As spring nears, the weather warms and days become longer — we and our pets spend more time out of doors. This is the time of the traditional spring clean, which may include the house, garden and patio. There is also an abundance of spring flowers which may be attractive to pets. Pets may be exposed to fertilisers used to get the garden ready for spring planting and the summer ahead. This article discusses some of the seasonal spring poisoning hazards for pets.
Fertilisers
Both indoor and outdoor domestic fertilisers tend to be ‘NPK-based’, containing nitrogen (N), phosphorus (P) and potassium (K). Various products are available (Figure 1). Houseplant fertilisers are usually liquid preparations, diluted before use, although tablets and sticks are also available. Outdoor fertilisers may be powder, granules or liquid, again usually diluted or dissolved in water for use.
Phosphorus in fertilisers may be in the form of animal bone (bone meal) or phosphorus pentoxide. Bone meal is used as an organic, slow-release fertiliser. It comprises ground animal bones and slaughter-house waste products, and is high in calcium, nitrogen and phosphorus. The addition of fish, blood or bone meal may make fertilisers more attractive and palatable to cats and dogs.
Some products also contain moss killers (usually iron sulphate) or weedkillers (usually phenoxy derivative herbicides such as mecoprop, dichlorprop or 2-methyl-4-chlorophenoxyacetic acid (MCPA)).
Clinical effects
Fertilisers are poorly absorbed by the gut (Marshall, 2011) and are generally of low toxicity. Many animals remain well after ingestion (Veterinary Poisons Information Service (VPIS) data), but in those that develop signs, most have only gastrointestinal irritation that generally starts within 1–2 hours of ingestion.
Systemic poisoning is not typically seen with fertiliser ingestion. Impaction (reportedly associated with ingestion of >0.5 g/kg), constipation, abdominal pain, hind limb weakness, muscle stiffness, rigidity, urticaria, pruritus and muzzle oedema have been reported (Means, 2016). Pancreatitis may occur following ingestion of a very large volume of bone meal or blood, fish and bone fertiliser (Means, 2016). Bone meal is an abrasive substance that has the potential to clump and harden as it moves through the gastrointestinal tract. There is therefore the risk of gastrointestinal tract injury and/or rupture. Concurrent ingestion of packaging material could also contribute to the risk of gastrointestinal obstruction, which can lead to severe complications that may be fatal (VPIS case data). The duration of signs will depend on the severity of clinical signs, but recovery usually occurs within 12–48 hours.
In human medicine, there are occasional reports of patients with hyperkalaemia and acidosis after intentional ingestion of NPK liquid fertiliser involving large volumes (Gouault et al, 1996; Blais et al, 2013), but hyperkalaemia has not been reported in cats or dogs after ingestion of fertiliser.
Dermal exposure to fertiliser may cause urticaria, pruritus and muzzle oedema.
Treatment
It is important to establish the product involved, as there is a huge variety available, and they can contain ingredients other than fertilisers. This will involve questioning the owner about the intended use of the product, if it was used correctly or whether the product was eaten directly from the container or from the plant pot or lawn. If in doubt, a poisons information service should be consulted.
Treatment of animals following fertiliser ingestion is symptomatic and supportive, particularly ensuring adequate hydration.
Emesis could be considered if a dog has ingested >0.5 g of fertiliser/kg (Means, 2016). Administration of activated charcoal is not recommended as it does not absorb fertiliser and may exacerbate constipation. Dermal decontamination may also be required, and exposed skin and feet should be washed.
An antiemetic may be used if there is excessive vomiting and a bland diet may be helpful. Gastroprotectants may be given, if required (Marshall, 2011). If the dose of undiluted liquid fertiliser is very large, checking of electrolytes may be considered, particularly potassium.
Owners should be advised to observe for signs of obstruction (e.g. repetitive vomiting, weakness, inappetence, bloating). If signs are pronounced or persist beyond 48 hours, the animal should be assessed for complications of fertiliser ingestion. Surgery may be required in these cases (Marshall and Lee, 2011).
Spring plants
Pets can be attracted to spring flowers or dig up the bulbs. The VPIS often receives enquiries about pets — particularly dogs — that have eaten several different types of plants after chewing or eating the flowers, leaves or bulbs. Cut flowers may also be accessible when brought into the home. Gastrointestinal signs are expected in most cases but obstruction is a potential risk following ingestion of plant bulbs.
Bluebells
Bluebells (Hyacinthoides species) are found in woodland, hedgerows, parks and gardens. All parts of these plants contain scillarens, which are cardiac glycosides similar in structure to those of foxglove (Digitalis species) (Cooper and Johnson, 1998). These compounds can cause gastrointestinal and cardiac effects.
In cats and dogs, the most common signs after ingestion of bluebells are vomiting, abdominal pain and diarrhoea. Effects occur within a few hours and resolve within 1–3 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 species (Figure 2a) are widely cultivated and naturalised flowering corms (‘bulbs’). It is important not to confuse this plant with the more toxic autumn crocus (Colchicum autumnale, meadow saffron). The autumn crocus flowers from May to October, but the flowers that 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 flavour 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 2–4 hours and resolve within 24–36 hours.
Daffodil
Daffodils (Narcissus species) are very popular and have characteristic white or yellow trumpet-shaped flowers. They are part of the Amaryllidaceae family.
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. Lycorine is considered the main toxin in the Amaryllidaceae (Kretzing et al, 2011) and has irritant, emetic and purgative actions. Calcium oxalate crystals are also present and act as a mechanical irritant, potentially facilitating entry into cells of other irritants and allergens.
Cats and dogs mostly 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 bradycardia (Saxon-Buri, 2004). Hypo- or hyperglycaemia is reported occasionally (VPIS data).
Daffodils also contain allergens (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). Severe and fatal cases are occasionally reported with daffodil ingestion in pets (VPIS case data).
Grape hyacinth
Grape hyacinth (Muscari species, Figure 2b) is a common spring plant. It is of low toxicity, and ingestion may cause gastrointestinal upset in pets.
Hyacinth
Hyacinths (Hyacinthus orientalis, Figure 2c) are common house or garden plants. Hyacinth contains 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. Severe poisoning is not expected from ingestion of hyacinth (Lieske, 2002).
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).
Primrose
Primrose (Primula vulgaris) 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 ‘first rose’. Primroses are of low toxicity, but ingestion may cause mild gastrointestinal upset.
Snowdrops
Snowdrops (Galanthus nivalis, Figure 2d) are very commonly cultivated. Snowdrops contain Amaryllidaceae alkaloids including lycorine (Baraka and Harik, 1977). 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. Vomiting and diarrhoea may occur in the first few hours, with recovery within 24 hours.
Tulips
There are numerous species and cultivars of tulip (Tulipa species) and they are commonly available as cut flowers or bulbs. All parts of tulips are toxic, but particularly the bulb. The main toxins are the allergens tulipalin B and tulipalin A. In cats and dogs, the main signs are because of gastrointestinal irritation with hypersalivation, vomiting, diarrhoea (Lieske, 2002), 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 (‘tulip finger’), particularly in individuals who regularly handle tulip bulbs, such as bulb packers or florists. Dermal effects are generally not a problem in animals.
Wild garlic
Allium ursinum (wild garlic, wood garlic, ramsons; Figure 2e) is a common woodland plant in the UK, often found growing with bluebells. As a member the Allium genus, it contains a variety of organic sulphur compounds including n-propyl disulphide. These compounds cause oxidative damage to haemoglobin, which results in haemolytic anaemia with Heinz body formation. This is only likely to occur from ingestion of a large volume of wild garlic. Signs of haemolysis may be delayed from 1–5 days but Heinz bodies can appear within 24 hours and increase in number over the next few days before declining. Recovery usually occurs over 3–7 days, but can be longer in severe cases.
Gastrointestinal effects may occur after ingestion with inappetence, vomiting, abdominal discomfort and diarrhoea, and the breath and urine may smell strongly of garlic. Other clinical signs are those generally associated with anaemia, i.e. lethargy, weakness, pale mucous membranes, tachycardia and tachypnoea. Haematuria and haemoglobinuria are common (and can be the presenting signs in Allium poisoning).
Haematological changes reflect oxidative damage with low packed cell volume (PCV) and haemoglobin, and erythrocytes with Heinz bodies. There may also be leucocytosis and neutrophilia. Blood smears may reveal eccentrocytosis, spherocytosis, poikilocytosis and anisocytosis. During recovery, after the haematological parameters have reached a nadir, regenerative anaemia occurs until parameters return to normal.
Treatment of spring plant exposure
Gut decontamination is usually not required after ingestion of most spring flowers, although if vomiting has not occurred after ingestion of daffodils, an emetic could be considered. Washing any contaminated skin is advised to reduce the risk of dermal reactions. Dermatitis should be treated conventionally.
Management of animals with clinical signs from ingestion of spring flowers is supportive. Oral fluids should be encouraged, but intravenous fluids for rehydration 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. If animals with mild signs are being managed at home, owners should be advised about the risk of obstruction. If obstruction occurs, surgical intervention may be required.
Treatment of Allium poisoning is supportive. Anaemia is unlikely to occur if the pet has just been chewing on a few leaves. Activated charcoal (1–3 g/kg) orally can be given if a large volume has been ingested recently. A blood smear after 24 hours may be useful to establish whether the pet is at risk of Heinz body anaemia. Rehydration may be required but care should be taken if anaemia is severe. If practical, monitoring of haematological parameters for evidence and severity of anaemia, as well as monitoring of renal and liver function, should be undertaken following ingestion of a large volume of plant material. Antioxidants such as vitamin E, ascorbic acid and acetylcysteine are unlikely to be of benefit in Allium poisoning (Cope, 2005). Supplemental oxygen may also be required in severe cases (Cope, 2005).
Grayanotoxin-containing plants
Grayanotoxins are found in Rhododendron species (Figure 3a, which includes azaleas), Pieris species (Figure 3b). and Kalmia species. These plants contain several grayanotoxins in the nectar, flowers, leaves and stems; these compounds cause gastrointestinal and cardiac effects.
Grayanotoxin poisoning is very common in goats and sheep, and can cause gastrointestinal signs in cats and dogs (Milewski and Khan, 2006; Manhart et al, 2013). Severe poisoning in cats and dogs is not common but is reported occasionally (Bell, 2008; Manhart et al, 2013).
Clinical signs
Clinical signs of grayanotoxin poisoning affect the gastrointestinal and cardiovascular systems. Onset is usually rapid (often within 6 hours) and, in mild cases, recovery may occur within a few hours. In animals with more significant signs, recovery may take 1–3 days.
Initially, gastrointestinal signs are predominant with hypersalivation, vomiting and diarrhoea. There may also be depression, tremor, bradycardia or tachycardia, weakness and ataxia. Dilated pupils have been reported in cats (VPIS case data). In severe cases, tachypnoea, hypotension, pyrexia, opisthotonus and convulsions may occur. There is also a risk of aspiration pneumonia, secondary to profuse vomiting.
Treatment
Treatment of grayanotoxin poisoning is supportive as there is no antidote. If vomiting has not already occurred, an emetic can be given if ingestion was recent, followed by activated charcoal. An antiemetic can be given to control vomiting and atropine for severe bradycardia (0.01–0.03 mg/kg intravenously). Lidocaine and procainamide can be used for persistent or severe tachyarrhythmias (Adams, 2011).
Antibiotics may be required to prevent secondary infection following aspiration. Lipid infusion has been used in goats with grayanotoxin poisoning and it appeared to be effective, with one goat responding within 3 hours and two within 12 hours (although one subsequently died of aspiration pneumonia) (Bischoff et al, 2014). There is no experience of lipid infusion in the management of grayanotoxin poisoning in cats or dogs. Lipid infusion could be considered in cats or dogs with severe signs unresponsive to other therapies; however, severe cases are uncommon and it is unlikely to be necessary in the majority of cases.
Prognosis in cats and dogs with grayanotoxin poisoning is good with prompt supportive care, but more guarded in animals with convulsions or aspiration pneumonia.
Patio cleaners and disinfectants
Disinfectants are commonly used in the home, more so now with the coronavirus pandemic. These products usually contain cationic detergents (e.g. quaternary ammonium compounds (QACs)). The most common cationic detergents found in household products are benzalkonium chloride (BAC) and didecyldimethylammonium chloride (DDAC). They are found in disinfectant liquid (Figure 4) and wipes, antiseptic cleaners and patio cleaners (to remove mould and dirt). Patio cleaner products are usually intended to be diluted prior to use.
Although the concentration is generally low in house-hold disinfectants, they pose a significant hazard to pets, particularly cats, causing local tissue injury. Pets are usually exposed by walking over a treated surface and licking their feet. They may also drink from a spill or from a cleaning bucket containing a diluted product, grooming after a splash on their fur or an owner may use a disinfectant wipe to clean something off their pet's fur.
It is important to note that in many cases of cationic detergent exposure, the pet is presented for veterinary care hours later as signs may be absent initially. Cationic detergent exposure should be suspected in any pet (usually a cat) that presents with hyperthermia, hypersalivation and ulceration of the tongue. Owners should be asked about the use, within the previous day or so, of disinfectants, patio cleaners and other household products that can contain a cationic detergent. Cationic detergents are not used as general cleaning agents, but any product described as antibacterial, antiviral or disinfectant should be suspected of containing a cationic detergent.
Clinical effects
Common signs on presentation after exposure to cationic detergents are hypersalivation or drooling, buccal irritation, tongue and oral ulceration, hyperthermia and inappetence. There may also be depression, vomiting, glossitis and respiratory signs. In a review of 245 feline cases of benzalkonium chloride exposure, the mean time recorded for onset of the first clinical sign was 6.4 hours (Bates and Edwards, 2015). However, the VPIS was not contacted until 14 hours post exposure (which is a reflection of the presentation time); the median recovery time in these cases was 72 hours (Bates and Edwards, 2015). Dermal exposure may cause erythema, inflammation, ulceration, hair loss and contact dermatitis. Concentrated solutions may cause chemical burns and a splash in the eye may result in irritation and inflammation.
Treatment
Emesis and gastric lavage are contraindicated after ingestion of a detergent-containing product because of the risk of aspiration, and activated charcoal is not useful. Treatment is symptomatic and supportive with rehydration and an antiemetic, if required. If aspiration is suspected (e.g. coughing, wheezing, tachypnoea), the lung sounds should be checked and a baseline chest x-ray should be performed, if indicated.
After recent exposure to a cationic detergent, the oral cavity should be thoroughly washed and decontaminated. Atropine may be given for pronounced hypersalivation but should be used sparingly to ensure that damaged tissues do not become too dry as this may interfere with healing. Rehydration and gastroprotectants, may be required and a bland diet is recommended. Analgesia is usually indicated in animals with clinical signs, particularly those with severe oral ulceration. In animals with severe oral signs, syringe or nasogastric feeding may be necessary, although this is uncommon (Bates and Edwards, 2015). Owners should be advised that recovery from cationic detergent exposure may take several days.
After dermal exposure, the affected area should be thoroughly rinsed with water to ensure prompt decontamination. A collar should be considered to prevent grooming. Any signs of irritation should be managed conventionally. Affected eyes should be thoroughly irrigated with saline or water and stained with fluorescein to assess any injury. Sedation and/or anaesthetic drops may be required to facilitate this.
Conclusion
Ingestion of fertilisers and spring flowers or bulbs is common, particularly in dogs. In the majority of cases, the signs are mild, but there is a risk of more serious effects. Deaths are occasionally reported with these plants and some fertilisers. Grayanotoxin-containing plants can potentially cause significant toxicosis, but severe cases are uncommon in cats and dogs. Cationic detergents such as BAC and DDAC are common in the home and can cause severe local tissue injury in the mouth, requiring supportive care for several days. The exposure may have occurred hours before the onset of clinical signs — careful questioning of owners is thus required to establish the cause of the pet's signs.
KEY POINTS
- Fertilisers are poorly absorbed but can cause gastrointestinal signs and, in some cases, gastrointestinal obstruction.
- Ingestion of flowers and bulbs in the spring is common, particularly in dogs, but, in most cases, there are mild-to-moderate gastrointestinal signs.
- Rhododendron and Pieris species commonly cause gastrointestinal signs and can, occasionally, cause cardiac effects.
- Cationic detergents in household disinfectants and patio cleaners can cause delayed local tissue injury in pets, particularly cats.
- Questioning of owners may be required to establish how and when a pet was exposed to a spring poisoning hazard.