Diseases #29
Rat Poison causes clinical diseases in dogs and cats. The majority of them are lumped into a group known as Anti-Coagulant Rodenticides (ACR). The main cause of clinical disease is produced by the anticoagulant effects of these chemicals.
Rat poisons are put out mainly to keep rodents away from feed, homes, plant nurseries and garages. In my Ohio practice, I saw numerous poisoning cases in the fall months. This is the time of year when it is getting colder and rodents want to find places to stay warm. Out come the rodenticides!
Rodenticide Anti-Coagulants inhibit the effectivity of Vitamin K. This is a fat soluble vitamin that is responsible for many clotting factors in the blood. ACR compounds vary in the commencement of clinical signs. Some occur within hours after ingestion, others take at least a week to produce clinical signs of bleeding.
Anti-Coagulant effects following rat poison ingestion can occur anywhere in or on the body. Internal hemorrhages can occur in the brain leading to neurological signs such as seizures. Bleeding can occur in the chest leading to respiratory signs. Bleeding into the abdomen causes abdominal distention and loss of circulating blood. The result of all of this is that the animal can and often does go into shock and is presented recumbent. It can not sit up on its own. Pale mucous membranes plus rapid respiratory and heart rates and difficulty breathing are secondary to the blood loss. Petequiae and or echhymosis can occur on the skin. These are localized areas of subcutaneous hemorrhaging. Blood may be passed in the vomitus as well as in the stool or in nasal discharges.
Many times an animal is presented with signs of hemorrhaging and the owner is not sure of any contact with a rodenticide. Time is of the essence. Two immediate simple tests should be performed. A hematocrit and clotting time of the blood. Blood that is drawn into a syringe is watery and will almost never clot. Usual clotting time is about 6 minutes. A hematocrit also known as a packed cell volume tells whether or not there is a loss of red cells. In the case of rat poisoning it is always lower due to the blood loss in body cavities. CT scans can also be performed but you have to move fast in clinical cases.
A diagnosis of rat poison can be made if the owner saw an animal ingest a rodenticide. If a history is unknown, the time of year may be helpful. Many times clinical signs of rodenticide poisoning mimic those of car accidents. I usually looked for scrapes and road debris embedded on the animal as well as any fractures produced by trauma to figure out if this was a rodenticide or a car accident. Clotting time usually gives it away.
Even if a patient may have been exposed to rat poison or may have eaten the product, I still treat them to be on the safe side. The treatment of choice are multiple injections of Vitamin K. This compound literally saves lives. Animals are always hospitalized with intravenous fluids to support blood pressure. Hetastarch, Dextran® or other high molecular weight colloids are given to also support blood pressure. Ideally, patients would receive whole blood transfusions that include red cells and platelets. Once animals are stabilized they may be sent home on an oral vitamin K product known as Synkavite® (vitamin K3). Even though dogs are carnivores, feeding dark leafy vegetables such as spinach are helpful. Dark leafy greens are rich in vitamin K.
These can be extremely rewarding to treat. Years ago, I had a beautiful Golden Retriever presented with signs suggestive of a hit by car (HBC). I queried the owner about rodenticides and he was unaware of any. The animal already had fluids going in via an IV line. I decided to check the dogs clotting time. The blood would not have clotted in 100 years! Vitamin K and supportive care were given. The following morning, the dog was dying to get out of its cage. I personally took the dog out on a leash to meet the owner. I let the dog off of the leash. The dog ran into the open arms of his master. Saving a life had to be the most rewarding part of being a veterinarian. I will never forget that moment in time.
The prognosis for rat poisoning depends upon the location of clinical signs and whether or not a toxic dose of the rodenticide was ingested. There are rodenticides available that cause different times when coagulation becomes impossible. Just because your dog is not showing clinical signs after ingestion, does not mean that they are not going to happen.
Prevention of the condition is the best bet. Keep all rodenticides out of reach of all pets AND children. If dead rodents are found after putting out rodenticides, make sure they are removed so that a dog can not ingest them.
Cats rarely suffer from rat poison problems. I think this has to do with how picky a cat is. A cat has to walk around a food and sniff it a 100 times before it will even lick it. This cat behavior explains why many cats do not suffer from poisonings. Anyone that has tried to hide amoxicillin drops mixed into a can of tuna will understand the concept.
A retro orbital abscess is one that is located around the eye. It often forms above and around the medial canthus (inner corner of the eye near the nasal planum) of either eye. The most common cause is a foreign body, tumor or an infected upper molar that sets up a bacterial infection in the area.
The most common cause of a retro orbital abscess is an infected upper molar. In either case, bacteria penetrate dorsal (above) and an infection commences. Components of infection are inflammation and pus produced by the invading bacteria. This than becomes an abscess that is extremely painful.
The most common clinical signs are: extreme pain in opening the mouth, anorexia, fever, a hot swelling around the medial canthus of the eye, lethargy, enopthalmos (the eye is pushed inward making it appear smaller) and an elevated third eyelid.
A CBC and Chemistry profile should be completed. An elevated white cell count is usually present due to the abscess. Radiographs or ultrasounds of the area will delineate the abscess shape and location.
Diagnosis is made by the presence of a fluctuant, warm abscess below the eye and associated clinical and lab signs. An oral exam will demonstrate an infected upper molar, foreign body or a tumor.
Treatment is oriented towards treating the abscess and eliminating the primary cause. The abscess is usually drained through the hard palate on the affected side of the mouth. The area is flushed with hydrogen peroxide and infused with Panalog® or facsimile. The animal is put on a broad spectrum antibiotic. Abscess contents can be cultured and than one can select the appropriate antibiotic that is sensitive to the bacteria. Staphylococcus sp, Clostridium sp and Pasteruella sp are common invaders. The foreign body is removed and the infected tooth root may need to be split and than extracted. Tumors of the area may require radiation or chemotherapy. Warm compresses and Rimadyl® will help relieve the pain and discomfort.
The prognosis for retro orbital abscesses caused by foreign bodies or infected molars is good. When tumors are involved the abscess may resolve but the tumor will often cause abs cessation to relapse over time.
Feline Rhinotracheitis is also known as Feline Herpes Virus (FHV-1). It causes severe respiratory infections in cats; particularly in kittens.
Feline Herpes Virus is a tricky little bug. Like all Herpes viruses, a patient is never free of the virus. They may recover from the illness but the virus is always present. Herpes virus is a latent virus. It hides in neutrophils and other blood cells and effectively evades the immune system. Once the cat is stressed from some exogenous cause, the virus leaves its hiding place and pounces on the cat causing a repeat of respiratory signs.
Feline Herpes Virus is transmitted by direct contact from cat to cat by any nasal or eye secretion. Bedding and food bowls can be a source of contamination to susceptible cats. It is seen most commonly in places where there are large numbers of cats in close quarters such as shelters and catteries. Young kittens are at a higher risk since they just have an immature immune system. The tricky part in cat exposure is the carrier cat. Those cats have a latent infection. They are not clinically ill but can easily transmit the virus to a susceptible cat.
Clinical signs in cats are always respiratory. Intense sneezing, coughing, nasal discharges, runny eyes and infected conjunctiva are all part of the disease process. A severe head cold! Animals will be anorexic and, like most sick cats, will just sit in one place for hours with their heads held down.
Veterinarians will initially draw a CBC and Chemistry profile to check bodily functions. Being a virus, herpes cats will often have a drop in their white cell count (leukopenia). Swabs of the nasal secretions or conjunctive will be sent to the lab for culture and hence a definitive diagnosis. Chest films may be taken in case of severe respiratory infections.
Diagnosis of Feline Herpes Virus is made through a good history and physical exam. Many other viruses can mimic the FHV-1 virus. Conclusive diagnosis is made by culturing the virus in the lab.
There is no specific treatment for Feline Herpes Virus. Antibiotics are usually prescribed to prevent secondary bacterial infections. Nebulization therapy is also effective in clearing the respiratory tract of secretions making it easier for the cat to breathe. Topical ophthalmic antibiotics are usually prescribed to treat the bilateral conjunctivitis. L-Lysine (Viralys®) has been found to minimize the clinical signs associated with herpes virus by slowing down the intracellular replication of the herpes virus. L-Lysine is a nutritional supplement and comes in gel form for easy administration to the cat.
The prognosis for most Feline Herpes Virus patients is very good. Providing a stress free environment for the cat and high quality nutrition goes a long way in helping improve the life of the cat. It is a latent virus and can cause issues in the future.
Prevention is the key. Feline Viral Rhinotracheitis is one of the three diseases commonly vaccinated for in cats beginning at six weeks of age. No vaccine is perfect but this one is a good bet for all cats. The kitten needs to go through a complete series of shots than boostered once annually to maintain effective antibody levels to the disease.
Right sided heart failure is not as commonly seen as failure of the left side but is most commonly caused by heartworm disease in dogs.
The heart has two sides, the left and the right. The right side of the heart is responsible for the return flow of deoxygenated blood from the vena cava. It than passes through the right side of the heart than to the lungs for oxygenation of hemoglobin anew. When heartworms clog the right ventricle, the heart has to work harder and the mechanical presence of the worms causes a regurgitation of fluid in the lungs. This explains the clinical signs.
Clinical signs of right sided heart failure are: lethargy and breathing difficulty (dyspnea), swelling (edema) of the forelimbs or hindlimbs, an enlarged liver secondary to congestion plus the presence of fluid in the abdomen (ascites). Due to congestion, the jugular vein is usually distended and visible.
A CBC and Chemistry profile are drawn. An occult heartworm test is performed. The right sided heart failure can be visualized on regular radiographs or a cardiac ultrasound.
Diagnosis is made by historical findings plus clinical signs. A distended jugular vein plus murmurs over the tricuspid valve plus imaging techniques will confirm the diagnosis. A positive occult heartworm test will confirm the cause.
Treatment is geared towards treating the primary cause plus clinical signs of right sided heart failure. If the dog has heartworm, the animal is treated for that. Right sided heart failure is treated with diuretics (furosemide) to clear out the chest and make it easier for the dog to breath. Ace inhibitors such as benazepril ease the strain on the heart. Inotropic (positive contractile strength of the myocardium) agents such as Vetmedin® may be prescribed. Diuretics will usually take care of the limb swelling. If there is fluid in the abdomen, the majority of the time it has to be drained. Animals are sent home on appropriate medications and the animal is evaluated frequently with concurrent chest imaging.
Heartworm disease can be treated and the animal cured but the right sided heart failure is not curable. It can be controlled with medications and frequent visits to your veterinarian. Prognosis for long term survival is good as long as clinical signs are kept under control.
The best prevention is never getting right sided heart failure in the first place. All dogs should have an occult heartworm test performed, and if negative, the pet should be put on a monthly preventative for life.
Ringworm is actually not a worm! It is a misnomer in that ringworm is actually caused by a fungal organism known as Microsporum canis. This is the most common but can also be caused by Microsporum gypseum and Thrichophyton mentagrophytes. They fall under a general group called dermatomycosis. This fungus causes skin disease in dogs and cats and is highly transmissible to humans. It can also go from humans to pets.
The fungal organisms in question cause pathology at the level of the hair follicle where they live and reproduce. Ringworm is transmitted by direct contact between animals and human to animal and vice versa. Ringworm spores in the environment also serve as another source of infection even though lesions may have been successfully treated. Clinical signs arise from the lifestyle of the organism. Animals that are immunosuppressed from a pathological process or from a drug agent are more prone to develop fungal organisms. They are what is called opportunistic organisms.
Common clinical signs of ringworm are: white, circular areas of the skin are seen with alopecia (hairloss) within the circular lesion. The hair loss is not smooth but the hairs are brittle and appear "moth eaten". Scales, pustules and other debris may also characterize these lesions on the skin. They also may cause the animal to scratch at them.
The first order of business is a skin scraping to rule out parasitic mites such as Demodex canis and Sarcoptes sp. Another deep scraping is needed to culture the organism in a Fungassay® jar (with a color indicator dye) or sent to a lab for culture and microscopic diagnosis. A Wood's Lamp is always used in a dark room to shine on the lesions. Ringworm lesions will flouoresce a green color characteristic of the fungal organism.
Diagnosis is made on historical findings, clinical signs plus fungal culture results and a positive response to a Wood's Lamp.
If there are just a few lesions, a topical anti-fungal drug such as miconazole is prescribed. In case of general lesions oral drugs are used. Ketoconazole, Griseofulvin or itraconazole may be used in dogs only! When using these drugs, liver function tests have to be performed to prevent hepatic diseases secondary to drug therapy. Ringworm in cats is treated with lime sulfur dip. This is a malodorous product and gloves and proper ventilation must be provided. Cure can take months in some cases. Fungal cultures must be repeated frequently; until at least one of them is negative.
Prognosis is generally good but there are organisms that can be difficult to eradicate due to drug resistance. Drugs than get switched and cultures are taken to insure effectivity. Ringworm can be difficult to eradicate in animals with a compromised immune system.
The problem for home owners is that the home is going to be full of ringworm spores for a long time to come. Coming in contact with dog hair or a dog being treated for ringworm can transmit the disease to people; particularly young children. Dogs remain infective for about 4 weeks after treatment begins. Many of the lesions I saw on people in my office were on their forearms. They carried their pet in their arms exposing themselves to the fungal organism. In people, if reddened, scaly small lesions are seen anywhere on the body in a home with a pet diagnosed with ringworm seek immediate medical care for your family member.
Vacuuming the home frequently and keeping an animal confined to easily cleaned areas of the home keeps spore levels down. Dilute chlorox may also be used on tile floors or others than can be disinfected with it.