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Logic Firm (previously Diar-Stop) for Dogs & Cats

Logic Firm (previously Diar-Stop) for Dogs & Cats
Cats & Dogs 2 - 7kg » 10ml Syringe
Diarsanyl Foals » 60ml Syringe

Images are for illustration purposes only. Packaging may change from time to time and images on our website may or may not be updated.

  • Cats & Dogs 2 - 7kg » 10ml Syringe £10.99
  • Diarsanyl Foals » 60ml Syringe £16.00
  • Dog » 7 - 30kg » 24ml Syringe £11.99
  • Dog » 30 - 60kg » 60ml Syringe £14.99

Selection of 4 products from

£10.99 to £16.00


Digestive upsets in dogs and cats occur when the intestines become irritated. This can be caused by a sudden change in diet or by eating inappropriate food, e.g. scavenging on a walk or eating from the rubbish bin.

Logic® Firm is a pharmaceutical grade formulation which helps support a dog or cat’s digestion.


  • Montmorillonite - Coats and protects the intestinal lining and absorbs toxins
  • Sodium, Magnesium & Potassium - Help to restore electrolytes lost through diarrhoea
  • Dextrose - Provides an energy source for the small intestine
  • Prebiotics (FOS – fructo-oligosaccharides) - Help to restore the normal bacterial flora



Fructo-oligosaccharides, Dextrose, Glycerol, Sodium chloride, Magnesium salts of organic acid.


Bentonite - montmorillonite (E558) 40%, Potassium sorbate.

Analytical constituents

  • Crude ash - 35%
  • Total sugars - 30%
  • Moisture - 22%
  • Sodium - 2.5%
  • Crude protein - 0%
  • Crude fibre - 0%
  • Crude oils & fats - 0%

Feeding guidelines

Pet Weight

Syringe Size
Syringe Size
Syringe Size
0 – 7 For Cats and Dogs
7 – 30 For Dogs only
> 30 For Dogs only
Body Weight Number of Graduations
Morning Evening
2kg - 7kg 1 1
8kg - 30kg 1 1
> 30kg 1 1

Need help or advice? Contact us:

  • Landline: 01582 842096
  • Mon - Fri: 8:30am - 5:00pm
  • Sat: 9:00am - 1:00pm (Collections only)
  • Email: [email protected]

All prices include VAT where applicable.

Delivery Information

How quickly do you deliver?

Under almost all products on our website is an Estimated dispatch time, check this for a delivery prediction specific to the item you are looking to purchase. These badges are updated live based on the stock levels we have and also those of our suppliers - so are usually very accurate, but cannot be guaranteed. In more general terms, we aim to dispatch all orders within 1 working day of receiving payment (and a prescription if required). If we cannot do so within 3 working days we will contact you by email.

What do you charge for delivery?

For UK delivery, we charge the following:

Order Total Weight Delivery
£0-£28.99 Under 2kg £2.99
2kg+ £4.99
£29-£38.99 Under 2kg Free
2kg+ £4.99
£39+ Under 2kg Free
2kg+ Free

Prices quoted are for delivery to all parts of mainland UK except certain Scottish postcodes (where the price is higher for items sent by courier. Delivery of food abroad (including Channel Islands, N. Ireland and other islands around the UK) is charged at a higher price and free delivery is not available. Temperature controlled products are also not always subject to the standard and/or free delivery options.

For full information on our delivery charges, including prices on heavy deliveries to Scotland and abroad, see our delivery information page.

We can deliver most items to all around the world, but prices do vary. To find the exact cost of shipping your item, and to see all options available, follow these steps:

  1. Put the items you wish to order in your basket
  2. Proceed to checkout and enter your delivery address, including country
  3. Delivery information including price will automatically update to what is available to you

Delivery of aerosols

Due to restrictions aerosols can't be sent by Royal Mail. We appreciate your understanding.

Delivery of temperature controlled items

Some products, such as non-ambient items and frozen food, need to be delivered in insulated packaging to prevent them from getting too warm (or too cold) during transit from us to you. Purchasing any of these items in your order will result in a £1.99 charge being added to the total to cover the high cost of the insulated packaging materials. You only pay the £1.99 once per order, regardless of how many temperature controlled items you purchase in that order.

How do I cancel or return an order?

Please call us as soon as possible if you need to amend or cancel an order on 01582 842096. If your order has been processed for dispatch we will be unable to cancel or amend the order. You will however be able to return your product for a full refund*.

To return an item, you must contact us by phone or email to arrange this BEFORE posting any product back to us. We will explain the process at this stage for you.

*For full details on returns, see our terms and conditions page.

Reviews (51)

Q & A

Below are some recent questions we've received regarding Logic Firm (previously Diar-Stop) for Dogs & Cats, including answers from our team.

10 October 2018 at 8:46pm

How long will a syringe last

Charlotte Green

  • VioVet customer since 2014
  • From: Buckinghamshire, United Kingdom

How many doses will I get out of the relevant syringe for a 38kg dog?

  • Veterinary Advisor

Your dog would need 1 graduation morning and evening of the 60ml syringe. Each graduation is 4ml so there wil be 15 doses.

3 August 2018 at 10:18am

Dosage for puppy


I have a tube of 30kg /60kg paste at home and want to give a dose to a 10kg puppy , how much should I give ?

  • Customer Service Advisor


Thank you for your question.

The 30kg-60kg 60ml syringe is not suitable for a 10kg dog/puppy so I cannot advise on that.

You would need the 24ml syringe which is suitable for dogs weighing 7kg - 30kg.

Hope that helps,


8 March 2018 at 9:08am

9 week puppy


Can I give this paste to 9 week old puppy

  • Veterinary Advisor

This is fine to be given to puppies once they are weaned off their mother. Ideally give several small meals per day, but each meal should be a bit less than your puppy would choose to eat. The digestion settles much better if it is not overloaded with too much food, then your puppy will recover faster.

14 February 2018 at 11:05am



What size in mare the graduations on the 24ml size and the 10 ml size ?

  • Customer Service Advisor

Hi Richy

Thanks for your questions. The graduations are 1ml on the 10ml size and 2ml on the 24ml size.

Hope this helps.

Kind regards


11 October 2017 at 12:44am

Suitable for kittens?


I have two 14 week old kittens who have been suffering diarrhoea. Is this product suitable for them?

  • Veterinary Advisor

Yes you can give this product to kittens once they have been weaned from their mother. It is a good idea to reduce the amount of food they are getting and give several small meals a day. They will recover much better if their digestion is not overloaded. You should see your vet though if the diarrhoea lasts for some time or the kittens look unwell.