In the daily routine of pet ownership, many owners may have encountered the question of why their beloved dogs or cats experience diarrhea, bloating, or other indigestion symptoms after feeding them milk or lactose-containing dairy products. The reason behind this is often related to lactose intolerance in dogs and cats.

PART.01 Overview of Lactose and Lactose Intolerance

Lactose is a disaccharide composed of glucose and galactose and is commonly found in mammalian milk, including cat milk and dog milk. Lactose is broken down in mammals into monosaccharides primarily through the action of the enzyme lactase, which is absorbed into the bloodstream by the small intestine. However, some dogs and cats have insufficient or deficient levels of the enzyme lactase in their bodies, causing them to be unable to break down lactose efficiently, which in turn leads to symptoms of lactose intolerance. Lactose intolerance, also known as lactose indigestion or lactose malabsorption, refers to the insufficiency or lack of lactase enzyme in the body, resulting in lactose not being able to be broken down in a timely manner, which leads to fermentation in the intestines to produce gas, causing symptoms such as bloating, diarrhea, abdominal pain and even gastroenteritis. This phenomenon is more common in dogs and cats, especially when they consume dairy products with high lactose content, such as milk, cheese and yogurt.

PART.02 Causes of lactose intolerance in dogs and cats

The causes of lactose intolerance in dogs and cats can mainly be attributed to the following points: low lactase levels: when dogs and cats are lactating, they have the highest levels of lactase in their bodies to break down the lactose in breast milk. However, with weaning and age, lactase levels gradually decrease. Lactase levels in adult dogs and cats are usually only about 10% of what they were during lactation. Therefore, when they consume a large amount of lactose, as the intestines cannot secrete sufficient amounts of lactase to digest and absorb lactose, a large amount of lactose will ferment in the colonic segment, producing bacteria that attack the digestive system and break down lactose into lactic acid, thus destroying the alkaline environment of the intestines and stimulating the intestines to secrete a large amount of alkaline digestive juices to neutralize the lactic acid, which will trigger diarrhea and indigestion. Difference in lactose content between different milks: The lactose content of different milks is different. For example, the lactose content of cow's milk and goat's milk is higher than that of cat's milk and dog's milk. As a result, dogs and cats are more likely to show signs of lactose intolerance when ingesting these dairy products with higher lactose content. Acquired Habits and Gene Expression: As mammals, the first food dogs and cats are born with is often breast milk, so they are born with a gene that produces lactase. However, as weaned dogs and cats seldom drink as much milk and as often as they did during breastfeeding, the lactase enzyme is gradually put to no use, and the gene for lactase production gradually loses its activity, which in turn greatly reduces the level of lactase in the body.

PART.03 Symptoms of lactose intolerance in dogs and cats

Diarrhea: Diarrhea is one of the most common symptoms of lactose intolerance. As lactose cannot be effectively broken down in the intestines, it leads to increased osmotic pressure in the intestines and a large amount of water enters the intestines, thus causing diarrhea. Bloating: Lactose ferments in the intestines and produces gas, leading to abdominal distension and discomfort. Abdominal pain: Abdominal pain and discomfort may be caused due to irritation of the intestinal wall by gas and lactic acid produced by lactose fermentation in the intestines. Loss of appetite: Lactose intolerance may lead to loss of appetite in dogs and cats as they may experience abdominal discomfort or pain. Weight loss: Long-term lactose intolerance may lead to weight loss in dogs and cats as they may not be able to absorb nutrients effectively from food.

PART.04 Strategies for coping with lactose intolerance in dogs and cats

Choose zero-lactose or low-lactose dairy products: For dogs and cats with obvious symptoms of lactose intolerance, it is recommended to use lactose-free or low-lactose dairy products, such as zero-lactose milk and soy milk. Moderate supplementation of probiotics: Probiotics help regulate intestinal flora and promote intestinal health. Adequate supplementation of probiotics can help dogs and cats relieve symptoms such as diarrhea and indigestion caused by lactose intolerance. Maintain the habit of milk drinking: regular and moderate feeding of milk to dogs and cats from childhood can maintain the activity of the lactase production gene. However, it should be noted that do not feed too much, so as not to aggravate the burden on the intestinal tract. Adjust the dietary structure: in addition to dairy products, other nutritious foods can be provided to dogs and cats, such as meat, vegetables, fruits, etc., to ensure that they get comprehensive nutrition.