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Newsletter 4 March 2018 - Spirocerca Lupi

 Dear dog breeding enthusiasts

Look at our website for more information on dog reproduction http://www.rantendal.co.za.

Semen can now be frozen on demand at our premises with as little as 1 weeks’ notice. Contact Gigi at reports@rantendal.co.za to make a booking. 

Newsflash about emerging disease (Spirocerca Lupi)

Spirocerca lupi (worm in the throat or esophagus) has increased at an alarming rate. We are now confirming cases on almost a daily basis. The problem has now escalated to a stage where we can no longer just adopt a wait and see approach and only act once a dog within the household or colony is diagnosed. Dog breeders at risk should strongly consider introducing monthly preventative treatment of their dogs. Breeders of large to medium breeds are at increased risk. Other risk factors are, residing on large properties, small holdings and farms as well as co habitation with other animals. Although the above puts breeders at increased risk, other breeders should not assume that if they are not on large premises they are free from risk. Ordinary pet owners are also frequently affected anywhere in Gauteng and other areas over South Africa. Within a South African context, it is not true that Hadida,s or their stools are the main culprits. Many bird species and other species are all involved. Preventative treatment is key. We do not advocate embarking on a killing spree of hadida and other wildlife suspected to be intermediates.

Some breeders have already been administering preventative treatment for years. Breeders that are sceptic about preventative treatment should speak to others that have extensive experience in preventative treatment. Besides controlling Spirocerca Lupi, these products also have some efficacy against other worms and good efficacy against skin and ear mites. Numerous products are now available but the jury is not out as to which are best. Cost of some may be prohibitive whilst others are relatively cheap and all indications are that they are effective as well. New products are likely to become available and we will let you know if they do. We are frequently asked if the products are safe during pregnancy. The answer is that we think they are as we have not seen adverse reactions in pregnancy and have used them in pregnant dogs. The companies producing these products however state that “safety during pregnancy and lactation has not been established”. We therefor recommend that they are not used during pregnancy or lactation and only use them in bitches when they have been diagnosed with Spirocerca and happen to be pregnant as well. Also, breeders ask at what age we may start treating dogs preventatively. We do not have clear answers here either but starting at six months of age appears safe. Breeders have to clearly understand that they should be in close consultation with their veterinarian regarding the use of any product in this regard. This is so because these products are potentially fatal in some breeds and almost none are registered for use in dogs. Routine preventative treatment thus becomes a decision made by the breeder in consultation with their veterinarian based on the individual risk benefit assessment of each individual case. Those that surf the internet will notice that in the USA, many breeder advice forums advise not to use long acting avermectins against heartworm but rather use the short acting products in breeding males and bitches. This is because they are not sure whether the long acting products have effects on fertility or not. The problem with Spirocerca Lupi however is that we have no alternative. These heartworm remedies are not effective at all against Spirocerca Lupi. It would be irresponsible of any professional to make any claims one way or another but evidence in practice over many years suggests that there is no problem using them. The breeder has to weigh up the risk of anecdotal reports of possible harm against the reality of fatal and devastating Spirocerca Lupi in their Kennels.

However, once the breeder has been fully informed about the risks of treating and risks of not treating, the breeder of the dogs takes full responsibility for outcome. Some procducts that have claimed efficacy are available but are rather expensive and others may emerge soon. Please read the following article very carefully.

 Topic 2 Spirocerca Lupi  in breeding kennels

Spirocerca Lupi is a nematode (roundworm) that is found primarily in dogs (but also wild carnivores) and occurs throughout the world in warmer to temperate climates. It is not a new parasite but seems to be more prevalent in recent years. The exact reasons for its recent emergence is not known but adaptation of its intermediate host to colder climates (temperate versus subtropical) is speculated to play a role. The adult worm lives in the oesophagus of dogs where it embeds itself in the oesophageal wall and forms large nodules which may later become cancerous. Infected dogs will usually have 2-4 nodules but many more are also possible. Whilst in the oesophageal nodules, the adult worm produces eggs that are shed in the dog’s stool. The eggs are then ingested by dung beetles which act as the intermediate host. The dog can be infected by directly eating the dung beetle or eating the lizard or bird that has ingested an infected beetle. Once in the dog’s stomach, the worm larvae enter intestinal blood vessels and travel to the aorta where they may mature (this may take up to 4-6 months). Following this migration, they pass through the wall of the arteries into the wall of the oesophagus. En-route they cause damage to the blood vessels which may cause aneurisms. Aneurisms are weakened areas in the walls of arteries which in time may bulge (balloon) due to the blood pressure. Dogs with aneurisms may not show symptoms and appear perfectly normal. Aneurisms require specialised equipment to diagnose and small ones may be missed. When the aneurism bursts however, the dog will die within seconds from massive internal haemorrhage. Spirocerca Lupi is therefore a common cause of sudden unexplained death in areas where the worm occurs. Most frequently however, they just cause lumps in the oesophagus that slowly grow bigger. Initially when the lumps are about pea size they do not cause any problems and the dog shows no visible signs of infection. As the lumps grow bigger the dog may show a poor appetite, lose weight, start regurgitating food after meals, gagging, show a low grade fever and appear listless. Anaemia and presence of dark to black stool due to the presence of half-digested blood in stool (melaena), may also be noted in advanced cases. Although most worms will migrate to the oesophagus as final destination, in rare cases, the worm migrates to other sites (called aberrant migration) and may end up in brain, eye, spinal cord, skin or any other tissues causing a variety of symptoms depending on location. In long standing cases, the lump in the oesophagus may become neoplastic (cancerous).

Although dogs of all sizes may be infected, dogs of large breeds are more commonly affected than smaller breeds. All ages may be affected with a peak incidence between 1-4 years. The habit that some dogs have to eat their or other dog’s stools or even stools of other species (all called coprophagia), clearly increases risk of ingestion of dung beetles and thus infection. Agile athletic dogs that frequently catch birds, lizards or small mammals are also at increased risk. The risk increases if the dogs actually consume the meat of their catch. Dogs belonging to multiple dog households are more likely to be infected as are dogs residing on large properties. Co-habitation with other farm animals also increases risk of infection. The biggest risk factor of all appears to be the presence of at least one infected dog in the colony. This dog may act as source of infection to dung beetles and indirectly to other in-contact dogs. The practical significance is, that if one dog in the colony is diagnosed with Spirocerca Lupi, not only are the other dogs at risk for infection, but the chances are great that at least some of the dogs are already infected as well.

Even though the clinical signs may lead to the suspicion of Spirocerca Lupi infection, special tests are required to confirm this. Radiographs of the chest and stool examination for worm eggs may be helpful in this regard but is not sensitive as many cases can be missed using these diagnostic modalities. Oesophagoscopy (looking down the throat with small flexible endoscopic camera) is the most accurate means of diagnosis. Only the smallest nodules, as is found in the start of the infection, will escape detection. This procedure requires full anaesthetic It is important that early diagnoses of infection is made whilst the nodules are still small as this favours outcome of treatment. Advanced cases with large granulomas respond poorly to treatment and if the lump has progressed to cancerous transformation, treatment is not possible. Advanced cases may therefore have to be euthanized. Surgical excision of the nodules has been attempted but is associated with high mortality rates.

Treatment of infected dogs is the only option in dogs not euthanized as all untreated dogs usually die from complications. Earlier cases may respond to some avermectin containing formulations. Treatment may stretch over a period of six months or longer. Generally, the earlier the treatment commences, the higher the success rate.

Preventative measures include the regular removal of dog faeces to prevent colonization by dung beetles (which usually happens within minutes). The faeces should be disposed of in a manner that ensures it is not accessible to dung beetles, birds, small mammals and reptiles, which may all spread the larvae of this parasite. Dead birds either caught by the dogs or dragged into the garden by cats should be removed immediately to prevent ingestion by the dogs. In one study the administration of avermectins at regular intervals (4 weeks) did reduce the incidence of the worm infestation and reduced fatalities significantly. Breeders residing in areas where the risk of Spirocerca Lupi infection is high, should strongly consider on-going preventative treatment using an avermectin contain product. Many breeders have been doing this for years in any event because it has some efficacy against other worms and very good efficacy against ear and skin mites. Numerous registered and unregistered (for dogs) avermectin containing products exist on the market in most countries. It is very important that breeders be aware that some breeds are genetically susceptible to adverse reactions to some drugs in the avermectin group. A single administration of these drugs to susceptible dogs may prove fatal. The known susceptible breeds are Border collie and other collie-types. Individual dogs of other breeds may also carry the gene determining susceptibility to these drugs, albeit it very rare. Fortunately there is a genetic test available to determine whether a dog carries the gene (MDR1) or not. Affected breeders may opt to test all individual dogs for the presence of the gene prior to preventative treatment. Due to the cost of individual gene testing and very low risk in most breeds, some breeders opt to treat without prior gene testing. It is fair to speculate that the emergence of Spirocerca Lupi and associated threat to dogs in some parts of the world will lead to routine preventative treatment of all dogs in that area as is already the case with Dirofilaria immitis (heartworm). Affected breeders should consult their veterinarians regarding treatment and preventative treatment options before randomly administering drugs to their dogs. Most anthelmintic (deworming) agents including heartworm remedies, used for routine deworming of dogs, are not effective in either treating or preventing Spirocerca Lupi infections in dogs.

Breeders of dogs that are mainly outdoors should strongly consider using monthly preventative treatment against Spirocerca Lupi. It is not worth losing valuable breeding stock to a very much preventable parasite.

More information about breeding matters can be obtained from our website and my book “Breeding is a bitch”. For further details go to http://www.rantendal.co.za.