Loobani AcademyAbstract
Infected by canine distemper virus (CDV), canine distemper is a highly contagious infectious disease that can affect not only canines but also a variety of wild animals such as raccoons, skunks, foxes, ferrets and big cats animals (such as lions). Symptoms of canine distemper infection are the respiratory, gastrointestinal, urothelial, central nervous system, and optic nerves. The disease is common in areas with low vaccine coverage, so it can occur globally. In this case, the dog has respiratory symptoms, and I’ll talk about how to diagnose and treat canine distemper infection to give you a better understanding of the disease.
Key words: canine distemper infection, diagnosis, pneumonia.
1.Before therapy
Name: WangWang
Breeds: Border Collie
Age: 4 months old
Sex: Male（no castrate）
History: No
Main problem by the owner
The dog was bought from a kennel and the director fed it at home for two weeks. The owner found it coughed, sneezed, and had a runny nose yesterday, then became depressed, lost appetite, and had diarrhea. This is the first time the owner has fed the dog, and there is no other dog history. The dog has no complete vaccination history (the first dose of Vanguard® Plus 5 was given a month ago) and no deworming history.
2 .Physical examination
The patient in this case was depressed, with pale and dry oral mucosa, arrhythmia, rapid breathing, and a large amount of purulent secretions. The basic physiological body temperature was 39.9°C, the inferred hyperthermia, the heart rate was 120 beats/min, and the respiratory rate was 20 beats per minute. Capillary refill time (CRT) normal (<2s), with a body weight of 2 kg and a moisture assessment of 8%. A small amount of discharge was found in both ears. Lymph nodes were palpated without significant swelling or pain. Induce a positive cough reflex. There was no obvious abdominal response to abdominal palpation.
3.Laboratory examination
3.1 completed blood count（CBC）
Form 1 Complete Blood Count（CBC）result【BC-2600Vet(Mindray)】
Project | Result | Reference range |
WBC | 6.8×103/uL | 6.0~17.0 |
Lymph# | 2.4×103/uL | 0.8~5.1 |
Mon# | 0.3×103/uL | 0.0~1.8 |
Gran# | 4.1×103/uL | 4.0~12.6 |
Lymph% | 35.2% | 12.0~30.0 |
Mon% | 4.7% | 2.0~9.0 |
Gran% | 60.1% | 60.0~83.0 |
RBC | 5.43×1012/uL | 5.5~8.5 |
HGB | 109g/L | 110~190 |
HCT | 36.7% | 39.0~56.0 |
MCV | 64.6fL | 62.0~72.0 |
MCH | 20pg | 20.0~25.0 |
MCHC | 197g/L | 300~380 |
RDW | 13.1% | 11.0~15.5 |
PLT | 836×109/uL | 117~460 |
MPV | 8fL | 7.0~12.9 |
PDW | 18.1 |
|
PCT | 0.668% |
|
Eos% | 1.9% |
3.2 CRP test
The resulT of CRP testing【AnigenV2000】
Project | Result | Reference Range |
CRP | 36.61mg/L | <0.5 |
3.3 Infectious disease sample testing
Examination for infectious diseases【AnigenV2000】
Project | Result | Reference Range |
CDV-AG | 52.6 | <1 |
CIV-AG | 0.3 | <1 |
3.4 X-ray examination
Picture 1 Increased bronchial markings in dog with bronchitis – VD radiograph
Picture 2 Increased bronchial markings in dog with allergic bronchitis – lateral radiograph
4.Diagnosis: canine distemper infection
4.1 Here are the Introduction of the diagnosis methods
Complete blood count: Severe leukopenia is common. Other potential findings include anemia, thrombocytopenia, mononucleosis, and neutropenia.
Biochemical profile: results are normal or variable.Hyperphosphatemia, hypoalbuminemia, and hypoalbuminemia have been reported.
Serology: Antibody titer tests can indicate the presence or absence of protective levels of antibodies against CDV, and in-house test kits are available and reliable. 15,17 Antibody testing helps determine the protection status of previously vaccinated dogs, where vaccination may pose a risk, and helps determine immunity in dogs entering shelters. Please note that for 17 antibody tests, negative titers do not indicate sensitivity. Some immunized dogs may have undetectable antibody levels but are able to mount an appropriate response when exposed to CDV. Internal testing may not accurately distinguish between maternal immunity and innate immunity in 4-6 month old dogs, but 17 IgM levels can be detected in acute cases of canine distemper. It may be present for up to 3 weeks after vaccination with CDV. IgG titers are nonspecific. Elevated IgG titers may indicate current infection, previous infection, or previous vaccination.
Cytology: CDV cytoplasmic and intranuclear inclusions are occasionally found in cells on stained peripheral blood smears or conjunctival swabs/scraps. Inclusion bodies are single, oval, gray bodies up to 3 µm in diameter. Inclusion bodies are more common in lymphocytes and epithelial cells, less common in neutrophils, monocytes, eosinophils and red blood cells. The erythrocyte inclusion bodies are eccentric, round and light blue.
Radiography: Alveolar or interstitial patterns are common in chest radiographs of dogs with pneumonia. Radiographic changes consistent with hypertrophic osteodystrophy may also be noted.
Cerebrospinal fluid (CSF) analysis: In the setting of acute, non-inflammatory encephalomyelitis, CSF analysis may be normal. In chronic CDV encephalomyelitis, elevated protein levels (>25 mg/dL) and cell counts (>10 cells/µL, mainly lymphocytes) are possible and inclusion bodies can be found in the cells. CDV antibody levels can be measured in CSF. Antibody levels in the CSF were not increased in vaccinated dogs or in dogs with systemic disease without CNS infection. However, antibody levels may increase secondary to blood contamination during CSF collection.
Autopsy: Possible pathological changes include diffuse interstitial pneumonia, enteritis, conjunctivitis, rhinitis, thymic atrophy, poliomyelitis, leukoencephalomyelitis, demyelination, neuronal degeneration, and myelin degeneration.
Virus isolation: CDV is difficult to isolate from conventional cell cultures.
Polymerase chain reaction (PCR) testing: PCR testing is a highly specific method for diagnosing CDV. PCR testing can be performed on whole blood, conjunctival swabs, buffy coat smears, and urine sediment. Using a cutoff of 107903 viral particles can help real-time PCR differentiate vaccine interference from wild-type infection. PCR assays are 30% more sensitive than immunofluorescent antibody (IFA) assays in diagnosing CDV.
IFA test: IFA tests can be performed on the conjunctiva, tonsils, respiratory tract, and genital epithelium. Antigens can also be detected in urine sediment and buffy coat samples. Note that immunofluorescence is usually only positive for the first 3 weeks after infection in conjunctival and urothelial samples. Buffy coat samples are usually positive 2-5 days after infection, after which antigen levels begin to decline 8-9 days after infection. CDV persists for at least 60 days in uveal tissue, CNS tissue, skin samples, and footpads.
Immunochromatography: Conjunctival swabs have been subjected to immunochromatography using two anti-CDV antibodies. This assay has higher sensitivity and specificity compared to nested PCR assays. Results from nasal swabs and peripheral blood lymphocyte samples were less sensitive and specific than PCR assays.
Other tests: Virus neutralization and hemagglutination inhibition are the gold standards for accurate detection of CDV antibody protection levels.
4.2 Analysis of this case
In this case, the differential diagnosis was based on clinical signs, physical examination and laboratory tests, including viral infectious diseases (such as CDV or CIV), bacterial infectious diseases and some parasitic diseases. Complete blood count (CBC) and CRP tests showed acute to moderate inflammation. The X-ray and lateral films of VD inferred that the inflammation was caused by bronchitis, which is one of the typical symptoms of canine distemper infection. In addition, the vaccine history in this case is not of our concern, the dogs tested for CDV and CIV infection, and the CDV test was positive and CIV negative. Therefore, we initially diagnosed that the dog was infected with canine distemper. In addition canine distemper is sometimes associated with other systemic infections (eg, leptospirosis, canine hepatitis, rabies, canine respiratory disease, Rocky Mountain spotted fever). So PCR is an important tool to help us make an accurate diagnosis.
5.Treatment
5.1 SPECIFIC THERAPY
There is currently no specific therapy for CDV, and management is primarily supportive. Ribavirin, an antiviral drug that inhibits CDV replication in vitro, has not been thoroughly evaluated in infected dogs. This requires further research.
5.2 SUPPORTIVE THERAPY
Fluid therapy (IV, SC) may be required to correct dehydration and replace ongoing losses. Coupage and nebulization may be beneficial for bronchopneumonia. CDV pneumonia is often complicated by secondary bacterial infection and may also require treatment with broad-spectrum antibiotics. Antibiotic therapy may be required for several weeks, or as a combination therapy. Antiemetic therapy is indicated for patients with vomiting. Dexamethasone can be administered once intravenously at a dose of 1-2 mg/kg to temporarily stop neurological signs associated with cerebral edema. Anticonvulsant therapy is indicated for seizures. Diazepam (5-10 mg IV or rectally) and other drugs can be used to treat status epilepticus. Phenobarbital (10-20 mg/kg IV once effective, then 2-8 mg/kg PO q 12 hours) or other anticonvulsants can be used for acute and maintenance therapy.
RX:
1) Ampicillin: 20 mg/kg PO, IV, SC q8h
2) Interferon: 100IU/kg s.c q24h
3) Anti-CDV protein: 100IU/kg s.c q24h
4) Lactated Ringer + 0.9%NaCl 1:1:60mg/kg/d ivgtt
After 1 week of treatment, the dog’s symptoms were controlled. After 3 weeks of treatment, the dog recovered and the owner took him home.
6.Conclusion
Most of us have heard of canine distemper infection in dogs and thought it was bad. The basic vaccine for dogs is often referred to as the “canine distemper vaccine,” although it also covers several infections in addition to canine distemper. Fortunately, this is the canine distemper that most people have heard of. Thankfully, first-hand experience of this dreaded disease has become limited due to widespread vaccination. However, if you are reading this, you may have a dog suspected of having this dreaded infection. A typical canine distemper suspect is a rescue or pet store dog or puppy, often with a suspicious vaccination history or an uncompleted vaccination series. Dogs or puppies are housed with other rescue dogs or a group of dogs/puppies that are transported together. Symptoms begin with:
Respiratory signs are more common, and mild canine distemper may present with lethargy, decreased appetite, fever, cough, dyspnea, and serous to mucopurulent nasal discharge. Fever can appear 3-6 days after infection, with a second peak a few days later. More severe clinical illness usually occurs in immunocompromised puppies. Fever, runny nose, serous to mucopurulent conjunctivitis cough, dyspnea, vomiting, diarrhea, tenesmus, weight loss, and dehydration may occur. Secondary bacterial infection can worsen the clinical presentation. Neurologic manifestations may appear 1-3 weeks after systemic disease or may occur concurrently with systemic disease. Neurological signs may be acute or chronic and are usually progressive. Possible clinical abnormalities include hyperesthesia, cervical stiffness, vestibular signs, seizures, ataxia, cerebellar signs, paraparesis, tetraparesis, and myoclonus (ie, involuntary rhythmic muscle twitching). Ophthalmic and dermatological findings may also be reported.
Diagnosis and treatment have been covered before, so here I will emphasize monitoring and prognosis to the reader. Antibody titer testing can be used to determine whether enough circulating antibodies are present to prevent CDV infection. Prognosis depends on the virus strain and the immune response of the host. 3 Nervous system signaling is the most important factor affecting prognosis. The prognosis for dogs with neurological signs is considered poor. The reported mortality rate is about 50%. Older dogs with an adequate immune response may be asymptomatic or mildly diseased. Puppies or puppies with an insufficient immune response tend to develop more severe disease. Dogs recovering from CDV may be long-term immune to reinfection and may be immune for life.
Finally, I’ll talk about how to prevent it. Control is accomplished through vaccination. Current vaccines include strains of American ancestry (Onderstepoort or Lederle strains). Immunity can last for years after recovery from a natural infection or after a booster vaccination. CDV vaccination can start as early as 6-8 weeks of age with booster immunizations every 2-4 weeks until at least 16 weeks of age. In puppies or adult puppies vaccinated after maternal immunity has weakened (approximately 16 weeks of age), a single live or recombinant vaccine should be sufficient for protection. In vaccinated older dogs, canine distemper vaccination is recommended annually or every three years, depending on the risk of infection. Customer education about purchasing puppies from crowded pet markets is important. CDVs are susceptible to UV light, heat, drying and all commonly used disinfectants. No vaccine is 100% effective, but regular vaccinations can help protect animals.
