COCCIDIOSIS IN GOATS
by Lilly Griffiths BVSc MRCVS, Giulia Frezzato DVM MRCVS & Rachel A Jones, DPhil
As we head into the main kidding season, now is a good time to refresh our knowledge of the most common illnesses that can affect young goats. Coccidiosis can be an extremely serious illness in young goats and may result in death.
Coccidiosis is a gut infection which can cause serious illness, particularly in young kids (generally older than 4 weeks). The most common symptom is diarrhoea (‘scouring’), although it’s important to know that some very ill goats do not have diarrhoea. Serious illness is usually seen when goats are exposed to large numbers of parasites, generally through infected bedding, and/or to particularly pathogenic coccidia species which are better able to cause disease. Coccidiosis is diagnosed by a combination of symptoms and a fecal egg count which helps to rule out other causes. Good hygiene is the main way to combat coccidiosis. Treatment is prescribed by a vet and is usually in the form of an oral drench and electrolytes to replace lost fluids.
What is coccidiosis?
Coccidiosis is caused by a type of parasite called a protozoan, (part of the same family of parasites that cause the serious human illnesses malaria and toxoplasmosis). In the UK, there are nine different species of coccidia which infect goats. Although other species can develop coccidiosis, including sheep, cattle and poultry, in general, each coccidia parasite is species-specific, meaning that the coccidia parasite which causes illness in chickens won’t be able to infect goats and vice versa.
Coccidia are transmitted between goats by the faecal-oral route, meaning that they pass out of a goat in their poo and are transmitted to the next goat when they ingest infected material. All goats are infected by coccidia to some extent but young goats are less able to tolerate an infection because their immune system is less developed, and because they tend to explore their environment by ‘mouthing’ things which increases the likelihood that they will ingest material contaminated with infected poo. In addition, stresses to your goat, such as weaning, transport and/or bad weather can bring on an onset of illness.
Serious illness usually develops when a goat is infected by a large number of parasites, or if they are infected with a particularly pathogenic species. Coccidia reproduce by developing tough, egg-like structures called oocysts which pass out of the gut in poo and can survive for a long time in the environment. Where large numbers of oocysts are allowed to build up, for example in dirty bedding or if goats only have access to a small area of pasture, there is an increased likelihood that a young goat will ingest large numbers of oocysts, which subsequently develop in the cells lining their gut and cause illness.
Of the nine different goat coccidia species in the UK, some are more pathogenic (able to cause serious illness) than others: The more pathogenic the species, the fewer parasites are needed to cause serious illness. A goat without symptoms may have between 1000 and 1,000,000 oocytes per gram of poo while an ill goat may have between 100 and 10,000,000 per gram(1). This means that two goats of the same age from different herds may have the same number of parasites, but one will be very ill and one will appear normal.
A goat which is carrying a large number of coccidia, but has no symptoms, has what is known as a ‘subclinical infection’. Although this goat may not be visibly sick, the large numbers of parasites in the gut damage the intestinal cells and can interfere with the absorption of food. These goats may be slower to grow and/or slimmer than goats with low numbers of parasites. In addition, a subclinical infection may quickly turn serious if the goat is exposed to stress or develops another illness which may depress their immune system. A regular fecal egg count by your vet (around £10-15) will tell you how many oocysts are present in your goats’ poo and your vet will then be able to advise whether any treatment is needed.
Symptoms and treatment
The symptoms of coccidiosis include some or all of diarrhoea, listlessness, loss of appetite, weight loss, dehydration and in extreme cases sudden death. Unfortunately these symptoms can overlap with those caused by other illnesses. Diagnosis is generally based on a combination of all the symptoms, plus details about the age of the goat and its environment. If your vet suspects a goat has coccidiosis, then a fecal egg count can help to rule out other possible causes for these symptoms. If the symptoms suggest coccidiosis, but there are low numbers of oocysts in the fecal egg count, your goat may be infected with a more pathogenic strain of coccidia. It needs specialist tests to tell the different types of coccidia apart so a sample may be sent to the lab. Time is of the essence when treating an ill kid, so your vet is likely to start treatment for the most likely cause of the infection while waiting for lab results. Treatment for coccidiosis is usually by an oral drench, together with electrolytes to replace lost fluids.
It takes around 3-4 weeks for an oocyst to develop into the mature parasite and cause infection. For this reason, diarrhoea in very young kids (less than 4 weeks) is less likely to be coccidiosis, but may be due to another parasite such as E.coli bacteria, which also infects the gut. Regardless of the cause, diarrhoea in young kids can be life threatening and contacting a vet early is always recommended.
Good hygiene is the main way to combat coccidiosis (and many other transmissible illnesses). House your goats in clean, dry bedding, in housing which is regularly cleaned out, particularly while young goats are present and avoid overcrowding.
(1) Diseases of The Goat, 4th Edition by John G. Matthews
This article was first published in ‘Pygmy Goat Notes’ Issue 158 March 2022 and was written by Lilly Griffiths BVSc MRCVS Veterinary Surgeon and Giulia Frezzato DVM MRCVS Veterinary Surgeon and Pygmy Goat Club member Rachel A Jones, DPhil, who all work for Priory Vets in Cardigan.