Can Cats Drink Spoiled Milk?

If you know your cat well, you might notice its behavior changes after it drinks milk. This is because cats are lactose intolerant. Especially adult cats. 

The nutrients found in the milk do not have any benefits to the body of your cat. As a matter of fact, cats are lactose intolerant. 

When cats transition from drinking milk to eating solid food, their bodies lose the ability to digest lactose which is the largest component in milk. The digestion problem might result in some other complications such as;

  • Stomach upset
  • Vomiting
  • Kidney stones
  • Chronic kidney disease
  • Struvite crystals
  • Obesity
  • Weak bones and in extreme cases death. 

Since there is no known benefit to feeding your cat milk, I recommend you train your cat to drink water. Cats may not be natural water drinkers, however, you can create a fun way for them to drink water. 

  1. Provide your cat with a clean bowl every day: Cats are very elegant animals. To entice them to drink water you should ensure you clean the water bowl every day. 
  2. Don’t use a plastic or a metal bowl: Cats hate the smell produced by plastic. This might make them not drink the water. If your cat has a collar, the noise made by the collar when it hits the metal bowl will make the cat lose interest in drinking that water. 
  3. Use a big bowl: Cats don’t like when their whiskers touch the sides of the bowl. To make sure they are comfortable when drinking water from the bowl, find a wide bowl. 
  4. Train your cat to drink from a fountain: if you can make your cat drink water from the tap. This will make your cat have fun when drinking water. It will also drink freely without the distractions made by the bowl. 
  5. Try incorporating water into your cat’s milk: if your cat is used to drinking milk, stopping it might become a big hustle. Start introducing water to the milk. Dilute in a ratio of 5:1 to make sure the lactose is diluted enough. 

After some weeks of training your cat will stop drinking milk entirely. 

In this article, I will go deep into the effects of feeding your cat milk and what alternative you have if you cannot stop feeding your cat milk. We will also go through the possible outcome of when your cat drinks spoiled milk. So, keep reading to learn how you can take good care of your pet. 

Can cats drink spoiled milk?

Any form of milk is harmful to a cat. Cats are lactose intolerant and cannot digest lactose found in milk. This however does not stop cats from drinking milk. A cat will drink milk, get sick, and go back to drinking milk again. So if you don’t know the effects of your cat drinking milk, you are in luck. 

To start off, a cat’s milk is very different from a cow’s milk. The milk of the mother cat provides immunity needed by the cats to grow. That is the reason cats breastfeed their kitten for the first 2-3 months. After the third month, the cat stops breastfeeding and transition to solid food. 

The moment the cat stops breastfeeding, it develops some lactose intolerance. This is the exact time when we start feeding our cats milk from cows. However, intolerance is already developed. And the cat will start reacting to the lactose. 

To find out if your cat is lactose intolerant, feed your cat milk and observe its health in the next 24 hours. If your cat is;

  • Vomiting
  • Has diarrhea
  • Looks weak
  • Cannot sleep on it’s stomach
  • Is behaving funny,

Then your cat is lactose intolerant and you should stop feeding it milk. When the cat keeps feeding milk despite its intolerance, it may develop some kidney and urinary problems. 

In cases where you have to feed your cat milk, you should find the best-manufactured milk. Manufactured milk has a 98% reduced lactose and about 89% water content. This way your cat will remain hydrated, and protected from the common cat diseases brought by milk, and they will remain comfortable. 

There are other instances where you might feed a cat milk without knowing of it is spoiled. On other occasions, the cat just has access to spoiled milk. Will the spoiled milk harm the cat? The answer will be discussed in detail in the section below. 

What happens if my Cat drinks spoiled milk?

What level of spoiled are we talking about? How much-spoiled milk did your cat drink? Does your cat have an underlying health condition, How old is your cat? 

These are some of the questions you can ask to know what will happen to your cat.

  • The level of spoiled

If the milk is just a little sour, then there is nothing wrong with that. Besides, spoiled milk is just yogurt. If your cat is not lactose intolerant or the milk is lactose-free, then your cat will survive. You should, however, check your cat to find out if there is any issue. 

However, if your cat drank milk that was too spoiled, there is a high risk of having stomach upset and might vomit and diarrhea. 

  • How much-spoiled milk did your cat drink?

If your cat drank just a small amount of spoiled milk, then there is nothing that will happen. However, if your cat drank a whole 500ml packet, then you might find yourself rushing to a vet. Your cat might develop some stomach complications like the ones we get when we have food poisoning. 

Give your cat water if this happens since water will reduce stomach complications.

  • How old is your cat?

Kittens might have a hard time handling the effects brought about by drinking spoiled milk than adult cats.  So, consult with your vet to find out if spoiled milk has an effect on adults and kittens.

  • Does your cat have any underlying health condition?

Cats that have kidney conditions should not meet with any milk or spoiled milk at any chance. Milk increases the progression of chronic kidney disease. The phosphates in the milk also create mineral deposits which can cause might also cause kidney and bladder stones. A cat with all those complications cannot survive. 

To prevent any harm to happen to your cat, ensure all the spoiled milk is spilled down the wash. You should also feed kitten milk formulas that are less than 24 hours out of the refrigerator and 48 hours for refrigerated milk formula.  

Why sour milk can be bad for cats?

Cats are still drawn to the smell of milk even when it is slightly bad. Your cat will also finish up the sour milk provided it can feel the taste of fat. If a cat over-drinks the sour milk, it might have severe stomach upset which might lead to vomiting and diarrhea. 

Milk has many components. When the milk becomes bad, the chemicals found in the milk might react to create dangerous chemicals. 

According to FDA, pets are more susceptible to Aflatoxin poisoning. Aflatoxin is a dangerous chemical formed in milk when it gets bad. 

Consuming Aflatoxin a few times might not cause harm to your cat. However, if the cat keeps consuming milk with Aflatoxin over a long period, your cat may end up developing Aflatoxin poisoning. These diseases are associated with symptoms such as;

  • Sluggishness
  • Vomiting
  • Diarrhea
  • Loss of appetite
  • Jaundice which is indicated by the yellow tint in the eyes of the cat 
  • In severe cases, your cat may develop permanent liver damage which leads to death. 

If it is a matter of your cat drinking milk, always check the validity before feeding the cat. You can boil the milk to find out if the milk is still good.

Always cover the milk when the cat is not drinking its milk. This way you prevent toxins from touching the food. 

can cats drink expired milk?

If the cat drink expired milk, it might end up having stomach upset. This might lead to vomiting and diarrhea. 

If the cat only consumed a small amount of expired milk, it might go unharmed. However, if the cat is drinking milk that is expired for a long time, then it might develop more complications. 

Some of these complications are ;

  • Aflatoxin poisoning: Expired milk might have aflatoxin buildup. If a cat keeps consuming expired milk without the owner’s knowledge, there is high chance your cat might develop aflatoxin poisoning. This poisoning might lead to your cat developing jaundice and permanent liver damage. 
  • Struvite crystals 

Since spoiled milk still has lactose in it, when the milk expires, water might separate from the milk causing the lactose to be in high concentration than before. 

When a cat drinks that spoiled milk, the mineral deposit night cause Struvite crystals which normally results in a cat feeling pain when urinating. 

  • Kidney failure

A lot of undigested milk components are deposited in the kidney. The kidney therefore cannot fulfill its function of filtering blood. This might cause your cat to have kidney failure which also brings about urinary infections.  

How long will my cat be sick after drinking spoiled milk?

If your cat has just drank spoiled milk, it might start showing signs of stomach upset, bloating, vomiting, and diarrhea within 12-24 hours. After 24 hours the cat is back to normal.

Cats with underlying health conditions such as kidney diseases make experience this symptom for more than 24 hours. If your cat is still sick from drinking spoiled milk after 24 hours, you should take him to a veterinarian. 

Which symptoms of drinking spoiled milk can seen in cats?

Just like humans, drinking spoiled milk can also cause gastrointestinal distress and other health issues in cats. Some of the symptoms of drinking spoiled milk in cats can include:

  1. Vomiting: Cats may vomit after drinking spoiled milk, and it can be accompanied by retching, gagging, or coughing.
  2. Diarrhea: Cats may experience diarrhea, which can be accompanied by a change in the color, consistency, and frequency of their stool.
  3. Abdominal pain: Cats may exhibit signs of abdominal discomfort or pain, such as restlessness, meowing, or reluctance to move.
  4. Loss of appetite: Cats may refuse to eat or drink anything if they are experiencing gastrointestinal distress from drinking spoiled milk.

Will cats die if they drink spoiled milk?

A cat cannot die from drinking spoiled milk. It will only be sick for like 12-24 hours. After that the will be back to its normal self looking for anything else to put in its mouth. 

A kitten may react differently to the spoiled milk effect. If a kitten is a few days old and it gets hold of spoiled milk, its body might not have the necessary immunity to recover from the effects. The vomiting and diarrhea might overwhelm your cat which might lead to its death. If by any chance your kitten drinks spoiled milk, take it to the vet within the first 12 hours. You might be able to save your kitten. 

What to do if my cat drinks Spoiled milk?

Although spoiled milk might not have extreme effects on your cat, it is important you take your cat to a veterinarian. The cat might have some underlying conditions which might affect the health of your cat even more. 

However, in most cases, you don’t need to do anything if your cat drinks spoiled milk. The cat may have diarrhea and vomiting for a short period then get back to normal.

The moment you notice your cat drank spoiled milk, give it plenty of water and keep a close check for the next 24 hours. If the sickness worsens, you can take it to the vet. 

What to do if my kitten drinks Spoiled milk?

Your kitten might not have any reaction to spoiled milk. This is because when milk becomes spoiled, the lactose breaks down into lactic acid which separated the sour milk and bad smell. Spoiled milk has a reduced amount of lactose in it. Therefore your kitten might still be okay if it drinks spoiled milk. 

However, if by any chance the bad milk has disease-causing bacteria, it would be better if you observed the health of your kitten for 24 hours. If it shows extreme signs of sickness, you should stop feeding it milk of any type and take it to a veterinarian immediately.

 Ensure you give your cat plenty of water if it drinks spoiled milk. 


Spoiled milk might not always cause any harm to your cat. Furthermore, the bacteria formed after milk expires can be beneficial to the stomach of kittens and not adult cats. So you can just observe your cat’s health for 24 hours after it drinks spoiled milk. 

Most cats will react to drinking spoiled milk with diarrhea, vomiting, and sluggishness. If these signs are still present after 24 hours, then you should consider taking your cat to a vet for a check-up. 

Amelia Kteylor

Amelia Kteylor, DVM, attended the University of Georgia. She is a cat expert with 20 years of experiences in field. She has a passion as a writer and editor for pet publishing industry too. Amelia contributes to numerous pet magazines in the areas of pet health and groom. Further, she volunteered in cat rescue centers in her leisure time.

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