Look at your dog’s gums while she is at rest. Lift your dog’s upper lip and look at the color of the gums above an upper canine tooth — the gums should be pink.
Do a capillary refill test by pressing on the gums with your finger. When you remove your finger, the gums should briefly be white but should return to their pink color within two seconds.
The appearance of the gums is very informative. If the gums are blue, the dog lacks oxygen. If they are white, the dog has lost blood, either internally or externally. If the gums are purple or gray and there is a slow capillary refill, the dog is probably in shock. If they are bright red, she may be fighting a systemic infection or may have been exposed to a toxin.
Some dogs have black-pigmented gums, which can make assessment difficult. For these dogs, you need to examine the pink tissue on the inside of the lower eyelid by gently pulling the eyelid down. In this case, you can only observe the color of the tissue — you can’t perform the capillary refill test — but colors mean the same thing in gums and inner eyelids.
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Gum color and capillary refill time: a life saving symptom
Mucous Membranes in Dogs and Cats on dogscatshealth.com
Testing mucous membrane color and capillary refill time, also known as CRT, can save your pet's life. Unlike other symptoms, such as lethargy and vocalization, this symptom is a definite sign of an animal's critical condition.
There is no confusion when it comes to discolored mucous membranes, which you can see by looking at your pet's gum lines if your pet is exhibiting abnormal behavior, seems sick, or won't respond or stand up. If your pet is healthy, the gums should be pink, much like your own.
Yellow gums can indicate liver failure or disease. This might be expected if your pet has already been diagnosed with a liver condition or is on certain types of medication. White or pale gums can indicate blood loss. If there is not enough blood to circulate throughout your pet's body, or if your pet's body cannot properly circulate the blood, there will be very little color in the gum line. Brick red gums can indicate bacterial infection. This is often medically referred to as sepsis. Blue gums indicate hypoxia. This occurs when your pet cannot breathe or is not getting enough oxygen through breathing. Hypoxia could be due to any number of causes, including drowning, suffocation, unconsciousness, or lung, throat, or nasal problems. The significance of mucous membrane color is not limited to these examples, but it almost always indicates a serious health issue and should never be ignored.
Some dogs have dark or black patches on their gums. This is normal for some breeds. This dark discoloration does not develop overnight and is typically not a symptom. Even black tongues are characteristic to some breeds, such as chow chows.
Capillary refill time is the symptom that goes hand in hand with mucous membranes. CRT is, simply put, the time it takes for blood to return to the surface of mucous membranes after pressure has been lifted. This is observed by pressing your finger on the surface of the gum line until there is no color beneath your finger. When you remove the pressure, the color should resurface within 1 to 2 seconds. It can take longer for the blood supply to resurface if your pet is anesthetized or sedated, but normal, healthy animals will average a 1 second CRT.
Understanding these symptoms should increase your confidence as a pet owner. If your pet is ever injured or ill, these simple tests can alert you to a very serious problem. Always contact your veterinarian as soon as possible when your pet is sick. If your pet has discolored gums or a long CRT, your pet will probably depend on emergency care. It is a good practice to know the emergency hospitals near your house and have their phone numbers on hand. This is especially important if you are in a new area with your pet, traveling, or camping. The difference could save your pet's life.