FrançaisCan cats eat onions or garlic?
No. Onions, garlic, chives and leeks all belong to the Allium family, and cats are the most sensitive species to them, followed by dogs [1]. Garlic is 3 to 5 times more toxic than onion [1]. Cooking, drying and processing do not remove the toxic effect [12]. If your cat ate any of them, call your vet or a pet poison line now, even if it seems fine: signs of anemia often take several days to show [1].
Do not give anything at home. Tell the vet what was eaten, how much and when, including sauces, soups and seasoned meat. The same plants harm dogs, explained in onion and garlic toxicity in dogs; this page covers what is different in cats. Other dangers in the kitchen are listed in toxic foods for dogs and cats.
Why cat red blood cells are so fragile
Onions and garlic release sulfur compounds when they are chopped, cooked or chewed, and gut bacteria release more [1]. These oxidants attack hemoglobin, the protein that carries oxygen in red cells. When the sulfhydryl groups on hemoglobin are oxidized, the protein loses its shape, precipitates and forms small clumps called Heinz bodies [6].
Cat hemoglobin is especially easy to oxidize, more than that of other species [4, 7]. For this reason Heinz bodies are a very sensitive sign of oxidative stress in cats [4]. A cat’s spleen is also inefficient at removing red cells that contain Heinz bodies, so these cells stay in the blood longer [5].
This explains a feature of cat blood work: small, harmless Heinz bodies can be found in many healthy cats, while they are abnormal in other species [6]. In one study, healthy cats had on average 0.6% of red cells with Heinz bodies [4]. A few small ones mean little on their own; large or numerous Heinz bodies, especially with anemia, point to real oxidative damage [7].
Where onion and garlic hide: powders, soups and baby food
In cats and dogs, poisoning is most often linked to concentrated forms: dried flakes, powders and dry onion soup mixes [1]. Cooked dishes count too. Poisoning has been reported in a cat after butter-cooked onions [12], and two cats developed Heinz body anemia after eating caramelized onions [8]. Table scraps and leftovers can be a source [13], and so can meat seasoned with garlic or onion powder, since powders are a concentrated form [1].
Baby food is a classic trap, because some baby foods contain onion powder. In a study at the University of California, Davis, healthy cats fed baby food with onion powder for 5 weeks had Heinz bodies in 33 to 53% of their red cells at the peak, against cats fed the same food without onion powder [2]. In a second part of the study, the diet with the most onion powder lowered the hematocrit [2]. The authors advise against feeding cats baby food or other foods with similar amounts of onion powder [2].
Amounts reported in references: poisoning has been reported in cats after less than a teaspoon of cooked onion, or 5 g of raw onion per kg of body weight [1, 12]. These figures are not a safe limit, and daily feeding of small amounts may add up [13]. Call your vet or a pet poison line whatever the amount.
Signs and timing: why the anemia comes days later
The damage starts quickly, but the cat often looks normal at first. Signs are generally not noticed until many red cells have been destroyed, usually a few days after eating [1].
| When | What happens | What you may see |
|---|---|---|
| First 24 hours | Heinz bodies and methemoglobin start to form [1] | Sometimes vomiting, diarrhea, belly pain, poor appetite or dullness [12] |
| Around 3 days | Oxidative damage peaks [1] | Often nothing obvious yet [1] |
| 3 to 5 days | Red cells break down (hemolysis) [1] | Weakness, tiredness, not eating, fast breathing and heart rate, pale or yellow gums, red-brown urine, collapse [1, 12] |
Cases in cats vary. Of 4 cats reported to a UK poison service over 15 years, one had digestive signs, tiredness and drank more, one had anemia and jaundice, one stayed well without treatment, and one died from bleeding into the chest and belly [12].
What the blood count, smear and urine show
The diagnosis rests on the history of eating Allium, the signs, and a Heinz body anemia on the blood work [1]. The vet usually repeats the tests over several days, because the anemia develops after the first visit [1]. The general cat panel is explained in cat blood work explained.
- Abbreviation HCT or Hct: the share of the blood made of red cells. PCV (packed cell volume) is a close equivalent.
- Result 21% in this illustrative line: a clear anemia. A smear comment such as “numerous Heinz bodies” points to oxidative damage [6, 7].
- Unit %: the percentage of blood volume taken up by red cells. Some reports give it as a fraction (0.21 L/L).
- Laboratory interval The example uses the cat interval of the Merck Veterinary Manual; the dog interval is higher (35–57%) [11]. Each laboratory sets its own.
- Flag L: below the interval. The vet reads it with the reticulocytes and the smear, and repeats it over the next days [1, 10].
| Test | What can be found | Why it matters |
|---|---|---|
| Hematocrit (HCT or PCV) | Falls as red cells are destroyed [1] | Shows how severe the anemia is; a severe anemia can need a blood transfusion [1]. See anemia in cats |
| Blood smear with new methylene blue | Heinz bodies, sometimes eccentrocytes [6] | Small Heinz bodies are hard to see with routine stains and show clearly with new methylene blue [6]. Large or numerous Heinz bodies point to oxidative damage [7] |
| Reticulocytes (young red cells) | Rise when the bone marrow responds [10] | The marrow needs 3 to 5 days to respond, so an anemia can look non-regenerative at first [10]. In cats, the vet counts aggregate reticulocytes [10] |
| Methemoglobin | Can be raised; the plasma can look brown [6] | It may already be back to normal when the anemia appears [1]. In the baby food study it stayed at or below 1.2% [2] |
| Hemoglobin and MCHC | Can read falsely high [9] | Many large Heinz bodies disturb the machine reading [9]; one cat that ate caramelized onions had a very high MCHC [8] |
| White blood cell count | Can read falsely high on some analyzers [8] | In two cats after caramelized onions, the machine count was very high but the manual count was normal [8] |
| Bilirubin | Can rise | Comes from the breakdown of hemoglobin; it supports a hemolytic anemia [16] |
| Urine and kidney values | Red-brown urine (hemoglobinuria) [1, 6] | Free hemoglobin can damage the kidneys [1] |
These machine errors are why the vet or the laboratory looks at the blood smear and does not rely on the analyzer alone [8]. Red cell destruction in general is explained in hemolytic anemia in cats.
Other reasons a cat has Heinz bodies
Onion and garlic are not the only cause. In a study of 120 cats with many Heinz bodies, three diseases stood out: diabetes, hyperthyroidism and lymphoma, which together explained nearly 40% of cases, against less than 12% of control cats [3]. These cats had a lower PCV on average (29.8% against 35.3%) [3]. In diabetic cats, ketoacidosis is the strongest link: 28.3% of red cells carried Heinz bodies in ketoacidotic cats, against 6.5% in other diabetic cats and 0.6% in healthy cats [4].
Medicines and food additives can do it too. Acetaminophen (Tylenol) is a classic cause of oxidative damage in cats [7]. Propylene glycol, an ingredient of some soft-moist foods at the time of the study, raised Heinz bodies in cats in a dose-related way [15].
These causes can add up: the baby food study authors warn that cats with a disease that causes oxidative stress may suffer more damage when they eat onion powder [2]. This is why the vet reads the Heinz bodies together with the history and the cat’s other illnesses.
Care and outlook
There is no specific antidote [12]. Care depends on how recent the meal was and how severe the anemia is: if the cat ate the plant recently, the vet may try to remove it from the gut; a cat with severe anemia may need oxygen or a blood transfusion; and fluids help protect the kidneys [1].
Do not try supplements at home. In an experimental study, antioxidants (N-acetylcysteine, vitamin E or vitamin C) given to cats did not significantly reduce the Heinz bodies or the anemia caused by onion powder [14]. Published data on outcomes in cats are limited, and the case series above includes a cat that died [12], so follow-up blood counts matter.
Related articles
Another plant that is especially dangerous for cats: lilies.
En français : oignon, ail et chat.
Questions to ask your veterinarian
- Is my cat anemic, and are aggregate reticulocytes rising?
- How many Heinz bodies were seen on the smear, and are they more than a healthy cat would have?
- When should we repeat the blood count?
- Are bilirubin, the urine and the kidney values normal?
- Could another illness, such as diabetes or hyperthyroidism, add to the Heinz bodies?
Get your cat’s blood count explained.
AI DiagAnimals reads the hematocrit, reticulocytes, smear comments, bilirubin and urine results with your laboratory’s cat intervals, and prepares the questions for your vet. The service opens soon: leave your email to be told first.
Frequently asked questions
Will a little bit of garlic hurt a cat?
It can. Cats are the most sensitive species to Allium plants, and garlic is 3 to 5 times more toxic than onion [1]. Poisoning has been reported after less than a teaspoon of cooked onion [1], and small amounts eaten every day may add up [13]. Call your vet or a pet poison line whatever the amount.
Can cats eat meat seasoned with garlic?
No. Cooking does not remove the toxic effect [12], and powders and other concentrated forms are the most common cause of poisoning [1]. Table scraps and seasoned leftovers can all be a source [13]. Give your cat only food without onion or garlic.
My cat accidentally ate chicken with garlic. What should I do?
Call your vet or a pet poison line now, even if your cat seems fine, and say how much was eaten and when. Do not give anything at home. Signs of anemia usually appear 3 to 5 days later [1], so the vet may check the blood count and a blood smear over the following days.
What food is most toxic to cats?
Cats are the species most sensitive to onion and garlic [1], so these are among the most important foods to keep away. Chocolate, grapes, xylitol and other dangers are compared in toxic foods for dogs and cats; for plants, see lily poisoning in cats.
Are chives and leeks toxic to cats?
Yes. Chives and leeks belong to the same Allium family as onion and garlic and can cause the same red cell damage, although onion and garlic are the most common causes of poisoning [1].
Sources
- Hayes C. Garlic and Onion (Allium spp) Toxicosis in Animals. Merck Veterinary Manual, reviewed 2024. merckvetmanual.com/toxicology/food-hazards/garlic-and-onion-allium-spp-toxicosis-in-animals
- Robertson JE, Christopher MM, Rogers QR. Heinz body formation in cats fed baby food containing onion powder. J Am Vet Med Assoc. 1998;212(8):1260-1266. pubmed.ncbi.nlm.nih.gov/9569166
- Christopher MM. Relation of endogenous Heinz bodies to disease and anemia in cats: 120 cases (1978-1987). J Am Vet Med Assoc. 1989;194(8):1089-1095. pubmed.ncbi.nlm.nih.gov/2708116
- Christopher MM, Broussard JD, Peterson ME. Heinz body formation associated with ketoacidosis in diabetic cats. J Vet Intern Med. 1995;9(1):24-31. doi.org/10.1111/j.1939-1676.1995.tb03268.x
- Christopher MM, White JG, Eaton JW. Erythrocyte pathology and mechanisms of Heinz body-mediated hemolysis in cats. Vet Pathol. 1990;27(5):299-310. doi.org/10.1177/030098589002700501
- eClinPath (Cornell University). Red blood cell inclusions: Heinz bodies. eclinpath.com/hematology/morphologic-features/red-blood-cells/rbc-inclusions
- eClinPath (Cornell University). Causes of anemia: oxidant injury. eclinpath.com/hematology/anemia/causes-of-anemia
- Johnson CE, Seelig DM, Moore FM, Ruska TJ, Heinrich DA. Spurious, marked leukocytosis in 2 cats with Heinz body hemolytic anemia. Vet Clin Pathol. 2020;49(2):232-239. doi.org/10.1111/vcp.12860
- eClinPath (Cornell University). Hemoglobin. eclinpath.com/hematology/tests/hemoglobin
- eClinPath (Cornell University). Assessment of regeneration. eclinpath.com/hematology/anemia/assessment-regeneration
- Merck Veterinary Manual. Hematology (complete blood count) reference ranges. merckvetmanual.com/reference-values-and-conversion-tables/reference-guides/hematology-reference-ranges
- Cortinovis C, Caloni F. Household Food Items Toxic to Dogs and Cats. Front Vet Sci. 2016;3:26. doi.org/10.3389/fvets.2016.00026
- Kovalkovičová N et al. Some food toxic for pets. Interdiscip Toxicol. 2009;2(3):169-176. doi.org/10.2478/v10102-009-0012-4
- Hill AS, O’Neill S, Rogers QR, Christopher MM. Antioxidant prevention of Heinz body formation and oxidative injury in cats. Am J Vet Res. 2001;62(3):370-374. doi.org/10.2460/ajvr.2001.62.370
- Christopher MM, Perman V, Eaton JW. Contribution of propylene glycol-induced Heinz body formation to anemia in cats. J Am Vet Med Assoc. 1989;194(8):1045-1056. pubmed.ncbi.nlm.nih.gov/2708106
- eClinPath (Cornell University). Bilirubin. eclinpath.com/chemistry/liver/cholestasis/bilirubin
Laboratory methods and reference intervals vary. This article explains; it does not diagnose. For a decision about your pet, use the original report and talk to your veterinarian. Our editorial policy.