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

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

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  • Cats & Dogs 2 - 7kg » 10ml Syringe £18.32
  • Diarsanyl Foals » 60ml Syringe £13.35
  • Dog » 7 - 30kg » 24ml Syringe £20.52
  • Dog » 30 - 60kg » 60ml Syringe £25.40

Selection of 4 products from

£13.35 to £25.40


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

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All prices include VAT where applicable.

Reviews (56)

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

Overall 5
Ease Of Use
Value For Money
Absence Of Side Effects
56 out of 56 (100%) customers would recommend this product.
5 stars (52 reviews)
4 stars (3 reviews)
3 stars (1 reviews)
2 stars (0 reviews)
1 stars (0 reviews)

Only verified purchasers of this product can leave a review.

55 It works for minor stomach upsets
Verified Purchase

By on 12 April 2021

My spaniel Ted has a sensitive stomach - unfortunately he's also a bit of a scavenger and once his stomach is upset, the effects can last for a few days if not treated. I've found this product works within 24 hours. He doesn't particularly like it but, unlike tablets, it's hard to spit out so I always make sure I have a tube in the house.

Customer recommends this product

55 Very useful to have in a cupboard
Verified Purchase

By on 5 January 2021

This is a good product, does what it supposed to do helping with little tummy problems. Baxter isn’t particularly excited about it but takes it if he has to.

Customer recommends this product

55 Does what it says!
Verified Purchase

By on 6 April 2020

All dog owners should keep a tube of this in the house, especially if your dog has a sensitive tummy and eaten something he shouldn't have! Firms them up within a day and so easy to use.

Customer recommends this product

45 This works
Verified Purchase

By on 8 March 2020

This paste appears to be palatable and has the desired effect quite quickly.

Customer recommends this product

45 Good product
Verified Purchase

By on 30 December 2019

Seems to be ok, Raffa seems to tolerate it ok.

Customer recommends this product

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Q & A

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

12 November 2021 at 10:33am

Logic Firm for puppies

Andrea Robertson

Is Logic Firm safe to give my 14kg, 5 month old puppy?

  • VioVet Staff

Yes Logic Firm is safe for use in a 14kg 5 month old puppy. You will need to order the 7-30kg dog size product (24ml syringe).

17 June 2021 at 3:02pm

Logistics firm


How long does it take to work?

  • VioVet Staff

This product should start working within a day or two. The average intestinal upset will take 3 to 5 days to resolve on a stool firmer. If you need this for longer than 7 days then you should discuss the problem with your vet.

7 July 2020 at 6:51pm

How long can I keep tune once opened

Fiona Davidson

Hi, I didn’t need to use the whole tube. How long can you store the tube once opened? thanks

  • VioVet Staff

Once opened the product will keep until the stated expiry on box, however any paste exposed to air may degrade. I would advise covering the syringe tip and keeping it in the fridge. It is already recommend to dispose of the first bit of paste you express from the syringe in later uses.

27 April 2020 at 9:41am

Dosage quantity

Jason Durkin

Hello, what is the dosage quantity for a 30kg dog, is is 3ml twice per day ??

  • VioVet Staff


Thank you for your question.

For a 30kg dog they will need 1 graduation in the morning and 1 graduation in the evening.

I do hope this helps.

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?

  • VioVet Staff

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 ?

  • VioVet Staff


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

  • VioVet Staff

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 ?

  • VioVet Staff

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?

  • VioVet Staff

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.

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