Tea tree oil is critical oil native the Australian tea tree Melaleuca alternifolia and also is sometimes supported as a organic or herbal treatment because that fleas in pets. Although products containing low concentrations of tea tree oil room not meant to it is in a trouble in pets, the use of pure tea tree oil directly on the skin is potentially an extremely serious in pets and also should never ever be used. Exposure may cause ataxia, salivation, lethargy, coma and tremor. Dermal exposure come tea tree oil might also an outcome in dermatitis together the oil is irritant come skin. Also a couple of drops of pure tea tree oil used dermally can cause clinical signs, and deaths have arisen in pet treated with pure tea tree oil. Treatment consists of dermal decontamination and supportive care.

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Tea tree oil exposure in cats and also dogs

Tea tree oil is periodically used by owner as a ‘herbal’ or ‘natural’ therapy for fleas, however it is possibly hazardous, specifically when used undiluted. Poisoning has even emerged when pure tea tree oil has actually been included to water and also sprayed ~ above pets.

Source the tea tree oil

Tea tree oil, additionally known together melaleuca oil, is crucial oil acquired by heavy steam distillation from the leaves and also terminal branches the the Australian tea tree, Melaleuca alternifolia (Carson et al, 2006). Necessary oils are developed by plants and also give the plant your characteristic odour. Some human being find the camphor-like odour that tea tree oil unpleasant. Crucial oils space volatile oils the evaporate in ~ room temperature (compared with solved oils which carry out not). Tea tree oil is a colourless to pale yellow fluid containing a complicated mixture of compounds consisting of terpene hydrocarbons; much more than 100 individual compounds have been determined in tea tree oil (Hammer et al, 2006).

Biological impacts of tea tree oil

Tea tree oil is used in skin treatment products because that its antibacterial and antifungal properties; it also has antiviral, antiprotozoal and anti-inflammatory activity (Carson et al, 2006). Use of the extracted oil fairly than plant material itself started in the 1930s following the publishing of documents demonstrating the antimicrobial activity (Carson et al, 2006).

There is no good quality proof to display that tea tree oil is efficacious in any dermatological problem in people (Ernst and Huntley, 2000; Cao et al, 2015).

Availability

Pure tea tree oil is readily available in ‘health food’ shops, generally in a 10 ml opaque bottle with a dropper optimal (Figure 1). The ingredient of tea tree oil marketed is regulation by an worldwide standard which sets maximum and minimum concentrations of 14 contents (International company for Standardization (ISO), 2004). Tea tree oil is sold in an opaque bottle due to the fact that when exposed to light, air and also heat, tea tree oil experience oxidative degradation, yielding compounds that can increase the danger of disadvantage dermal effects.

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figure 1. A common container the tea tree oil. Keep in mind the opaque party to prevent destruction of the oil.

In terms of person products, the European cosmetic Toiletry and also Perfumery association (COLIPA) proposal ‘that tea tree oil need to not be supplied in cosmetic commodities in a way that results in a concentration higher than 1% oil being used to the body. Once formulating tea tree oil in a cosmetics product, carriers should consider that the sensitisation potential rises if particular constituents the the oil come to be oxidised. To reduce the development of these oxidation products, manufacturers should take into consideration the usage of antioxidant and/or certain packaging come minimise exposure to light (COLIPA, 2002).

Tea tree oil is an active ingredient in numerous commodities such as facial washes, spot treatments, hand wash, hair care products and shower gels because that humans. Commodities for pets encompass shampoos, skin creams, lotions and also balms, insect repellents and ear cleaners. In the UK there space no license is granted veterinary medications containing tea tree oil.

Use of tea tree oil in companion animals

There is very restricted information top top the use of tea tree in the monitoring of conditions in companion animals. Tiny studies have actually evaluated the impact of tea tree oil in various skin conditions in dogs.

In a research on the antifungal impact of tea tree oil on the yeast Malassezia pachydermatis isolated native dogs with cutaneous skin disease, every the strains tested proved high susceptibility come tea tree oil (Weseler et al, 2002).

In an open, multicentre research in 53 dogs through chronic dermatitis and also pruritus a 10% tea tree oil cream was applied twice daily for 4 weeks. Evaluate by investigate veterinarians showed a great or very an excellent response to therapy for 82% of the dogs, moderate in 7.8% and also unsatisfactory in 9.8%. In ~ the finish of the examine a solid and far-ranging reduction in signs and resolution of major signs to be observed. Four dogs were withdrawn indigenous the examine for poor efficacy, non-compliance, concurrent disease or persistent licking of the applications site. There were adverse events in ripe dogs, three of which were withdrawn. Only two the the adverse events were assessed as maybe related to tea tree oil. One had actually local irritation and also hyperaemia and also the other had actually mild reversible hyperaemia, erythema and also pruritus in ~ the website of applications (Fitzi et al, 2002).

A 10% cream was also evaluated in a randomised, double-blind controlled trial in 57 dogs through localised pruritic dermatitis. The tea tree oil cream (28 dogs) or the manage cream (29 dogs) was used twice daily. ~ 10 days, success rates of 71% for the tea tree oil cream and 41% for the regulate cream differed significantly. By day 10, the tea tree oil cream brought about significantly more rapid relief 보다 the manage cream for pruritus (occurring in 84% the dogs) and alopecia. By day 20 there was clinically far-reaching improvement in the severity of dermatitis in both therapy groups. Just one adverse occasion was reported in the tea tree oil group, but was not considered causally related to the examine drug. Five other dogs withdrew native the study: two because of lack that efficacy (one in each group), one because of non-compliance (tea tree oil group), one as result of inappropriate inclusion (control group) and one due to a mild concomitant disease leading to exemption (tea tree oil group) (Reichling et al, 2004).

These researches demonstrated a positive result of 10% tea tree oil cream in dogs through chronic dermatitis and pruritus, yet it is precious noting the there show up to be no studies evaluating tea tree oil therapy in cats or any studies on the usage of the oil in the regulate of fleas.

Clinical signs

The various constituents of important oils are extremely lipophilic (fat soluble) and therefore are fairly rapidly absorbed from the gastrointestinal street and throughout the skin. The oil are regional irritants the mucous membranes, but the mechanism of systemic toxicity remains unknown. Most exposures space dermal or oral and dermal; dental exposure alone is less common (Khan et al, 2014).

Signs of essential oil toxicity in companion pets can happen within 2–8 hrs (Villar et al, 1994) and also typically much less than 24 hrs (Genovese et al, 2012), but can originally be non-specific and easily overlooked. Recovery regularly occurs in ~ 24 hours, however can be longer.

Hypersalivation (particularly in cats), depression, lethargy, ataxia, weakness, tremor, muscle fasciculation, paresis and ab discomfort may take place in pets following oral or dermal exposure to necessary oils (Thornton, 1990; Villar et al, 1994; Bischoff and Guale, 1998; Kaluzienski, 2000; Khan et al, 2014). Vomiting and hypothermia occur occasionally (Bischoff and also Guale, 1998). In severe instances there might be collapse, coma and also convulsions (Thornton, 1990). The breath, vomitus, urine and also faeces might smell strongly of the oil. Hepatic and also renal results may occur complying with exposure come some essential oils (Bischoff and also Guale, 1998). In addition, essential oils are volatile and also can be aspirated into the lungs leading to aspiration pneumonia (Wismer and Means, 2012).

Essential oil are likewise irritant come the skin and also may reason erythema, dermatitis, pruritus, rash, alopecia or burns (Norris, 1990; Khan et al, 2014).

Adverse results have to be reported in cats and dogs with other ‘natural’ products containing crucial oils provided for the control of fleas, even when the product was offered as directed (Genovese et al, 2012).

Adverse effects reported in cats

In a evaluation of 106 feline cases of pure (100%) tea tree oil exposure the most typical signs to be hypersalivation (44%), ataxia (23%), lethargy or listlessness (20%), coma or recumbency (16%), tremor or muscle fasciculations (9%), hypothermia (8%) and dermatitis, pruritus or rash (2%). The result was well-known in only six cases and also all 6 cats recovered (Khan et al, 2014).

In a case collection three Angora cats ended up being unwell after being shaved and treated with 100% tea tree oil; 60 ml was supplied in total on the three cats. In ~ 5 hours cat 1 was hypothermic and also uncoordinated. On join on the job of application cat 2 was comatose v dehydration and also hypothermia. Cat 3 was alert, nervous, mildly ataxic and also trembling. All cats had actually elevated liver enzymes and also were listed to have actually a solid odour of tea tree oil and also were washed v a detergent. Cat 3 recovered in ~ 24 hrs of admission and also cat 1 recovered after 48 hours. Cat 2 enhanced over job 2 and 3 however remained ataxic, dehydrated and also obtunded. On job 3 it began to control its very own body temperature, yet was discovered dead that evening. Pooled urine from all the cat was positive for terpinen-4-ol, a ingredient of tea tree oil (Bischoff and also Guale, 1998).

Death emerged in an 8-month-old chinchilla cat 14 hours after she had actually been sprayed v a water and also tea tree oil mixture as a flea repellent. Signs consisted of collapse, laboured respiration, far-ranging abdominal pain, dermatitis, depression and also a strong odour that the oil (Norris, 1990).

Adverse results reported in dogs

In a review of 337 canine cases of pure tea tree oil exposure the most typical signs to be depression, lethargy, listlessness or being subdued (54%), paresis or weak (45%), ataxia (43%), tremor or muscle fasciculation (10%), vomiting (6%), coma, fallen or recumbency (5%), dermatitis, pruritus or decision (4%), and also elevated liver enzyme (2%). Where the outcome was known 24 dogs (94%) recovered at residence (with bathing and observation), two recovered with veterinary care and also two passed away (Khan et al, 2014). In one fatal situation a 7.5-year-old English Sheepdog was accidentally provided 0.3–0.4 ml of tea tree oil intravenously. He automatically collapsed and died in asystole. In the various other reported fatal instance a 15-year-old miniature poodle to be treated dermally with about 28.5 ml that pure tea tree oil applied over 3 days. After ~ the 3rd dose he ended up being ataxic and also was taken to a veterinary practice. He showed up to recover with donate care and was discharged, yet died at residence 60 hours after the last applications (Khan et al, 2014).

Partial paralysis of the hind limbs, ataxia and also depressed behaviour was reported in 2 dogs cure with just 7–8 drops of 100% tea tree oil as a flea repellent used along their spines. Indications resolved quickly with decontamination and also they both recovered (Kaluzienski, 2000).

A cross breed was euthanased about 4 job after 30 ml that tea tree oil was rubbed into a life eczematous skin surface. Initial signs included intense thirst and respiratory distress. She progressed to vomiting, ataxia, drowsiness, convulsions, putrid diarrhoea, constricted pupils, dehydration, increased respiratory rate, abdominal muscle pain and also muscle fasciculation and also was euthanased after failing to respond come supportive treatment (Thornton, 1990).

Management

Treatment of essential oil toxicity is supportive. Emesis is contraindicated if the oil has been ingested, as vital oils room volatile and there is a hazard of aspiration pneumonia if vomiting wake up (Villar et al, 1994; Wismer and Means, 2012). Triggered charcoal can be offered (Alpert, 2016), however its efficacy in crucial oil toxicosis is unknown and the quantity ingested is regularly small. Triggered charcoal is contraindicated in animals with main nervous system depression or vomiting, because of the danger of aspiration.

If the tea tree oil has been applied dermally, decontamination is essential. If the owner applied the oil they should be asked around the amount of oil given, the concentration that the oil and where it was applied. The pet should be washed promptly through water and also detergent, as essential oils space not conveniently soluble in water. Tea tree oil has a strong odour, therefore this deserve to be supplied as a overview to recognize the efficiency of dermal decontamination, and collaring may be helpful to prevent more grooming. The animal should it is in examined very closely for any type of signs the dermal irritation, which should be treated v antihistamines or corticosteroids, as forced (Khan et al, 2014).

Animals have to be assessed for evidence of aspiration, e.g. Coughing, noisy breathing (which might occur complying with ingestion or perhaps from grooming), and also in those with heavy contamination and far-ranging signs, liver enzymes should be monitored.

Further monitoring is supportive. Methocarbamol have the right to be offered for tremor or muscle fasciculation, and also diazepam is the drug of an option for convulsions. Liver protectants can be taken into consideration in severe situations (Khan et al, 2014).

Poison centres collect info on adverse reactions to and inappropriate use of important oils. A poison details centre will also be able to advise on proper management in a specific case.

Prognosis

Prognosis is great in animals with mild signs of tea tree oil exposure that deal with rapidly following decontamination, but in pets with hefty contamination and also neurological or an extensive signs failing to respond to donate care, the prognosis is more guarded.

Prevention

If an owner asks around the use of tea tree oil because that the administration of fleas or a skin condition, they have to be advised the pure (100%) or focused tea tree oil must never be provided orally or applied directly to the skin or fur, also when combined in water (the oil is not miscible v water); even a few drops of 100% tea tree oil applied dermally has caused clinical signs in companion animals. Cats might be much more at hazard of disadvantage effects because their organize behaviour may lead to a higher exposure after dermal application (Khan et al, 2014), and because metabolism of the terpene in tea tree oil involves glucuronidation (Kohlert et al, 2000) and also cats are poor glucuronide conjugators. In addition, pets with liver an illness may be an ext at danger of toxicity. Alternate treatments because that the administration of fleas must be questioned with the owner.

Products comprise tea tree oil and formulated for use on the skin or fur are not expected to cause essential oil toxicity, due to the fact that the concentrations supplied are small.

Conclusion

Some owner may find natural or herbal products attractive as therapies for fleas in pets, and also pure (100%) tea tree oil is conveniently available. Organic does not mean safe, however, and also dermal application of tea tree oil can cause poisoning which generally manifests together neurological (ataxia, tremor, lethargy, weakness, coma) and also dermatological indications (dermatitis, pruritus or rash). Cats and dogs had died after dermal application of tea tree oil, and even a few drops can cause clinical signs. If a pure or concentrated essential oil has been applied, the skin have to be to wash promptly through detergent and water. Administration is supportive.

KEY POINTS

Tea tree oil is vital oil promoted as a ‘natural’ or ‘herbal’ therapy for fleas in pets.

Tea tree oil applied to the skin can cause neurological and dermal effects, an especially when undiluted oil is used.

Even a couple of drops that pure 100% oil can reason clinical indicators in pets.

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Deaths have actually been report in companion pets following dermal applications of tea tree oil.