Common Questions with Dr. Matt: Is Your Indoor Environment Making Your Pet Sick?

It's not uncommon to think about how the indoor environment can affect you and the other people that you live with, but have you ever considered how your pets feel inside? Dr. Matt Pratt-Hyatt dives into the consequences of a contaminated indoor environment for your favorite furry friends.

Hello again.  In our next item of common questions, we are tackling “Is your indoor environment making your pet sick?”  Most of us love our pets and want to do whatever it takes to make their lives enjoyable.  We provide them toys and give them the best food to keep them healthy, and if they get sick, we take them to the vet in order to help them feel better.  In today’s article, I will delve into the how our homes can make our pets sick.  When we are talking about the indoor environment and drivers of illness there are two main toxin sources we need to consider, which are mold toxins (mycotoxins) and volatile chemicals(VOCs).  

Toxins are defined as a poisonous substance that is specific of the metabolic activities of a living organism.  It is a common saying in toxicology that “the dose makes the poison” meaning that anything is toxic if you are given enough of it.  However, another part that is true is that how well you detoxify plays a big role in the equation.  As seen in this figure (Figure 1) from Michael Court you can see that for different molecules humans, cats, and dogs detoxify at vastly different rates. Since mycotoxins and VOCs are detoxified mainly through conjugation, this can sometimes be problematic.

Mold and their toxins (Mycotoxins) are present in many different environments.  These toxins are toxic secondary metabolites that are produced by fungi in the Aspergillus, Penicillium, Fusarium, and Stachybotrys genera.  These toxins have a wide range of harmful effects including immunotoxic, nephrotoxic, hepatotoxic, and carcinogenic.  Because of these deleterious aspects of mycotoxins millions of dollars are spent yearly on monitoring food supplies.  Strict limits have been imposed on the amounts of different mycotoxins that can be present in foods have across both the European Union and the United States.  However, even with these safeguards acute poisoning and deaths of dogs fed with food containing maize infested with toxin-producing fungi were reported in 1951, 1998, 2005, and 2020in the United States.  Because of monitoring these incidences are rare.  Still, one source of mycotoxin exposure that is starting to be identified in the scientific community is the exposure of fungi and mycotoxins in water damaged buildings (WDBs).  One of the earliest studies was from Tuomi et al in 2000.  This study showed high levels of mycotoxins in WDBs6. This study has been backed up by multiple other studies including one from Andersen et al in 2011.  Even though there have been multiple studies showing mycotoxins in homes and in people, there have been little to link the two together and nothing to link home mycotoxins to pet exposure.  In order to improve the field, I ran a study to help produce normal ranges and diagnostic ranges for humans exposed to mold and mycotoxin.  This was published in the Townsend letter in 2019.  Recently, Stephanie Medcroft, DVM, and I performed a pilot study utilizing 8 dogs who were exposure to mold (proved by ERMI test) to obtain a range of values. As can be seen in Figure 2, we have observed increased mycotoxin values in dogs that were exposed to mold.  These dogs seemed to suffer from many of same symptoms that we see in humans such as lack of energy, tremors, hormone issues, and tumors.

The next group of toxins to discuss are VOCs. For more information I suggest reading my earlier blog (LINK).  As with humans, pets are being exposed to more harmful chemicals with each passing year. Pets might be more exposed because of their low proximity to the ground.  Safety and toxicity are not widely performed before chemicals go on the market.  This leads to an environment where chemicals need to cause damage to a significant portion of the population before they are recalled or banned from public consumption.  This can be seen in the BPA, which after release was shown to possess estrogenic effects and DNA methylation properties.  Another case study was described in Lehner et al which showed how flame-retardant chemicals could have led to the deaths of several dogs.  In this report, the authors conclude that the ingestion of car seat cushions containing the chlorinated flame retardants TCEP and TCPP induced epileptiform seizures by inhibiting GABA.  

The best we can do to help our pet family as well as our human families is to make sure our homes are as safe as possible. We can help you in this endeavor by providing comprehensive mold, mycotoxin, and VOC inspections of your living spaces.    


1. Court, M.H. Feline drug metabolism and disposition: pharmacokinetic evidence for species differences and molecular mechanisms. Vet Clin North Am Small AnimPract 43, 1039-54 (2013).

2. Jedidi,I. et al. Mycoflora isolation and molecular characterization of Aspergillus and Fusarium species in Tunisiancereals. Saudi J Biol Sci 25, 868-874 (2018).

3. Ferruz,E. et al. Inhibition of Fusarium Growth and Mycotoxin Production in Culture Medium and in Maize Kernels by Natural Phenolic Acids. J Food Prot 79, 1753-1758 (2016).

4. Bailey,W.S. & Groth, A.H., Jr. The relationship of hepatitis X of dogs and moldy corn poisoning of swine. J Am Vet Med Assoc 134, 514-6 (1959).

5. Stenske,K.A., Smith, J.R., Newman, S.J., Newman, L.B. & Kirk, C.A. Aflatoxicosis in dogs and dealing with suspected contaminated commercial foods. J Am Vet Med Assoc 228, 1686-91 (2006).

6. Tuomi,T. et al. Mycotoxins in crude building materials from water-damaged buildings. Appl Environ Microbiol 66,1899-904 (2000).

7. Andersen,B., Frisvad, J.C., Sondergaard, I., Rasmussen, I.S. & Larsen, L.S.Associations between fungal species and water-damaged building materials. Appl Environ Microbiol 77, 4180-8 (2011).

8. Shaw,W. & Pratt-Hyatt, M. Biochemical Markers in the Urine Associated with Gastrointestinal Mold-Overgrowth Are Linked with Elevated Urinary Mycotoxins in Patients with Suspected Mold Illness. Townsend Letter (2019).

9. Qin,T. et al. Epigenetic Alteration Shaped by the Environmental Chemical Bisphenol A. Front Genet 11, 618966(2020).

10. Lehner, A.F., Samsing, F. &Rumbeiha, W.K. Organophosphate ester flame retardant-induced acute intoxications in dogs. J Med Toxicol 6, 448-58 (2010).

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