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Donkey Colic
C H A P T E R
Donkey Colic
76
NICOLE du TOIT FAITH BURDEN
A
s is true in horses, there are many causes of abdominal pain in donkeys, most of which are gastrointestinal in origin. These can be classified into dietary motility disorders, displacements, infections (bacteria, protozoa, endoparasites), and inflammation, including ulceration. There are, however, physiologic and behavioral differences between donkeys and horses that influence the presenting signs in donkeys such that they are not as characteristic or prominent as in horses. Spasmodic colic is the most common type of colic seen in horses in first-opinion practice, but this type of colic is seen in only a small percentage of donkeys with colic. This difference may be related to the differences in donkey behavior in not exhibiting overt clinical signs and the usual short duration of spasmodic colic. In contrast, impaction colic is regarded as the most common type of colic seen in donkeys. Other common gastrointestinal causes of colic seen in donkeys include colon displacement, intestinal torsion, and colitis.
CLINICAL SIGNS
Pain-related clinical signs in donkeys are much more subtle than those observed in horses. Because donkeys are sedentary by nature, it may be difficult to identify sick donkeys unless their normal behavior is understood. It is believed that donkeys frequently exhibit anhedonia (absence of behavior) rather than unique pain-response behaviors. Subtle changes in behavior, such as lowered head carriage, reduced ear movements (Figure 76-1), reduced social interaction, inappetence, and reduced response to stimuli may be the only indication of colic. Also, sick donkeys often exhibit sham eating, wherein they stand near the feed trough and prehend the occasional mouthful of food but do not swallow or truly eat. This may give the false impression that anorexic donkeys are still eating and cause further delays in requesting veterinary assistance. Because of their subtle clinical signs, all sick donkeys should be regarded as clinical emergencies, with the disease process likely being of longer duration than reported. In cases of acute abdominal pain such as gastrointestinal torsion, donkeys may exhibit overt colic signs such as flank watching, kicking, sweating, and rolling.
CLINICAL EXAMINATION
Clinical examination of a donkey may be useful in determining the cause and severity of colic. Donkeys may have tachycardia (heart rate > 44 bpm) with colic, but in some instances, such as with impaction colic, the tachycardia may be relatively mild (44 to 60 bpm). Donkeys with other causes of colic may have severe tachycardia (>80 bpm). Heart rate is affected by pain, but also by hemoconcentration, hydration status, and endotoxemia, which collectively usually result in a greater increase in heart rate. Donkeys have a more marked physiologic response to dehydration, compared with horses. As with horses, the donkey hindgut acts as a reservoir for
water, so that reduced fecal dry weight and fecal water loss occur during times of water restriction. Donkeys also can maintain plasma volume even when they are as much as 20% dehydrated, so they are often more than 10% dehydrated before clinical signs associated with dehydration become apparent. Assessment of the mucous membranes is useful in determining the severity of colic. Healthy donkeys normally have pale pink mucous membranes and are less likely to show the yellow discoloration characteristically seen in horses that are inappetent or anorexic. Dry mucous membranes with pro longation of capillary refill time (normal, <2 seconds) are a good indicator of moderate to severe dehydration. In donkeys with endotoxemia, the mucous membranes, like those of horses, may become dark red or purple tinged with red. Higher-than-normal rectal temperature is most likely to be observed in donkeys with endotoxemia, such as occurs with gastrointestinal torsion or colitis. Mild tachypnea (respiratory rate > 20 bpm) may be observed with colic, but this is more likely to be marked in donkeys with respiratory disease. However, donkeys with intestinal displacement or visceral enlargement that is causing pressure on the diaphragm may present with severe tachypnea. Abdominal auscultation will identify an increase or decrease in the frequency of borborygmus. Colic caused by impaction, large colon displacement, or torsion is more likely to be accompanied by reduced gut sounds.
Ancillary Diagnostic Aids Rectal palpation is an important diagnostic tool in evaluating a sick donkey. It is possible to perform a safe rectal examination on very small donkeys, but the procedure should be undertaken with good restraint (with or without sedation) and copious lubrication. In cases of large intestinal torsion with colon distension, it may be difficult to gain access to the abdominal cavity because of the small size of the donkey and the distended intestines. Impactions may be more difficult to detect on rectal examinations in donkeys than in horses. The pelvic flexure is the most common site for intestinal impactions in donkeys but, unlike in horses in which pelvic flexure impactions are palpable as a large doughy mass in the pelvic canal, in donkeys impactions are usually small, very hard, and oval-shaped (Figure 76-2). These often displace cranially or ventrally into the abdominal cavity and can be mistaken for primary colon displacements. The presence of dry, mucuscovered fecal balls within the rectum should alert the practitioner to the likelihood of hyperlipemia. Hyperlipemia can be a primary disease or can develop secondary to other diseases, such as colic. Therefore rectal examination should still proceed if hyperlipemia is suspected. Abdominal ultrasound can be a useful diagnostic tool for clinicians experienced with horses and can often be used to
333
334
SECTION
VI Gastrointestinal Disease
Figure 76-1 Low head carriage, reduced ear movements, and reduced social interaction are subtle clinical signs indicative of a sick donkey.
Figure 76-3 Ventral abdominal subcutaneous fat deposits at the linea alba are commonly 4 to 5 cm thick but may be in excess of 10 cm in some donkeys. This can complicate abdominocentesis in donkeys.
of hyperlipemia (triglyceride concentration > 2.7 mmol/L). Because any donkey with colic is at high risk for developing hyperlipemia, triglyceride concentration should be monitored every 6 to 8 hours. In cases in which gastrointestinal disease cannot be confirmed or complications are suspected, blood tests may also be useful in assessing the health of other organs such as the liver, kidney, and pancreas.
COLIC TREATMENT
Figure 76-2 Postmortem photograph of a typical hard, oval-shaped pelvic flexure impaction that did not resolve with medical treatment.
diagnose visceral distension, displacements, or inflammation before rectal palpation is performed. Similarly, it may be useful in donkeys. In particular, ultrasound may be useful for diagnosing colitis, which may be observed as an increase in the thickness of the colon wall. Abdominocentesis is also a useful diagnostic aid in donkeys and can help to differentiate between medical and surgical colic. Obtaining a peritoneal fluid sample in donkeys is slightly more difficult than in horses because donkeys often have a large fat pad in the region of the linea alba. A spinal needle or teat cannula is needed to obtain a sample because the thickness of this subcutaneous fat can be in excess of 10 cm (Figure 76-3). A nasogastric tube should be passed to assess for gastric reflux in any donkey with gastrointestinal stasis or distended viscera. Using a small-diameter tube (9 to 11 mm) with lubricant facilitates passage and reduces the risk for hemorrhage from the nasal mucosa. In smaller donkeys, a reflux volume greater than 1 L should be regarded as suggestive of gastric stasis and distension. A blood sample is important to assess the hematocrit and total protein concentration for hydration status; even more important in donkeys, it is required to check for the presence
General principles of colic treatment in horses apply to donkeys: provide analgesia, maintain hydration status, and reestablish normal gastrointestinal tract outflow and motility. However, in donkeys it is also important to maintain a positive energy balance to prevent development of hyperlipemia. The most commonly used nonsteroidal antiinflammatory drugs (NSAIDs) in donkeys are phenylbutazone (4.4 mg/kg, IV, every 8 to 12 hours) and flunixin meglumine (1.1 mg/kg, IV, every 12 to 24 hours). The correct dosing intervals for analgesic efficacy coupled with minimal likelihood of toxicosis still need to be determined in donkeys, but these drugs may need to be given more frequently than in horses because of a shorter plasma half-life in donkeys. The only exception is carprofen (0.7 mg/kg, IV, every 24 hours), which has a longer plasma half-life in donkeys. Because plasma half-life is not necessarily an indication of the clinical effectiveness of drugs, clinical response to NSAID administration may be a better indication of an individual donkey’s requirements. In severe cases of colic, flunixin meglumine administration every 12 hours may be required to provide good clinical analgesia. In cases of spasmodic colic, the use of a spasmolytic, such as N-butylscopolammonium bromide1 (single injection of 0.3 mg/kg body weight or 1.5 mL/100 kg) or a combination of N-butylscopolammonium (4 mg/mL) and metamizole (500 mg/mL),2 in countries where it is available, can be beneficial. The dosage of the latter is 5 mL/100 kg, given intravenously. Fluid therapy can be provided by intravenous administration of balanced electrolyte solutions or as oral fluids, or by
1
Buscopan, Boehringer Ingelheim Vetmedica Inc., St. Joseph, MO. Buscopan Compositum, Boehringer Ingelheim Limited, Berkshire, UK.
2
a combination of both. Oral fluids should not be administered to donkeys with gastric reflux or surgical causes of colic, but their use is recommended for impactions. Because there is always a risk for hyperlipemia in donkeys, complete withholding of food is not recommended for medical colic. The feeding of small frequent meals with easily digestible fiber is recommended. Access to grazing or offering soaked sugar beet without molasses or soaked fiber pellets ensures a proportion of water intake as well as providing nutrients. Primary large colon displacements often resolve with medical therapy that includes analgesia, oral and intravenous fluids, and frequent small feeds of easily digestible food such as green grass. Treatment of pelvic flexure impaction in donkeys is often less successful than in horses because the hard impaction is often impenetrable to oral laxatives or osmotic purgatives such as Epsom salt (MgSO4) or Glauber’s salt (NaSO4). The hard impaction within the small-diameter viscus often results in circumferential mucosal and submucosal inflammation, reduced blood flow, and eventually necrosis. Depending on the age of the donkey and the duration of colic, surgery may be an option for pelvic flexure impactions. Similarly, in cases of small or large intestinal volvulus, careful clinical assessment of the donkey to determine duration of the colic and clinical status will help determine the prognosis for success of surgical treatment. Unfortunately, because of donkeys’ subtle behavior in response to pain, donkeys may be presented too late for a successful surgical outcome. Colitis cases generally have a poor prognosis despite aggressive medical treatment (intravenous fluids, antimicrobials, analgesia, anthelmintics, and corticosteroids). This may be a result of the fact that the etiology of colitis in donkeys appears to be multifactorial, with stress being a major contributor. Furthermore, there is usually more extensive involvement of the large bowel, with the cecum and ventral colon affected, rather than just the right dorsal colon, as is often seen in horses. Gastric ulcers may also be a primary cause of colic in donkeys but are more commonly the result of other diseases such as hyperlipemia or renal disease. Feeding of concentrate diets is a high risk factor for the development of squamous epithelial ulcers.
DIETARY MANAGEMENT
Donkeys can easily be maintained on a forage-based diet; the inclusion of cereal grain products such as straight grains, sweet feeds, and mixes increases the risk for gastric ulcers in donkeys and should be strictly avoided. Changes in pasture availability with climatic seasons need to be anticipated because any sudden changes in diet are likely to cause
CHAPTER
76 Donkey Colic
335
gastrointestinal upsets in donkeys. A gradual introduction of dietary changes over a period of 4 to 6 weeks will minimize the risk for developing diet-related colic. The practice of meal feeding is also to be discouraged because donkeys fed large ‘meals’ once or twice a day are at significantly increased risk for developing colic, gastric ulcers, and hyperlipemia. When supplementary feeding is required, such as when donkeys have dental disease, are pregnant or lactating, or are underweight, additional feeds should be “trickle fed” by providing shortly chopped fiber or forage ad libitum (for dental cases) or by increasing the energy density of the forage ration by providing increased amounts of hay or haylage in the ration. The key to preventing impaction colic in the donkey is to ensure that palatable water is freely available. Because they are animals adapted to desert life, they are thirst tolerant and, unlike horses, will maintain appetite even when severely dehydrated. In addition, donkeys can be particularly fastidious about the water they drink. In particular, when temperatures are low, donkeys will frequently refuse cold or icy water. For these reasons, monitoring water intake and providing warmed water during cold weather are essential to prevent impaction colic and its late diagnosis.
Suggested Readings Burden FA, du Toit N, Hazell-Smith E, et al. Hyperlipaemia in a population of aged donkeys: description, prevalence and potential risk factors. J Vet Intern Med 2011;25:1420-1425. Burden FA, Gallagher J, Thiemann A et al. Necropsy survey of gastric ulcers in a population of aged donkeys. Animal 2009;3(2):287-293. Cox R, Burden FA, Gosden L, et al. Case control study to investigate the risk factors for impaction colic in donkeys in the UK. Prevent Vet Med J 2009;92:179-187. Duncan J, Hadrill D, eds. The Professional Handbook of the Donkey. 4th ed. Wiltshire, UK: Whittet Books, 2008. Du Toit N, Burden FA, Getachew M, et al. Idiopathic typhlocolitis in 40 aged donkeys. Equine Vet Ed 2010;22: 53-57. Grosenbaugh DA, Reinemeyer CR, Figueiredo MD. Pharmacology and therapeutics in donkeys. Equine Vet Educ 2011;23:523-530. Kasirer-Izraely SMA, Choshniak I, Shkolnik A. Dehydration and rehydration in donkeys: the role of the hind gut as a water reservoir. J Basic Clin Physiol Pharmacol 1994;5:89-100. Mealey KL, Matthes NS, Peck KE, et al. Comparative pharmacokinetics of phenylbutazone and its metabolite oxyphenbutazone in clinically normal horses and donkeys. Am J Vet Res 1997;58:53-55. Morrow L, Smith KC, Piercy RJ, et al. Retrospective analysis of post-mortem findings in 1,444 aged donkeys. J Comp Pathol 2010;144:145-156.
Donkey Colic
76
NICOLE du TOIT FAITH BURDEN
A
s is true in horses, there are many causes of abdominal pain in donkeys, most of which are gastrointestinal in origin. These can be classified into dietary motility disorders, displacements, infections (bacteria, protozoa, endoparasites), and inflammation, including ulceration. There are, however, physiologic and behavioral differences between donkeys and horses that influence the presenting signs in donkeys such that they are not as characteristic or prominent as in horses. Spasmodic colic is the most common type of colic seen in horses in first-opinion practice, but this type of colic is seen in only a small percentage of donkeys with colic. This difference may be related to the differences in donkey behavior in not exhibiting overt clinical signs and the usual short duration of spasmodic colic. In contrast, impaction colic is regarded as the most common type of colic seen in donkeys. Other common gastrointestinal causes of colic seen in donkeys include colon displacement, intestinal torsion, and colitis.
CLINICAL SIGNS
Pain-related clinical signs in donkeys are much more subtle than those observed in horses. Because donkeys are sedentary by nature, it may be difficult to identify sick donkeys unless their normal behavior is understood. It is believed that donkeys frequently exhibit anhedonia (absence of behavior) rather than unique pain-response behaviors. Subtle changes in behavior, such as lowered head carriage, reduced ear movements (Figure 76-1), reduced social interaction, inappetence, and reduced response to stimuli may be the only indication of colic. Also, sick donkeys often exhibit sham eating, wherein they stand near the feed trough and prehend the occasional mouthful of food but do not swallow or truly eat. This may give the false impression that anorexic donkeys are still eating and cause further delays in requesting veterinary assistance. Because of their subtle clinical signs, all sick donkeys should be regarded as clinical emergencies, with the disease process likely being of longer duration than reported. In cases of acute abdominal pain such as gastrointestinal torsion, donkeys may exhibit overt colic signs such as flank watching, kicking, sweating, and rolling.
CLINICAL EXAMINATION
Clinical examination of a donkey may be useful in determining the cause and severity of colic. Donkeys may have tachycardia (heart rate > 44 bpm) with colic, but in some instances, such as with impaction colic, the tachycardia may be relatively mild (44 to 60 bpm). Donkeys with other causes of colic may have severe tachycardia (>80 bpm). Heart rate is affected by pain, but also by hemoconcentration, hydration status, and endotoxemia, which collectively usually result in a greater increase in heart rate. Donkeys have a more marked physiologic response to dehydration, compared with horses. As with horses, the donkey hindgut acts as a reservoir for
water, so that reduced fecal dry weight and fecal water loss occur during times of water restriction. Donkeys also can maintain plasma volume even when they are as much as 20% dehydrated, so they are often more than 10% dehydrated before clinical signs associated with dehydration become apparent. Assessment of the mucous membranes is useful in determining the severity of colic. Healthy donkeys normally have pale pink mucous membranes and are less likely to show the yellow discoloration characteristically seen in horses that are inappetent or anorexic. Dry mucous membranes with pro longation of capillary refill time (normal, <2 seconds) are a good indicator of moderate to severe dehydration. In donkeys with endotoxemia, the mucous membranes, like those of horses, may become dark red or purple tinged with red. Higher-than-normal rectal temperature is most likely to be observed in donkeys with endotoxemia, such as occurs with gastrointestinal torsion or colitis. Mild tachypnea (respiratory rate > 20 bpm) may be observed with colic, but this is more likely to be marked in donkeys with respiratory disease. However, donkeys with intestinal displacement or visceral enlargement that is causing pressure on the diaphragm may present with severe tachypnea. Abdominal auscultation will identify an increase or decrease in the frequency of borborygmus. Colic caused by impaction, large colon displacement, or torsion is more likely to be accompanied by reduced gut sounds.
Ancillary Diagnostic Aids Rectal palpation is an important diagnostic tool in evaluating a sick donkey. It is possible to perform a safe rectal examination on very small donkeys, but the procedure should be undertaken with good restraint (with or without sedation) and copious lubrication. In cases of large intestinal torsion with colon distension, it may be difficult to gain access to the abdominal cavity because of the small size of the donkey and the distended intestines. Impactions may be more difficult to detect on rectal examinations in donkeys than in horses. The pelvic flexure is the most common site for intestinal impactions in donkeys but, unlike in horses in which pelvic flexure impactions are palpable as a large doughy mass in the pelvic canal, in donkeys impactions are usually small, very hard, and oval-shaped (Figure 76-2). These often displace cranially or ventrally into the abdominal cavity and can be mistaken for primary colon displacements. The presence of dry, mucuscovered fecal balls within the rectum should alert the practitioner to the likelihood of hyperlipemia. Hyperlipemia can be a primary disease or can develop secondary to other diseases, such as colic. Therefore rectal examination should still proceed if hyperlipemia is suspected. Abdominal ultrasound can be a useful diagnostic tool for clinicians experienced with horses and can often be used to
333
334
SECTION
VI Gastrointestinal Disease
Figure 76-1 Low head carriage, reduced ear movements, and reduced social interaction are subtle clinical signs indicative of a sick donkey.
Figure 76-3 Ventral abdominal subcutaneous fat deposits at the linea alba are commonly 4 to 5 cm thick but may be in excess of 10 cm in some donkeys. This can complicate abdominocentesis in donkeys.
of hyperlipemia (triglyceride concentration > 2.7 mmol/L). Because any donkey with colic is at high risk for developing hyperlipemia, triglyceride concentration should be monitored every 6 to 8 hours. In cases in which gastrointestinal disease cannot be confirmed or complications are suspected, blood tests may also be useful in assessing the health of other organs such as the liver, kidney, and pancreas.
COLIC TREATMENT
Figure 76-2 Postmortem photograph of a typical hard, oval-shaped pelvic flexure impaction that did not resolve with medical treatment.
diagnose visceral distension, displacements, or inflammation before rectal palpation is performed. Similarly, it may be useful in donkeys. In particular, ultrasound may be useful for diagnosing colitis, which may be observed as an increase in the thickness of the colon wall. Abdominocentesis is also a useful diagnostic aid in donkeys and can help to differentiate between medical and surgical colic. Obtaining a peritoneal fluid sample in donkeys is slightly more difficult than in horses because donkeys often have a large fat pad in the region of the linea alba. A spinal needle or teat cannula is needed to obtain a sample because the thickness of this subcutaneous fat can be in excess of 10 cm (Figure 76-3). A nasogastric tube should be passed to assess for gastric reflux in any donkey with gastrointestinal stasis or distended viscera. Using a small-diameter tube (9 to 11 mm) with lubricant facilitates passage and reduces the risk for hemorrhage from the nasal mucosa. In smaller donkeys, a reflux volume greater than 1 L should be regarded as suggestive of gastric stasis and distension. A blood sample is important to assess the hematocrit and total protein concentration for hydration status; even more important in donkeys, it is required to check for the presence
General principles of colic treatment in horses apply to donkeys: provide analgesia, maintain hydration status, and reestablish normal gastrointestinal tract outflow and motility. However, in donkeys it is also important to maintain a positive energy balance to prevent development of hyperlipemia. The most commonly used nonsteroidal antiinflammatory drugs (NSAIDs) in donkeys are phenylbutazone (4.4 mg/kg, IV, every 8 to 12 hours) and flunixin meglumine (1.1 mg/kg, IV, every 12 to 24 hours). The correct dosing intervals for analgesic efficacy coupled with minimal likelihood of toxicosis still need to be determined in donkeys, but these drugs may need to be given more frequently than in horses because of a shorter plasma half-life in donkeys. The only exception is carprofen (0.7 mg/kg, IV, every 24 hours), which has a longer plasma half-life in donkeys. Because plasma half-life is not necessarily an indication of the clinical effectiveness of drugs, clinical response to NSAID administration may be a better indication of an individual donkey’s requirements. In severe cases of colic, flunixin meglumine administration every 12 hours may be required to provide good clinical analgesia. In cases of spasmodic colic, the use of a spasmolytic, such as N-butylscopolammonium bromide1 (single injection of 0.3 mg/kg body weight or 1.5 mL/100 kg) or a combination of N-butylscopolammonium (4 mg/mL) and metamizole (500 mg/mL),2 in countries where it is available, can be beneficial. The dosage of the latter is 5 mL/100 kg, given intravenously. Fluid therapy can be provided by intravenous administration of balanced electrolyte solutions or as oral fluids, or by
1
Buscopan, Boehringer Ingelheim Vetmedica Inc., St. Joseph, MO. Buscopan Compositum, Boehringer Ingelheim Limited, Berkshire, UK.
2
a combination of both. Oral fluids should not be administered to donkeys with gastric reflux or surgical causes of colic, but their use is recommended for impactions. Because there is always a risk for hyperlipemia in donkeys, complete withholding of food is not recommended for medical colic. The feeding of small frequent meals with easily digestible fiber is recommended. Access to grazing or offering soaked sugar beet without molasses or soaked fiber pellets ensures a proportion of water intake as well as providing nutrients. Primary large colon displacements often resolve with medical therapy that includes analgesia, oral and intravenous fluids, and frequent small feeds of easily digestible food such as green grass. Treatment of pelvic flexure impaction in donkeys is often less successful than in horses because the hard impaction is often impenetrable to oral laxatives or osmotic purgatives such as Epsom salt (MgSO4) or Glauber’s salt (NaSO4). The hard impaction within the small-diameter viscus often results in circumferential mucosal and submucosal inflammation, reduced blood flow, and eventually necrosis. Depending on the age of the donkey and the duration of colic, surgery may be an option for pelvic flexure impactions. Similarly, in cases of small or large intestinal volvulus, careful clinical assessment of the donkey to determine duration of the colic and clinical status will help determine the prognosis for success of surgical treatment. Unfortunately, because of donkeys’ subtle behavior in response to pain, donkeys may be presented too late for a successful surgical outcome. Colitis cases generally have a poor prognosis despite aggressive medical treatment (intravenous fluids, antimicrobials, analgesia, anthelmintics, and corticosteroids). This may be a result of the fact that the etiology of colitis in donkeys appears to be multifactorial, with stress being a major contributor. Furthermore, there is usually more extensive involvement of the large bowel, with the cecum and ventral colon affected, rather than just the right dorsal colon, as is often seen in horses. Gastric ulcers may also be a primary cause of colic in donkeys but are more commonly the result of other diseases such as hyperlipemia or renal disease. Feeding of concentrate diets is a high risk factor for the development of squamous epithelial ulcers.
DIETARY MANAGEMENT
Donkeys can easily be maintained on a forage-based diet; the inclusion of cereal grain products such as straight grains, sweet feeds, and mixes increases the risk for gastric ulcers in donkeys and should be strictly avoided. Changes in pasture availability with climatic seasons need to be anticipated because any sudden changes in diet are likely to cause
CHAPTER
76 Donkey Colic
335
gastrointestinal upsets in donkeys. A gradual introduction of dietary changes over a period of 4 to 6 weeks will minimize the risk for developing diet-related colic. The practice of meal feeding is also to be discouraged because donkeys fed large ‘meals’ once or twice a day are at significantly increased risk for developing colic, gastric ulcers, and hyperlipemia. When supplementary feeding is required, such as when donkeys have dental disease, are pregnant or lactating, or are underweight, additional feeds should be “trickle fed” by providing shortly chopped fiber or forage ad libitum (for dental cases) or by increasing the energy density of the forage ration by providing increased amounts of hay or haylage in the ration. The key to preventing impaction colic in the donkey is to ensure that palatable water is freely available. Because they are animals adapted to desert life, they are thirst tolerant and, unlike horses, will maintain appetite even when severely dehydrated. In addition, donkeys can be particularly fastidious about the water they drink. In particular, when temperatures are low, donkeys will frequently refuse cold or icy water. For these reasons, monitoring water intake and providing warmed water during cold weather are essential to prevent impaction colic and its late diagnosis.
Suggested Readings Burden FA, du Toit N, Hazell-Smith E, et al. Hyperlipaemia in a population of aged donkeys: description, prevalence and potential risk factors. J Vet Intern Med 2011;25:1420-1425. Burden FA, Gallagher J, Thiemann A et al. Necropsy survey of gastric ulcers in a population of aged donkeys. Animal 2009;3(2):287-293. Cox R, Burden FA, Gosden L, et al. Case control study to investigate the risk factors for impaction colic in donkeys in the UK. Prevent Vet Med J 2009;92:179-187. Duncan J, Hadrill D, eds. The Professional Handbook of the Donkey. 4th ed. Wiltshire, UK: Whittet Books, 2008. Du Toit N, Burden FA, Getachew M, et al. Idiopathic typhlocolitis in 40 aged donkeys. Equine Vet Ed 2010;22: 53-57. Grosenbaugh DA, Reinemeyer CR, Figueiredo MD. Pharmacology and therapeutics in donkeys. Equine Vet Educ 2011;23:523-530. Kasirer-Izraely SMA, Choshniak I, Shkolnik A. Dehydration and rehydration in donkeys: the role of the hind gut as a water reservoir. J Basic Clin Physiol Pharmacol 1994;5:89-100. Mealey KL, Matthes NS, Peck KE, et al. Comparative pharmacokinetics of phenylbutazone and its metabolite oxyphenbutazone in clinically normal horses and donkeys. Am J Vet Res 1997;58:53-55. Morrow L, Smith KC, Piercy RJ, et al. Retrospective analysis of post-mortem findings in 1,444 aged donkeys. J Comp Pathol 2010;144:145-156.