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Toxoplasma Abortion in SheepToxoplasma Abortion in Sheep

The Cause:

A protozoal parasite, Toxoplasma gondii, causing 20-30% of ewe abortions in this country.

The Disease Cycle:

Cats, notably kittens, are important in the parasite life cycle and the parasite cysts shed in cat faeces may be eaten by pregnant ewes.  An important factor is hay feeding – wild cats frequently raise kittens in haybarns, the hay becomes soiled and the use of this hay in winter ensures that a large number of ewes can come in contact with the infective cysts.  These resistant cysts may also last up to two years in hay or soil.

However, toxoplasmosis also occurs when no hay is used and it is worth noting that a single gram of faeces from a cat that is shedding toxo (not all do) contains enough toxoplasma to abort up to 2000 ewes!

Importantly, the parasite is not passed from ewe to ewe and once infected, the ewe is strongly immune.

The Abortion:

Depending on the stage of pregnancy at which the ewe is exposed to Toxoplasma, you may see:

  • a. More dry ewes, as very early abortions may go unnoticed.
  • b. Small, premature lambs aborted in late pregnancy.
  • c. Weak lambs born near full-term but die soon after birth.

With so much opportunity for infection, Toxoplasmosis has been shown to cause an average 8% drop in lambing percentages, even on farms where a Toxoplasmosis problem was not thought to exist.

There are few consistent specific signs of Toxoplasma infection in aborted lambs and these should be submitted to the veterinary clinic for post mortem and sampling.

What do you do?

Until Toxoplasma is confirmed as the cause of the abortions, you should collect and destroy all products of abortion and isolate aborted ewes for 7-10 days.  This is aimed at limiting spread of possible Campylobacter abortion, the other major cause of abortion in New Zealand sheep.

Unfortunately, there is nothing you can do to halt the outbreak this year.

In future, a vaccine, TOXOVAX, can be used to artificially infect non pregnant ewes so that they have lifelong immunity.

The vaccine costs approximately $1.62 excl. per ewe and is given to replacement stock at least four weeks before tupping.  In the first year, as a minimum, all incoming replacement ewes should be vaccinated – either hoggets or two tooth ewes. 

Note that if you intend to mate hoggets you will need to make your selection and get the vaccination done at least a month before mating begins. Use of Toxovax when mating/lambing hoggets is considered “best practice”.

Ideally, in severe cases, older ewes should also be vaccinated, especially four and six tooth ewes.

Aborted ewes will already be immune.

The vaccine is manufactured to order so you must place your order at least three weeks before the date required.

NOTE:  This is a live vaccine and, as such, pregnant women should not handle the vaccine.


Camplyobacter Abortions in Sheep

Read more >Friday 1st of April 2016: The Cause: The bacterium, Campylobacter fetus. Formerly known as "vibrio".


Refugia

Read more >Friday 1st of April 2016: One of the tools in the parasite battle toolbox is the concept of "refugia". It goes against a farmer's natural instinct to kill every parasite because it means deliberately leaving 5-10% of each mob undrenched. This is done to maintain parasites susceptible to drenches because they've never been exposed.


Reproduction Cycle

Read more >Friday 1st of April 2016: Dogs have an interesting reproductive cycle, rather different to most domestic animals that cycle either seasonally or throughout the year. In the domestic canine, females cycle more or less every six months, with larger breeds tending to cycle less frequently - sometimes only once a year.


Feeding Working Dogs

Read more >Friday 1st of April 2016: Eukanuba Adult Large Breed Premium Performance Formula. Recommended for large and giant breed adult dogs weighing 25kg or more.


Equine Dentistry

Read more >Friday 1st of April 2016: With the current surge in interest in equine dentistry, more than a few myths have crept into popular belief. Find out more.


Laminitis

Read more >Friday 1st of April 2016: Spring and early summer are the high risk periods for pasture - induced laminitis, so this is a timely reminder of what this disease is and how you can avoid it.


Vaccination

Read more >Friday 1st of April 2016: There have been some statements regarding vaccination in dogs (and Dobermans in particular) floating around the internet for some time now which in my opinion are a cause for concern. Vaccination of dogs is done for one reason only - to protect the health of the animal by providing it with immunity against certain very serious diseases.


Sheep Measles

Read more >Friday 1st of April 2016: Sheep measles (Taenia Ovis) unlike true hydatids (Echinococcus granulosus) has no human health risks, but its importance lies in the fact that it leads to cysts through the carcass of the animal which are unsightly and lets face it, who wants to eat meat with visible oozing cysts.


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Gastric Torsion in Dogs

Read more >Friday 1st of April 2016: We have in the past few weeks seen a number of dogs suffering from acute bloat caused by torsion (twisting) of the stomach. This is one condition which constitutes a true emergency as these animals need surgery very early in the course of the bloat if they are to be saved.


Death by Chocolate: When to call the vet

Read more >Friday 1st of April 2016: As we enter the time of year where a lot of chocolate is about, we often get phone calls from owners wondering what to do after their pet has possibly or almost certainly eaten some chocolate, or cocoa containing cakes and biscuits.


Treating the Itch

Read more >Friday 1st of April 2016:


Prescription Diets for Skin Disease

Read more >Friday 1st of April 2016: There are many skin conditions that we see on a regular basis, one of the most common being Canine Atopy which is essentially itchy skin caused by allergies. The severity of the disease is variable and can range from mild itching and redness to more severe skin and ear infections.


Case Study - The Bionic Dog and Cutting Edge Technology

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Read more >Friday 1st of April 2016: Arthritis is one of the most common conditions we see in a variety of dog breeds and results in pain, loss of athletic ability, and worst case scenario euthanasia. Hip arthritis is common and can affect both young and old dogs. The primary cause of hip arthritis is excessive hip laxity otherwise known as hip dysplasia.

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