Thursday, May 1, 2014

Vitamin B deficiency and pet diets

Minty poses the question: What can we do to protect our pets from preventable dietary deficiencies?

One of the fantastic things about being a vet is being able to collaborate on interesting projects that might benefit the welfare of animals. I was fortunate enough to work alongside the talented Drs Ye Yao and Richard Miller investigating a case of serious vitamin B deficiency that caused neurological signs in the cat.

The reason we published this case is that although this is by no means new – there are some fantastic reports of vitamin B1 or thiamine deficiency (see references below) it’s a known phenomenon in humans and in animals – but it’s an on-going, preventable issue.

[I was interviewed about this by Kaye from Pet Talk via Skype. Feel free to watch the video but note it may not display if you're viewing this page via a tablet or smartphone - so try this link: . ]

Here’s my summary: vitamin B1, aka thiamine, is an important component of lots of pathways in your body, especially aerobic energy metabolism and synthesis of neurotransmitters. Without thiamine, humans and animals develop progressive encephalopathy – in plainspeak, that is disease of the brain.

In humans, chronic alcohol consumption is one route to thiamine deficiency and is thought to be behind much alcohol-related braindamage. Its one reason, aside from the shear desperation to feel better, that everyone rushes for the vitamin pills when they have a hangover.

Obviously our pets don’t have this issue, but within Australia, some pet foods (and I must stress this DOES NOT APPLY TO ALL PET FOODS) contain sulphur-dioxide preservatives that deplete thiamine. A diet containing high levels of these preservatives can lead to CLINICAL vitamin B deficiency.

What does that look like? Well, early in the course of the disease affected animals suffer from inappetence, vomiting and diarrhoea. A lot of these signs would go unnoticed, especially where animals toilet outside (and trust me that's always nice, but what I mean is it can be easier to note diarrhoea if your cat is presenting it conveniently in the litter tray).

But later more worrying signs develop – impaired vision, difficulty walking, tremors, seizures and even death.

What kind of foods? Mostly those sold as fresh pet meat or pet mince. In the case of this cat, it was a kangaroo-based meat product that the cat was totally addicted to. We actually went and tested the food and it contained around 875mg/kg of sulphur dioxide preservatives compared to 35mg/kg in another brand.

There were no other identified potential causes in the case of this cat.

Fortunately she responded pretty well to supplementation with vitamin B and dietary change.

That’s one cat. But what about the other pets affected by this? Not all will show obvious clinical signs. What can be done?

We can change legislation. In Australia the pet food industry is effectively self-regulated under the Pet Food Industry Association of Australia Code of Practice, which requires that manufacturers adhere to Australian Standards. But Pet meat producers don’t operate under this legislation.

Why do they put this stuff in food? Sulphur dioxides mask the signs of putrefaction, extending the shelf life (well, fridge life) of these products. In this day and age, in our regulated world, it seems sensible that all pet food manufacturers should be working to a minimum and enforceable standard – after all, we want to keep our pets safe.

But legislative change takes time. We believe that this is a wonderful opportunity for the major supermarket chains to take a leadership role, test the fresh meat they supply and refuse to stock products containing these preservatives.

Pets are extremely vulnerable as they tend to eat the same thing most if not all the time. The risk of adverse effects from your diet is always increased when you eat a uniform diet.

So what can pet owners do?

First educate yourself. Read product labels, look out for sulphur dioxide and sulphite preservatives, and when it comes to fresh meat, buy the human-grade stuff. OR feed a premium commercial tinned or dry food that complies with the Australian Standard for Manufactured Pet Food.

Secondly, ask your vet about the best way to vary your pet’s diet. Too much variety can cause problems – from gastrointestinal upsets to nutritional issues – so it is important to find out what is best for your individual animal. Some animals, such as those on prescription or elimination diets, should NOT have a varied diet.

Finally, when you do talk to your vet, make sure you provide a full history of what your pet is eating. This is helpful because diet impacts the health of your pet!


Fawcett A, Yao Y and Miller R (2014) Probable dietary-induced thiamine deficiency in a cat fed pet meat containing sulfur dioxide preservative. Australian Veterinary Practitioner 44(1):554-559.

Malik R, Sibraa D. Thiamine deficiency due to sulphur dioxide preservative in ‘pet meat’: a case of deja vu. Australian Veterinary Journal 2005;83:408–411.

Singh M, Foster DJ, Child G et al. Inflammatory cerebrospinal fluid analysis in cats: clinical diagnosis and outcome. Journal of Feline Medicine and Surgery 2005;7:77–93.

Steel RJS. Thiamine deficiency in a cat associated with the preservation of ‘pet meat’ with sulphur dioxide. Australian Veterinary Journal 1997;75:719–721