By Emily Gantt
Published: 10/13/2023, edited: 11/17/2023
Reviewed by a licensed veterinary professional: Dr. Linda Simon, MVB MRCVS
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Vitamin A, also known as retinol, is necessary for all vertebrate species, humans and dogs included. Retinol is a fat-soluble vitamin found in many foods, supplements, and even human skincare products.
Canines store vitamin A in their fat cells, where it helps with many bodily processes from mucus production to cell growth and division. Dogs need vitamin A in all stages of life since their bodies cannot function properly without it — but more on that later.
Now that we've established that vitamin A is vital for dogs, what does it do exactly?
Functions of Vitamin A for Dogs
This essential vitamin helps maintain nearly every organ system, from the skeletal to the reproductive system.
Vitamin A is most well-known for supporting vision and skin health, but its functions stretch far beyond the eyes and coat. The need for vitamin A starts in utero, where it is imperative for brain and skeletal development. Vitamin A functions at the molecular level, helping cells transform into more specialized cells through a process called cellular differentiation.
Vitamin A even prevents dogs from getting sick since it helps power the immune response, helping to create the protective mucus that lines the lungs. Since it’s present in almost every body system, some vets compare vitamin A to the “oil” that keeps human and canine bodies running properly.
Daily Recommended Intake
Experts recommend 3,333-5,000 IU of vitamin A per kilogram of dry matter diet for dogs of all life stages and breeds. Though, according to the Merck Veterinary Manual, dogs can ingest up to 100 times that amount safely.
Animals get vitamin A by digesting foods that contain beta-carotene which their bodies convert to the essential vitamin. You probably know that green leafy vegetables like spinach are chock full of beta-carotene, but this essential vitamin is hiding in some foods that might surprise you.
Other whole foods that contain vitamin A include:
- Sweet potatoes
- Summer and winter squash
- Red bell pepper
- Milk (in moderation)
Signs of Vitamin A Deficiency in Dogs
The most well-documented side effects of a vitamin A deficiency in dogs are skin and coat problems. Vitamin A deficient dogs commonly have sparse fur or hairless patches and dry, scaly skin with bumps or lesions.
Sometimes these open sores will develop bacteria or yeast infections, which can cause an unpleasant odor. It's not uncommon for dogs with low vitamin A levels to have ear irritation or frequent ear infections too.
Low vitamin A is known to cause abnormalities in the cells that produce mucus. These abnormalities can manifest as dry, itchy eyes and lung problems like a tendency to develop pneumonia when fighting a (usually mild) common cold.
Dogs with severe vitamin A deficiency tend to be very weak and may refuse food altogether. They may also have difficulty navigating at night due to deficiency-related night blindness.
Vitamin A deficiencies are especially hard on young dogs since retinol plays a crucial role in bone growth and restructuring. This can translate into stunted growth and irregularities of the bones in the inner ear, causing some dogs to become deaf or hard-of-hearing. Fetal deformities can also occur in pregnant dogs who are deficient in vitamin A.
Vitamin deficiencies rarely have anything to do with food, especially when dogs are eating high-quality, nutritionally balanced food. More often than not, deficiencies stem from genetics and malabsorption — or a little bit of both.
Treatment of vitamin A deficiency
The first line of treatment for mild vitamin A deficiencies in dogs is to up their dietary intake of vitamin A. The best dietary sources of vitamin A for dogs include:
- Liver products *
- Sweet potatoes
- Egg yolks
*Large amounts of liver products can sometimes cause unpleasant side effects, so watch your dog for joint issues and diarrhea when first introducing this food. If they show signs of an adverse reaction, you may need to decrease their intake or switch to another vitamin-rich food like kale or pumpkin.
Your vet may also prescribe prescription meds or supplements to help boost your pet's vitamin levels.
Underlying conditions like malabsorption are trickier to treat since this condition can be caused by a wide variety of problems, including bacterial overgrowth, a decrease in pancreatic secretions, anatomical problems within the digestive tract, parasites, and infections. Depending on the root cause, the dog may require medication, prescription dog food, enzyme replacement therapy, or even chemo.
Signs of Vitamin A Overdose in Dogs
Like most things, too much of a good thing can be a bad thing, and this rings true for Vitamin A too. Skin creams like retinol serums and the like can cause vitamin A overdose in dogs that eat them.
Signs of an overdose include:
Severe cases of vitamin A overdose can cause cardiac arrest and even death.
Call your vet immediately if you suspect your pet has gotten into your skincare products or any other product with high concentrations of vitamin A.
Vets will typically administer activated charcoal to treat vitamin A overdose for short-term occurrences (like a dog eating a tube of skin cream). If the pet is brought in promptly enough after ingestion, they may also induce vomiting. Prolonged vitamin A toxicity is more difficult to treat and may require surgery to repair bones damaged by the excess vitamin A. This type of toxicity sometimes occurs in dogs who exclusively eat human food.
Treatment of vitamin A overdose
Seek immediate vet care if you suspect your dog is having an acute vitamin A overdose due to ingesting too much vitamin A at one time (say, if they got into a bottle of supplements). Long-term damage can often be avoided with prompt vet treatment, as they can induce vomiting or administer activated charcoal to reduce vitamin absorption.
Chronic vitamin A overdose, as is seen when dogs are fed an unbalanced diet or a lot of vitamin-rich liver, will require dietary changes to reduce the intake of vitamin A.
Vitamin A Supplements for Dogs
While a balanced diet usually takes care of a dog's vitamin A needs, some dogs require supplements for various reasons.
As we mentioned above, not all dogs can absorb vitamin A from food; this can be because of medications that block absorption or digestive problems. Some genetic mutations can make metabolizing certain vitamins difficult or even impossible. These pups will typically benefit from vitamin A supplements for dogs.
Vitamin A supplements are a great energy booster for dogs with minor deficiencies. Supplementation can also promote a healthier, shinier coat and clearer skin. Since vitamin A is crucial in bone development, puppies can benefit from a little extra vitamin A to keep their growth on track.
Vitamin A supplements can also help dogs as they age since they promote eye health and may reduce the onset of night blindness.
However, importantly, owners should never supplement Vitamin A without first consulting with their vet as supplementing it when not needed could do more harm than good.
Excessive vitamin A intake during pregnancy has been associated with cleft palate formation and other fetal abnormalities
While you can buy dog-specific vitamins over-the-counter, it's a good idea to talk to your vet about them before giving them to your pet. Your vet may want to run blood tests to see where your pup's vitamin levels are before going ahead with a vitamin regimen.
Never give your dog human vitamin supplements without explicit instruction from your vet. These may be too strong or contain ingredients that will hurt your dog. Instead, opt for a dog-specific vitamin — preferably a flavored one — to make administration easier (and tastier too!).
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