Intestinal Obstruction by Trichobezoars in Five Cats

Abstract

Between 1997 and 1999, five domestic crossbred cats (four long haired, one short haired) presented with a palpable abdominal mass and were shown to have small intestinal trichobezoars at laparotomy or necropsy. Hair balls were associated with partial or complete intestinal obstruction and were situated in the proximal jejunum to distal ileum. In four cats obstructions were simple, while the remaining cat had a strangulating obstruction. Three of the cats were 10 years or older, and two were less than 4 years. In the three older cats abdominal neoplasia was suspected and investigations were delayed or declined in two of these cats because of a perceived poor prognosis. Predisposing factors identified in this series of cats included a long-hair coat, flea allergy dermatitis, inflammatory bowel disease and ingestion of non-digestible plant material. This report shows that the ingestion of hair is not always innocuous and that intestinal trichobezoars should be considered in the differential diagnoses of intestinal obstruction and intra-abdominal mass lesions, particularly in long-haired cats.

Because of their fastidious grooming habits and barbed tongues, cats commonly ingest large quantities of hair. Ingested hair is either passed undigested in the faeces or accumulates in the stomach, from where it is vomited periodically as a ‘hair ball’. This is considered a normal physiological process (Wilkinson 1984). Hair may be retained in the stomach following ingestion because cats lack interdigestive migrating myoelectric complexes (IMMC) that clear non-digestible material from the gastrointestinal tract in other species. IMMC begin in the stomach and result in strong peristaltic contractions that continue along the intestinal tract, moving large particulate material to the colon. In cats, IMMC have only been detected near the ileum (Twedt 1994). In some cats, excessive amounts of hair may accumulate in the gastrointestinal tract as a result of overgrooming secondary to pruritus or gastrointestinal motility disorders (Crystal 1998). Affected cats are usually long haired since short hair passes more readily through the pylorus and intestines.

To the authors' knowledge there are no published case reports of small intestinal obstruction by trichobezoars in cats, although one case is documented briefly in a textbook (Green 1993).

Case reports

Case 1

A 15-year-old spayed domestic long-haired (DLH) cat presented with a 4-day history of anorexia and vomiting. Physical findings included dehydration, pale mucous membranes and slow capillary refill. A thickened, solidly distended segment of intestine (approximately 8 cm in length) was palpated in the cranial abdomen. Haematology demonstrated neutrophilia with a left shift (segmented neutrophils 25.5 × 10⁹/l; band neutrophils 6.0 × 10⁶/l) and monocytosis (1.9 × 10⁹/l). Abnormal serum biochemistry results included hypokalaemia (3.5 mmol/l), azotemia (urea 23 mmol/l), hypoalbuminaemia (20 g/l) and metabolic alkalosis (bicarbonate 31 mmol/l). Intravenous fluids, amoxycillin and trimethoprim–sulfoximazole were administered parenterally. Intestinal neoplasia was considered likely and the cat was referred to the University Veterinary Centre, Sydney (UVCS) 3 days later for further investigation.

The cat was moribund and hypothermic (rectal temperature 36.8°C) at presentation. Mucous membranes were pale and tacky with prolonged capillary refill. The cranial abdomen was grossly distended with gas and fluid and the intestinal mass was still palpable. A right lateral abdominal radiograph showed massive distension of the stomach with gas and fluid (Fig 1). Thoracic radiographs showed distension of the oesophagus, probably with fluid, associated with ventral displacement of the trachea. An area of poorly defined interstitial-alveolar opacity in the region of the right middle lung lobe was consistent with aspiration pneumonia (Fig 2). After passage of a stomach tube, 640 ml of brown fluid containing digested blood was drained. Laboratory tests demonstrated anaemia (haematocrit 0.17 l/l), hypoproteinaemia (45 g/l), hypokalaemia (2.0 mmol/l), hyponatraemia (135 mmol/l), hypochloraemia (85 mmol/l) and metabolic alkalosis (bicarbonate 32 mmol/l, base excess 7.5 mmol/l, pH 7.41). The cat was considered to have complete small intestinal obstruction. Diagnostic possibilities included intestinal neoplasia, a foreign body or intussusception. Abdominal ultrasonography demonstrated the mass was a segment of bowel distended with solid material; the intestinal wall was not thickened and a multi-layered appearance characteristic of an intussusception was absent. A needle aspirate from the lumen of the intestinal segment yielded material with a foetid odour. An intestinal foreign body was considered most likely and an exploratory laparotomy was performed immediately, as the cat's condition was rapidly deteriorating. The cat was given intravenous colloids (15 ml/kg; Haemaccel, Hoechst), amoxycillin/clavulanic acid (20 mg/kg subcutaneously; Clavulox, Pfizer) and enrofloxacin (5 mg/kg subcutaneously; Baytril, Bayer) pre-operatively. A typed blood transfusion (50 ml type B blood) was given intra-operatively. At laparotomy, the duodenum was distended with gas and fluid and a segment of proximal jejunum (12 cm) was distended with solid material (3 cm diameter). The intestinal wall was discoloured purple and the mass could not be moved within the intestinal lumen. Regional lymph nodes were moderately enlarged. The segment of intestine was considered non-viable and was resected. It contained a large trichobezoar (Fig 3). An end-to-end intestinal anastomosis was performed using single interrupted sutures of 4–0 polydiaxanone (PDS). Towards the end of the procedure the cat suffered a cardiac arrest. It was resuscitated, but had another cardiac arrest 1 h later and could not be resuscitated. Permission for necropsy was not given. Histology of the resected bowel showed necrosis of the mucosa, submucosa and some of the muscularis. The outer muscularis and serosa were considered viable, although there was a heavy neutrophilic infiltration and blood vessels were dilated.

Fig 1.

Right lateral abdominal radiograph of Case 1 shows massive distention of the stomach with gas and fluid. Caudal to the stomach, a greatly distended loop of small intestine is evident containing material of heterogeneous radio-opacity.

Fig 2.

Left lateral thoracic radiograph of Case 1 shows distention of the oesophagus with soft-tissue or fluid opacity. There is a localised area of pulmonary infiltrate superimposed on the cardiac silhouette in the region of the right middle lung lobe, suggestive of aspiration pneumonia.

Fig 3.

Resected length of proximal jejunum from Case 1. Note the trichobezoar obstructing it.

Case 2

A 4-year-old castrated DLH cat had a history of recurrent ‘miliary dermatitis’ associated with heavy flea infestations. The cat presented to UVCS with a 3 day history of malaise, vomiting and inappetence. A similar episode had occurred 5 months previously and had resolved following intravenous fluid therapy and amoxycillin/clavulanic acid (125 mg every 12 h per os). On physical examination the cat was dehydrated, had a moderate flea burden and a matted hair coat. An abdominal mass was palpated and thought to be a thickened loop of small intestine. Haematology showed a mild segmented neutrophilia (10.5 × 10⁹/l) with granulation and hyper-segmentation of neutrophils and monocytosis (1.29 × 10⁹/l), consistent with inflammation and stress. The haematocrit (0.45l/l) and total plasma protein (95 g/l) were increased, suggestive of haemoconcentration. Serum biochemistry showed azotaemia (urea 22 mmol/l, creatinine 185 mmol/l), hyperglycaemia (13.2 mmol/l), elevated ALT activity (145 U/l), hyperkalaemia (5.4 mmol/l), hyponatraemia (141 mmol/l), hypochloraemia (94 mmol/l) and metabolic alkalosis (bicarbonate 30 mmol/l). The urine specific gravity was > 1.050 and there was no glucosuria.

Abdominal radiographs showed distension of the stomach with fluid and gas, dilated, fluid-filled loops of small intestine and bunching of small intestinal loops in the mid-ventral abdomen (Fig 4). The physical findings, radiographic changes and electrolyte abnormalities were suggestive of a proximal small intestinal obstruction. Given the cat's age and acute onset of clinical signs, a foreign body or intussusception was suspected and an exploratory laparotomy was performed. A 10 cm length of jejunum was hyperaemic and distended but considered viable (Fig 5). A longitudinal enterotomy incision was made distal to this area and a long matted trichobezoar was removed with Adson thumb forceps (Fig 6). The enterotomy incision was closed with simple interrupted sutures of 4–0 PDS. A small tear occurred in the hyperaemic area of jejunum during enterotomy closure and was repaired. A bilateral serosal patch was placed over the hyperaemic area using adjacent loops of jejunum sutured with 4–0 PDS. The liver was normal on gross appearance and on histopathology of a liver biopsy there was mild central fibrosis in some lobules, considered unlikely to be of clinical significance. Amoxycillin/clavulanic acid (20 mg/kg subcutaneously every 12 h) was administered post-operatively. The cat recovered unremarkably and prior to discharge from hospital the hair coat was clipped short and a topical insecticidal spray (fipronil; Frontline, Rhone Merieux) was applied. The owners were advised to use ongoing, regular flea control and to groom the cat frequently to prevent excessive ingestion of hair.

Fig 4.

Lateral (a) and ventrodorsal (b) radiographs of Case 2 showing distention of the stomach with gas and fluid, dilated intestinal loops and bunching together of the small intestines in the mid-ventral abdomen.

Fig 5.

The distended loop of proximal jejunum in Case 2.

Fig 6.

The intestinal trichobezoar from Case 2 during removal from the proximal jejunum.

Case 3

A 10-year old spayed Persian-cross cat presented to UVCS with a 4-day history of anorexia and a 1-day history of dry-retching. The cat had a chronic history of intermittent vomiting and was fed tinned fish, dry cat food and raw meat. It was in poor body condition (3.3 kg) and a large mass was palpated in the mid-abdomen. Serological screening tests for feline leukaemia virus antigen and feline immunodeficiency virus antibody were negative. Serum biochemistries were unremarkable. An abdominal ultrasonographic examination demonstrated a region of distended colon or ileum adjacent to a region of circumferentially thickened intestinal wall and enlargement of several mesenteric lymph nodes. An intestinal obstruction secondary to neoplastic infiltration of the gut wall with metastases to the mesenteric lymph nodes was suspected; however, cytology of aspirates from the enlarged lymph nodes was consistent with reactive change (70% small lymphocytes, 20% medium lymphoid cells and scattered large lymphoblasts, occasional eosinophils, plasma cells, neutrophils and macrophages). Abdominal radiographs taken subsequently demonstrated a large tubular mass of heterogeneous gas and soft tissue opacity in the cranioventral abdomen in the region of the ascending and transverse colon. Several loops of small intestine in the left craniodorsal abdomen were dilated with gas and displaced by the mass (Fig 7).

Fig 7.

Lateral (a) and dorsoventral (b) radiographs of Case 3 showing a tubular mass of heterogeneous gas and soft tissue opacity in the cranioventral abdomen in the region of the ascending and transverse colon. Note also the increased amounts of gas within numerous loops of small intestine.

At exploratory laparotomy, intestinal obstruction was detected at the ileocaecocolic junction. The affected area of bowel appeared abnormally thickened and was resected from the distal end of the ileum to the proximal colon, including the ileocaecocolic junction. It contained a large mass of matted hair. End-to-end anastomosis of the remaining ileum to the colon was performed using single interrupted, obliquely angled sutures of 4–0 PDS. Histopathology of the distal ileum showed villous atrophy, crypt abscesses and oedema of the submucosa and muscularis. In the submucosa, fibroplasia and a heavy eosinophilic infiltrate was apparent. The proximal colon was normal histologically and the mesenteric lymph nodes were reactive. Amoxycillin/clavulanic acid (20 mg/kg every 12 h subcutaneously) was administered following surgery and the cat recovered unremarkably. Since food allergy was considered a possible aetiology for the eosinophilic enteritis, the owner was advised to feed a restricted diet by avoidance of dry cat food and tinned fish. The cat was returned for vaccination 1 year later and was considered to be in good health, having gained 1.8 kg (bodyweight 5.1 kg) since the time of surgery. It was fed a diet of raw beef and chicken and had no recent history of vomiting.

Case 4

An approximately 10-year old spayed domestic short-haired cat was presented for lethargy and inappetence. A small abdominal mass was palpated on physical examination, which in other respects was unremarkable. Diagnostic possibilities including lymphosarcoma or intestinal adenocarcinoma were considered likely by the attending clinician. Further investigations including haematology, biochemistry and abdominal ultrasonography were recommended; however the owners requested that the cat be euthanased. A post-mortem examination revealed the mass detected on physical examination to be within the lumen of the proximal jejunum. The small intestine oral to the mass was dilated to three times its normal diameter, while distal to the mass the intestine was of normal calibre. When the intestine was incised longitudinally, the mass was found to consist of a spherical ball of hair approximately 1 cm in diameter. Irregular erythemic mucosal erosions orientated longitudinally were evident immediately oral to the hair ball. No other significant necrospy findings were recorded.

Case 5

A 7-month-old castrated Birman presented to Creek Road Cat Clinic with a 4-day history of inappetence, lethargy and vomiting. Physical findings included moderate dehydration and depression. A small, firm mass was palpated in the mid-abdomen, while some intestinal loops were considered to be dilated with fluid and gas. The cat was normothermic (38.6°C). Results of in-house haematology and serum biochemistries were normal. At exploratory laparotomy, a 5 cm long cylindrical mass (2 cm diameter) was present in the ileum approximately 5 cm oral to the ileocaecal valve. There was marked erythema of the ileum at the site of obstruction. An enterotomy was performed and a trichophytobezoar consisting of hair tangled with ‘Cobbler's peg’ (Bidens pilosa) burrs was removed. The enterotomy incision was closed using simple interrupted sutures of 4–0 PDS. Gentamicin (6 mg/kg intravenously every 24 h) and amoxycillin (15 mg/kg subcutaneously every 12 h) were administered following surgery. The cat recovered uneventfully.

Discussion

Excessive accumulation of hair in the alimentary tract of cats may result in oesophageal obstruction, gastric outflow obstruction, small intestinal obstruction, constipation or colitis. Obstructions may be partial or complete. Intraoesophageal hairballs may occur secondary to underlying oesophageal hypomotility or stricture (Clifford et al 1970, Van Stee et al 1980, Regnier 1985) and also in cats with no evidence of oesophageal dysfunction due to incomplete vomition of hair from the stomach (Squires 1989, Court et al 1994).

Hair, or hair and plant material, if chronically retained in the stomach may cause pyloric outflow obstruction and may form calcified concretions (Frye 1972, Twedt 1994). Recurrence after surgical removal has been reported in cats despite regular grooming, flea control and administration of laxatives (Ryan et al 1978, Worwood & Jones 1979). Although not specifically characterised, gastric motility disturbances are hypothesised to cause recurrent gastric trichobezoars/trichophytobezoars and therapy with prokinetic drugs such as metoclopramide or cisapride represent an appropriate component of therapy (Crystal 1998). Factors which may contribute to a decrease in gastric motility and trichobezoar formation include activation of the sympathetic nervous system secondary to pain or stress, hypokalaemia, uraemia, gastritis and anticholinergic drugs (Twedt 1994).

Gastric hair balls in rabbits commonly result from gastrointestinal stasis due to stress, pain or fright combined with a lack of dietary fibre, behavioural-related overgrooming or excessive hair loss, especially when combined with dehydration. In addition, rabbits are prone to the formation of hairballs since they are unable to vomit (Gillet et al 1983, Harcourt-Brown 1998, Ramer et al 1999). Gastric rupture in rabbits has been reported secondary to large or calcified bezoars (Lee et al 1978). In humans, gastric phytobezoars consisting of undigested cellulose fibres occur more commonly than trichobezoars and may develop as a complication of diabetic gastroparesis or following vagotomy. In these patients phase III interdigestive motor complex activity is characteristically reduced, providing the physiological explanation for the development of phytobezoars (Winkler & Saleh 1983).

Obstruction of the small intestine by hair has been documented incompletely in the cat (Bright & Bauer 1994, Crystal 1998). The entity has been well-described in rabbits where it may occur spontaneously or secondary to medical treatment of gastric hairballs (Sebesteny 1977, Harcourt-Brown 1998). Likewise, in human patients, small intestinal obstruction may occur secondary to spontaneous passage of gastric phytobezoars or following enzymatic digestion or endoscopic fragmentation (Rumley et al 1983, Nomura et al 1997).

The pertinent details concerning the five cats in this report are summarised in Table 1. It is noteworthy that in the three older cats abdominal neoplasia was considered likely by the attending clinicians and as a result, investigations were delayed or declined in two of these cases because of the anticipated poor prognosis. Mesenteric lymphadenomegaly was detected at laparotomy in Case 1 and during abdominal ultrasonography in Case 3. In Case 3, the sonographic findings were suggestive of intestinal obstruction; however, thickening of the intestinal wall and enlargement of regional lymph nodes were considered likely result from a neoplastic process. Abdominal radiographs taken subsequently were more suggestive of an intraluminal foreign body because of the size and heterogeneous soft-tissue density of the intestinal mass. Ultrasonographic imaging of the gastrointestinal tract is compromised by the presence of intraluminal gas which causes a highly hyperechoic interface associated with a distal acoustic shadow (Penninck et al 1989). Thus, when ileus or intestinal obstruction are suspected, plain abdominal radiographs should be obtained prior to abdominal ultrasonography.

Table 1.

Case details of five cats with intestinal trichobezoars

Case	Age (yr)	Sex	Breed	Clinical signs and physical findings	Location and type of obstruction	Factors contributing to bezoar formation
1	15	FN	DLH	Vomiting, dehydration	Proximal jejunum	Long hair coat
				Unkempt hair coat	Strangulated obstruction
				Pale mucous membranes
				Hypothermia
				Obtunded
				Abdominal mass
2	4	MN	DLH	Vomiting, dehydration	Proximal jejunum	Long hair coat
				Unkempt, matted hair coat	Simple obstruction	Matted hair coat
				Fleas		Pruritus associated with fleas
				Abdominal mass
3	10	FN	Persian	Anorexia, dry retching	Distal ileum and proximal colon	Long hair coat
			cross	Weight loss	Simple obstruction	Eosinophilic infiltration of ileocaecocolic region
				Abdominal mass
4	10	FN	DSH	Lethargy	Proximal jejunum	None identified
				Inappetence	Partial obstruction
5	4	MN	Birman	Vomiting, dehydration	Distal ileum	Long hair coat
				Obtunded	Simple obstruction	Plant material in coat
				Abdominal mass		(‘Cobbler's peg’ burrs)

DLH—Domestic long hair; DSH—Domestic short hair; FN—Female neutered; MN—Male neutered.

Causes of intestinal obstruction in cats include tumours (lymphosarcoma, adenocarcinoma, mast cell tumour), foreign bodies, intussusception, volvulus, intestinal torsion, incarceration of bowel in a hernia, adhesions or stricture, intramural abscess, granuloma or haematoma and congenital malformations (Sherding 1994). Due to the fascination of some cats with string-like objects, the majority of intestinal foreign bodies in cats are linear and the ingestion of nonplicating foreign bodies is generally considered uncommon. In the absence of historical evidence of foreign body ingestion, ingested hair should be considered as a potential cause of intestinal obstruction, particularly in long-haired cats.

Intestinal trichobezoars may cause a spectrum of clinical signs since obstruction may be partial or complete, involve any portion of the small intestine or colon, and be strangulating or non-strangulating. Case 1 was characterised by an acute, strangulating obstruction of the proximal jejunum. Strangulating obstructions involve severe vascular compromise of the obstructed bowel segment (Bright & Bauer 1994). In Case 1, the affected segment of intestine probably had venous drainage with intact arterial perfusion, resulting in intraluminal sequestration of fluid and blood, hypovolaemia and Gram-negative sepsis secondary to transmural migration of toxins and bacteria. In contrast, the clinical signs in Case 3 (anorexia and non-productive vomiting) and Case 4 (inappetence and lethargy) were more subtle, consistent with simple obstruction of the small intestine. Constipation is another sequel of ingesting large quantities of hair because its incorporation into the stool results in hard impactions that are difficult or painful to evacuate from the colon (Sherding 1994). Colitis occurs through a similar mechanism with physical abrasion of the colonic wall giving rise to painful defaecation and sometimes fresh blood in the stool (Menrath & Malik, unpublished observations).

Electrolyte imbalances observed in cats with intestinal obstructions depend on the level of the obstruction. Metabolic alkalosis is typically associated with pyloric outflow obstruction and may also occur with proximal intestinal obstruction (such as in Cases 1 and 2) because loss of gastric acid is prominent. Hypokalaemia, as seen in Case 1, occurs commonly in cats with intestinal obstructions and results from loss of potassium-rich alimentary secretions proximal to the obstruction and from renal potassium loss. It is thought that endotoxins secreted by bacteria in the obstructed intestinal segment activate cyclic-AMP-driven secretion as intestinal secretion does not occur in obstructed germ-free dogs (Guilford & Strombeck 1996). Other factors contributing to mucosal secretion of water, sodium and potassium proximal to the obstruction may include increased portal and lymphatic pressure, and ischaemia (Johnson 1992).

In Case 3, underlying disease of the small intestine may have predisposed the cat to intestinal obstruction by a hair ball. Fibrosis and inflammatory infiltration of the distal ileum may have resulted in a localised decrease in intestinal motility and failure to propel ingested hair through the ileocaecocolic junction. Although the histological changes were somewhat unusual, the cat's marked weight gain and resolution of chronic vomiting after surgery and dietary change are consistent with food hypersensitivity. In retrospect, multiple small intestinal biopsies from this cat at the time of exploratory laparotomy may have helped to clarify the nature and extent of its enteropathy. Structural lesions of the gastrointestinal tract should be ruled out as an underlying cause of intestinal obstruction by trichobezoars particularly if there is no historical or physical evidence of overgrooming secondary to pruritus or behavioural disorders.

In Case 4, the mucosal lesions seen at necropsy were presumably the result of traumatic damage as the hair ball was propelled aborally by intestinal peristalsis. Even though partial intraluminal obstruction was present, it was considered that the administration of a petroleum-based laxative by mouth would probably have resulted in the eventual passage of the hair ball into the colon.

Cases 2 and 5 were both young cats and intestinal obstruction was presumably the result of excessive ingestion of hair associated with flea allergy dermatitis (Case 2) or overgrooming to remove non-digestible plant material from the hair coat (Case 5). Plant material entangled in the hair may have impeded passage of the trichophytobezoar through the gastrointestinal tract. Any pruritic condition may result in overgrooming and should be considered a risk factor for the development of alimentary trichobezoars, particularly in long-haired cats.

Recommended treatments for hair balls in long haired cats include regular grooming and administration of semi-solid petroleum-based laxatives to lubricate the material and facilitate its aboral passage (Crystal 1998). Liquid preparations containing mineral oil should be avoided because of the risk of lipid pneumonia following aspiration. Access to lawn grass may be helpful since the ingestion of non-digestible plant material is associated anecdotally with the vomiting of hair balls. A commercial diet formulated to assist in the safe passage of ingested hair has recently become available (Hill's Science Diet, hairball control formula). Prokinetic drugs such as cisapride may be of therapeutic value in cats with underlying motility disorders. Clipping the coat of long-haired cats every 3 to 4 months to minimise hair ingestion should be considered also, especially in warmer environments where flea burdens are likely to be higher. Furthermore regular grooming and flea control is important in long haired cats.