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ABC’s of Vitamin Deficiencies: Hypovitaminosis A

Updated: Apr 27

I was just thinking about how many exotic pets I’ve been seeing since starting at this new clinic. I thought I had already posted about scurvy or vitamin C deficiency in guinea pigs, but I guess I didn’t - at least I couldn’t find it!

We all know that COVID has put a damper on our regular routines. I’ve had a few folks from GADVASU reading and sending me messages on what they can do to help them study when their restricted due to stay-at-home orders. I just wanted to acknowledge my friends at GADVASU for taking the time to read these posts!

Given that these veterinary scholars are reading, the next few posts are going to be geared towards them.

I thought I would start this series with Hypovitaminosis A. I thought, hey! I could do the ABC’s of vitamin deficiencies - it kind of rhymes!

Hypovitaminosis A is a vitamin A deficiency. Birds are the ones that I am looking for these signs in. However, we do see this is turtles as well.

Pet birds - psittacines, as well as food-producing poultry are both susceptible to this vitamin deficiency. Do you remember learning about squamous metaplasia of epithelium? Yea, I forgot too.

I think we all know that Vitamin A is good for vision in humans. Vitamin A is found in meat products as retinoids and in plant products as beta-carotene. The key is a balanced diet.

Those red and orange veggies are where you will want to chow down or feed to your parrots and poultry. All seed based diets are vitamin A deficient. That’s one of the first things to look for when you’re trying to determine why the bird

(or turtle) is sick: what are they feeding these animals?

What clinical signs are you going to look out for? Some you won’t see without a necropsy, so if you are planning on being a poultry veterinarian you will end up sacrificing an individual to gain information on the pathology of the disease that is affecting the flock. See here for more on poultry pathology.

The dietary history should direct you to a possible diagnosis. Vitamin A is responsible for reducing keratinization of epithelium, and regulates cell division. It’s important in the immune response. Digestion will be affected because of the mucosal lining being affected. Reproductively active birds on a seed-based diet are likely vitamin A deficient. They might present with egg binding as it affects the epithelium of the reproductive tract, or bleeding from the reproductive tract from hemorrhaged follicles.

On physical exam, you may see blepharoedema or swelling of the eyelids, conjunctivitis, plaques in the oral cavity, and I’m always looking for blunting of the choanal papillae.

Hyperkeratosis can occur on the feet. The lining of the esophagus and trachea may be affected if you get to necropsy.

In turtles, it’s usually the eyes that we are looking at. Bulging, swollen eyes; it’s usually hypovitaminsis A. For the future exotic pet vets, here is a little article on the condition in turtles.

Treatment involves injectable vitamin A and transitioning the birds/reptiles to a different diet that is balanced, usually a balanced pelleted diet for the parrots, and well a feed analysis for the poultry. In poultry flocks they may supplement Vitamin A in the water. Vitamin A should be given at a higher dose for two weeks, then dialed down to a maintenance amount. Keep in mind that fat soluble vitamins such as vitamin A can also be over supplemented causing toxicosis. Do not overdose with injectable Vitamin A. When in doubt for your tiny patients, give an oral dose.

As always, Merck Veterinary Manual outlines a little information on exotic pet birds as well as poultry. You can also visit here for some photos. If you want a list of foods to offer your turtle patient, check out this list of foods high in Vitamin A.

See you with the next letter - B!

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