To My Quyen, 

Nguyen Khanh Thuan, Nguyen Phuc Khanh, Nguyen Thanh Lam*

1. Introduction

Feline trichobezoars (Hairball) formation in cats is generally considered to arise as a result of the routine activity of grooming where cats ingest varying quantities of hair. Single strands of ingested hair cannot be moved by peristalsis, thus become enmeshed in the gastric mucosa, eventually conglomerating into solid masses in either the stomach or intestine (DeBakey, 1938). Cats can generally rid themselves of this problem by retching until the hairball is vomited. Occasionally the aggregated ball of hair can accumulate to such an extent that a potentially serious obstruction can occur. Clinical signs of hairballs include vomiting, anorexia, and abdominal pain (Krugner-Higby et al., 1996).

2. What causes hair balls? 

The fastidious grooming habits and barbed tongues can be considered as a main reason that led to commonly ingest large quantities of hair in cats. 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. 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, 1984). 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 (Barzilai et al., 1998). Affected cats are usually long haired since short hair passes more readily through the pylorus and intestines.

Hair, or hair and plant material, if chronically retained in the stomach may cause pyloric outflow obstruction and may form calcified concretions (Frye, 1972). Recurrence after surgical removal has been reported in cats despite regular grooming, flea control and administration of laxatives. 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 (Norsworthy, 2018). 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 (Sherding, 1994).

3. Pathogenesis 

3.1 Alteration of upper gastrointestinal motility

Chronic gastrointestinal disease or increased sympathetic nervous stimulation secondary to other factors such as chronic pain and/or stress can alter upper gastrointestinal motility. 

✜ In the author’s experience frequent vomiting of hair balls is a common feature in the clinical history of shorthaired cats suffering from chronic gastrointestinal disease (eg, due to a dietary intolerance or inflammatory bowel disease). Appropriate management of the primary gastrointestinal disease frequently results in significant reduction of hair ball vomiting. 

In shorthaired cats regular vomiting of hair balls may therefore be an indication of primary gastrointestinal disease, flea infestation or other skin disease but many owners will mistakenly believe it to be normal behaviour and will rarely bring the problem to the attention of their veterinarian. 

Owners should be questioned about hair ball elimination during history taking at routine visits and as part of the initial assessment of cats presenting with gastrointestinal signs or occult weight loss. In these cases, a previous history of frequent hair ball elimination should alert the veterinarian to the potential for chronic gastrointestinal disease. This may be important when deciding whether or not to investigate the case further or to recommend long-term dietary modification, versus instituting short-term palliative treatment for what may initially appear to be an acute gastrointestinal upset (Cannon, 2013).

3.2 Consequences of hair balls

In the majority of cases a hair ball that forms in the stomach and reaches a size that is too large to pass into the duodenum is eventually eliminated by vomiting. Owners will frequently describe this action as ‘coughing up’ a hair ball, and further questioning is important to make the distinction between chronic coughing and frequent hair ball elimination. Occasionally the hair ball cannot be ejected by vomiting and, although clinical experience tells us that this is rare, these are the cases that tend to be presented to the veterinarian for investigation and treatment – and indeed that make their way into the veterinary literature. Justly so, as a hair ball that is not eliminated by vomiting can cause significant morbidity and even potentially mortality by one of three routes: 

✜ Passage into the small intestine where it may cause partial or complete intestinal obstruction leading to vomiting and abdominal discomfort. Physical examination is likely to reveal dilated loops of small intestine proximal to the obstruction and, if the hair ball is large enough, a palpable ‘mass’. Since gastrointestinal masses in the cat are most commonly neoplastic the owner may be given an erroneously poor prognosis unless appropriate investigations are undertaken (Trepanier, 2010).

✜ Entrapment in the oesophagus producing signs of oesophageal obstruction and potentially leading to oesophagitis and oesophageal stricture. In the few published reports of oesophageal hair balls, co-existing oesophageal disease is a frequent finding. In such cases it may be difficult to establish whether the hair ball caused oesophageal damage or whether it became entrapped because of pre-existing oesophageal disease. The latter possibility should be investigated once the oesophageal hair ball has been cleared. 

✜ Vomition into the nasopharynx (Figure 3) producing sudden-onset sneezing, retching and subsequent halitosis as well as nasal discharge (Haynes et al., 2010). Smaller hair balls may pass through the stomach and then cause partial intestinal obstruction, with associated discomfort, but may eventually be passed in the faeces resulting in complete resolution of clinical signs. Hair balls that are retained in the gastrointestinal tract for a prolonged length of time may become partly mineralised. These are generally larger and harder than ‘normal’ hair balls and therefore more difficult to pass, or to vomit. So, although much less common, when they do occur, they are more frequently associated with severe clinical signs (Cannon, 2013)

4. Radiography diagnosis

Radiography was crucial to the diagnosis of this case. The presence of pleural effusion on the initial abdominal radiographs was fortuitous from a diagnostic point of view, as it focused attention on the thorax. Pleural effusion develops secondary to mediastinitis or oesophageal perforation in severe cases of oesophageal obstruction (Silverman et al., 1976). Because of the risk of oesophageal perforation, a contrast study was only carried out after careful consideration, and a water-soluble contrast agent was used rather than barium sulphate. The absence of an oesophageal rupture as determined oesophagoscopically, and the rapid resolution of the pleural effusion after removal of the foreign body suggest the effusion was caused by mediastinitis in this case (Squires, 1989). 

5. Control and prevention

5.1 Hair ball control diets 

Where underlying gastrointestinal disease is not a contributory factor, other dietary approaches to management may be helpful. Commercial diets formulated to reduce the incidence of hair balls contain increased levels of insoluble fibre with the aim of improving gastric motility and gastric emptying. There are no published studies that directly demonstrate this correlation in conscious cats, but a 2-week study into the use of a palatable chew containing psyllium (a source of soluble fibre) and slippery elm (used in herbal medicine as an emollient, expectorant and diuretic) reported a 29% reduction in clinical signs associated with hair balls (coughing, retching and vomiting), although there was no significant reduction in actual vomiting (Dann et al., 2004). Hair ball control diets may also employ an increased kibble size because ‘radiographic gastrointestinal transit studies indicate that a larger kibble size is associated with an increased tendency for hairballs to exit the stomach and be passed in the faeces’ (Hand et al., 2011). However, the studies to which this statement refers are not within the public domain. Published data regarding the efficacy of hair ball control diets are lacking, but the experience of cat owners feeding hair ball control diets, manufactured by a number of different nutrition companies, would seem to support a degree of efficacy for these products (Cannon, 2013). 

5.2 Natural diets

Proponents of the feeding of raw carnivorous diets and diets based on meat on the bone contend that this also has a significant effect in reducing the incidence of hair balls, as well as promoting dental and skin health, among other benefits. Published data are again lacking and currently the debate rages as to which nutritional approach is best – premium quality commercial diets versus ‘natural’ raw meat and bone diets. No doubt readers will have their own opinions, and until controlled studies are undertaken, we can only rely on anecdotal reports from both camps (Barzilai et al., 1998). 

5.3 Other preventive strategies 

For cats that regularly or intermittently suffer with hair balls preventive treatment is indicated. Consideration of the possible presence of underlying disease is the initial priority and dietary manipulation may also be an effective means of control, as previously discussed; whether one advocates the use of commercial hair ball control diets or the feeding of raw meat on the bone will, for the time being, depend on personal preference. Beyond this, a number of other approaches can also be adopted and, as ever in this field, in the absence of any studies there is currently no evidence base to support one approach over another. 

Reducing the ingestion of loose hair 

Hair balls are more common in longhaired cats than in shorthaired cats, presumably due to the artificially increased length of the fur. Daily grooming to remove as much loose hair as possible may help to reduce the amount of excess hair being ingested. In severe cases, clipping the coat may also help by shortening the fur to a length more akin to that which the gastrointestinal tract has evolved to handle.

Encouraging efficient gastric emptying 

Physiological studies suggest that cats have limited ‘housekeeper contractions’ helping to sweep indigestible material from the stomach (Bortoff et al., 1984; De Vos, 1993). Furthermore, gastric emptying appears to be quicker when the stomach is handling small meals rather than large meals (Goggin et al., 1998). This combination of factors has led to the advice that more frequent feeding of small meals throughout the day may improve upper gastrointestinal motility, which may in turn help to reduce the incidence of hair balls. 

Gastric lubricants 

Daily use of inert oils (e.g. liquid paraffin) or flavoured paraffin wax pastes can provide a lubricant effect that helps to move strands of fur from the stomach into the duodenum, from where they will be processed into the faeces rather than condensing into a hair ball. As liquid paraffin is relatively tasteless and odourless it can be safely dosed to most cats when mixed with food. Owners should be advised not to attempt to syringe liquid paraffin into their cat’s mouth, as accidental inhalation can lead to severe lipid-induced pneumonia. In humans, this is recognised as a significant issue, especially in paediatric medicine, but also as an occupational hazard for fire eaters  and even as a consequence of the over-enthusiastic use of lip gloss (Beermann et al., 1984). How commonly exogenous lipid pneumonia occurs in cats is unclear – there are no published case reports describing the problem but nonetheless we know it to be an entirely avoidable hazard that can have serious consequences (Figure 4). Concerns have also been raised that the addition of inert oils to the food may reduce the availability of fat-soluble vitamins. Studies in human patients on long-term treatment with liquid paraffin do not show any clinically significant effects in this regard (Sharif et al., 2001); nevertheless, where flavoured paraffin waxes or liquid paraffin are given long-term on a daily basis, it may be prudent to ensure that at least  one meal per day is left unadulterated.

HAIRBALL CURE (VEMEDIM)

 Hairball cure is a nutritional supplement gel with natural lipids and fiber to feed dogs and cats above 6-month-old. It helps pets have a healthy coat, improves digestion and prevents the formation of hairballs in the gastrointestinal tract and its associated problems such as constipation and vomiting as well.

           Dosage

-Give directly into mouth or mix in feed (with spoon included):

- For first feeding or eliminating hairballs: 1/2 - 1 spoon, 2 times a day or follow the veterinarian’s directions.

- Prevention of hairball: 1/4 - 1/2 spoon, 2-3 times a week.

6. Treatment 

The use of lifelong medication to reduce the incidence of hair balls should not be necessary. Before resorting to such measures, a diligent search for any underlying disease must be undertaken, and dietary manipulation, use of gastric lubricants and clipping of longhaired cats should be employed. Medications that may promote more effective gastric emptying in cats include metoclopramide, cisapride and ranitidine. 

✜ Metoclopramide (0.2–0.4 mg/kg q6h PO) has a prokinetic effect on the stomach in cats, resulting in increased antral contractility. Its practical utility as a long-term preventive treatment may be limited by its short half-life, requiring oral dosing q6h to maintain effect. Less frequent dosing may be effective in some cases. 

✜ Cisapride (1.5 mg/kg q12h PO) is not licensed for use in the cat but is an effective prokinetic agent in this species, with effect at all levels of the gastrointestinal tract from lower oesophageal sphincter through to colon. In dogs, it has been shown to be a more effective gastric prokinetic than metoclopramide. Cisapride has been withdrawn from the human market due to the potential for QT prolongation and ventricular arrhythmias at high plasma concentrations. In cats it appears to be well tolerated although QT prolongation and ST depression were induced when it was given at very high doses (30 mg/kg q12h for 7 days). 

✜ Ranitidine (3.5 mg/kg q12h PO)43 is also not licensed for use in the cat but this H2 -antagonist likewise appears to have prokinetic effect throughout the gastrointestinal tract in cats. Its inherently bitter taste makes dosing of both liquid and tablet formulations difficult, but compliance may be improved by disguising the tablet form of the drug in a gelatin capsule prior to dosing (Cannon, 2013).

7. References

Barzilai, M., Peled, N., Soudack, M., Siplovich, L., 1998. Trichobezoars. Harefuah 135, 97-101, 167.

Beermann, B., Christensson, T., Möller, P., Stillström, A., 1984. Lipoid pneumonia: an occupational hazard of fire eaters. British Medical Journal (Clinical research ed.) 289, 1728.

Bortoff, A., Sillin, L.F., Sterns, A., 1984. Chronic electrical activity of cat intestine. American Journal of Physiology-Gastrointestinal and Liver Physiology 246, G335-G341.

Cannon, M., 2013. Hair balls in cats: a normal nuisance or a sign that something is wrong? Journal of Feline Medicine and Surgery 15, 21-29.

Dann, J.R., Adler, M.A., Duffy, K.L., Giffard, C.J., 2004. A potential nutritional prophylactic for the reduction of feline hairball symptoms. The Journal of nutrition 134, 2124S-2125S.

De Vos, W.C., 1993. Migrating spike complex in the small intestine of the fasting cat. American Journal of Physiology-Gastrointestinal and Liver Physiology 265, G619-G627.

DeBakey, M., 1938. A Bezoars and concretions: A comprehensive review of the literature with an analysis of 303 collected cases and a presentation of 8 additional cases. Surgery 4, 934-963.

Frye, F., 1972. Hiatal diaphragmatic hernia and tricholithiasis in a Golden cat: a case history. Veterinary medicine, small animal clinician.

Goggin, J., Hoskinson, J., Butine, M., Foster, L., Myers, N., 1998. Scintigraphic assessment of gastric emptying of canned and dry diets in healthy cats. American journal of veterinary research 59, 388-392.

Hand, M.S., Novotny, B., Zicker, S.C., 2011. Small animal clinical nutrition quick consult. Mark Morris Institute.

Haynes, K.J., Anderson, S.E., Laszlo, M.P., 2010. Nasopharyngeal trichobezoar foreign body in a cat. Journal of feline medicine and surgery 12, 878-881.

Krugner-Higby, L., Wolden-Hanson, T., Gendron, A., Atkinson, R.L., 1996. High prevalence of gastric trichobezoars (hair balls) in Wistar-Kyoto rats fed a semi-purified diet. Laboratory animal science 46, 635-639.

Norsworthy, G.D., 2018. The feline patient. John Wiley & Sons.

Sharif, F., Crushell, E., O'driscoll, K., Bourke, B., 2001. Liquid paraffin: a reappraisal of its role in the treatment of constipation. Archives of disease in childhood 85, 121-124.

Sherding, R.G., 1994. The cat: diseases and clinical management.

Silverman, S., Poulos, P., Suter, P., 1976. Cavitary pulmonary lesions in animals. Veterinary Radiology 17, 134-146.

Squires, R., 1989. Oesophageal obstruction by a hairball in a cat. Journal of Small Animal Practice 30, 311-314.

Twedt, D., 1984. Diseases of the stomach, Scientific proceedings of the... annual meeting-American Animal Hospital Association (USA).

Trepanier, L., 2010. Acute vomiting in cats: rational treatment selection. Journal of feline medicine and surgery 12, 225-230.