Many flowers appear in the spring when the weather starts to warm and days become longer, and pets can be attracted to the flowers or dig up the bulbs. Exposure to the bulbs may also occur in the autumn when they are planted. The Veterinary Poisons Information Service (VPIS) often receives enquiries about dogs that have eaten several different types of plants after digging up the newly planted bulbs. Most of these plants cause only gastrointestinal signs, but others such as the lilies and daffodil can cause significant toxicity. In this article each plant will be described in detail outlining the spe-cific risks with treatment recommendations provided.
| Plant | Dogs | Cats |
|---|---|---|
| Lilium species | 58 | 172 |
| Daffodils | 84 | 8 |
| Tulips | 37 | 6 |
| Crocus species | 24 | 3 |
| Bluebells | 12 | 2 |
| Hyacinths | 14 | 2 |
| Iris species | 6 | 3 |
| Day lily | 2 | 3 |
| Primrose | 1 | 1 |
| Snowdrop | 7 | 0 |
| Total for 2011 | 245 | 200 |
Bluebells
Bluebells (Hyacinthoides non-scripta) are bulbous plants found in woodland, hedgerows, parks and gardens. They are part of the Asparagaceae family. The flowers are often fragrant, blue to violet-blue (occasionally striped with a different shade of blue) or sometimes pink or white, and appear from April to June (Figure 1).
All parts of these plants contain scillarens, which are cardiac glycosides similar in structure to those of foxglove (Digitalis species) (Cooper and Johnson, 1998). The cardiac glycosides found in plants are generally precursors. These are primary glycosides that undergo enzymatic hydrolysis when plant material is dried or damaged to give the active (or secondary) glycosides. The gastrointestinal absorption of manyprimary glycosides is poor and toxic concentrations are rarely reached following plant ingestion (Frohne and Pfänder, 2005). Cardiac glycosides are negative chronotropes and positive inotropes; therefore, they cause decreased frequency and increased force of contraction of heart muscle. They inhibit sodium-potassium adenosine triphosphatase (Na+K+ATPase) on myocardial cells, preventing outflow of sodium into the extracellular space. The resultant high concentration of sodium within the cell increases the amount of calcium available for release during depolarization, which increases the force of contraction and therefore cardiac output (hence their use medicinally in heart failure).
In cats and dogs the most common signs after in-gestion of bluebells are vomiting, abdominal pain and diarrhoea. Effects occur within a few hours and resolve within 1 to 3 days. There is a risk of arrhythmias but these are generally not reported in cats or dogs, presumably because the quantity ingested is generally small compared with grazing animals. Severe toxicity has been reported in cattle (Thursby-Pelham, 1967; Cutler, 2007) and horses after grazing on bluebells (Forsyth, 1968).
Crocus
Crocus (Crocus species) belong to the iris family (Iridaceae); they are widely cultivated and natural-ized flowering corms (‘bulbs’). The leaves are usually very narrow and green with a pale or white stripe. The colour of the flowers is variable, but includes bright orange or yellow, violet or white (Figure 2). Flowering occurs from late winter to spring. It is important not to confuse this plant with the more toxic autumn crocus (Colchicum autumnale, meadow saffron). This plant flowers from May to October but the flowers which are pink to lilac-purple or rarely white, appear before the leaves.
The spring flowering crocus is considered to be of low toxicity. Saffron, which is used to favour and colour a variety of foods, is actually the dried flower parts of a crocus species (Crocus sativus). Ingestion of crocus leaves, flowers or corms may cause mild gastrointestinal irritation in cats and dogs with vomiting and diarrhoea. Effects typically occur within 2 to 4 hours and resolve within 24–36 hours. In humans poisoning has been reported from ingestion of saffron and 5–10 g of saffron is enough to cause toxicity and possibly death (Frank, 1961; Frohne and Pfänder, 2005). However, since approximately 100 flowers are required to produce 1 g of saffron, severe toxic-ity from ingestion of plant material is very unlikely.
Daffodil
Daffodils (Narcissus species) belong to the amaryllis family (Amaryllidaceae) and are perennial plants that grow from a white bulb. They have long erect green leaves and a pale green hollow stem which when broken exudes a clear sticky sap. The plant flowers from March to April with characteristic white or yellow trumpet-shaped flowers (Figure 3).
Daffodils contain alkaloids and glycosides which are responsible for the clinical effects observed. These compounds are present in all parts of the plant but are most concentrated in the bulbs. The alkaloids are all phenanthridine derivatives and include nar-cissine, narciclasine, galanthamine and lycorine, of which lycorine occurs at the highest concentration.The glycosides include scillitoxin. Calcium oxalate crystals are also present. Lycorine is considered the main toxin in the Amaryllidaceae (Kretzing et al, 2011) and has irritant, emetic and purgative actions whereas calcium oxalate acts a mechanical irritant and can facilitate entry into cells of other irritants and allergens. The substance(s) responsible for the cardiovascular effects are unknown but in animal experiments extracts of Chinese daffodil (Narcissus tazetta) caused dose-related hypotensive responses in rats (Chiu et al, 1992).
Cats and dogs most commonly ingest daffodil flowers or bulbs. Mild poisoning is also possible if animals drink the water in which cut specimens have been standing. The effects typically occur within 12 hours and commonly include vomiting, diarrhoea, abdominal tenderness, anorexia, hypersalivation, pyrexia and lethargy. In severe cases there may be dehydration, collapse, hypothermia, hypotension and brady-cardia (Saxon-Buri, 2004). Hyperglycaemia and convulsions are reported occasionally (VPIS data).
Daffodils also contain allergens, particularly the alkaloids masonin and homolycorine (Gude et al, 1988), and allergic and contact dermatitis is a problem in people who regularly handle the plants such as pickers and packers. Urticaria or pruritus is occasionally reported in animals (VPIS data).
Hyacinth
Hyacinths (Hyacinthus orientalis) are common bulbous house or garden plants. Like bluebells they belong to the Asparagaceae family. The flowers are pink, white, blue, purple or pale yellow, usually strongly scented and borne in loose to very dense clusters on a single leafless upright stem (Figure 4).
Hyacinths contain amaryllidaceae alkaloids, including lycorine, which is also found in daffodils. The outer scales of hyacinth bulbs contain calcium oxalate crystals, present as bundles of needle-like crystals known as raphides. These act as mechanical irritants. The bulbs contain up to 6% of calcium oxalate (Hjorth and Wilkinson, 1968).
Ingestion of hyacinths can cause gastrointestinal irritation with vomiting, diarrhoea and lethargy. Effects are expected to occur rapidly and generally last for a few hours; in some cases signs have persisted for up to 24 hours.
Handling hyacinths can cause contact dermatitis (‘hyacinth itch’) in humans, especially in bulb planters and sorters (Lovell, 1993). The dermatitis is highly pruritic, and has been described as a combination of mechanical, chemical and allergic factors (Van der Werff, 1959). Dermal effects are occasionally reported in animals (VPIS data).
Iris
There are many wild and cultivated Iris species, but only two have been reported to cause poisoning. Iris foetidissima (stinking iris) is an evergreen plant that produces an unpleasant smell when damaged. It is found mainly in open woods, hedgerows, fields and pastures and cliffs, but is also commonly cultivated. It has showy, violet flowers that are tinged with yellow, that appear from April to July. Iris pseudacorus (yellow fag) is found by rivers, streams or ponds, and is also commonly cultivated. The flowers are yellow often with purple and orange markings and appear from April to August.
All parts of iris are toxic, particularly the rhizomes. The toxicity is mainly due to the presence of irritant compounds. The identity of the toxin responsible has not been clearly defined and it may be a phenol glycoside which has variously been called irisin, iri-din or irisine. Myristic acid and an acrid compound of unknown composition have also been mentioned as possible toxic substances (Cooper and Johnson, 1998). The toxicity of other iris species is unknown but they are likely to cause similar signs.
Stinking iris has a bitter taste and unpleasant smell and it is unlikely to be eaten in any quantity. Inges-tion of this or other Iris species may cause discomfort in the mouth and throat, and gastrointestinal irrita-tion with abdominal pain, vomiting and diarrhoea (Cooper and Johnson, 1998). The effects occur within a few hours and usually resolve over 24–36 hours with supportive treatment. In humans the plants have also caused irritation to the skin and dermatitis (Calnan, 1970; Mitchell and Rook, 1979), but this does not appear to have been reported in animals.
Lilies
Companion animals may be exposed to lilies either in the garden, or more commonly, to indoor plants or lilies in bouquets. There are many types of lilies including Lilium x asiatica (Asiatic lily), Lilium lancifolium (previously Lilium tigrinum (tiger lily), Lilium longiforum (Easter lily) and Lilium orientalis (stargazer lily/oriental lily). Lilies are flowering plants belonging to the Li-laceae (true lily) family; they grow from bulbs and have large showy flowers (Figure 5). Day lilies (Hemerocallis species) are garden plants and are part of the Hemero-callidaceae family. They also have large showy flowers, which typically last only a day (hence the name). Note that there are numerous other plants that have lily in their name that are not true lilies or day lilies.
Cats are very sensitive to lilies, including day lilies; ingestion of less than one leaf may cause severe poisoning (Volmer, 1999).They are the only species reported to develop renal damage from lilies and all parts of the plant are nephrotoxic to cats. Ingestion of lilies in dogs generally only causes gastrointestinal upset and does not cause renal failure (Hall, 2007). The toxic principle(s) and mechanism are unknown (Tefft, 2004), but renal failure in cats is due to necrosis of renal tubular epithelial cells. The basement membrane remains intact (Volmer, 1999; Brady and Janovitz, 2000; Volmer 2002), and prompt, aggressive treatment can result in regeneration of tubular epithelial cells (Volmer, 1999).
In cats the initial signs are due to gastrointestinal irritation (hypersalivation, vomiting, anorexia, lethargy and depression) and usually start within 2–6 hours. From 24–72 hours renal function starts to deteriorate. Biochemical changes with rising urea, cre-atinine, potassium and phosphorus concentrations generally occur from 18–24 hours (Fitzgerald, 2010). There is tubular nephrosis with haematuria, pro-teinuria, glycosuria and isosthenuria; squamous and epithelial cells and numerous casts may be present in the urine, particularly after 48 hours (Rumbeiha et al, 2004). There may be polyuria and polydipsia, and enlarged painful kidneys may be noted (Tefft, 2004). Convulsions can occur in animals with severe renal failure (Rumbeiha et al, 2004) and vomiting can start again at 36–48 hours (Hall, 2007). These late effects are due to uraemia. There may also be mild elevation in liver enzymes (Berg et al, 2007; Hall, 2007). Death occurs after 3–7 days (Hall, 2007; Fitzgerald, 2010). In cats that survive, chronic renal insufficiency may occur as a long-term consequence of lily nephrotoxicity (Langston, 2002; Steenberger, 2002).
Prognosis is excellent in cats if decontamination is prompt and treatment is started before onset of renal impairment. Treatment started more than 18 hours after ingestion or the presence of anuria is associated with a poor outcome (Volmer, 1999, Steenberger, 2002) and mortality is high (Rumbeiha et al, 2004).
Primrose
Primrose (Primula vulgaris) belongs to the primrose family (Primulaceae). It is a low growing plant with pale cream to yellow flowers. Pink or white flowered varieties are also known. It grows as a wild woodland or hedgerow plant but numerous cultivars are found in parks and gardens. It is one of the first flowers to be seen in the spring, and its name means ‘frst rose’. Primroses are not toxic but ingestion may cause a mild gastrointestinal upset.
Snowdrops
Snowdrops (Galanthus nivalis) belong to the Amaryllis family, like daffodils. They are bulbous perennial plants found throughout the UK and are very commonly cultivated. The flowers are white and green and appear from December to April (Figure 6).
Snowdrops contain amaryllidaceae alkaloids including lycorine, galanthamine (Baraka and Harik, 1977) and tazettine (Clemo and Felton, 1952). All parts are poisonous but the concentration of toxic alkaloids is low, even in the bulbs.
Ingestion of snowdrops in cats and dogs is not as common as ingestion of other spring flowers. Signs are usually vomiting and diarrhoea which occur within a few hours. Recovery is usually within 24 hours.
Tulips
Tulips (Tulipa species) belong to the Lily family (Lil-iaceae). There are numerous species and cultivars of tulips and they are commonly available as cut flow-ers or bulbs. The flowers are variable in shape but are often cup or star shaped and are brightly coloured red, pink, lilac, purple, yellow, cream, white or orange (Figure 7). The petals may also be striped or have a frilly edge. Flowering occurs from February to June, but tulips are available as a cut flower throughout the year.
All parts of tulips are toxic, but particularly the bulb. The main toxins are the allergens tulipalin B and tulipalin A (alpha-methylene-gamma-butyrol-actone). In cats and dogs the main signs are due to gastrointestinal irritation with hypersalivation, vomiting, diarrhoea, flatulence and abdominal pain. The signs usually occur within a few hours of ingestion and often resolve within 24 hours. In humans the main problem with tulips is allergies particularly in individuals who regularly handle tulip bulbs such as bulb packers or florists. This is known as tulip finger and is caused by tulipalin A present in the sap (Verspyck Mijnssen, 1969). Dermal effects are generally not a problem in animals.
Treatment
Gut decontamination is usually not required after ingestion of spring flowers (except for lily ingestion in cats, see below), although if vomiting has not occurred after ingestion of daffodils an emetic could be considered. Gut decontamination is usually not required after lily ingestion in dogs. Washing any contaminated skin is advised to reduce the risk of dermal reactions. Dermatitis should be treated conventionally.
More aggressive treatment is required after in-gestion of lily plant material in cats. It is essential to wash the cat thoroughly to remove any residual pollen on the coat and an emetic can be given if in-gestion is recent, followed by administration of activated charcoal. Treatment is aimed at preventing renal shutdown and enhancing renal perfusion and this includes administration of intravenous fluids at twice the normal maintenance rate for at least 48 hours. The fluid should be either isotonic saline or a balanced polyionic solution, such as Hartmann's solution (Tefft, 2004). The renal function, hydration status and electrolytes should be monitored and in cats with a low tolerance to fluids (such as those with cardiomyopathy), and care should be taken to prevent fluid overload. The bodyweight and central venous pressure should be monitored if possible (Tefft, 2004). Urine analysis will show evidence of renal tubular injury before onset of azotaemia (Malik, 2011) and changes can be observed as early as 12 hours post ingestion (Fitzgerald, 2010).
In cats that are presented with evidence of renal impairment following lily ingestion management is supportive. Haemodialysis or peritoneal dialysis has been successful in some cases (Volmer, 2002; Hall, 2007; Berg et al, 2007) but is rarely available. Other drugs commonly used in the management of renal failure (e.g. furo-semide, mannitol) are not very effective in lily-induced renal toxicity in cats (Tefft, 2004; Hall, 2007).
For ingestion of other spring and cut flowers treatment is otherwise supportive. Oral fluids should be encouraged, but intravenous fluids for rehydra-tion should be given if there is significant fluid loss through vomiting and/or diarrhoea. An antiemetic may be given for persistent vomiting, particularly after daffodil ingestion. Warming measures may be required after daffodil ingestion and atropine can be used for bradycardia. In most cases monitoring of blood biochemistry is generally not required unless gastrointestinal signs are significant and dehydration is a risk.
Conclusions
Ingestion of spring flowers or bulbs is common, particularly in dogs. There may also be incidents in the autumn when the bulbs are planted. For cut flow-ers, exposure may occur in cats that nibble the plant material or sniff at lilies and become exposed to the pollen. For most plants ingestion generally results in gastrointestinal irritation and this can be significant after ingestion of daffodils. Most animals respond to rehydration and, if required, an antiemetic. Serious toxicity from this type of ingestion is not common, except after ingestion of lilies in cats which requires prompt and aggressive treatment to prevent renal impairment. Some of these plants also contain allergens but in most cases the coat of cats and dogs provides some protection from dermal contact. In most cases the allergens in the plants are only a problem in people who have repeated contact with the plant, such as bulb planters, flower pickers and packers and florists.