Vet Times The website for the veterinary profession https://www.vettimes.co.uk Poisoning in cats: toxic triggers and raising owner awareness Author : Samantha Taylor Categories : Clinical, RVNs Date : August 27, 2015 International Cat Care (ICC) has teamed up with the Veterinary Poisons Information Service (VPIS) and Agria Pet Insurance to launch a Keeping Cats Safe campaign. 1 / 7
Working with VPIS, ICC will produce information on the most common cat poisonings, as well as those that may occur at certain times of year. Advice will be available for owners on various poisonous substances and where they can be encountered, what the signs of poisoning are, what to do and how the risks can be minimised. Many cat owners will be unaware of the dangers of some substances, so we hope our accompanying social media campaign will spread widely to help prevent needless suffering and promote faster recognition and treatment of toxicity if it occurs. Prevention is better than cure and guiding owners on how to avoid poisoning is our goal. Owner information can be found at http://icatcare.org/advice/keeping-cats-safe 2 / 7
Treatment advice for vets, VNs and technicians will appear in ICC s publication Feline Focus (www.icatcare.org/nurses), as well as on the website of ICC s veterinary division, the International Society of Feline Medicine (http://icatcare.org/vets/keeping-cats-safe-campaign). Why are cats affected by toxins? Cats are affected by toxins through ingestion in the same way dogs are, but their metabolism and lifestyle play a role in delaying diagnosis and explain why the prognosis for poisoned cats is worse than for dogs. Factors include: lack of certain enzymes and hepatic metabolic pathways that differ from other species, resulting in a reduced ability to detoxify certain chemicals; a drive to keep clean, resulting in ingestion of substances from their coat and feet; an outdoor lifestyle, meaning contact with toxins is not observed hence clinical signs are not associated with poisoning delaying treatment; and a natural tendency to hide illness until a later stage, meaning treatment is less effective (this is true for many feline illnesses). What are common causes of poisoning? According to the VPIS, the most common inquiries concerning feline toxicities are: Lilium species agent unknown permethrin ethylene glycol benzalkonium chloride imidocloprid paracetamol disinfectant white spirit/turpentine substitute moxidectin These common feline toxins are discussed in further detail later on. Remember, if any exposure to toxins is suspected, consultation with a veterinary poisons advice service, such as the VPIS, is recommended to ensure the correct treatment is administered. Time is of the essence when managing such cases, so don t hesitate to seek specific advice. Lilium species 3 / 7
Figure 1. Lilies may look pretty, but are highly toxic to cats, causing acute kidney injury. Lilium species (true lily) and Hemerocallis (Hemerocallidaceae; day lily) are highly toxic to cats (Figure 1) and feature in many flower arrangements with minimal warnings and lack of owner awareness of the dangers. Toxicity seems more common in cats confined indoors perhaps due to the drive to consume plants not being met by grasses outside. Exposure can also occur in the garden and all parts of the plant are toxic even brushing against a flower and grooming away the pollen can cause severe illness, while as little as one leaf ingested can be fatal. The mechanism of toxicity remains unknown. Signs develop rapidly, with gastrointestinal irritation, followed by polyuria, dehydration and then acute kidney injury (AKI). Seizures can occur in severe cases. Treatment is aimed at reducing absorption with emesis and/or activated charcoal, enhancing renal perfusion with intravenous fluid diuresis for at least 48 hours. Once acute kidney injury has occurred, treatment options are limited and referral should be considered. Prognosis is good in cats 4 / 7
where decontamination is prompt and treatment has been started before the onset of renal impairment. Cats with acute kidney injury have a more guarded prognosis. Permethrin Pyrethrins and pyrethroids are insecticides found in flea and tick treatments sold in veterinary practices and over the counter in pet shops. Cats are particularly susceptible to intoxication due to their high surface area to weight ratio and reduced capacity for hepatic glucuronidation contributing to accumulation of toxic metabolites. They are exposed via direct application by owners or contact with treated dogs. The pyrethroids are absorbed through the skin, as well as being groomed off and ingested. Pyrethroids principally affect the peripheral and CNS. They reversibly alter the function of sodium channels within the axon in such a way it prolongs their conductance and leads to repetitive firing of the nerve fibre. This effect is enhanced by low temperatures. Due to their lipophilic properties, pyrethrins pass easily through the blood-brain barrier and can induce CNS signs, including seizures and muscle tremors. Treatment should include rapid decontamination with bathing (avoiding hypothermia) and once clinical signs are observed, treatment should focus on control of muscle tremors and seizures using benzodiazepines, phenobarbitone or propofol for example. Specialist therapies such as intravenous lipid infusion may be beneficial in some cases. Prognosis for mildly affected cases is good, but severely affected cats may die or be euthanised due to the severity of clinical signs. Educating owners to avoid exposing their cats to dog flea products is vital to preventing toxicity. For more information, visit http://icatcare.org/permethrin/vetinfo Ethylene glycol Antifreeze products containing ethylene glycol (EG) are used in car radiators, screen washes and, occasionally, brake and transmission fluid. Malicious poisoning is also unfortunately suspected in some cases. Ingestion of just a small amount (1.4ml/kg) is toxic. The toxic products of the metabolism of EG cause metabolic acidosis and renal tubular damage, resulting in AKI. EG is metabolised by the enzyme alcohol dehydrogenase (ADH) to glycoaldehyde and further metabolised to acidic products and oxalate. Formation of calcium oxalate crystals occurs resulting in hypocalcaemia and crystalluria. Clinical signs are gastrointestinal and neurological before the development of AKI 12 to 24 hours post-ingestion, when oliguria or anuria, depression, vomiting and bradycardia may be noted. Diagnosis is based on clinical/clinicopathological findings consistent with AKI, as well as hypocalcaemia and an increased anion gap. Urinalysis may reveal calcium oxalate monohydrate crystals and renal ultrasound may demonstrate hyperechoic cortices. Treatment, if seen rapidly 5 / 7
after exposure, should include gastric decontamination, unless consciousness is impaired. Metabolism of EG can be inhibited by ethanol, which acts as a preferred substrate for ADH. This is unlikely to be effective if exposure was more than 12 hours previously and AKI has developed. Advice should be taken from the VPIS and a veterinary specialist centre on management of AKI due to EG. Unfortunately, prognosis for cats with AKI is poor, but early aggressive treatment may result in recovery in some cases. For more information, visit http://icatcare.org/vets/practiceresources/ethylene-glycol-toxicity-cats Benzalkonium chloride/other disinfectants Figure 2. Hypersalivation and inflammation of a cat s tongue 12 hours after licking a patio treated with a cleaner containing benzalkonium chloride. IMAGE: Bates and Edwards, 2015. Benzalkonium chloride is commonly found in household products particularly disinfectants, hand cleansers, and some patio cleaners and mould removers. It is a cationic detergent and exposure can result in clinical signs such as hypersalivation, hyperthermia, oral ulceration (Figure 2) and inappetence. Treatment is supportive and the majority of cats will recover. To reduce the risk to cats from disinfectants, products should be stored securely, diluted correctly, cats kept away from treated surfaces until a product has dried, and spills and puddles mopped up promptly. Clients can be advised to use alternative methods of cleaning (for example, steam 6 / 7
Powered by TCPDF (www.tcpdf.org) cleaners) or alternative agents such as dilute bleach to clean surfaces on which cats are likely to walk. For details, visit http://icatcare.org/sites/default/files/pdf/benzalkonium-chloride-exposure.pdf Paracetamol Owners may administer paracetamol to their cat if they perceive it to be in pain. Unfortunately, cats are particularly sensitive to paracetamol (acetaminophen) toxicity due to their limited ability to metabolise the drug to non-toxic metabolites. Alternative metabolic pathways lead to production of toxic metabolites, which cause methaemoglobinaemia, cyanosis, anaemia and jaundice. Even one paracetamol tablet can cause severe toxicity in a cat. Treatment is aimed at ensuring adequate oxygenation, preventing further metabolism of paracetamol to toxic metabolites with use of antidotes, particularly acetylcysteine, to prevent damage to the liver and red blood cells. As with all toxicities, owner education is vital to reduce misguided home treatment. Conclusion ICC hopes this campaign will raise awareness of the causes of poisoning in cats and reduce the cases seen in clinics. Many owners are unaware of potentially fatal chemicals and plants they keep close to their cats and all practices have an opportunity to educate clients and help protect cats from preventable illness due to toxicity. To find out more, visit http://icatcare.org/about-us/ourcampaigns/keeping-cats-safe and http://vpisglobal.com References Bates N and Edwards N (2015). Benzalkonium chloride exposure in cats: a retrospective analysis of 245 cases reported to the Veterinary Poisons Information Service (VPIS), Vet Rec 176(9): 229. 7 / 7