Dr. Revital Netta

Dr. Revital Netta

Dr. Revital Netta is a practicing veterinarian, specializing in domestic animals. She graduated in 2015 from the Koret School of Veterinary Medicine - Hebrew University of Jerusalem. After receiving her DVM Revital began practicing at Yokneam Medical Centre, treating mainly dogs and cats by medicine and surgery. In addition to her veterinary practice, Dr Netta supervises Biogal’s regulatory affairs and product management.

Why did the veterinarian order the vaccination of the puppy with core vaccine component, 3 times at 3-week intervals?

For over a decade canine vaccine has been categorised into core, non-core and non-recommended groups, with canine distemper, parvovirus and adenovirus considered as the core vaccine components. These categories have been further developed and currently form the basis of the World Small Animal Veterinary Association (WSAVA) Guidelines for the Vaccination of Dogs and Cats.

With regard to vaccinations of puppies, the WASVA guide lines recognizes that maternally derived antibody (MDA) significantly interferes with the efficiency of most current core vaccines administered to pups and kittens in early life. The vaccine consists of attenuated living virus and therefore the antibodies identify it and lead to its destruction. As the level of MDA varies significantly amongst litters, the guidelines recommend the administration of multiple core vaccine doses to pups and kittens, with the final dose of these being delivered at 16 weeks or older and then followed by a booster at 6- or 12-months of age.

Vaccination of neonates and infants is problematic with two main issues: the immature immune system of neonates and the presence of inhibitory maternal antibodies.

When a pup is born, its immune system is not fully developed making it susceptible to a variety of infectious agents. Fortunately, this is not the case for most of the neonatal, as they can receive passive protection from their mothers through maternal immunity.

Passive immunity occurs by the passage of antibodies to the fetus through the placenta (~3%), and more significantly, by the absorption of maternal antibodies of the new born through the colostrum (~97%). Defined as the first 12-24 hours of milk flow following birth, colostrum is a highly concentrated mixture of large protein antibody molecules, vitamins, electrolytes, and nutrients. The pup can absorb the colostral antibodies into its blood system through the intestine only for its first days of life; the amount of absorption depending on the strength of each individual pup.

Unfortunately, the maternal antibodies will break down through natural aging of up to approximately 8-20 weeks. At this point the MDA decaying (Blue line in the graph below) may not provide optimal protection and may even act as inhibitor to the effectiveness of the vaccine (In between the two interrupted lines ~8-16 weeks). This situation is highly risky for the exposed and unprotected puppy. To avoid this situation the core vaccines are being given at 3-4 point intervals, as shown in the graph below.

 

 

Initial Vaccination (Dogs 16 Weeks of Age)

  • Beginning as early as 6 weeks of age, the puppy is administered with sequential doses of a combination vaccine at an interval of 2 to 4 weeks until at least 16 weeks of age.
  • Dogs that are 16 weeks of age when presented for initial vaccination should receive a second dose 2 to 4 weeks later.
  • NOTE: Dogs residing in a HIGH-RISK environment may benefit from receiving a final dose at 18 to 20 weeks of age. HIGH RISK is a subjective assessment applicable to dogs residing at locations in which the incidence of CDV and/ or CPV is considered to be high; it may also include puppies known to have significant exposure to other dogs or contaminated environments.

Revaccination (Booster)

  • A single dose of a combination vaccine is administered within 1 year following the last dose in the Initial Vaccination series. Subsequent boosters should be administered at intervals of 3 year or longer.
  • Measuring antibody levels (quantitative or qualitative) provides a reasonable assessment of protective immunity against CDV, CPV, and CAV2.
Wednesday, 08 August 2018 11:35

VacciCheck for disease detection

A vet, having encountered a large number of kittens suspected of Panleukopenia (FPV), approached us at Biogal. The kittens in question were of a private home cattery. The owner noticed that two of the kittens were in a very poor condition. The two sickly kittens were brought to the clinic for hospitalization with a suspicion of FPV. None of the kittens had been vaccinated.

The suspected disease was due to a compatible blood results (Low white blood cells) and suggestive clinical signs.

Slowly, at the cattery, other kittens began to show signs of lethargy, diarrhoea and a lack of appetite.

Feline Panleukopenia Virus (FPV), also known as Feline Infectious Enteritis, Feline Parvoviral Enteritis and Feline Ataxia, is a viral infection affecting cats. It is caused by Feline Parvovirus, Fast progressive with an incubation time of ~2-10 days, highly contagious and can be fatal. The name Panleukopenia comes from the low white blood cell count (Leucocytes) exhibited by affected animals.

Knowing how fatal and highly contagious FPV can be, the owner knew that something had to be done for the sickly and the still healthy kittens. Early treatment and possible isolation of the unaffected kittens, would be wise.

She was glad to hear that the exposed kittens could be differentiated from the healthy ones by using Feline VacciCheck, a simple in-house blood test.

Feline VacciCheck measures IgG antibodies specific to FPV. IgG antibodies rises within days to weeks after exposure to the disease or to vaccination and persist for a long period. In cases with no vaccination history and suggestive clinical signs of the disease the presence of IgG can support the diagnosis.

In young kittens the presence of IgG could be from Maternally Derived Antibodies (MDA). The MDA passively pass to the kittens through colostrum on their first hours of life and disappears within a few weeks from their blood stream.

In this case none of the kittens had been vaccinated. Most of the kittens were estimated to be around 5 months old, where the presence of MDA is less likely. Therefore, the presence of IgG antibodies probably will indicate exposure and will require a close monitoring of the kittens who are at risk and proper disinfection actions to the whole cattery.

Feline VacciCheck testing was run on eleven kittens in the cattery:

 

The other two antibodies tested are two highly contagious respiratory diseases: Feline Herpes Virus (FHV) and Feline Calici Virus (FCV).  

The kittens who showed positive results to all the 3 pathogens, are perhaps those with MDA presence (younger kittens) or those who were exposed to all these 3 diseases (which is very likely in a very crowded cattery).

The two negative FPV kittens were isolated from the others. The whole cattery was properly disinfected with solution of diluted bleach.

All the other kittens, positive FPV IgG, were closely monitored. Being positive means that they had been exposed to the disease but would not necessarily develop the disease. This would depend on the individual immune system of each kitten.

After further investigation, these results were validated using a PCR (Biogal PCRun) technic which confirmed the presence of the panleukopenia virus in all positive kittens.

In total, five out of the nine positive kittens who were closely monitored showed clinical signs and were treated promptly. Thanks to early diagnosis and treatment, the recovery was quick and successful for all five kittens.

Recently, a veterinarian from a large clinic contacted me as he suspected Parvo disease in "Tommy”, a five month old mixed breed dog.

Tommy was adopted a few months ago from a shelter and since then he has begun receiving all three-core vaccines - Canine Parvo Virus (CPV), Canine Distemper Virus (CDV) and Canine Adeno Virus (CAV), according to the recommended protocol (which is from the age of 8 weeks, at 3 week intervals).

About a week after receiving his last vaccine injection, Tommy began to show suspicious signs of Parvo - loss of appetite, lethargy and watery diarrhea. A blood count test showed no Parvo signs. Tommy was hospitalized because of his poor condition, and still the suspicion for Parvo.

1st Titer Test Result

We ran Tommy’s blood sample using VacciCheck in order to get the full picture of his immune status and response to the vaccines. We realized Tommy's immune system responded well to the distemper vaccine and to the Adenovirus vaccine components. However, and amazingly so, no response to the Parvo virus component was seen

A possible reason for not responding to the vaccine, may be genetically based; Non-Responders who cannot respond specifically to one of the vaccine components (1: 1000 for Parvo, 1: 5000 for Distemper, and 1: 100,000 for Adenovirus). Potential additional reasons may be the presence of maternal antibodies that interfere with the vaccine (which is not common at the age of 5 months), or any other cause like improper vaccine manufacturing or storage which can lead to a non-response to the vaccine.

Two days after being hospitalized, Tommy’s blood count tests showed clear signs of Parvo (↓↓↓Whole Blood Count).

2nd Titer Test Result

We are glad to note that Tommy recovered. Sufficient Parvo antibodies were found by using VacciCheck, showing the unlikelihood that Tommy is a genetic Non-Responder.

 Parvo is a very contagious disease, with high morbidity and mortality rates. The disease breaks out very quickly by attacking dividing cells, such as the cells of the intestine, causing severe diarrhea and bone marrow cells, which aggravate the condition due to secondary infections. 

Untreated dogs could die within 2 days after signs of illness appear. The survival percentage in treated dogs is 68% - 92%.

My take home message: in order to be sure that your beloved puppies are protected from this severe disease, it is possible to verify protection by a simple examination, and so avoiding unnecessary suffering and long and expensive hospitalization.

At the start of my work as a vet, the owner of an elderly female dog, Ginger, with a chronic renal disease, brought her in to receive the annual vaccination [core diseases vaccines, Canine Parvo virus (CPV), Canine distemper virus (CDV) and Canine adeno virus (CAV)].

The first question was “is it really necessary to automatically revaccinate every year for core vaccines, especially in an elderly dog with chronic health problems?”.

Intrigued by the question, I looked for answers.

I have come across a number of studies showing proof that core diseases vaccines may last for several years. The high prevalence of adequate antibody levels in a large population implies that annual revaccinations against CPV, CDV and CAV aren’t necessarily needed.

The scientific arguments in favour of less frequent revaccinations are traditionally based on antibody titers. Protection against most viral diseases is indeed antibody-mediated, and antibodies are easily measured.

Due to these findings the WSAVA (World Small Animal Vaccination Association) Vaccination Guidelines states “The presence of antibody (no matter what the titre) indicates protective immunity and immunological memory is present in that animal. Giving more frequent vaccines to animals in an attempt to increase antibody titre is a pointless exercise. It is impossible to create ‘greater immunity’ by attempting to increase an antibody titre.”

Ensuring Ginger was immunized, I took a blood sample and ran the VacciCheck antibody test for the presence of antibodies against core disease. Results were conclusive -  Ginger was immunized with regard to all the three core diseases, and so no need for further vaccination.

 

*Ginger's titer test results by VacciCheck

Needless to say, Ginger's owner was delighted.  I imagine that Ginger was delighted as well… 

Feline VacciCheck - A Case Study About the Need to Validate After You Vaccinate

Wednesday, 11 April 2018 16:54

Yearly Re-Vaccinations

“Doctor, why does my dog get yearly revaccinations when neither of my children nor I get vaccinated every year?”

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