than that for survivors for medically (77 ± 27 and 49 ± 14 beats/min, respectively) and surgically (70 ± 34 and 59 ± 18 beats/min, respectively) treated horses. However, medically treated nonsurvivors had a higher heart rate than surgically treated nonsurvivors and medically treated survivors had a lower heart rate than surgically treated survivors.

The respiratory rate for nonsurvivors was higher than that for survivors for medically (30 ± 16 and 20 ± 7 breaths/min, respectively) and surgically (28 ± 18 and 23 ± 13 breaths/min, respectively) treated horses. Surgically treated survivors had a significantly higher respiratory rate than medically treated survivors; however, there was no difference between medically and surgically treated nonsurvivors.

Similarly, the CRT for nonsurvivors was higher than that for survivors for medically (2.8 ± 0.8 and 2.2 ± 0.5 s, respectively) and surgically (2.7 ± 0.6 and 2.4 ± 0.6 s, respectively) treated horses. Surgically-treated survivors had a longer CRT than medically treated survivors; however, there was no difference between medically and surgically treated nonsurvivors.

The volume of NGR for nonsurvivors was higher than that for survivors for medically (4.1 ± 5.8 and 1.6 ± 3.9 l, respectively) but not surgically (3.0 ± 5.1 and 2.9 ± 4.6 l, respectively) treated horses. Surgically-treated survivors had a large volume of NGR than medically treated survivors; however, there was no difference between medically and surgically treated nonsurvivors.

Laboratory data

Admission laboratory data are shown in Table 2.

Table 2. Admission laboratory data in geriatric (age ≥16 years) compared to mature (age 4–15 years) horses and nonsurvivors compared to survivors
 Age classificationTreatmentOutcome
GeriatricMatureMedicalSurgicalNonsurvivorSurvivor
  1. *Significant difference between categories indicated; significant interaction between age classification and outcome; § significant interaction between age classification and treatment; # significant interaction between treatment and outcome. Level of significance was P<0.05. PCV, packed cell volume, TPP, total plasma protein, TP, total protein, Nucl., nucleated, Perit, peritoneal.

PCV (%)#43 ± 1141 ± 1043 ± 10*42 ± 10*48 ± 12*39 ± 8*
TPP (g/l)§68.0 ± 11.9*65.2 ± 8.9*68.5 ± 9.2*65.6 ± 10.8*68.6 ± 11.9*65.6 ± 8.9*
Leucocyte count (x109/l)§9.39 ± 4.25*8.44 ± 5.17*8.56 ± 5.359.30 ± 3.978.81 ± 6.728.97 ± 3.42
Neutrophil count (x109/l)7.75 ± 4.80*6.36 ± 3.40*6.40 ± 3.65*7.77 ± 4.65*6.92 ± 4.507.12 ± 4.08
Fibrinogen (g/l)3.88 ± 6.973.25 ± 1.323.38 ± 1.383.77 ± 7.144.06 ± 8.603.32 ± 1.26
Creatinine (mg/l)20.5 ± 10.519.0 ± 10.219.6 ± 10.319.8 ± 10.525.1 ± 12.9*17.1 ± 7.6*
Lactate (mmol/l)#3.8 ± 3.63.1 ± 3.93.2 ± 3.93.7 ± 3.76.1 ± 4.8*2.0 ± 2.0*
Perit. TP (g/l)32.0 + 17.8*22.6 + 15.7*27.3 ± 18.329.0 ± 16.838.3 ± 16.5*21.3 ± 14.7*
Perit. nucl. cells (x109/l)21.72 + 61.3422.79 + 103.035.20 ± 111*8.96 ± 18.86*43.25 ± 11.89*8.37 ± 3.45*
Perit. red cells (x109/l)174.6 + 853.2100.1 + 203.4178.1 ± 933.0111.7 ± 213.3130.7 ± 202.315.30 ± 850.2

Age classification and outcome: There was a significant interaction between age classification and outcome for admission plasma creatinine concentrations. The difference in plasma creatinine concentration between nonsurvivors and survivors was greater for mature (26.7 ± 14.9 and 16.5 ± 6.4 mg/l, respectively) than for geriatric horses (24.2 ± 11.6 and 17.8 ± 8.8 mg/l, respectively); the difference between nonsurvivors and survivors was significant for both age classifications.

Treatment and outcome: There was a significant interaction between treatment and outcome for admission PCV and blood lactate concentration. The PCV for nonsurvivors was higher than that for survivors for medically (50 ± 13 and 39 ± 7%, respectively) and surgically (45 ± 11 and 39 ± 8%, respectively) treated horses. Medically treated nonsurvivors had a higher PCV than surgically treated nonsurvivors; however, there was no difference for medically and surgically treated survivors. Blood lactate concentration for nonsurvivors was higher than that for survivors for medically (6.8 ± 4.8 and 1.5 ± 1.4 mmol/l, respectively) and surgically (5.6 ± 4.7 and 2.6 ± 2.4 mmol/l, respectively) treated horses. Medically treated nonsurvivors had a higher lactate than surgically treated nonsurvivors; however, surgically treated survivors had a higher lactate than medically treated survivors.

Age classification and treatment: There was a significant interaction between age classification and treatment for TPP and total leucocyte count. There was no difference in TPP between medically and surgically treated mature horses (65.3 ± 8.9 and 65.0 ± 8.9 g/l, respectively). Medically treated geriatric horses had a higher TPP than surgically treated geriatric horses (70.3 ± 9.0 and 66.1 ± 12.0 g/l, respectively) as well as medically treated mature horse. Total leucocyte count was not different between medically and surgically treated mature horses (8.53 ± 6.15 and 8.32 ± 3.41 × 109 cells/l, respectively). Surgically treated geriatric horses had a higher total leucocyte count compared to medically treated geriatric horses (10.01 ± 4.21 and 8.61 ± 4.17 × 109 cells/l respectively) as well as a higher total leucocyte count compared to surgically treated mature horses.

Geriatric horses were more likely to have abdominocentesis performed compared to mature horses (110/300 [37%] vs. 74/300 [25%], P = 0.004) and nonsurvivors were more likely to have abdominocentesis performed compared to survivors (82/197 [42%] vs. 106/400 [27%], P<0.001). There was a significant association between the gross appearance of the peritoneal fluid and age classification (P = 0.005) and outcome (P<0.001) (Fig 4). There were more geriatric than mature horses with green/brown peritoneal fluid and more mature than geriatric horses with red peritoneal fluid. There were more nonsurvivors than survivors with green/brown and red peritoneal fluid and more survivors than nonsurvivors with yellow peritoneal fluid.

image

Figure 4. The percentage of horses (y axis) with different colours of peritoneal fluid at admission (yellow, orange, red or green/brown) based on age classification (geriatric, mature), treatment (medical, surgical) and outcome (nonsurvivor, survivor). The asterisk represents a significant difference between the categories indicated by the bar. Level of significance was P<0.05.

Download figure to PowerPoint

Discussion

  1. Top of page
  2. Summary
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Manufacturers' addresses
  8. References

Geriatric horses did not show more signs of cardiovascular compromise (shock) or were not more critically ill than mature horses. There was no difference between geriatric and mature horses in measurements that have been used previously to predict survival in horses with colic including heart rate, PCV and plasma creatinine and blood lactate concentrations (Grulke et al. 2001; Proudman et al. 2002, 2005a,b; Linden et al. 2003; Southwood 2004; Garcia-Seco et al. 2005; Johnston et al. 2007). These measurements were also associated with survival in the present study. While there can be several reasons for alterations in heart rate, PCV and plasma creatinine and blood lactate concentrations, these measurements provide some indication of cardiovascular status including haemoconcentration and tissue perfusion. Therefore, it was concluded from this information that the survival rate of geriatric horses is not lower than that of mature nongeriatric horses because they were more cardiovascularly compromised or critically ill at admission.

While we did not detect a difference in critical illness based on measures of impaired cardiovascular status, there was evidence that geriatric horses had different, and possibly more severe, gastrointestinal disease compared to mature nongeriatric horses. Geriatric horses: 1) were more likely to be moderately painful and less likely to be bright and alert and not showing signs of pain; 2) were less likely to have normal intestinal borborygmi; and 3) had a higher peritoneal fluid total protein compared to mature horses. These findings suggest that there was a higher proportion of geriatric horses with more severe gastrointestinal disease (Grulke et al. 2001). Therefore, while there may have been no difference in the degree of cardiovascular compromise (i.e. shock) between geriatric and mature horses, based on the admission data there may be some evidence suggesting that geriatric horses have more serious disease and a greater degree of gastrointestinal injury.

It was also proposed that duration of colic prior to admission would be longer for geriatric compared to mature horses because geriatric horses are more stoic; however, there was no difference in the duration of colic between geriatric and mature horses. The lack of difference could be attributed to the variability in duration of colic as indicated by the large standard deviation of the mean because of a wide range in the causes of colic. However, when this was investigated more closely by comparing geriatric and mature horses managed medically vs. surgically and geriatric and mature nonsurvivors vs. survivors there was still no difference between geriatric and mature horses (i.e. no interaction). Therefore, a longer duration of colic prior to presentation does not appear to be the reason for the lower survival of geriatric compared to mature nongeriatric horses with gastrointestinal disease.

While it is the perception of some clinicians that geriatric horses are less likely to demonstrate dramatic signs of abdominal pain, conclusions cannot be made regarding this from these results because a direct comparison between signs of pain for a particular type of lesion (e.g. strangulating vs. nonstrangulating) would be necessary.

Abdominal distention was less in geriatric compared to mature horses, which may indicate a higher occurrence of small intestinal disease. Freeman and Schaeffer (2001) demonstrated that geriatric horses commonly suffer from strangulation of the small intestine by a pedunculated lipoma, which is likely to explain the lack of abdominal distention, moderate signs of pain, and high peritoneal fluid total protein in geriatric horses with colic. Peritoneal fluid was significantly more likely to be green/brown in geriatric compared to mature horses. This finding may indicate that geriatric horses were more likely to have a gastrointestinal perforation compared to mature horses. Causes of colic are addressed in Part 2 of this series (Southwood et al. 2010).

The relationship between age classification and outcome for RR, RT and plasma creatinine concentration was complex with the difference between nonsurvivors and survivors being higher for mature than for geriatric patients. One interpretation of these findings is that geriatric horses may be subjected to euthanasia for less severe disease (i.e. nonsurviving geriatric horses had a lower respiratory rate, rectal temperature and creatinine concentration) than nonsurviving mature nongeriatric horses. Short-term survival of geriatric compared to mature nongeriatric horses is addressed in Part 2 of this series (Southwood et al. 2010).

Medically treated geriatric horses had a high TPP. When a subgroup of geriatric horses aged ≥20 years was analysed (data not shown), the difference in TPP between geriatric and mature nongeriatric horses was significant; however, the interaction was no longer significant. The high TPP was not a result of marked hyperfibrinogenaemia; however, albumin and globulin were not evaluated and therefore it is difficult to determine the exact reasons for the higher TPP. While haemoconcentration is an obvious explanation, a similar finding with other measurements such as PCV would have been expected. The total leucocyte and segmented neutrophil counts were also higher in surgically treated geriatric compared to mature horses. Possible reasons for the high leucocyte and neutrophil counts include a stress response associated with pain or underlying pituitary pars intermedia dysfunction (PPID). Neutrophilia and lymphopenia have been reported in a subset of horses with PPID (Schott 2002) and aged horses have a proinflammatory state compared to mature horses (McFarlane and Holbrook 2008). The implications of these findings in geriatric horses with colic require further investigation.

The definition of the term geriatric is variable and is probably not best defined by age. The progression from young through mature to geriatric is a continuum and different for different horses. We chose age ≥16 years to include horses in their late teens and older. This age was also chosen because it was similar to an earlier study that evaluated colic in the aged horse which was considered to be age ≥17 years (Carson-Dunkerley and Hanson 1996) and in a study evaluating cytokine dysregulation (McFarlane and Holbrook 2008) in aged horses. Others have defined geriatric horses as those age ≥20 years (Krista and Kuebelbeck 2009). In order to address different definitions of geriatric, admission heart rate, PCV, blood lactate concentration were compared as well as admission pain level, abdominal distention, intestinal borborygmi and peritoneal fluid colour for mature nongeriatric horses to geriatric horses age ≥20 years and the results were not different (data not shown).

Based on the results of this study, geriatric horses do not appear to have more severe signs of cardiovascular compromise nor a longer duration of colic prior to presentation compared to mature nongeriatric horses. However, there is some indication based on physical examination findings that geriatric horses may have different and potentially more serious disease than mature horses. There is also some indication that geriatric horses may be subjected to euthanasia for less severe disease than mature horses. Causes of colic and short-term survival are discussed in Part 2 of this series (Southwood et al. 2010).

Manufacturers' addresses

  1. Top of page
  2. Summary
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Manufacturers' addresses
  8. References

1 Microsoft, Seattle, Washington, USA.

2 PROC MIXED, Statistical Analysis System, SAS Institute Inc., Cary, North Carolina, USA.

References

  1. Top of page
  2. Summary
  3. Introduction
  4. Materials and methods
  5. Results
  6. Discussion
  7. Manufacturers' addresses
  8. References
  • Brosnahan, M.M. and Paradis, M.R. (2003) Demographic and clinical characteristics of geriatric horses: 467 cases (1989-1999). J. Am. vet. med. Ass. 223, 93-98.
  • Carson-Dunkerley, S.A. and Hanson, R.R. (1996) Survival from colic in the aged horse: 104 cases (1990-1996). Proc. Am. Ass. equine Practnrs. 42, 262-263.
  • Freeman, D.E. and Schaeffer, D.J. (2001) Age distributions of horses with strangulation of the small intestine by a lipoma or in the epiploic foramen: 46 cases. J. Am. vet. med. Ass. 219, 87-89.
  • Garcia-Seco, E., Wilson, D.A., Kramer, J., Branson, K.R., Johnson, P.J. and Tyler, J.W. (2005) Prevalence and risk factors associated with outcome of surgical removal of pedunculated lipomas in horses: 102 cases (1987-2002). J. Am. vet. med. Ass. 226, 1529-1537.
  • Grulke, S., Olle, E., Detilleux, J., Gangl, M., Caudron, I. and Serteyn, D. (2001) Determination of a gravity and shock score for prognosis in equine surgical colic. J. vet. Med. A Physiol. Pathol. Clin. Med. 48, 465-473.
  • Johnston, K., Holcombe, S.J. and Hauptman, J.G. (2007) Plasma lactate as a predictor of colonic viability and survival after 360 degrees volvulus of the ascending colon in horses. Vet. Surg. 36, 563-567.
  • Krista, K.M. and Kuebelbeck, K.L. (2009) Comparison of survival rates for geriatric horses versus nongeriatric horses following exploratory celiotomy for colic. J. Am. vet. med. Ass. 235, 1069-1072.
  • Linden, M.A., Van Der Laffont, C.A. and Sloet van Oldruitenborgh-Oosterbaan, M.M. (2003) Prognosis in equine medical and surgical colic. J. vet. intern. Med. 17, 343-348.
  • McFarlane, D. and Holbrook, T.C. (2008) Cytokine dysregulation in aged horses and horses with pituitary pars intermedia dysfunction. J. vet. intern. Med. 22, 436-442.
  • Proudman, C.J., Edwards, G.B., Barnes, J. and French, N.P. (2002) Long-term survival of equine surgical colic cases. Part 2: modelling postoperative survival. Equine vet. J. 34, 438-443.
  • Proudman, C.J., Edwards, G.B., Barnes, J. and French, N.P. (2005a) Factors affecting long-term survival of horses recovering from surgery of the small intestine. Equine vet. J. 37, 360-365.
  • Proudman, C.J., Edwards, G.B., Barnes, J. and French, N.P. (2005b) Modelling long-term survival of horses following surgery for large intestinal disease. Equine vet. J. 37, 366-370.
  • Schott, H.C. (2002) Pituitary pars intermedia dysfunction: Equine Cushing's disease. Vet. Clin. N. Am.: equine Pract. 18, 237-270.
  • Southwood, L.L. (2004) Postoperative management of the large colon volvulus patient. Vet. Clin. N. Am.: equine Pract. 20, 167-197.
  • Southwood, L.L., Gassert, T. and Lindborg, S. (2010) Colic in geriatric compared to mature nongeriatric horses. Part 2: Treatment, diagnosis and short-term survival. Equine vet. J. 42, In Press.
  • Southwood, L.L., Dolente, B.A., Lindborg, S. and Russell, G. (2008) Survival rate of horses admitted on an emergency basis to a university referral hospital. Equine vet. J. 41, 459-464.