Common Diseases in Guinea Pigs
By Dr. Laurie Hess, DVM, Diplomate ABVP (Avian Practice)
Guinea pigs are easy to care for and, if handled frequently and carefully, make great family pets. They are generally hardy animals but are susceptible to certain diseases. Some of the more common problems guinea pigs develop include respiratory infections, diarrhea, scurvy (vitamin C deficiency), tumors, abscesses due to infection, urinary problems, skin parasites, ringworm (skin fungus), and foot sores (pododermatitis). Guinea pig pet parents should be aware of the signs associated with these common problems so that they can seek veterinary care for their pets if these signs arise.
Pneumonia occurs commonly in young guinea pigs whose immune systems are not yet fully developed and can be caused by several bacteria, including Bordetella and Streptococcus. Guinea pigs can naturally carry these bacteria in their respiratory tracts and may be asymptomatic (apparently healthy) carriers of these organisms. These bacteria are called opportunistic bacteria in that that they can cause infection when asymptomatic carriers become stressed or ill with other diseases. Stress includes moving to a new home, poor nutrition, living in an overcrowded habitat with too many other animals, or exposure to poorly ventilated conditions (such as from dirty, urine-soaked habitat bedding). Pneumonia-causing bacteria are spread from animal to animal by direct contact, through the air, and on contaminated hands or other objects. Guinea pigs should never be housed with rabbits or other pets, as these other animals may also be asymptomatic carriers of disease that can be transmitted to guinea pigs to cause illness. Guinea pigs infected with pneumonia may have decreased appetites, discharge from their eyes or nose, sneezing, or trouble breathing. Guinea pigs with difficulty breathing should be seen by a veterinarian as soon as possible. The veterinarian can take a sample of discharge for culture to identify the causative organism so that appropriate antibiotics can be prescribed. Very weak, dehydrated guinea pigs with severe respiratory problems may need to be hospitalized for additional supportive care.
Guinea pigs are herbivores (plant eaters) that rely on a normal population of bacteria in their gastrointestinal (GI) tracts to digest their food. These bacteria require high-fiber to function properly; thus, high-fiber hay should be the mainstay of a guinea pig’s diet with some fresh vegetables and a smaller amount of commercially available pelleted food enriched with vitamin C. Guinea pigs love to eat pellets, as they contain a lot of carbohydrates and are tasty. However, too much carbohydrate can upset their normal population of GI bacteria, resulting in an increase in gas-producing bacteria that generate large amounts of GI gas. Excess GI gas makes guinea pigs uncomfortable and often decreases their appetite. When guinea pigs ingest less, the passage of food through the GI tract slows down resulting in a potentially life-threatening illness called GI stasis or ileus. With GI stasis, there is no actual physical obstruction blocking passage of food through the GI tract but rather a slowing down of food movement due to decreased intestinal contractions and gas build-up. Guinea pigs with GI stasis eat and drink less and pass less feces. Other causes of GI stasis in guinea pigs beside excess carbohydrate ingestion include dental disease, stress, or any other illness that leads to decreased appetite. Guinea pigs showing signs of GI stasis should be seen by a veterinarian right away to receive pain medication, fluids injected under their skin, and syringe-feeding with specially formulated liquid diets to help re-start movement of food through their GI tracts.
In addition to GI stasis, when the normal healthy population of GI bacteria are upset, guinea pigs can develop diarrhea. Unhealthy, gas-producing bacteria overgrow in the GI tract and release toxins that can cause diarrhea and death in severe cases. In addition to bacterial infections, some intestinal parasites, such as cryptosporidia and coccidia, can cause diarrhea in guinea pigs. Other signs that may occur with diarrhea in guinea pigs include decreased appetite, lethargy, weakness, dehydration, and low body temperature. Guinea pigs with these signs need immediate veterinary treatments including fluids under the skin and medications such as antibiotics and anti-parasitic drugs. As guinea pigs can only tolerate certain antibiotics, these drugs should only be prescribed by a veterinarian familiar with guinea pig care and never purchased over-the-counter in a store.
Scurvy (Vitamin C Deficiency)
Like people and other primates, guinea pigs cannot make vitamin C in their bodies and rely on ingested vitamin C to stay healthy. Vitamin C is crucial to the normal development and maintenance of skin, joints, and mucosal surfaces like gums. It is also essential to wound healing and proper immune system function. Without adequate vitamin C, guinea pigs develop skin problems, difficulty healing wounds, and are more likely to develop other infections. Signs of vitamin C deficiency in guinea pigs include rough hair coat, decreased appetite, diarrhea, reluctance to move, swollen painful joints, and hemorrhages and ulcers on the gums. Guinea pigs need 10-50 mg of vitamin C per day, depending on their age and overall health. Vitamin C is found in green and red vegetables (such as bell peppers) and is typically added to commercially available guinea pig pellets and treats. However, it is relatively unstable in food and breaks down quickly. Therefore, most veterinarians recommend that guinea pigs receive a daily vitamin C supplement as a liquid or pill given by mouth. Vitamin C supplements should not be administered in the drinking water, as they break down rapidly in water and lose potency.
Like other animals, guinea pigs can develop tumors anywhere in their bodies, but skin tumors and mammary (breast) tumors are most common. Guinea pigs with growths of any kind should be examined by a veterinarian who can aspirate (take a sample with a needle) of the mass to determine its origin and whether surgical removal is indicated. In most cases, surgery is curative.
Abscesses (pockets of infection within a body tissue containing accumulations of pus) can develop within skin, lymph nodes, muscles, and bone. Guinea pigs with dental problems often develop abscesses within their mouths and jaws secondary to infected teeth that can become large and painful. Abscesses are typically treated with antibiotics (based on culturing the pus within them), pain relievers, and surgical removal. Some abscesses (such as those involving the jaw and teeth) are more challenging to treat, because they are very difficult to remove surgically. Abscesses that are incompletely removed commonly recur and can spread bacteria through the bloodstream to other areas of the body.
Urinary Tract Problems
Guinea pigs are very prone to developing urinary tract stones (also called calculi). These stones most often form in the bladder, but some may form in the kidney or become lodged in the ureter (the tube draining urine from the kidney to the bladder) or the urethra (the tube carrying urine from the bladder to the outside), causing a life-threatening urinary tract obstruction. Guinea pigs with bladder stones often show decreased appetite, bloody urine, straining to urinate, and a hunched posture (due to straining). If obstruction occurs, the guinea pig will be unable to pass any urine and will ultimately die if left untreated. Guinea pigs with bloody urine or straining to urinate should be seen by a veterinarian immediately. The veterinarian may be able to feel the bladder stone(s) when palpating the guinea pig’s abdomen and will usually be able to see them with the help of x-rays and abdominal ultrasound. Unlike dogs and cats, guinea pigs do not typically develop bladder infections with bacteria, as the pH of their urine is very high (from ingesting a high-fiber diet), and bacteria do not typically grow at such a high pH. Very sick, painful guinea pigs with bladder stones may require hospitalization for supportive care (such as fluids and pain relievers), as well as surgery to remove the stones once the guinea pig’s condition has stabilized. Even with complete surgical removal of bladder stones, guinea pigs frequently redevelop these stones, sometimes within weeks after surgery. Long-term prognosis for recurrent stone formers is poor.
Reproductive Tract Disease
While not as common as in rabbits, reproductive tract disease does occur in guinea pigs. Guinea pigs can develop tumors in their ovaries and uterus, as well as infection, particularly if they are mated with males. Female and male guinea pigs must be separated within days after birth, or brothers and sisters will start mating within weeks. To prevent this, males should be neutered after if they are to be housed with females. Females with uterine infections or tumors may show bloody, pus-like discharge from their vulvas, while females with cystic (fluid-filled) tumors (common in guinea pigs) may have no signs or simply hair loss due to the effects of hormones produced by the ovarian tumor. One or both ovaries may be affected. Treatment for both uterine infections and tumors and for ovarian tumors involves surgical removal of the ovaries and uterus (a “spay” or ovariohysterectomy). Surgery can be curative if disease is caught early. In general, since guinea pigs are often at increased risk of dying under anesthesia due to their prey-like nature, spaying to prevent reproductive disease in female guinea pigs is not typically recommended.
Ringworm (Skin Fungus)
Guinea pigs (especially young ones) are prone to ringworm, which is a fungus, not a parasite. Animals with fur, including guinea pigs, rabbits, cats, and dogs, may carry this fungus on their coats without showing any signs of illness. The fungus forms microscopic spores that are carried on the fur and that can persist literally for years in the environment. Infected, asymptomatic animals can spread the disease to susceptible animals or develop disease themselves if they become stressed by overcrowding, poor nutrition, a new environment, or other illnesses. Young, stressed animals are at increased risk of infection due to their underdeveloped immune systems. Skin affected by ringworm typically becomes dry, flaky, hairless, sometimes crusted with scabs, and may sometimes be itchy. Ringworm lesions are found most commonly around the face, head, and ears, but may spread to the back and legs. Ringworm is contagious to people, and affected animals should be handled carefully, ideally with disposable gloves. After proper diagnosis by a veterinarian, lesions are treated topically and/or orally with anti-fungal medications. The habitat, bedding, toys, and food bowls of affected animals must be completely disinfected, or reinfection of an animal may occur.
Skin Parasites (Ectoparasites)
Like other pets, guinea pigs can get fleas, lice, and mites, all of which can cause itchy skin and hair loss. Fleas are typically diagnosed by seeing the adults or their feces on the skin or in the fur; lice and mites are often diagnosed microscopically by observing either the adults or eggs (nits) on hair and skin debris. Lice eggs are laid on the hair shafts, often around the face, behind the ears, or between the shoulders. Some guinea pig mites can cause such intense itching as to cause seizures. With a mite infestation, the skin is typically crusty, scabbed, and red from scratching. Sometimes guinea pigs with skin parasites develop secondary bacterial skin infections from scratching. Fleas that affect guinea pigs can also affect other pets and people. Lice are typically species-specific, and some mites that affect guinea pigs can also affect people and other animals. Guinea pigs with hair loss, itchiness, scabs, or red skin should be examined by a veterinarian so that the specific cause may be identified and the appropriate anti-parasitic medication can be prescribed. Secondary skin bacterial infections typically require treatment with antibiotics, as well. The affected pet’s environment must be thoroughly cleaned, too, to prevent reinfection of the pet.
Other Skin Diseases
When guinea pigs are bored or live in overcrowded conditions, they may chew on their own hair or on the hair of their habitat-mates. Such chewing is referred to as barbering, and when it is severe, it can make the guinea pig look like it has a "brush cut." Treatment involves providing the guinea pig with more stimulation, such as more time out of its habitat with its pet parents and redirecting chewing behavior to more appropriate objects such as hay or chew toys. If barbering was done by another guinea pig, the guinea pigs may need to be separated. Guinea pigs often also develop sores on the bottoms of their feet (referred to as pododermatitis or bumblefoot). This condition occurs most commonly in overweight animals housed on wire-bottomed habitats that cause pressure on the feet soles. Pododermatitis also occurs in animals housed on filthy habitat floors that abrade the soles, leading to chronic, deep infections that causes lameness and pain, especially when they affect underlying muscles, tendons, and bones. Pododermatitis typically requires veterinary treatment with antibiotics, anti-inflammatory medications, foot bandaging, and surgical debridement if lesions are severe. Overweight animals with pododermatitis need to lose weight, and dirty environments need to be cleaned up. Treatment may be challenging and is often long-term.
The best way to eliminate disease in pet guinea pigs is to have them checked annually by a guinea pig-savvy veterinarian. Ensuring that they are eating, drinking, active, and passing normal stool also helps. Any guinea pig with decreased activity, appetite, or stool production should be examined by a veterinarian as soon as possible. With proper preventative medical care and monitoring for unusual signs or behavior, guinea pigs can live long, healthy lives.