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What is Fish Allergy?

Fish is a food that is frequently utilized as a healthy source of protein for felines, although in some cases it can cause dangerous levels of contaminants like mercury to build up in your cat’s system. Some cats may also develop an allergy to fish or shellfish, causing unsightly and uncomfortable skin conditions. In order to reliably determine the proper allergen that is affecting your pet, an elimination diet may be required. This can be time-consuming but is frequently necessary in order to deduce which ingredient is causing the reaction.

Fish and seafood are common ingredients in food and treats that are formulated with cats in mind. For cats who develop an allergy to this food, it can cause an uncomfortable skin condition.

Symptoms of Fish Allergy in Cats

A food intolerance often accompanies and sometimes precedes a full-blown allergy to the food. The intolerance generally presents as gastrointestinal distress and gurgling sounds from the digestive system. Symptoms of food allergies generally start on the head and neck on felines and can include signs such as:

  • Acute moist dermatitis
  • Crusty papules
  • Hair loss
  • Itchy skin
  • Lesions on skin

Types

Food Allergy

An allergy is a response by the body’s immune system to defend itself against something that it perceives as a threat. An allergic reaction from food doesn’t happen the first time an individual is exposed to the ingredient but rather after repeated ingestions. Any food is capable of finding an allergic reaction, but certain ingredients, such as beef, dairy, fish, and eggs tend to cause allergies in felines more often than others.

Food Intolerance

While a food allergy is the immune system responding to a perceived threat, an intolerance to a food has no immune involvement. An intolerance to a food type is more likely to cause a gastrointestinal response than allergies do. Further symptoms, such as gurgling sounds from the digestive system or a change in the consistency or color of the stools are also customary with a food intolerance.

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Causes of Fish Allergy in Cats

Allergies, including food allergies, are due to an abnormally intense defensive response to a protein that the immune system views as an invasive substance. It is estimated that around 60-70% of our immune system cells actually reside in the digestive system, and the same applies to our felines. The process of digestion is designed to break down our foods into amino acids, the smallest parts they can be broken down into. These amino acids are then absorbed by a type of immune cell called an enterocyte, specialized white blood cells, and then transported into the bloodstream. When proteins are only partially broken down, the enterocytes see the fragments of food as intruders rather than nutrients, and they attack. Over time the reaction of these cells becomes more and more aggressive, and the symptoms intensify. 

Although allergies can develop to any food, some foods are more likely to generate a reaction than others. Frequent offenders for felines can include:

  • Beef
  • Corn
  • Dairy products
  • Eggs
  • Fish
  • Lamb 
  • Seafood
  • Soy
  • Wheat gluten
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Diagnosis of Fish Allergy in Cats

The symptoms related to allergies in felines closely mimic other disorders such as mites or bacterial infections, and will typically prompt the veterinarian to collect skin scrapings as samples to be examined under a microscope, a process known as cutaneous cytology. When the skin cells don’t reveal any other micro-organisms or problems, then an allergy may be suspected. Although both serum and intradermal testing are available for cats with allergies, they are not as reliable for detecting allergies that are related to food. The veterinary gold standard for diagnosis of food allergies is the elimination diet. This diet is implemented by changing the cat’s daily diet to either a limited ingredient or hypoallergenic commercial cat food, or in some cases, to a diet of unseasoned human food. In choosing the proper diet for your allergic cat, novel ingredients are generally required.

Novel ingredients can include any proteins and carbohydrates that are not currently used in the cat’s current diet and preferably ones that have never been introduced. It is of particular importance to check for additional ingredients in commercial diets if you suspect a fish or seafood allergy as fish meal and fish oil are often added to food to increase the amount of omega-3 vitamins. Once signs of the allergy have been eliminated, new ingredients can be reintroduced into the diet one at a time, to uncover which one is triggering the reaction.

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Treatment of Fish Allergy in Cats

Revealing the specific allergen that is bothering your pet may require several weeks on the elimination diet, and during this time your cat may continue to experience residual symptoms of the allergy. Corticosteroids are frequently recommended as a way to reduce swelling and antihistamines are often effective at calming itching sensations. Use of either treatment may mask the symptoms of the allergy, however, and this can make it more challenging to single out which ingredient in your cat’s diet is triggering the reactions. Because of this, many veterinary professionals prefer to administer the elimination diet before adding these types of medications to the regimen.

Secondary skin infections are a common occurrence for cats that are experiencing the symptoms of allergies, and antibiotics are usually prescribed to combat and sometimes prevent this particular complication. Once the particular allergen has been defined, this ingredient should be completely eliminated from the cat’s diet and other supplements, including probiotics and non-fish based Omega-3 oils, are frequently recommended for all sorts of allergies as a support to the immune system. This will assist your companion’s body in handling any accidental exposure to allergens and in preventing the cultivation of new allergies.

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Recovery of Fish Allergy in Cats

Food allergies are not curable, but symptoms tend to cease fairly rapidly when the allergen is eliminated from the animal’s diet. Any repeat exposure to the allergen can trigger a relapse, so caution should be taken in which treats and flavorings you offer your cat, particularly as fish oil and fish meal are frequently added to products that are not labeled as fish based. Unfortunately, if your feline has experienced an allergic response to one ingredient, then they are more likely to develop allergies to other ingredients as well. The approach to combat this situation varies within the veterinary profession, with some doctors advocating that your cat remain on a single source of food, while others maintain that a steady rotation of three of four foods with proteins is optimal.

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Fish Allergy Questions and Advice from Veterinary Professionals

Need pet health advice? Ask a vet

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Shorthair cat

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5 months

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Unknown severity

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0 found helpful

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Unknown severity

Has Symptoms

No Appetite, Sick, Prolapse Of Rectum

My cat ate half a tin of tuna in brine i took her to the vets and she is just getting worse. How can i help her at home if she isnt eating

Sept. 29, 2020

Owner

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Dr. Michele K. DVM

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0 Recommendations

Thank you for your question, I'm sorry your kitten is not feeling well. At this point, I'm not sure there's a lot you can do at home, and if the kitten is not improving, having a recheck with your veterinarian would be the best thing to do. They know more about your kitten's situation, and will be able to let you know what the next step might be. I hope that everything goes well and he is okay soon.

yesterday

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Chloe

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Mixed breed

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10 Years

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Serious severity

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2 found helpful

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Serious severity

Has Symptoms

Losing Fur, Skin Is Loose

Chloe’s fur is falling out and irritated. She is licking it. Skin is red and inflamed. She is eating some but is less social and hiding. Her blood work is normal. Has seen several vets. Has an appointment with animal dermatologist on Friday. Was given a pain relief shot today. No one knows what it is. She eats quality food and has glass bowls. Indoor cat.

Aug. 14, 2018

Chloe's Owner

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2 Recommendations

It can be difficult to narrow in on a specific cause for fur loss especially in an older dog; hormonal conditions, allergies, nutritional deficiencies, psychological disorders (excessive grooming) among other causes may lead to fur loss. You should consult with the Dermatologist and see what they find. Regards Dr Callum Turner DVM

Aug. 14, 2018

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Freya

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Burmese

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8 Months

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Serious severity

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2 found helpful

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Serious severity

Has Symptoms

Diarrhea

What can i give my cat if she accidently ate fish she is alergic to. Ive taken her twice to a vet witch has cost me a lot of money and i did not get any answers. After she ate snoek again for the 3rd time i realised she is alergic to snoek. She dont get sick after eating tuna.

Aug. 10, 2018

Freya's Owner

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2 Recommendations

If you’ve identified that Freya is allergic to pike (snoek), you shouldn’t purchase it and stick with fish you know is safe; it is always best to limit the exposure to allergens. Regards Dr Callum Turner DVM

Aug. 10, 2018

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Max

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Feline

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3 Years

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Moderate severity

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5 found helpful

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Moderate severity

Has Symptoms

Excessive Scratching
Excessive Shedding
Excessive Shedding,Shedding,Enough.

My cat was scratching has had a steroid shot about every 3-4 months.So I said let’s just do the allergy test.Drew his labs came back allergic to mixed fish and chicken.Whats left to feed him?Tried rabbit and he’s not too fond.Thanks.

Aug. 4, 2018

Max's Owner

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5 Recommendations

Fish and chicken diets are the cornerstone of many different feline diets; however there are other protein sources available including rabbit, duck, venison, kangaroo or using a hydrolysed protein diet. You should discuss the offerings your Veterinarian has at the clinic and check your local pet shop. Regards Dr Callum Turner DVM

Aug. 5, 2018

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Gracie

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Maine Coon

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6 Years

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Moderate severity

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2 found helpful

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Moderate severity

Has Symptoms

Pulling Fur Out Of Tail

I have a six-year-old (indoors only) female Maine Coon cat who, in the last year or so, has started pulling her fur out of her tail. Her once beautiful fluffy tail is now so skinny! She is not biting her skin, which looks fine. I took her to the vet a few months ago and the vet gave her a steroid shot which seemed to help a bit, but the vet isn't sure what's going on. She's still pulling fur out and she wants me to scratch her face a lot. She has a sibling cat who is fine. There are no fleas. I don't use scented cat litter. There have been no changes in the house that might account for psychological problems. I'm thinking it might be a food allergy, so thought I'd try eliminating any cat food that has fish in it (which she has been eating all her life). She gets wet and dry food. I've made sure to read labels so there's no fish listed, but I'm just guessing that fish cat food might be the problem. She's eaten both fish/seafood cat food, as well as chicken, etc., all her life with no problems. Any advice? Thank you.

July 29, 2018

Gracie's Owner


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Dr. Michele K. DVM

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2 Recommendations

Environmental allergies are much more common that food allergies in animals, and it can be difficult to get to the bottom of itchy skin. She may benefit from medication for allergies, such as Apoquel or CADI injections, or she may need a hypoallergenic food if she has food allergies, as it can be very hard to identify the cause of the problem. Since allergies and itchy skin can be so difficult to resolve, it might be best to work closely with your veterinarian to identify a therapy that works.

July 29, 2018

Thank you! :)

July 30, 2018

Gracie's Owner

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2P

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tabby

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11 Years

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Fair severity

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Fair severity

Has Symptoms

Scratching

Oh dear where do we start, first cat Pooha ferrule kitten bit my hand, however loo tray trained in 3 days had him done and off we went on the fish allergy trail. In those days difficult to get fish free foods. He did eat our food so had beef and pork and lamb etc that reduced the problem dramatically. Next was a stray including collar who adopted us. Brought him to France with us and after he started the biggest cat group in France had him done. Sitting in the garden watching him as the females turned up for a bit of rumpy dumpy was funny at first, he got hold of the females necks and off he would go. Next came a ferrule cat now call 2P. She wanted food and came in for it so I ensnared her and hoped she would calm down, she did not. After a week of yowling and hissing we let her out. She ran up our apple tree, sat there for a week and then one morning opened the back door, she roared down the tree, though the door and begged for food. She used to go in and out but one day came back without the skin on her tail, so that had to come off. She lives here still and now does not bother to go out, but has serious fish problem. Next and also still here Fluffy, had a prolapsed rectum, had her "done" and the prolapse fixed. Daddies little girl that loves her tummy rubbed and her paws played with, Has to be fed away from others, she is a princess dont you know. And then there is Tom, poor old Tom was poisoned when a kitten, turned up here under the bonnet of my daughters car. He does have problems with his life however he copes and he is ruddy romantic. He sits on my lap, falls against me and looks up and rolls his big eyes. I cannot normally sit down without him on my lap. Oh well that is our catistory, if we know nought about cats we damn well should do. It summed it all up, we had to take 2P to the vet, the flea injection caused a problem and they gave her a transfusion. She was sick in the vets for 3 days and would not eat and hissed at the staff and threatened them. I came to see her, they opened the door to the cage, the cat looked at me and lunged, paws around my neck and me supporting her bum (no tail remember) She soon got well but now there is a large sickle hanging over the 1 year flea injection. There thats our 3 wild cats. Ps 2P has been on Hills and away from Canin for about 2-3 days and she is now sleeping peacefully without the regular scratching. Her skin of course is still covered in abrasions from scratching. Hopefully that is it again.

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Helló

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Persian

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3 Years

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Moderate severity

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0 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

Has Symptoms

Itchiness
Over Grooming
Skin Biting

I have been giving Tin fish for the past 2 years. he gradually started developing symptoms by grooming and pulling the fur too much on his tummy front left, complete baldness on back legs, and biting one paw for now. The tin fish which I was giving him is human food, not pet food. I started seeing the symptoms in Jan 2020. I completely stopped giving Tin fish and now I give only sardines and Sprats.he doesn't like sprats much. I have conned him so that he will not injure his skin and pull all of his furs. He doesn't have mites or fleas. I have been applying lime sulfur twice a week. He is not on any medication. Do you think sprats could contribute to his allergic reaction?

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Fatboy

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Dont know

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13 Years

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Moderate severity

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0 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

Has Symptoms

Weight Loss
Peeing Outside Litter Box
Hair Loss By Tail,
Begging For Food

My husbands 13 year old cat fatboy is a love bug. In the past 4 years i have been with him fatboy has lost weight and started peeing outside the litter box. Whats weird is he will poop inside the litter box. My husband said that when he was a kitten he had to have his stomach scrapped because his stomach went rock solid from eating fish. We did have a flea infestation but we got that cleared up. His sister died around 3 months ago. So if i cant give him omega 3 for his skin what do i do? Plus why is only peeing outside the litter box and not pooping. Hes always begging for food from us but we feed him 1/4 cup every day at night. Are we feeding him too little food? We also give him wet food every other weekend. Ones that dont contain fish. Or maybe hes just getting old? Please help.

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Nova

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Lynx Point Siamese

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3 Years

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Serious severity

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0 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Serious severity

Has Symptoms

Diarrhea
Vomiting
No Appetite
Nausea
Colitis

My 3 year old Lynx point Siamese mix gets bad stomach issues after eating sometimes. It started suddenly. He will vomit multiple times- undigested food and bile, have colitis and go to the litter box frequently, followed by not eating or drinking from 12-36 hours. If he does try to eat a little bit hole will immediately throw it up and the symptoms continue. I've taken him to the vet twice, once they had to give him subdermal fluids because he could not eat. I'm highly suspicious of fish and fish oil in the food as he was fine for over 3 weeks on a canned chicken food diet, then I overlooked an ingredient in a chicken canned food which had fish oil, he was immediatly sick again in the evening for 1.5 days.

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Teddy

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Ocicat

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5 Years

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Serious severity

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0 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Serious severity

Has Symptoms

Swelling Of The Mouth And Face,
Swelling Of The Mouth And Face, Itc

Ted has a pronounced allergy to fish. Just eating products with fish oil in cause him to have very itchy skin and itchy anus - he scoots his bottom along the floor. If he eats fish itself, his mouth and face swell, his breathing rate increases, his bowel seems to prolapse (I’m guessing his whole digestive system swells too), and he’s very itchy. The only complete vet diet that controls this is Royal Canin Hypoallergenic. He enjoys the biscuits, so that’s reassuring.

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