Pansystemic Diseases

Chapter 9 Pansystemic Diseases


Pansystemic diseases include those that involve multiple body systems in addition to the primary target organ. The causes of these diseases may be viral, bacterial, or parasitic, and secondary infections are common. Box 9-1 lists some of the most commonly seen pansystemic diseases of the dog and cat.



Box 9-1 Common Pansystemic Diseases



Feline



• Feline leukemia

• Feline immunodeficiency virus

• Feline infectious peritonitis

• Feline panleukopenia

• Toxoplasmosis


Canine



• Canine distemper

• Canine rabies

• Canine parvovirus

• Ehrlichiosis

• Lyme disease


FELINE PANLEUKOPENIA (FELINE DISTEMPER)


Feline panleukopenia is caused by a DNA virus of the family Parvoviridae, which is closely related antigenically to the canine parvovirus (CPV), type 2. The disease is primarily one of young, unvaccinated cats and feral animals. Transmission is by direct contact or from a contaminated environment. The virus shed into the environment may remain infectious for years.


Feline parvovirus multiplies within mitotic cells of the neonatal brain, bone marrow, lymphoid tissue, and in the intestinal lymphoid tissue, causing destruction of the cells with release of a large number of virions. The incubation period is usually 4 to 5 days. Signs may be peracute, acute, subacute, or subclinical.




CLINICAL SIGNS



• Fever

• Depression

• Vomiting

• Fetid diarrhea

• Dehydration

• Anorexia

• Fetal death, spontaneous abortion, or reabsorption in the pregnant queen

• Cerebellar or retinal defects in neonates


DIAGNOSIS



• Complete blood cell count (CBC): moderate to severe panleukopenia

• Positive fecal test using CITE test for CPV

• Serum antibody titers

• Viral isolation


TREATMENT




TECH ALERT


Isolate these cats from other animals. All body secretions contain virus.



Aggressive supportive therapy



• Maintain hydration and electrolyte balance.

• Force-feed after vomiting is controlled.

• Broad-spectrum antibiotics are required.


INFORMATION FOR CLIENTS



• Cats who survive the infection acquire a lifelong immunity.

• To prevent disease, kittens should be vaccinated between 8 and 10 weeks of age, then again after 12 to 14 weeks. Yearly boosters should be given to all cats. (New vaccination guidelines may be available in the near future.)


FELINE INFECTIOUS PERITONITIS


Feline infectious peritonitis (FIP) is primarily a disease of catteries and multicat households. FIP does not occur without exposure to feline coronavirus. Eighty percent to 90% of cats in catteries have antibodies to feline coronaviruses (mostly feline enteric coronavirus [FECV]), and these cats shed virus intermittently. FECV is highly contagious through the feces, as well as urine and saliva. Current thinking is that this virus may mutate to feline infectious peritonitis (FIPV) within some infected cats. FIPV then enters the macrophages, spreading throughout the body.


FIPV and FECV are difficult to differentiate with current testing procedures. Enzyme-linked immunosorbent assay (ELISA) and immunofluorescence assays are nonspecific for FIPV. Even the polymerase chain reaction cannot differentiate the two viruses.


FIP occurs in two forms: the effusive, or “wet,” form (75%) and the noneffusive, or “dry,” form. About 45% of cats that have the dry form will have ocular or neurologic lesions. In the effusive form, perivasculitis results in the accumulation of a protein-rich fluid in the thoracic and/or abdominal cavity, the scrotum, the pericardial cavity, and the renal subcapsular space. The inflammatory process may also involve the liver and the pancreas. The clinical progression is more rapid than with the dry form.


Signs of noneffusive FIP are vaguer. The pyogranulomatous lesions may be found anywhere in the body, especially the eyes and the neurologic system. Clinical signs may include ataxia, seizures, behavioral changes, paresis, and/or hyperesthesia. Ocular signs include iritis, retinitis, uveitis, hyphema, corneal edema, retinal hemorrhage, and retinal detachment.




CLINICAL SIGNS



Wet form



• Ascites, pleural effusion

• Anorexia

• Depression

• Weight loss

• Dehydration

• May or may not be febrile


Dry form



• Fever of unknown origin

• Anorexia

• Depression

• Weight loss

• Ocular lesions

• Neurologic signs

• Enlarged kidneys (uncommon)


DIAGNOSIS



• Clinical signs

• Rule out other diseases

• Cytology and chemical analysis of abdominal and pleural fluid show the following:
Viscous, clear to yellow fluid

Less than 20,000 nucleated cells/μl

Protein-rich (>3.5 g/dl)

Albumin/globulin ratio <0.81

• High antibody titers may be suggestive of FIP


TREATMENT



Supportive



• Aspirate pleural/abdominal fluids to make cat more comfortable

• Steroids (daily)

• Broad-spectrum antibiotics


Immunotherapy



• ImmunoRegulin

• Ribavirin and adenine arabinoside inhibit FIPV in cell culture (clinical effect unknown)


Prevention



• Isolate pregnant queens 2 weeks before giving birth.

• Remove weaning kittens from queens by 5 weeks of age.

• Vaccinate seronegative cats with Primucell FIP (Pfizer), an intranasal vaccine, at 16 weeks of age. This drug provides good protection against FIP but is ineffective in cats already exposed to FECV.


INFORMATION FOR CLIENTS



• The virus is inactivated in the environment by most household disinfectants.

• Diagnosis of this disease can be difficult and may require a series of expensive tests to rule out other possibilities.


FELINE LEUKEMIA VIRUS


Feline leukemia is caused by a retrovirus that is associated with both neoplastic and nonneoplastic (immunosuppressive) disease. Both vertical and horizontal transmission occurs. The virus is unstable in the environment; therefore, close contact between cats is required for infection to occur. The virus can be isolated from saliva, urine, tears, and milk, and it can be spread through fighting, grooming, or exposure to contaminated food bowls, food, water, or litter pans. Transplacental and transmammary transmission does occur. The outcome of exposure to the virus is variable and depends on several host factors: age, immunocompetence, concurrent disease, viral strain, dose, and the duration of exposure.


Exposed cats may experience development of the following conditions: (1) a regressive infection (transient), (2) a progressive infection (persistent viremia) with no clinical signs, or (3) active infection with clinical signs. Clinical signs associated with feline leukemia virus (FeLV) include anemia, anorexia, depression, weight loss, nervous system disease, and secondary infections. Vomiting and diarrhea may be seen if the gastrointestinal tract is involved.


Lymphoma is the most common FeLV-associated neoplastic disease. Tumors can occur in the thymus, the alimentary tract, or various lymph nodes throughout the body.


Treatment is primarily supportive, and prevention is through vaccination and limited contact with infected cats. All cats should be tested for FeLV using the standard peripheral-blood ELISA test before vaccination. If positive, cats should undergo an immunofluorescent antibody (IFA) test or be retested by ELISA in 3 to 4 months. Cats with recurring positive results will usually be positive for life and should be isolated from all other nonvaccinated cats. Many may remain in good health for prolonged periods if not stressed.




CLINICAL SIGNS



• Fever

• Anorexia

• Weight loss

• Anemia

• Secondary infections

• Vomiting and diarrhea

• Spontaneous abortion

• Renal disease

• Tumors of lymphoid origin

• Neurologic signs


DIAGNOSIS



• FeLV positive on ELISA test

• CBC: nonregenerative anemia

• IFA: positive

• Clinical signs of recurring infections


TREATMENT



Husbandry



• FeLV-positive cats should be isolated from all other cats.

• FeLV-positive cats should be kept indoors.

• FeLV-positive cats should be vaccinated for other feline diseases and rabies on a routine schedule.

• Eliminate stress in affected cats.


Medical



• No cure currently exists for FeLV; however, drug therapy may alleviate symptoms

• Immunomodulator drugs:
Acemannan (CarringtonLab): orally (PO), subcutaneously (SQ) daily, or intraperitoneally (IP) once a week for 6 weeks

Propionibacterium acnes (ImmunoRegulin): intravenously (IV) 1 to 2 times weekly

Human recombinant interferon-α (r-HuIFN-α [Roferon, Roche Pharmaceuticals]): every 24 hours PO for 7 days, repeated every other week

• Antiviral drugs:
Azidothymidine (AZT; Zidovudine): PO every 12 hours

9-(2-phosphomethoxyethyl) adenine (PMEA): SQ every 12 hours



TECH ALERT


These drugs are toxic to bone marrow. Cats should have hemograms reevaluated frequently during treatment. Limit treatment to 3-week course to avoid marrow toxicity.



• Broad-spectrum antibiotics to control secondary infections

• Appetite stimulants:
• Oxazepam (Serax, Wyeth Laboratories): PO

• Diazepam (Valium, Roche Pharmaceuticals): IV

• Chemotherapy for solid tumors


INFORMATION FOR CLIENTS



• A healthy FeLV-positive cat does not need to be euthanized.

• If your cat is positive for FeLV, you should do the following:
Keep the animal indoors.

Isolate from all other cats.

Keep up with vaccinations.

See your veterinarian if any signs of disease develop.



TECH ALERT


The public health significance of FeLV is controversial. The virus does grow in human cell cultures, although there is no evidence of the infection in any nonfeline species. However, immunosuppressed humans, pregnant women, and neonates should not be exposed to FeLV-positive cats.



FELINE IMMUNODEFICIENCY VIRUS


Feline immunodeficiency virus (FIV, or feline AIDS) is a lentivirus associated with an immunodeficiency disease in domestic cats, which is morphologically and biochemically similar to the HIV virus but is antigenically distinct. FIV is highly species specific, growing only in feline-derived cells. Most infections are acquired by horizontal transmission among adult cats. Male, sexually intact cats living outdoors are at greatest risk for acquiring FIV infection. Fighting and bite wounds appear to be the major route of transmission. There is little or no sexual transmission in cats. Neonatal kittens may become infected by contact with infected queens, although plasma antibodies against FIV may be passed to kittens in colostrum when nursing. Because the ELISA test for FIV detects antibodies, kittens should not be diagnosed using these tests until after 6 months of age.


Clinical signs of FIV involve chronic, unresponsive infections (gingivitis, stomatitis, and skin, ear, and/or respiratory tract infections), anemia, ocular and/or neurologic signs, and weight loss. Chronic fever and cachexia are common findings. Cats may remain asymptomatic for long periods after infection or may suffer from recurring bouts of illness interspersed with periods of relatively good health. Cats infected with FIV are at increased risk for development of chronic renal insufficiency.


Prevention of infection is by limiting exposure to outdoor cats. Spaying and neutering outdoor cats can limit exposure by decreasing aggressive behaviors. A vaccine for FIV currently is available. Cats receiving this vaccine may test positive for FIV at a later date.




CLINICAL SIGNS



• History of recurrent bouts of illnesses

• Cachexia, anorexia

• Gingivitis, stomatitis

• Chronic, nonresponsive ear or skin infections

• Chronic upper respiratory infections

• Diarrhea

• Vomiting

• Neurologic disorders

• Ocular disease (anterior uveitis, glaucoma)

• Pale mucous membranes

• Chronic fever


DIAGNOSIS



• Clinical history

• Positive ELISA test (blood)

• CBC: anemia, lymphopenia


TREATMENT



Husbandry



• Keep infected cats indoors.

• Isolate if aggressive to other cats in the household.

• Transmission from fomites or casual contact is unlikely.


Medical



• No cure currently exists for FIV; however, drug therapy may alleviate symptoms

• Immunomodulator drugs:
Acemannan (Carrington Labs): PO, SQ daily, or IP weekly for 6 weeks

ImmunoRegulin (Immunovet): IV 1 to 2 times weekly

Interferon-α (Intron-A, Schering-Plough): 30 IU/cat PO every 24 hours for 5 days on alternate weeks

• Antiviral therapy: AZT (Retrovir, Glaxo-Wellcome): PO every 12 hours; if anemia develops, stop medication until CBC returns to normal, then restart at previous dose and increase to original dose over 1 to 2 weeks


Surgical



• Whole-mouth extraction of teeth may be necessary in cats with chronic stomatitis and gingivitis.


INFORMATION FOR CLIENTS



• FIV poses no health hazard for humans.

• Infected cats may survive for prolonged periods before experiencing advanced stages of the disease.

• For cats with severe gingivitis and stomatitis, tooth extraction may be the best course of treatment. Cats are able to eat well even after whole-mouth extractions.

• Keeping your pet indoors will prevent infection.

• Keeping an infected cat free from stress and concurrent disease is extremely important.

• A vaccine is available for this disease; however, cats that receive the vaccine may test positive for FIV on later examination. Owners should be aware of this.


TOXOPLASMOSIS


Toxoplasmosis is caused by Toxoplasma gondii, an intracellular coccidian parasite with worldwide distribution. The feline is the only definitive host, but other warm-blooded animals, including humans, can serve as intermediate hosts. Exposure to Toxoplasma is common; an estimated 30% to 60% of adult humans are seropositive for exposure.


Transmission can occur by three routes: (1) eating contaminated meat from an intermediate host, (2) fecal-oral route, and (3) transplacental route. In carnivores, ingestion of infected intermediate hosts is responsible for most infections.


Once sporulated oocysts are ingested, tachyzoites form and invade any tissue in the body. Clinical signs of disease are related to the tissue involved. The disease may be especially severe in immunocompromised animals or in very young animals. In the cat, the two tissues most commonly involved are the lung and the eyes, whereas in the dog, the gastrointestinal, neurologic, and the respiratory systems are commonly infected. However, Toxoplasma infections are rare in the dog.


After infection, the cat sheds oocysts in the feces for 1 to 2 weeks. Because of this limited shedding of organisms, exposure to these infective oocysts is probably not an important source of infection for humans and other cats. Ingestion of uncooked or undercooked meat is most likely the main route of infection in both cats and humans. Therefore, prevention of infection involves eliminating hunting and feeding of raw meat to the cat, cooking all meat properly before feeding, and following good hygiene practices when handling cat feces.


Humans who are immunosuppressed should avoid contact with infected cats. Congenital infection in the first or second trimester can result in serious birth defects. Although infected cats are unlikely to pose a major threat to most pregnant women, the following steps can be taken to prevent infection:


• Avoid feeding raw meat to cats.

Related posts:

  1. Diseases of the Endocrine System
  2. Diseases of the Nervous System
  3. Overview of Ferrets, Rodents, and Rabbits
  4. Diseases of the Musculoskeletal System

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Aug 31, 2016 | Posted by in GENERAL | Comments Off on Pansystemic Diseases

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