In addition to basic research studies, the laboratory provides a comprehensive diagnostic histopathology service for the evaluation of veterinary neuromuscular disease.

Muscle biopsy samples are examined using a variety of histochemical and immunohistochemical techniques. Small animal (dog and cat) muscle samples are also received and evaluated in collaboration with Dr. Diane Shelton's laboratory in California. Atypical myopathy testing is now available for the toxin known to cause this disorder. Both serum and plant samples can be tested. Lactate and pyruvate testing is available through a collaboration with Great Ormond Street NHS foundation trust. Carnitine and organic acid profile assays are evaluated in collaboration with Sheffield Children's NHS foundation trust. For mitochondrial enzyme analysis and mutational screening, please contact the laboratory. Vets with clinical queries should contact Richard Piercy at the Equine Referral Hospital. Trainers and horse owners should contact the laboratory indirectly via their own veterinary surgeon.

For shipment of samples from outside the UK (but within Europe) please include a copy of the facilitation letter both inside and outside the packaging.

A podcast that covers recent developments in the field of equine exertional rhabdomyolysis is available free via iTunes: please follow this link and scroll down to RVC 32.

Links to our privacy notices for both clients and veterinary practices can be found here

All of our submission forms, prices and address label are now available within each test section below.

Muscle Biopsy Histopathology

Until further notice we will only be open Tuesdays, Wednesdays and Thursdays and can only receive samples on these days. We will be limiting the number of biopsy samples we can receive on each of the three days and these samples will need to be booked in in advance via email please ( with a minimum of 48 hours’ notice, but preferably with a week’s notice. There may be times, when the service is oversubscribed, that we cannot book your biopsy samples in for the requested day however we will offer you an alternative date or dates. We will do our best to expedite samples that involve welfare cases but please contact the laboratory to discuss it beforehand. We will only be offering a full panel for equine biopsies at this time, however small animal muscle and nerve sample tests remain unchanged.


For thorough pathological evaluation we require a fresh muscle biopsy that is sent to the laboratory chilled (on ice packs). Keeping the sample cold, but not frozen is crucial to avoid artefact. Although we also suggest that you send a biopsy sample fixed in formalin, this latter sample is only used as a back up, in case of unexpected delays. Many routine tests cannot be performed on formalin-fixed muscle. Use a reliable courier for same day/ overnight delivery.

Please collect and package muscle biopsy samples according to our muscle biopsy procedure and send to the laboratory in a clearly labelled polystyrene box.

We recommend you send in a sample of blood in EDTA (approximately 10ml) and in a plain tube as we bank DNA samples from horses with neuromuscular diseases and in case of further testing. Client and horse details will remain confidential. Blood samples can be sent together with muscle samples in the same package

Equine Muscle Biopsy Evaluation

We will only be offering a full panel at this time. It offers the most detailed evaluation of biopsy samples encompassing routine histological staining which looks at muscle fibre morphology and glycogen content plus special histopathological staining, immunohistochemistry and oxidative stains to assess lipid content, fibre types & mitochondrial enzymes. It is suitable for all cases.

The first muscle is charged at £299.50 (exc. VAT) and additional samples from the same horse submitted at the same time are charged at £117 (exc. VAT) 

Small animal Biopsy Evaluation

In collaboration with Diane Shelton's laboratory at UCSD small animal muscle and nerve samples are evaluated. Serum antibody tests for myasthenia gravis (AChR) and masticatory muscle myositis (2M) can also be run- Collect 1-2mls of serum prior to initiation of corticosteroid or other immunosuppressive therapy. A full list of tests available and their prices (excluding VAT) are available below:

Muscle or Nerve Profile: £299.50

Combined Muscle and Nerve Profile: £338

Additional Muscle or Nerve Profile (sent in at the same time form the same animal): £121

2M Antibody test: £115

AChR Antibody test: £115

The required downloadable and printable forms for submitting muscle biopsies from both horses and small animals are available below:

Address label

Biopsy & Blood Submission Form

Muscle Biopsy Procedure For Vets

Facilitation Letter (for use with samples sent from outside the UK from January 2021)

PSSM1 (Polysaccharide storage myopathy) Genetic Testing

For some practitioners, it may be convenient to send blood or hair plucks(to include follicle) (either separately or with a muscle sample) for genetic testing for the glycogen synthase mutation reported by McCue et al. 2008 seen in many horses with polysaccharide storage myopathy (PSSM / EPSM).

Glycogen synthase (GYS1) mutation causes a novel skeletal muscle glycogenosis. Molly E. McCue, Stephanie J. Valberg, Michael B. Miller, Claire Wade, Salvatore DiMauro, Hasan O. Akman, James R. Mickelson. Genomics 91 (2008) 458–466

Unlike with muscle biopsy samples, there is no restriction on the number of PSSM1 samples we can accept each day however we can only receive samples on Tuesdays, Wednesdays and Thursdays. Samples are run in batches every 2-3 weeks and results are generally available in 1 month from submission. Blood or hair submitted to the laboratory without accompanying muscle samples, may be sent at room temperature via first class post however they must meet royal mail requirements i.e blood tubes should be placed in a secondary container with enough absorbent material to absorb the entire contents of the tube. Please make sure you send samples using the address label and not to the Diagnostic Laboratories at the Hawkshead Campus or addressed purely to the Royal Veterinary College.

5-10mls of EDTA blood or approximately 50 hair follicles are required.

The price for the PSSM test is: £59 (exc VAT)

The address label and submission form for PSSM test are available to download and print below:

Address label

Biopsy & Blood Submission Form

Import Licence (for samples outside the UK)

Serum HGA/MCPA testing for Atypical Myopathy

       We will only be open Tuesdays, Wednesdays and Thursdays and can only receive samples on these days. Unlike muscle biopsy samples, there is no restriction on the number of serum samples or plant samples we can accept.

Following research that was supported by The Horse Trust, we now offer vets and owners atypical myopathy testing.

For vets

Serum testing for the hypoglycin A toxin and its principal metabolite known to cause atypical myopathy is now available. This is a more rapid test than previously reported methods. We also offer combined profiles including hypoglycin A & acylcarnitine identification and hypoglycin A, acylcarnitine & organic acid identification at special prices. Please send either a whole blood tube, serum gel tube or separated serum using a next day delivery service and use the specific form below. For organic acids profiles please send a urine sample and for acylcarnitines please send a lithium heparin blood tube.

Whenever possible, samples received before 9am will be reported in 48 hours and samples received after 9am will be reported in 72 hours. Please note these turnaround times are for working days only (the lab is open Monday-Friday)

Prices (all excluding VAT) of the available atypical myopathy tests are as follows:

  • Serum hypoglycin A & MCPA- carnitine: £115
  • Serum hypoglycin A, MCPA- carnitine & acylcarnitine profile: £218
  • Serum hypoglycin A, MCPA- carnitine & urine organic acid profile: £231
  • Full atypical myopathy profile (HGA, MCPA-c, organic acids & acylcarnitine profiles): £329

Samples from overseas: Samples from abroad can be sent to us. The vet will need to send whole blood (e.g red topped vacutainer tube) or if they have the facility to spin down the blood, just the serum can be sent. The vet will need to send samples on a next day delivery (as sample decomposition can affect accuracy of results) only Monday-Thursday. It must include one of our import licences with the courier paperwork. The sample should be packaged correctly i.e if using a padded envelope the blood tube must be surrounded by enough absorbent material to soak up all of the tube contents and this should all be in a sealed bag. The paperwork should be separate from the bagged tube. 
If the vet takes a sample that cannot be sent immediately e.g. on a Friday, the sample should be spun, the serum placed into a new tube and frozen until ready to send. When sending samples that have been frozen, they do not need to be defrosted before being sent, the package will need to include ice packs and preferably be in an insulated container that will keep the tube cold.

Lactate Pyruvate Ratios

Please follow the protocol for precipitation of samples for lactate pyruvate ratios to ensure samples are correctly processed and complete the specific submission form for this type of sample available below. Samples must be sent to the laboratory on dry ice to avoid thawing using either a same day or next day delivery courier. Please contact the laboratory at least a day in advance to ensure we know when to expect delivery. Samples should not be sent out on a friday as they cannot be processed over the weekend and will be wasted. We recommend that you contact a reliable courier for shipment prior to obtaining the sample. Prices for lactate & pyruvate testing are also listed below.

Pyruvate/Lactate Sample Submission Form

Address label


First sample (e.g. Pre-exercise sample): £112

Second sample (e.g. Post-exercise sample): £38.50

Acylcarnitine and Organic acids profiles

Plasma acylcarnitines and urine organic acids are measured in collaboration with Sheffield Children's NHS trust and are often diagnostic in horses with atypical myopathy and other Multiple Acyl CoA Dehydrogenase Deficiencies (MADD). For organic acids please send 10ml of urine in a plain bottle. For acylcarnitines use a lithium heparin tube (not EDTA) for plasma. Please see below for the prices of each test.

Please send these on an ice pack for next day delivery and include a copy of the Biopsy & Blood Submission Form and send to the lab using the address label

If atypical myopathy is suspected please see information above on atypical myopathy testing.


Acyl-carnitine Profile: £116

Organic acids Profile: £139

Mitochondrial respiratory chain enzyme analysis and Mutational screening

Please contact the laboratory to discuss your requirements.

Horse Owners atypical myopathy test and information

Plant sample testing for atypical myopathy

We offer testing of seeds, leaves and seedlings for the Hypoglycin A toxin known to cause atypical myopathy. To find out if plant samples on your property contain the toxin owners can submit these samples directly to the lab. Please read the atypical myopathy information sheet below to learn more on atypical myopathy and how to collect samples. Payment is required upon receipt of our invoice and can be made via credit card, bank transfer or cheque. Full details are on the invoice. Please complete the owner's plant sample submission form below ensuring contact details are fully filled in. Results are available in 2-3 weeks submission however if you require a more rapid turnaround we offer an expedited service (at a higher cost) and results are, whenever possible, available within 72 hours. These turnaround times are for working days only (Tuesday-Thursday) and we can only accept credit/debit card payments for the expedited service.

Prices (including VAT)

  • Standard turnaround plant / tree sample test: £132 per sample
  • Expedited turnaround plant / tree sample test: £288 per sample

Unfortunately, due to staffing limitations, the Comparative Neuromuscular Diseases Laboratory is unable to discuss individual results or atypical myopathy testing in general by telephone or email. We do provide generic advice on each result sheet about how to interpret your test result and give advice and information about atypical myopathy on our owner information sheet as well as in the frequently asked questions (FAQ) document Please take some time to look through these. We recommend you contact your own vet if you have specific further queries.

Frequently Asked Questions (FAQ) for owners

Muscle biopsy / PSSM1 testing

If your vet has performed a muscle biopsy or PSSM1 test on your horse due to RCVS code of conduct and rules on data protection & confidentiality we cannot discuss your horse or the results with you without first speaking with your vet. If you have questions regarding muscle biopsy or PSSM1 testing please ask your vet to contact us directly at

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