« Food: 10 items pets must never eat » | This article presents pet owners with a list of 10 items of foods and ingredients pets must never eat because they are known to be poisonous.
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Why are some foods and ingredients poisonous to pets?
Certain foods and ingredients are poisonous to cats and dogs because they contain chemical substances leading to a wealth of negative effects for major organs of the body.
Some of those substances may have an antidote, however some do not. Besides, being able to provide timely emergency treatment is key meanwhile pet owners may remain unaware of their pets’ intoxication, until symptoms start to show. This may impact on quality of recovery and vital prognosis.
Thus, it is very important for pet owners to be aware of the risks certain foods and ingredients might pose to their pet’s health .
When in doubt, pet owners should never hesitate to speak to a qualified vet to obtain further advice and information on what is the best course of action to help their pets. Most of all, in the majority of the situations listed below, prevention remains one of the best cure.
So, this article introduces 10 items of foods and ingredients poisonous to pets and which can be found in their direct living environment.
Number 1: Bread dough
Bread dough is toxic in its uncooked version, such as people would be preparing a pizza or baking any other type of bread dough containing yeast and their dogs would swiftly get hold of it behind their back and eat it.
Pet owners might not realise about the dog’s involvement until they start showing symptoms: vomiting, retching, abdominal bloat potentially leading to a gastric-dilatation volvulus, aka the life-threatening GDV.
Other signs will include: cardiovascular problems as well as change in behaviour, neurological and respiratory issues. The dog may also become hypoglycaemic (low blood sugar levels).
Bread dough contains yeast. When it settles in a dog’s stomach, yeast is able to ferment and to produce ethanol gas. The ethanol is absorbed and broken down into other chemicals (acids) which can further impact on the dog’s general wellbeing.
Depending on the amount of dough ingested, the gas produced could trigger a GDV. This is a condition where the stomach ends up twisted. This is life-threatening because of the associated cardiovascular shock it triggers.
The treatment will aim to decontaminate the stomach and to provide supportive care depending on the severity of the situation. If there is a GDV, an emergency surgical procedure with further in-hospital intensive care becomes necessary to save the dog’s life.
Number 2: Calcium supplements
Although not highly toxic as such in healthy pets, calcium supplements often contain Vitamin D to facilitate the absorption of calcium through the digestive system.
Nonetheless, in some preparation, if Vitamin D is present in sufficient quantity, it might cause calcium to deposit on organs such as the kidneys, blood vessels or along the digestive tract.
Besides, higher levels of calcium in the blood stream (hypercalcemia), lead to several complications:
- muscle weakness and lethargy
- perturbation of calcium levels
- disturbances of certain hormones
- constipation, gastric irritation
- increase in urination
- renal failure by mineralisation
Mild cases of toxicity will be limited to vomiting, bearing a good prognosis. More severe cases will be accompanied with potential calcification of blood vessels, kidneys and gut lining.
Literature advises that ingestion of amounts of Vitamin D > 0.1g/kg of Body Weight (BW) may result in hypercalcemia.
Number 3: Chocolate and caffeine
Pet owners are certainly familiar with chocolate and its associated products being toxic to pets. Here the toxicity is down to molecules called methylxanthines such as caffeine and theobromine.
Those molecules act through a mechanism which involves releasing calcium to the heart and the muscles, among other things. Both are metabolised by the liver, although it takes longer for theobromine to be absorbed than it does for caffeine.
Caffeine is found in: caffeine tablets, tea, chocolate, coffee beans, coffee (all sorts) and colas
Theobromine is found in: cacao beans, baking chocolate, dark, white and milk chocolate, cocoa powder and cacao bean mulch
Dogs are more affected than cats because of their behaviour towards food. Pets suffering from pre-existing liver of heart conditions, will also be at increased risk of complications.
The symptoms are usually dose-dependent. Hence, the type and amount of ingredient ingested will lead to different scenario. Although, pet owners could expect the following:
- hyperactivity and vomiting within 1 to 4h, depending on the molecule involved
- accelerated heart rate, weakness, lack of coordination, diarrhea, seizure (rare)
- increased temperature
- death induced by respiratory failure, cardiac arrhythmias or severe seizures
With non complicated cases, the treatment often consists in decontamination of the stomach up to 6h post-ingestion and the provision of relevant supportive care, which involves treatment with activated charcoal.
Severe cases will require emergency critical care with close in-hospital monitoring, due to the life-threatening nature of the situation.
Number 4: Grapes, raisins (and currants)
Pet owners are increasingly becoming aware that grapes, raisins and currants are toxic to some dogs and not to others. Although the issue started to be reported circa the end of the 90’s, the exact mechanism by which those fruits lead to intoxication, and are potentially fatal to some dogs, is still mostly unknown. Scientific research on the phenomenon is ongoing.
In 2008, a review of cases concerning 43 dogs, established the major signs of poisoning as listed below:
- vomiting, lethargy, anorexia and diarrhea
- increased levels of blood urea nitrogen, creatinine and calcium
- lack of coordination, decreased in urination and weakness, associated with negative outcome
Several reasons have been cited as per why grapes, raisins and currants are toxic to dogs. It could be due to:
- presence of mycotoxins, pesticides or heavy metals on the fruits
- intolerance to tannins or to high levels of monosaccharides
- hypovolaemic shock, renal ischemia (i.e.: compromised blood circulation)
- other causes
The toxicity does not appear to be dose-dependent, so there is no established toxic dose for this type of food. This means that dogs should avoid eating grapes, raisins and currants as a matter of strict prevention. To provide a tangible idea, literature reports that estimated quantities of 19.6g/kg BW (grapes) and 2.8g/kg of BW (raisins) have led to acute kidney injury (AKI) in dogs (based on clinical records).
A study published last year (2020), describes the relevance and significance of reported neurological signs in the early stage of the poisoning, before the development of renal issues. This led researchers to question whether grape toxicity, in its initial stage, could be confused with other types of toxicity, such as what is observed with ethylene glycol toxicity (scroll down to category 10).
If a dog is known to have ingested grapes, raisins or currants, vets will recommend decontamination of the stomach, blood test monitoring and such other in-hospital care to support the kidney function. They will want to make sure the situation will not deteriorate. As a consequence, dogs are likely to stay hospitalised for a few days.
Severely affected dogs might have to be referred for dialysis, in an attempt to save their lives. There is no antidote for intoxication with grapes, raisins and currants.
Number 5: Macadamia nuts
It is not known exactly why macadamia nuts are toxic to dogs. Although, literature reports that as little as 0.7g/kg of body weight can cause clinical signs which are:
- pain (joints and abdomen)
- hind limb weakness
- elevated body temperature
Signs of macadamia nuts toxicity may be seen up to 12h following ingestion by the dog. Stomach decontamination might be recommended if the ingestion is recent and the quantity of nuts ingested accounts for more than 1g/kg of BW.
It is worth noting that macadamia nuts covered with chocolate may add another layer of complexity to the situation. This will be assessed depending on individual cases.
Generally, symptoms disappear within 24 – 48 hours. Thus, the patient can be sent home to be monitored by his owners.
There is no antidote for macadamia nuts toxicity. However, if the dog is otherwise healthy, no further complications should be expected.
Number 6: Aflatoxins (Aspergillus sp)
Aflatoxins are toxic substances produced by species of fungus belonging to the Aspergillus genera:
- Aspergillus flavus
- Aspergillus paraciticus
- Aspergillus nomius
The major reason why dogs get poisoned is through pet food, when it has been contaminated during its processing. So, generally, it would lead to several pets being affected in a given household/area, provided they received the same food. The symptoms might not show straight away and could be delayed for several weeks after initial ingestion.
Signs will be split in 2 categories:
- anorexia, depression
- vomiting, diarrhea (often with blood)
- fever, seizure
- clotting problems, nose bleed
- Chronic (liver failure):
- weight loss, rough haircoat
- anemia, jaundice
- low blood sugar and cholesterol levels
- clotting problems
- increased in urination and in drinking
- fluid in abdomen
The treatment will attempt to limit the damages to the liver and to other organs. Decontamination of the stomach is recommended, especially if the ingestion is known and recent. However, there is no antidote against aflatoxins. The treatment will be supportive and dependent on the symptoms, as well as the evolution of the situation.
Some dogs manage to survive and should be expected to do well or show evidence of cirrhosis. However, those who exhibit clinical signs are less likely to survive, even with treatment. In such cases, the prognosis is understood to be guarded to poor.
Number 7: Mycotoxins (Penicillum sp)
These types of toxins involve the toxin penitrem A which is produced by a fungus called Penicillum crustosum and the roquefortine toxin which is produced by Penicillum roqueforti.
Such toxins are found in moldy dairy foods, moldy nuts, other types of moldy grains and in compost or other decaying material. Their exact mode of action is not fully known but it is understood they act by a mechanism impairing the nervous system. The effect will be commensurate with the dose ingested.
This type of poisoning tends to affect dogs more than cats, due to behavioural differences. The symptoms can show within minutes to hours after ingestion:
- salivation (« drooling »), vomiting brown material (i.e.: compost)
- agitation and sensitivity to external stimulation (i.e.: noise, light, touch ect…)
- panting, increased temperature and heart rate
- lack of coordination and muscle tremors
Symptoms could last up to 48h in most cases, however, since the severity is dose-dependent, some patients can exhibit signs of mycotoxin toxicity up to 5 days.
Treatment involves decontamination of the stomach followed by hospitalisation to provide supportive care and monitoring relevant to the situation and the severity of signs. There is no antidote available to specifically treat this type of poisoning.
The prognosis is very good, with a complete resolution within 48h, when treatment is provided very early in the process and clinical signs are controlled. However, in some instances, the poisoning can lead to death if the amount of toxin ingested is important and stomach decontamination delayed.
As a matter of prevention, pet owners are often advised to prevent their pets from picking up and eating things (i.e.: some dogs are known to champion the art of « garbage & rubbish digging », for example) and/or to make sure their compost areas are secured and « dog proofed », so they cannot gain access to it (often done behind their owners’ backs).
Number 8: Onions and garlic
Propyl disulfides are molecules known to cause a condition called Heinz body anaemia in pets who ingest them. Those molecules are found in plants of the Allium species such as garlic, onions, chives and leeks.
Toxicity happens through an oxidative mechanism damaging red blood cells. It is worth noting that cooking, drying or processing those plants won’t make them any safer. The toxic dose depends on parameters such as:
- species of plants
- mode of consumption (dry, cooked, juiced ect…)
- time of year
- species of pets
- type of exposure (acute vs chronic)
Symptoms are partly linked to the oxidative damages imposed on the haemoglobin and red blood cells. Other symptoms are linked with gastrointestinal tract such as irritation, pain, vomiting, diarrhea and anorexia.
There is no antidote and treatment consists in stomach decontamination if ingestion is less than ~2h. Supportive treatment and monitoring of the situation will be recommended, depending on the clinical signs and specific findings in a blood test. In some cases, a blood transfusion might be necessary.
Number 9: Salt
Salt poisoning occurs when an excessive amount of salt is ingested, resulting in hypernatremia (increase in sodium levels in the blood). This can happen through consumption of homemade play dough, table salt, rock salt, paintballs, sea water and such other salt-containing sources.
Symptoms will include:
- depression, lethargy
- tremors, seizures, coma
Salt acts as an irritant to the stomach and will trigger the gastrointestinal signs. The severity of neurological signs will depend on the quantity of salt ingested, as well as the availability of water, and potential pre-existing health issues.
When an excessive amount of salt (sodium) is rapidly absorbed, it has an effect on cells. In the brain, the ultimate consequences of salt poisoning are:
- brain cells dehydration
- secondary haemorrhage in fine blood vessels
- cerebral oedema, due to the free drinking of water by the pet
Treatment will be provided in the vet hospital and will aim to slowly decrease the levels of sodium over a few days. Monitoring of the patient over the course of time is very important. The main complication would be the development of cerebral oedema. In some cases, the kidney and liver could also be affected.
As a matter of prevention, pet owners are advised to prevent their pets from accessing items containing large amounts of salt such as play dough, de-icing salts, paintballs ect…
It is also wiser not to use salt in an attempt to make a dog vomit at home.
Number 10: Xylitol
Xylitol is a replacement for sugar. It is found in items such as toothpastes, chewing-gums, sweets and many other edible goods. It is also present in smaller quantities in fruits and vegetables.
Unlike certain other sugar-free products, xylitol is toxic to dogs. It induces the release of insulin from the pancreas, resulting in hypoglycaemia (low blood sugar levels) and triggers hepatic necrosis.
A dose greater than 0.1g/kg could cause hypoglycaemia. The effect could be seen within 10 – 15 min after ingestion. With a dose greater than 0.5g/kg, hepatic necrosis could be seen up to 72h after consumption. However, literature reports that liver impairment might not necessarily be dose-dependent.
Signs initially observed:
- vomiting, diarrhea
- depression, weakness, ataxia
- coagulation problems
- seizure and potentially death
Following timely emergency treatment:
- If dogs are only affected with hypoglycaemia, their prognosis will be good.
- Dogs who show a progression into liver failure have a much more guarded prognosis. They are at increased risk of dying.
If you need further information or have further questions related to your pet’s health, don’t hesitate to reach out through our video appointment service. All the explanation on how the service operates can be found here
Further source of information and reading
- Macadamia nuts toxicity in dogs: Hansen SR, Buck WB, Meerdink G, Khan SA. Weakness, tremors, and depression associated with macadamia nuts in dogs. Vet Hum Toxicol. 2000 Feb;42(1):18-21
- Xylitol ingestion in dogs: a case report in a Chihuahua male dog