PCR tests for infectious diseases
Sample collection and PCR tests sent to an external laboratory, which detect the genetic material of viruses, bacteria and parasites, for when a rapid test or a smear does not give an answer.
What it involves
PCR (polymerase chain reaction) detects the genetic material of a specific pathogen in a sample: blood, fluid, swab, faeces. It is very sensitive and specific — it can confirm infection when there are too few parasites to see in a smear, or when a rapid antigen test gave an equivocal result.
We collect the material on site, and the test is carried out by the reference laboratory we work with. We most often order PCR for: babesiosis, anaplasmosis and ehrlichiosis (blood), feline coronavirus in fluid or tissue (FIP), mycoplasma and haemoplasma, feline respiratory pathogens (herpesvirus, calicivirus, chlamydia, bordetella), Giardia and other protozoa in faeces, parvovirus, distemper, leptospirosis and a tick-borne panel.
PCR answers the question “is the pathogen present”, but not always “is it responsible for the symptoms” — that is why the veterinarian always considers the result alongside the clinical examination and other results.
When it is used
We order PCR when the picture of an infectious disease is likely but rapid tests and basic tests do not confirm the diagnosis; in chronic or recurrent respiratory signs in cats; when FIP is suspected; in dogs with fever and tick-borne signs and a negative smear; before bringing a new animal into a home with cats; and in breeding establishments.
There is no point in doing PCR “for everything” — we choose the panel according to species, symptoms and history (ticks, contact with other animals, travel).
Indications: symptoms that should prompt a visit
- A dog bitten by a tick has a fever and anaemia, but no parasites are visible in the smear.
- A cat has a chronic runny nose and conjunctivitis that recurs after every course of antibiotics.
- A young cat has fluid in the abdomen and a fever — suspected FIP.
- An animal has chronic diarrhoea with a negative faecal test for parasites.
- A cat with anaemia where we suspect blood mycoplasmas.
- A dog has shifting lameness and a fever, and the basic tests are normal.
- You are bringing a new cat into a home where other cats live.
Conditions for which we use it in particular
Diagnostics beforehand
Before ordering PCR we carry out a clinical examination and basic tests in our laboratory: a blood count with smear, biochemistry, rapid antigen tests, faecal examination. This is often enough for a diagnosis, and PCR serves to confirm it or settle doubts.
The type of material depends on the suspicion: EDTA blood, a conjunctival or throat swab, faeces, fluid from a body cavity collected under ultrasound, a tissue biopsy. Please tell us about any antibiotics given in recent days — they can distort the result for bacteria.
How it proceeds
Collection takes place during an ordinary visit and takes a few minutes: taking blood, a dry swab, a faecal sample or puncture of the abdominal cavity under ultrasound guidance. We label and secure the sample and send it by courier to the reference laboratory, usually the same day.
The result arrives in 2–7 days depending on the panel. The veterinarian will phone you with an interpretation; if the animal's condition requires it, we start treatment straight after collection without waiting for confirmation.
Aftercare
After collection the animal needs no restrictions. If we have started empirical treatment, please give the medication as instructed and watch temperature, appetite and activity.
We discuss the result by telephone or at a follow-up visit, and adjust the treatment then. A negative PCR with severe symptoms does not end the work-up — we decide the next steps together. Please call immediately if there is deterioration: fever, lethargy, breathlessness, dark urine.
Frequently asked questions
How does PCR differ from a rapid test?
A rapid test detects an antigen or antibodies within 10–20 minutes, but it can be less sensitive or positive after vaccination. PCR detects the pathogen's DNA/RNA. It is more accurate, but it requires sending the sample away and takes a few days.
Does a positive PCR mean the animal is ill?
It means the pathogen is present. Some cats carry herpesvirus without symptoms; interpretation depends on the clinical examination and other results — that is the veterinarian's job.
How much does it cost and how long is the wait for the result?
The price depends on the panel; we will tell you before collection. The result usually takes 2–7 working days.
Do we have to wait for the result before treating?
Not always. When babesiosis or parvovirus is suspected, we start treatment immediately, and PCR serves to confirm and plan further steps.
We manage every case individually. The scope, indications and course described above are indicative; we agree the exact diagnostic and treatment plan during the consultation. This content is for information only and does not replace a veterinary consultation.
Have questions about PCR tests for infectious diseases?
Call us or book a consultation. We will set out the diagnostic and treatment plan in writing, before you decide.