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  • Writer's pictureutahspg

BACTERIA In the Bathing Room

Bacterial growth in expired and diluted products is a HUGE risk? It's crucial to check shampoo and conditioner shelf life dates, stagnant shampoo, or conditioner may cause irritation, and itchiness (due to bacterial growth, chemical changes and allergens).

Grooming products have preservatives to prevent bacterial growth, preservatives have time limitations. Shampoo left on the shelf past its expiration date or exposed to high temperatures is at risk of going stagnant prior to expiration.

Expired shampoo may cause skin infections depending on the bacteria's virulence factors. The infection may lead to extreme irritation, patchy hair loss or even severe wounds from excessive scratching.

Medicated shampoos expire more quickly; Hypo-allergenic, Tar & Sulfer, Flea & Tick, etc.

Diluted Products expose a much greater risk!

Bacterial growth in diluted products can cause severe ILLNESS or even DEATH!

Once diluted preservatives are no longer effective, bacteria is present in the water. Which means bacteria is being added to the mixture when diluting the shampoo and conditioner (warm water also increases bacteria growth). Not an issue if the diluted product is used within a few hours (it's a small number of bacteria). When it sits for a day or two, the bacteria multiplies in the bottle. When water is left in the mixing bottle bacteria will grow and each time we mix more shampoo or conditioner bacteria will be transferred, starting the cycle over. Make sure mixing bottles are dry and stored away from condensation. NOT in or near the bathtub.

Diluted products should NEVER be saved! This is something we've experienced in one of our shops, clean well ran shops, or even veterinary clinics have had a few or sudden outbreaks of unexplained skin issues in dogs.

We did not use products past their shelf life and went to a lot of effort to find out what caused the skin issues in random dogs. The problem was bacterial growth in the shampoo containers (plastic bottles), diluted shampoo left overnight, and diluted conditioners in the bathing area.

Once this new routine is established, the risk can be eliminated.

  • Check expiration dates and dispose of expired products.

  • Dispose of any diluted shampoo, conditioner or coat and skin products that have been diluted.

  • Make sure mixing bottles are clean and dry at the end of the day. NEVER use diluted products left over night or over a weekend.

  • Keep mixing bottles in a dry area for storage, not in or near moist, wet areas, or in the bathing tub.


This isn't isolated, many grooming shops have experienced the same problem. Pet groomers have been using diluted products that have been stored for days and have never had a problem that they may be aware of . . . they occasionally have dogs with an “allergic” reaction and assume the owner didn't tell them about their dogs sensitive skin, or that the shampoo is the problem. IT'S LIKELY A REACTION TO A BACTERIAL INFECTION!

Bacteria is everywhere: soil, water, skin, it likes dark, moist places. Can cause anything from mild skin infections to severe internal infections that can kill people or pets.

Most of the time bacteria isn't an issues, once there's too much, it can overwhelm the immune system of people and pets with an even greater risk to those with a compromised or weak immune system. Then it can cause severe problems that make it difficult to fight the exposure of a bacterial infection.

There is a huge variety of situations that may contribute to the chance and level of potential effects of bacterial infections.

Many people and pets have been on prolonged steroid treatment for a huge variety of conditions. Steroid treatments cause skin to be thin, fragile, and compromises the immune system leaving the user defenseless against bacterial infections.

Anything that irritates or causes inflammation to the skin opens it for bacteria to get further down into the skin and multiply. Brushing out or clipping a matted dog, plucking ears, scrubbing an oily or dirty animal. nicks, or scrapes, a geriatric pet, just to name a few possibilities. When bathing, warm water opens up the pores and helps the bacteria get even deeper into the skin.

If the dog is then bathed in a shampoo or conditioner that contains an excess of bacteria, it may be be more than their immune system can handle, bacteria will make its way down into the skin, multiply and overwhelm the immune system as it shuts it down. Infection with Pseudomonas aeruginosa in dogs with a compromised immune system can lead to sepsis and death. If an individual has damaged skin on their hands and a compromised immune system, they are also high risk to develop a severe skin infection that can lead to sepsis and death.

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Yikes, I had no idea!


It's pretty scary stuff. Luckily, we can make sure it doesn't happen by following a consistent routine.

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