ALIMENTARY SYSTEM INJURIES part 2
1) THE INTESTINES
Injuries:
Foreign bodies, Intussusceptions, Penetrating injury, blunt trauma, poisons, Infections, Torsions and herniation.
General Signs:
Pain, Vomiting, abdominal guarding, sometimes abdominal swelling. Shock. As always, the signs depend on the particular disease.
a/ Foreign bodies (FB's)
The severity of the problem depends on the location and type of the FB. Sharp FB's such as chop bones may cause perforation and hence much more severe pain and disease than smooth FB's, e.g. stones and pebbles.
Vomiting is the main sign of a foreign body, due to blockage. If the obstruction is very high in the intestines then vomiting of food a little while after eating can be expected. If the FB is lower in the tract then the food may be partly digested, and may have been the subject of bacterial fermentation. In such cases faecal vomit can result, when the animal brings up what appear to be faeces. These are usually reported by the owners.
Normal digestive processes require vast quantities of fluid to be discharged into the proximal small intestine ( from the pancreas and duodenum ) and reabsorbed in the lower small intestine and large intestine. Foreign Bodies situated in just the right area - below the level of secretion but above the level of reabsorption- can cause very rapid dehydration and shock.
Even smooth FB's will eventually damage the intestinal wall.
FB's occasionally cause diarrhoea, but usually the lower bowel just empties out, giving a dry rectum.
Treatment:
Fluid therapy, Ringer's (or Hartmann's) to aid replacement of lost ions. Nil by mouth.
b/ Intussusception
A segment of bowel is progressively drawn into an adjacent segment in a telescoping action. The effect is that of a foreign body, but because the blood supply is pinched off where one segment of bowel encloses the other, the inner bowel can die off and slough away.
Occurs in animals with motility disturbances, so often young animals (change of food ) or animals with bowel damage or disease (bowel wall cancer). Often seen at the ileo-caeco-colic junction when small bowel intussuscepts into the large bowel.
Diarrhoea is often seen, either as a precursor, or as a consequence of the problem.
Treatment:
Will need surgery so treatment is symptomatic. Intravenous fluids. Withhold food.
c/ Infections
Gastroenteritis. Some infections can cause permanent damage to the intestinal wall, e.g. parvovirus infection causes loss of villi which never regrow. Diarrhoea and vomiting are the usual signs, with vomiting usually preceding the onset of diarrhoea.
Treatment:
Fluids, per os or i.v. or both, depending on severity. Electrolyte replacer solutions are helpful. Withhold food.
d/ Poisons
Numerous poisons damage the intestines physically, including Arsenic , Lead and heavy metal poisons, Also slug bait ( metaldehyde ), disinfectants etc.
Treatment:
Specific for the poison or general supportive treatment. If the poison is still present in the gastrointestinal tract then activated charcoal, or kaolin or BCK granules can be given as adsorbents.
e/ Torsions and Hernias
Torsions occur when a segment of bowel rotates around its attachment to the body. The intestines lie suspended in the mesentery, a thin membrane attached to the dorsal abdomen. The blood vessels supplying the intestines pass from the aorta ( under the spine ) along the mesentery to the intestines. Occasionally a part or even all of the small intestine can rotate around this attachment, leading to pinching off of the blood supply to that area of bowel. Small torsions produce discomfort, inappettance, and eventually shock. Large Torsions are grave emergencies which rapidly produce shock due to loss of blood volume into the torsion, and bacterial toxins passing through a hypoxic bowel wall.
Hernias / ruptures allow intestines to pass through the abdominal wall. Hernias occur through natural areas of weakness ( umbilicus, inguinal, perineal ) whereas ruptures are traumatic openings, often following on from RTA's.
Narrow openings into a hernia or rupture can pinch off the blood supply to any contained intestines, but it is more usual for problems to arise if the piece of intestine rotates within the hernia and twists off the blood vessels ( a strangulated hernia ).
Treatment:
Surgical. Treat any shock with fluids.
f/ Penetrating injury
Release of intestinal contents into the abdomen usually produces a rapidly progressing shock and peritonitis. In the dog, small intestinal punctures can occasionally be sealed by the mesentery which quickly envelops sites of inflammation. An abscess often results from this.
Treatment:
Surgical. Treat for shock.
g/ Blunt trauma
Produces bruising of the outer (serosal) surface of the intestines, although is occasionally severe enough to cause a rupture. Bleeding is usually self- contained, but these patients require hospitalisation and regular monitoring.
2) THE RECTUM
Injuries:
RTA causing pelvic fractures, Perineal hernia, Foreign bodies, Prolapse.
a/ RTA
Pelvic fractures can cause short and long term complications. In the short term, they can caused lacerations and penetrations of the rectum and terminal large intestine as it runs through the pelvis. This is usually seen as blood at the anus or on the thermometer when taking the patient's temperature. The risk in these cases is of peritonitis.
As these fractures heal, the pelvis, which may already have been compressed onto the bowel, forms a callus of bone which can press on the bowel even more. The end result can be an effective block to the passage of normal faeces ( obstipation ).
b/ Perineal hernia
A perineal hernia develops in response to chronic straining to defaecate, due to either diarrhoea or an enlarged prostate. The so-called " pelvic diaphragm" ( which is really just a collection of muscles ) tears and allows the rectum to move sideways into the pouch which forms to one side of the anus under the tail. This is inconvenient to the patient, as faeces build up in this diverticulum. It can be a serious emergency also as the bladder can flip back on itself into the hernia. This closes off the urethra, causing a urethral obstruction.
Treatment:
In the long term, surgical repair of the hernia is usually necessary. If the hernia is small and/or the patient is old and unsuitable for surgery, it may be possible to manage these cases with enemas and faecal modifiers - liquid paraffin, fibre preps such as peridale.
c/ Prolapse
The rectum is everted through the anus. Minor prolapses consist of a small amount of mucous membrane which may self-cure. Major prolapses are like intussusceptions with the full bowel thickness being everted as a tube out of the anus. Often related to bouts of diarrhoea and colitis.
Signs are straining and dyschezia, and examination quickly reveals the protruding bowel.
Treatment:
If early and/or small, the prolapse may be reducible into the anus. Use plentiful lubricant and gentle pressure. If impossible, then keep the area moist and prevent self-trauma by the patient, using an Elizabethan collar.
Surgery may be necessary if the prolapse is gangrenous or excessively damaged.
This is quite a common problem in young small rodents such as hamsters, often very difficult to treat in these small patients.
3) THE ANUS
Injuries:
Anal gland abscesses, Last stop for foreign bodies, Trauma. (Furunculosis in German Shepherds).
Signs:
Hind quarter distress, scooting, frenzied licking, tenesmus (may be reported as constipation).
a/ Anal gland abscesses
The anal glands are located at 5- and 7-o'clock to the anal sphincter, just under the skin, and should empty automatically each time the animal defaecates. Failure to empty for whatever reason ( diarrhoea, anatomy, blockage) causes a build up of gland contents. This leads to characteristic scooting behaviour ( rarely associated with worms despite popular belief). If infection gets into the glands, an abscess ensues.
Treatment: Empty the glands ( ++ painful!). Antibiotics may be needed. The glands can be removed surgically.
b/ Foreign bodies
May "lock" at the anal sphincter. The only First Aid possible is to try gentle removal with lots of lubrication.
c/ Anal furunculosis
Is seen mainly in GSD's, and is a potentially severe infection of the skin of the perineum, possibly arising from an immune system problem or severe infection. Unobservant owners may present this as an acute emergency, but the appearance of raw ulcerated skin tracts around the anus is characteristic. This is not a case for first aid!