The importance of getting the right vitamin A levels for dogs 

What is vitamin A? 

Vitamin A is a fat-soluble vitamin, which means it is part of a group of vitamins that are absorbed alongside fats in the diet. Vitamin A in the form of retinol can be found in foods such as liver, eggs, and dairy products, but it can also be found as provitamin A carotenoids in certain fruits and vegetables, including carrots, sweet potatoes, and spinach. 

Vitamin A has a variety of important roles for us and our pets, including – 

• Vision – Vitamin A helps support healthy vision. Vitamin A is a component of rhodopsin, a protein found in the retina (the back of the eye), which helps us see in low-light conditions. This explains the saying ‘carrots help you to see in the dark’! 

• Immune system – Vitamin A helps to regulate the immune response. It supports the growth and distribution of white blood cells, which are needed to fight against infection. 

• Cell growth and repair – Vitamin A is necessary for the development of tissues and organs. The health of skin and mucous membranes also relies on vitamin A. These act as barriers to prevent infection from entering the body. 

• Antioxidant properties – Antioxidants help protect the body against free radicals, which cause damage to cells and DNA. Certain types of vitamin A, including beta-carotene, can therefore help to reduce the risk of chronic disease and cancer. 

• Reproduction – Vitamin A is needed for sperm production and to maintain a healthy pregnancy. 

It’s easy to see why we all need vitamin A in our diet! 

Why is vitamin A important for dogs? 

As we’ve discussed, there are many reasons why vitamin A is essential for health. If a dog has too little Vitamin A in their diet, this can cause several serious issues. 

Symptoms of a vitamin A deficiency in dogs include – 

• Poor skin and coat condition 

• Night blindness (struggling to see in low-level lighting – affected dogs may stumble, trip or bump into things) 

• Muscle weakness 

• Poor growth and development – especially notable in puppies 

• Increased risk of infection and delayed wound healing 

• Reproductive difficulties (struggling to get pregnant or maintain a healthy pregnancy) 

If your dog has been diagnosed with a Vitamin A deficiency, then it is important to follow your vet’s advice. Sometimes a change of diet is needed, to ensure your dog is on a well-balanced and complete pet food. Problems occur most commonly when a dog has been fed a homemade diet deficient in vitamin A. Transitioning them to an appropriate commercial diet will usually be advised in this case, or a referral to a veterinary nutritionist if you prefer to home cook for your dog. 

Feeding Vitamin A-rich ingredients like liver can also be helpful for deficient dogs, but veterinary administered supplementation could be required in some cases. However, it is important to follow your vet’s guidance as too much vitamin A can also be a bad thing… more on this next! 

Vitamin A toxicity 

Hypervitaminosis A occurs when a dog is receiving too much vitamin A. This can be just as problematic as receiving too little vitamin A, which is why it is so important that your dog is fed a correctly balanced diet. 

Causes of vitamin A toxicity in dogs 

Common causes of vitamin A toxicity include – 

• Regularly being fed large amounts of liver, a concentrated source of vitamin A 

• Supplementing inappropriately and without veterinary guidance e.g., cod liver oil 

• Feeding an unbalanced diet that hasn’t been properly formulated for your dog’s nutritional needs 

• Accidentally ingesting a large amount of vitamin A in one dose e.g., a dog that eats a whole bottle of vitamin supplements. 

Signs of vitamin A toxicity in dogs 

Signs of hypervitaminosis A in dogs may take a little while to develop. Symptoms from inappropriate diets or supplementation often take several weeks or months to be noticed. They may start off as mild gastrointestinal issues, but can progress to bone and joint abnormalities or neurological issues.  

• Diarrhoea or constipation 

• Reduced appetite 

• Weight loss 

• Lethargy 

• Weakness 

• Disorientation 

• Seizures 

• Painful joints 

• Loss of bone mineralisation 

• Reduced levels of thyroid hormone (this hormone helps control various metabolic functions) 

• Foetal abnormalities such as a cleft palate 

Sudden onset symptoms are much less common but could occur in cases where a dog has eaten a whole bottle of vitamin supplements in one sitting. In this scenario, you may see vomiting, drowsiness, irritability, and skin peeling. 

Diagnosis and treatment of vitamin A toxicity in dogs 

A diagnosis of vitamin A toxicity is usually made from taking a careful history. Your vet will ask you about your pet’s diet and any supplements they receive. Blood tests may also be performed to assess vitamin A levels, as well as to check organ function. 

Occasionally, X-rays may be needed to assess bone quality. Radiographic changes such as decreases in bone length, premature growth plate closure, and development of bony spurs (osteophytes) can sometimes be seen. 

The treatment of vitamin A poisoning may depend on the type of toxicity that has occurred – 

Acute vitamin A toxicity 

Where a single large amount of vitamin A has been ingested, your vet may induce vomiting in your dog. This can be followed by administering activated charcoal. The aim is to reduce the amount of vitamin A absorbed by your pet. You must not try to induce vomiting yourself; always take your dog to the vets if they have eaten something they shouldn’t have. 

Chronic vitamin A toxicity 

For dogs that have received too much vitamin A through their diet or supplements, a change is needed. This means cutting out raw liver, cod liver oil or any other vitamin A supplements. Your vet will also advise feeding a commercial diet, which is carefully formulated. Alternatively, if you wish to feed a homemade diet, then referral to a veterinary nutritionist will be recommended. 

Vitamin A levels in your dog’s blood should return to normal within a few weeks, though it can be stored in their liver for many years. However, some issues, for example, bone and joint abnormalities, may not be reversible. Mobility and pain levels for these dogs do tend to improve once the vitamin A toxicity has been corrected, but many may need long-term pain management. 

Vitamin A: a delicate balancing act 

The correct nutrition is essential for your dog’s well-being. Vitamin A is a good example of why it is so important to get your pet’s diet right. Too little or too much vitamin A could have devastating consequences for your dog’s health. 

Most vets recommend a good quality commercial diet, not for financial gain, but because we know they will have been formulated correctly for your pet’s age and size. It’s hard to go wrong if you follow the feeding guidelines of a reputable pet food manufacturer. These diets will have been rigorously checked and quality-controlled. 

As discussed earlier, most nutritional problems arise when a pet is being fed a homecooked diet or when an owner has chosen to supplement their pet without veterinary guidance. If you are still keen to home cook for your dog, then it is important to do this under the advice of a qualified veterinary nutritionist. They will work with you to ensure your pet is receiving the right levels of essential nutrients, including vitamin A. 

Many nutritional deficiencies or toxicities are entirely preventable if your pet is receiving the right food, in the correct amounts. If you are unsure about your dog’s diet or any aspects of your dog’s health, then make sure you speak to your vet for advice.