Hidden Killers in Dog Food

Mold-based toxins could be behind your dog’s strange symptoms.


I own a beautiful German Shepherd named Xeus. He comes from very well-known, healthy, wonderful lines. Xeus is sound, has personality galore and a wonderful temperament – he’s just an all-around great German Shepherd. One Saturday in late June 1999, a really nice, hot summer day, my entire family was hanging out in our back yard, enjoying our pool, as we watched Xeus enjoy his kiddie pool. All of a sudden, Xeus jumped out of his wading pool and made a bee-line for the house. I watched him go in, thinking he was just looking for another toy to bring out, but he didn’t come back out. After a minute or two I went in to see what he was doing, and I found him hiding in a corner of the bathroom, shaking like a leaf. I immediately assumed he had gotten stung by a bee, because chasing and eating bees is one of his favorite hobbies. I checked him over, but found nothing.

I tried to coax Xeus into coming back outside but he would have no part of it, so I figured he just got spooked by something and I would leave him inside until he was ready to come out. He has a dog door so he can come and go freely. However Xeus refused to come out the entire day. I kept going into the house to check on him, and though he wasn’t displaying any symptoms that made me feel it was necessary to rush him off to an emergency vet – this was a Saturday, after all – he was not himself and had me worried.

That night and the next morning Xeus seemed better. He woke up happy, anyway. The first sign that something was still wrong with him, however, was the fact that he refused to go out into the backyard to relieve himself. With some encouragement, he did go out into the front yard with me, but he ran right back into the house as soon as he had gone to the bathroom. I became convinced that whatever was wrong with him had something to do with the backyard – something spooked him when he weren’t looking, I thought. Inside, Xeus seemed better, and his temperature was normal.

As the day progressed and Xeus was still behaving strangely, I called my vet’s office and asked if I could bring Xeus in. My regular veterinarian was on vacation, but his partner examined Xeus, and took a blood and urine sample, but found nothing amiss. After hearing my story, the veterinarian was convinced something had spooked Xeus and he’d probably be fine in a day or two. Feeling somewhat silly, I took my German Shepherd home.

When we got home, I fed Xeus his usual bowl of kibble. It sounds crazy, but about 20 minutes after he ate, he got all weird again, shaking, hiding in a corner, almost like he was in a pre-seizure mode. I immediately brought him back to the vet’s office, but of course the trembling subsided and he just seemed very, very nervous. This time, the vet was more concerned – and I was scared to death! I was certain Xeus was having some kind of pre-seizure activity, and the vet thought the same. He suggested giving Xeus some Phenobarbital, but I have some knowledge about epilepsy and knew that unless we absolutely were sure that Xeus had epilepsy, I did not want to start messing with anti-seizure medications. Instead, we agreed to consult a specialist in neurology the next day.

Bringing in specialists
First thing on Monday morning I contacted a specialist and got an appointment to see a neurologist – three hours from my house! The neurologist did not feel Xeus had any kind of neurological disorder, and he sent me back to the veterinarian’s office with a list of two things to check for: a whipworm test and a bile acid test. Both were done, and both came back negative.

However, Xeus’ symptoms and total change of personality continued. He seemed to be really bothered by light, and would hold his urine all day, not going outside until the sun went down. He spent all day planted in a quiet corner, or with his head under the couch, and he had totally lost all his play drive. There was definitely something wrong, but what?

We made an appointment with another specialist who tested Xeus for all kinds of things, from tick-borne diseases to autoimmune diseases, to having all kinds of radiographs and ultrasounds, to continued blood work, but everything kept coming back normal.

Owner’s observations
In the meantime, I started to notice that Xeus’ worst clinical signs took place 20 to 30 minutes after he ate. I also noticed that he was his best when he had to fast for the tests. When I asked the vets if they thought Xeus’ food could be involved, they all thought that this was highly unlikely, since he had been eating the same brand of food for at least six months before this happened, without any problems. I had been very happy with the food and regarded it highly; in fact, it was a food that made WDJ’s “Top 10” list. Nevertheless, I decided on my own to change his food. It couldn’t hurt! I found a brand of food that had a totally different list of ingredients and began feeding it to Xeus. While I waited to see if there was a difference in his behavior, I got the idea of having his food tested. For what? I didn’t know! It just seemed like a good idea, although I admittedly did not know what kinds of things might be wrong with dog food!

I called my state health department to ask where I could have Xeus’ food tested. About this time, my regular veterinarian returned from vacation and I spoke with him, catching him up on all of the details of Xeus’ case. He suggested that I ask the lab to test the food for mycotoxins, explaining they were toxic substances that could grow in moldy food that can cause problems in some animals.

The State Department of Health referred me to the State Department of Agriculture, and I quickly found an interested person there. They actually sent a representative to my house and gathered up the dry dog food, the canned dog food, and even the biscuits Xeus had been eating. It was all very clinical and I felt confident in their work.

As we waited for the results to come back on the food, the veterinarians kept conducting tests on Xeus, to no avail. I, too, continued to examine my poor dog, and started to notice little strange things. For instance, the whites of his eyes seemed very yellowish to me. Also, I noticed that if I could coax him outside, he would still chase a ball if I threw it into the shade, but if I threw it into a sunny area, he would just stand there. His pattern of urine elimination seemed different than before, too. He would hold his urine all day, and then pee prodigiously at night. What these things meant, I had no idea.

Days crept by. Although Xeus seemed incrementally better, he was still not anything like his old playful, carefree self. My vet had scheduled an MRI and considered a spinal tap, but we kept postponing those tests as Xeus held his ground. He didn’t get any worse, but his improvement – if you could call it that – was so slow that it was almost imperceptible.

Given all the normal test results, one of the specialists we had consulted was beginning to think that Xeus’ problem was behavioral after all. He gave me a referral to a behavioral specialist, who sent me a long form to fill out, detailing all of Xeus’ behavior history. I wasn’t happy about all this, because I knew the change in my dog had happened literally in one day, and that nothing noticeable happened to Xeus that day! It wasn’t as if he had been attacked, or had run away, or had a trauma with fireworks or anything out of the ordinary.

Toxins in the food
Then the breakthrough came. The results of the food tests came back from the State Department of Agriculture. The canned food was fine, the biscuits were fine, but the dry food was found to contain a mold-based toxin called aflatoxin. I called my veterinarian with the news, but he was able to tell me little about mycotoxins – except that this indeed could have caused Xeus’ strange symptoms.

According to the results from the State Department of Agriculture, the level of aflatoxin found in Xeus’ food was 40 parts per billion (40ppb), double the amount generally considered to be tolerated by dogs. Needless to say, I was thrilled to have discovered the first possible explanation for Xeus’ problems, but it took several months’ worth of detective work before I was able to learn much more about this insidious toxin. I found it very, very difficult to find information regarding mold toxins in dog food.

Xeus slowly returned to normal as I spent my entire summer and fall researching the topic. I posted messages on the animal nutrition boards and the German Shepherd boards on America Online, and looked up everything I could about aflatoxins.

I found lots of information about the effects of toxin on livestock – this is apparently a much bigger and well-documented problem in livestock feeds – but the only reports I could find about aflatoxins in dog food were all related to cases where aflatoxin poisoning affected large numbers of dogs at once. There were a lot of reports about a case in 1998 where 25 dogs in the southern US died from aflatoxin poisoning. But I couldn’t find any documentation on sporadic incidents. I tried calling toxicologists at veterinary hospitals but they didn’t even have the correct documentation regarding aflatoxin in dog foods.

Finally, I called as many dog food companies as I could and spoke directly with their nutritionists. I explained what happened, and they were quite interested. Several food makers sent me information on who, what, and where to call for more information.

I was also given a number of Alltech, Inc., a Kentucky company that makes chemicals that helps preserve foods and eliminate toxins in animals feeds and Bingo! I finally got some answers. Alltech actually publishes a highly specialized newsletter for the feed industry called Mycotoxin Monthly, and several of their back issues were published on the Internet, including one that discussed mycotoxins and companion animals (see www.alltech-bio.com, click on “Technical Publications,” and look for the Mycotoxin Monthly).

Toxins you should know
I learned that aflatoxin is just one of more than 200 mold toxins commonly found in animal feeds. It affects different species of animals and animals of varying ages in different ways at different levels; dogs are more affected than cats, for example, and old and young animals are more seriously affected than middle-aged animals. However, one common theme is that aflatoxin affects the liver of all of its victims. Even though my veterinarians had conducted liver tests on Xeus, the specific damage caused by aflatoxin had gone unnoticed; I’m told this is rather common, unless one is looking for this exact effect. The most common signs of aflatoxin poisoning are lethargy, vomiting, heart problems, liver damage, and yellow discoloration of the skin and hair.

While some mold-originated toxins cause feed refusal and severe vomiting (such as one common mycotoxin known appropriately enough as “vomitoxin”), I discovered that many of the mold toxins found in animal food go unnoticed because the dog will continue to eat normally. Often the food will probably not even have a noticeably different odor. Indeed, Xeus had eaten the food with the same appetite he had always had, he never vomited and he never had diarrhea. But I did notice his worst neurological signs were always after he ate.

I also learned that aflatoxins often cause light sensitivity, neurological disorders, and can even kill a dog if the levels are high enough. While some dogs can tolerate a certain amount of the toxin, other dogs are highly sensitive to substance at any level.

Dog food manufacturers are constantly studying aflatoxin and other mold toxins and looking for new ways to try to eliminate this problem in all animal feeds. “Nearly all ingredients used in pet food, particularly corn and soybean meal, can be highly contaminated by aflatoxin, a potent carcinogen and immune system suppressant,” according the Mycotoxin Monthly. (Xeus’ food, incidentally, did not contain corn.) Most feed ingredients are tested individually – the grains, the meats, the fats – and the food is tested again after being mixed. The food manufacturers must concern themselves with testing for the molds at every level of production, how the food is packaged and transported, and even how it is stored in the pet stores. Anytime that moisture and/or heat (the combination of the two is the worst) can affect foods, molds can grow and produce their deadly toxins.

However, other foods that people feed to their dogs can also be infected with mycotoxins. Mycotoxin Monthly quotes Dr. John Richard of Romer Laboratories as saying he has heard of cases of mycotoxicosis in dogs who have eaten moldy walnuts, bread, or cream cheese.

While all breeds of dog are equally affected by mycotoxins, certain factors can influence the susceptibility of individual dogs. According to Mycotoxin Monthly, dogs in poor health are more likely to be affected, as are dogs with marginal nutrient deficiencies. Dogs that are already suffering from drug interactions or heat or environmental stress are more likely to have problems following mycotoxin exposure. And, obviously, dogs who were exposed to higher amounts of mycotoxins, or exposed for a longer period of time, are more likely to develop signs of poisoning.

Little-known problem
One thing that really bothers me is that, despite the ample opportunity for problems of this kind to crop up in pet foods, there was so little information available about the dangers of mold poisoning and prevention for the average dog owner. Never in my life had anyone warned me about the effects of mold toxins in dog foods, whereas the livestock people deal with this all the time and are constantly made aware of this problem. Livestock producers even have kits that they can use to check the feed before they give it to an entire herd of animals.

In my case, our bag of food was new; it had been open for just two weeks. I had bought the bag in early June 1999, and it had a “freshness date” of April 2000. Unlike many people, I always keep my dog food in a cool, dry place, but I didn’t know that preventing mold growth is why all bags recommend that you store the food in this way.

In a sense, we were lucky. As far as we know, Xeus had been exposed to the aflatoxin for just two weeks, and the amount in the food was not fatally high. However, there is a chance his immune system was affected. I do take special precautions now, minimizing his vaccinations, for instance. Instead of using all the regular booster shots, we have titer tests done to try to determine how necessary each vaccine might be.

Also, I now feed Xeus a dog food that comes directly from the plant to my home, to help ensure freshness. I buy smaller bags, and I supplement his kibble with a wet food mix that I cook. I have never used chemicals on our property, and I do not use any chemicals on his body. The only thing I still continue to use is heartworm preventative, since heartworm is deeply entrenched in the part of New York where I live.

If your dog has a major personality change, and the vets can’t find the problem, please consider having your dog’s food checked by either a veterinary college that has a toxicology lab, or your State Department of Agriculture. You will need a referral from your veterinarian, but ruling out the food is a must when trying to get to the bottom of a hard-to-diagnose illness.

Also With This Article
Click here to view “Toxins That Can Arise in Dry Dog Food”
Click here to view “Pet Food Disaster”

Author’s note: I would like to thank all the vets and staff at Aqueduct Animal Hospital for their care, concern, and help. Thanks, too, to my friends on the German Shepherd message boards on America Online for their invaluable help and encouragement as I went through this crisis with Xeus.

-By Cindy Cramer