Rico Vannini graduated in 1981 from the University of Zürich. 1987 he completed his surgical residency at The Ohio State University. For nine years he was faculty surgeon and lecturer at the University of Zürich. In 1994 he became a Diplomate of the European College of Veterinary Surgeons. Since 1996 he is owner of Bessy's small animal clinic, one of the largest private clinics in Switzerland. He was president of AO and ESVOT. He maintains an active interest in continuing education among others being international speaker and international chairmen of the Education Commission of AOVET. His hobbies are agility, scuba diving and cooking. He is a mobile cash machine for two young adults, master of 8 dogs and food provider of a cat.
Introduction
Clinical problems caused by foreign bodies are a very common problem in small animals. Foreign bodies (FB) can affect every organ system of our patients and cause a variety of clinical signs. Therefore foreign bodies' disease should always be on the list of differential diagnosis of a sick patient.
How Do FBs Enter the Body?
There are several ways, FB find their way into the body:
The most common route is through the natural orifices such as the mouth or nose. This happens usually by swallowing or aspirating the FB that then ends in a hollow organ of the GI tract or in the respiratory tree.
Foreign bodies can enter the body through wounds or by perforating the intact skin or mucosa. Typical FBs are bullets, arrows, wooden splinters, skewers, tooth picks, thorns, metal splinters, glass shards, plants like foxtails (Hordeum murinum) and teeth.
Many FBs are introduced in the body by the surgeons. Most of these, such as implants or sutures are very biocompatible and introduced on purpose, but others such as tissue clamps or gauze sponges are left in the body by mistake. Occasionally implants such as bone cement or braided sutures become infected and behave then like a typical FB.
What is Happening with the FB in the Body?
Once in the body, the FB may stay at the site of entry or starts to migrate. A swallowed FB may stay in the stomach for month or slowly try to pass through the intestinal tract until it successfully passed, get stuck or perforates the wall of the GI tract and migrates into the abdomen.3,4 An aspirated grass awn like a foxtail typically migrates through the trachea into the bronchial tree, then passes through the lung parenchyma and reaches the pleural space from where it slowly moves forward into the retroperitoneal area and finally gets stuck in the sublumbar region of the 3–4 lumbar spine.
Once the FB get stuck somewhere in the body, it may stay there silently or - more likely - provokes a classical so called "FB reaction." This is the inflammatory response of the body to the intruder and the body's attempt to get rid of it. Small FB may become slowly digested and reabsorbed by highly specialized white blood cells. If the FB is too big, the body will encapsulate it and form a granuloma or worse an abscess will result. In order to get rid of pus in association with FB, fistula can form. These are small channels that extend to the outside of the body. Through these tracks, the pus will slowly drain to the outside.
Depending the organ system affected, foreign bodies can cause a wide variety of different symptoms, such as anorexia, regurgitation, paresis, ataxia, diarrhea, tenesmus, dyspnea, cough, conjunctivitis, foul breath, exophthalmos, swelling, fever or pain.
One and the same FB can cause a variety of symptoms. A migrating grass awn might initially cause coughing, then fever and signs of pneumonia, later it even causes back pain and finally fistula might form.6
Some FB such as splinter might cause very mild clinical problems, other such as a forgotten sponge causing an abdominal abscess can be potentially life threatening.
Therefore FB should be put on the list of differential diagnosis of most clinical problems.
How can FBs be Detected?
Some FB can readily be detected, such as radiopaque stones, bones or metallic objects, other FB can't be seen on radiographs at all and therefore require a high level of suspicion in order to detect them.
Key signs/symptoms suspicious for FB are:
Abscesses or swellings of unknown origin
Draining fistula
Non-healing wounds
Fever of unknown origin
The reason you need a high level of suspicion is, that these FB are often extremely hard to find and need an extensive diagnostic work up using advanced diagnostic imaging such as ultrasound, CT or MRI.
How to Get Rid of the FB
The good thing about a FB is, that once it is removed from the body, the patient is cured.
Usually some form of surgical intervention is needed in order to remove the FB. This intervention can be quite simple or turn into a major surgical procedure.
Oral, esophageal, gastric, tracheal and bronchial as well nasal FB are usually successfully removed with endoscopic intervention.2
Occasionally an owner observes that its dog just swallowed a FB and brings the patient immediately to the clinic. In this case vomiting can be induced to make the dog throw the FB up again. Vomiting is usually induced in dogs with apomorphine, in cats with medetomidine. If the owner can't bring the dog immediately to the veterinarian's office the dog should be fed with regular dog food to prevent the FB to migrate into the intestines. As long as the stomach is full it will not pass any foreign particle through the pylorus, larger than 2 to 3 mm in diameter. Only if the stomach is empty than forceful sweeping contractions will either cause the dog to throw up or squeeze the FB into the intestinal tract.
Not all GI FB have to be removed surgically. In humans 70% of the FB do pass the GI tract normally and eventually will see daylight again.5 In dogs most stones will do the same as well as sewing needles unless there is still a silk attached.
Some FBs are surgical emergencies, such as an aspirated ball that got stuck in the glottis of a dog. It works like a valve: the dog can exhale, but if it tries to inhale forcefully it gets sucked in, occludes the glottis and the dog can't inspire any more. A "Heimlich maneuver" with the dog hanging upside down or manual removal is attempted. Occasionally an ultra-short acting anesthesia is required to be able to get hold of the ball back in the retropharynx.
Esophageal FBs are emergencies as well, especially if it occludes the esophagus completely and the patient can't swallow anymore at all. The dog, often West Highland Terriers, will lose fluids by saliva and dehydrates rapidly. The FB quickly causes pressure necrosis of the esophageal wall resulting either in perforation or severe stricture formation. Linear FBs such as cords, fishing lines or sewing threads are emergencies as well, as they easily lead to intestinal perforations. Often the end of the tread is stuck around the tongue. Thus always check the oral cavity in patients with acute anorexia and vomiting to look for the end of a sewing thread stuck under the tongue.
A dog with acute severe coughing after it was running through a dry grass field is suspicious for an aspirated grass awn and should also be seen as soon as possible. The best chance to remove the FB easily is early after aspiration, before the FB enters the lower bronchial tree.
Dogs jamming the end of a wooden stick in their mouth while playing with it should be seen as an emergency as well. The stick perforates the oral cavity and the end of the stick or of some splinters can break off and get stuck in the retropharyngeal tissue. Again they are easiest to find and to remove when the wound is fresh and still open. Additionally stick injuries can cause serious and life threatening bleedings.1
Conclusion
Foreign bodies are an important "pathogen" and a common cause for a variety of clinical problems.
All organ systems can be affected. Foreign body disease can be mild to life threatening. A high level of suspicion is needed to find a FB outside a hollow organ. Advanced diagnostics imaging such as ultrasound, CT or MRI is needed in these case to detect them. Even though they are often hard to find, they are usually quite simply to treat.
Prognosis is excellent - once the FB is removed, the patient is cured. However, some FB require emergency treatment for best possible outcome.
References
1. Doran IP, Wright CA, Moore AH. Acute oropharyngeal and esophageal stick injury in forty-one dogs. Vet Surg. 2008;37:781–785.
2. Gianella P, Pfammater NS, Burger IA. Oesophageal and gastric endoscopic foreign body removal: complications and follow up of 102 dogs. J Small Anim Pract. 2009;50:649–654.
3. Hayes G. Gastrointestinal foreign bodies in dogs and cats: a retrospective study of 208 cases. J Small Anim Pract. 2009;50:576–583.
4. Hunt GB, Worth A, Marcheveski A. Migration of wooden skewer foreign bodies from the GI tract in eight dogs. J Small Animal Pract. 2004;45:362–367.
5. Selivanov V, Sheldon GF, Cello JP, Crass RA. Management of foreign body ingestion. Ann Surg. 1984;199:187-191.
6. Schultz RM, Zwingenberger A. Radiographic, computed tomographic and ultrasonographic findings with migrating intrathoracic grass awns in dog and cats. Vet Radiol Ultrasound. 2008;49:249–255.